front 1 What 2 repeating disaccharide units constitute peptidoglycan? | back 1 1. N-acetylglucosamine (NAG) |
front 2 Peptidoglycan synthesis begins in the bacterial cytoplasm. Which molecule is first made as a sugar-building block? ____-____ | back 2 UDP-NAM |
front 3 What is the purpose of attaching NAM to UDP? To activate _____ for later _____ _____ synthesis | back 3 NAM cell wall |
front 4 Which lipid carrier helps move peptidoglycan building blocks across the bacterial cytoplasmic membrane? A. Cholesterol | back 4 C. Bactoprenol |
front 5 UDP-NAM attaches to bactoprenol through what type of linkage? A. Peptide bond | back 5 D. Pyrophosphate linkage |
front 6 When UDP-NAM attaches to bactoprenol, which molecule is released? _____ | back 6 UMP |
front 7 After NAM attaches to bactoprenol, what happens next? The unit is moved across the ____ | back 7 The unit is moved across the membrane |
front 8 Which enzyme moves the bactoprenol-linked peptidoglycan precursor to the outside surface of the membrane? _____ | back 8 Flippase |
front 9 Where is the NAG-NAM disaccharide added to the growing peptidoglycan chain? A. Inside the nucleus | back 9 C. Outside the plasma membrane |
front 10 Which sequence best summarizes peptidoglycan synthesis? A. Cross-link peptides → make UDP-NAM → flip bactoprenol
→ attach NAG-NAM | back 10 B. Make UDP-NAM → attach to bactoprenol → flip outside → add to peptidoglycan |
front 11 Transpeptidation in peptidoglycan synthesis mainly refers to what process? A. Sugar activation | back 11 B. Peptide cross-linking |
front 12 The transpeptidation reaction forms a bond between peptide side chains attached to which sugar? _____ | back 12 NAM |
front 13 The free amine used in transpeptidation is usually located on which position of the pentapeptide? _____ | back 13 3rd |
front 14 In many Gram-positive bacteria, the 3rd-position amino acid involved in cross-linking is commonly ______. | back 14 Lysine |
front 15 The 3rd-position amino acid cross-links to which residue on a neighboring chain? A. 1st-position alanine | back 15 C. 4th-position D-alanine |
front 16 What happens to the terminal D-alanine during transpeptidation? A. It becomes NAG | back 16 B. It is released |
front 17 Which enzyme performs the transpeptidation reaction? | back 17 Transpeptidase |
front 18 Penicillin-binding proteins are important because they normally function as _____. | back 18 Transpeptidases |
front 19 Beta-lactam antibiotics inhibit bacterial growth mainly by blocking: A. NAM production | back 19 C. Peptidoglycan cross-linking |
front 20 Lipoteichoic and teichoic acids are assembled from activated building blocks on the _____ and then translocated to the outer surface | back 20 bactoprenol |
front 21 Which organism is the most likely cause of hemorrhagic colitis? A. Enterotoxigenic Escherichia coli | back 21 B. Escherichia coli O157:H7 |
front 22 Which constituent of the Gram-positive bacterial cell wall is responsible for sequestration of Ca²⁺ ions? ____ ____ | back 22 Teichoic acid |
front 23 Unlike most Gram-negative bacteria, Neisseria species contain which endotoxin in their outer membrane? _______ (____ ) | back 23 Lipooligosaccharide (LOS) |
front 24 A light microscope has a resolution of ____ μm | back 24 0.2 μm |
front 25 The diameter of a red blood cell is ____ μm | back 25 7 |
front 26 Where does ATP production occur in prokaryotes? ____ | back 26 cytoplasm |
front 27 What bacteria cannot be classified by Gram staining? ____ ____ | back 27 Mycobacteria Mycoplasma |
front 28 Where are bacterial chromosomes present in the cell? ____ | back 28 nucleoid |
front 29 The prokaryotic ribosome consists of _____ and _____ subunits, forming a _____ ribosome | back 29 30S, 50S 70S |
front 30 The eukaryotic ribosome consists of _____ and _____ subunits, forming a _____ ribosome | back 30 40S, 60S 80S |
front 31 What is the difference between cytoplasmic membranes of eukaryotes and prokaryotes? Eukaryotes- _____ _____ | back 31 Eukaryotes- contain sterols |
front 32 Mycoplasma contains no _____ | back 32 peptidoglycan |
front 33 Peptidoglycan can be degraded by _____ | back 33 lysozyme |
front 34 lysozyme is found in human _____ and _____. lysozyme cleaves _____ backbone of peptidoglycan | back 34 tears and mucus glycan |
front 35 Lysozyme is able to cleave the ____-1,4 ____ linkage in peptidoglycan | back 35 β-1,4 glycosidic |
front 36 The presence of peptidoglycan in the cell well protects bacteria from damage against ____ ____. | back 36 osmotic pressure |
front 37 Disruption of the _____ _____ can provide entry of lysozyme to produce _____, which, like protoplasts, are osmotically sensitive. | back 37 outer membrane spheroplasts |
front 38 Removal of a cell wall produces a _____ that _____ unless it is osmotically stabilized | back 38 protoplast lyses |
front 39 What is the periplasmic space in gram negative baceteria? space between the: | back 39 1. Cytoplasmic membrane |
front 40 What is the function of the periplasmic space? 1. Contains components of transport systems for ______
and ______ | back 40 1. Contains components of transport systems for iron and
sugars |
front 41 What genus causes rabbit/deer fever, AKA tularemia? _____ | back 41 Francisella |
front 42 Lipoteichoic acid is only present in gram-______ bacteria. Lipoteichoic acid is anchored in the ______ ______ and extend towards the exterior | back 42 gram-positive cytoplasmic membrane |
front 43 In bacteria, immediately external to the cytoplasmic membrane is _______. | back 43 peptidoglycan |
front 44 The Shwartzman reaction is the event that occurs in disseminated _____ coagulation when there is a release of a large amount of _____. | back 44 intravascular endotoxin |
front 45 What protein restricts the entry of large and hydrophobic molecules across the outer membrane? _____ | back 45 porin |
front 46 The outer membrane is connected to the _____ _____ at adhesion sites and is tied to the _____ by _____. | back 46 The outer membrane is connected to the cytoplasmic membrane at adhesion sites and is tied to the peptidoglycan by lipoprotein |
front 47 Disruption of the outer membrane can provide entry of _____ to produce _____ | back 47 lysozyme spheroplasts |
front 48 The capsule and slime layer of the cell are both usually made up of _____ | back 48 polysaccharides |
front 49 Bacillus anthracis produces a _____ capsule | back 49 polypeptide |
front 50 _____ _____ will produce a polysaccharide biofilm when sufficient numbers are present. When sufficient numbers are present, this is referred to as a _____. | back 50 Pseudomonas aeruginosa will produce a polysaccharide biofilm when sufficient numbers are present. When sufficient numbers are present, this is referred to as a quorum |
front 51 A _____ is a sticky protective layer that helps bacteria attach to surfaces and resist antibiotics, immune cells, and disinfectants. | back 51 biofilm |
front 52 _____ _____ forms a _____ and _____ biofilm which promotes adhesion to tooth enamel and forms tooth-like plaque | back 52 Streptococcus mutans dextran levan |
front 53 What determines if a bacteria swims or tumbles when trying to find a chemoattractant? ____ of ____ spinning | back 53 direction of flagellar spinning |
front 54 What is the role of fimbriae? promote adherence of _____ to _____ _____ | back 54 bacteria cell surface |
front 55 What are the 3 constituents of LPS? 1. ____ ____ (responsible for ____ activity) | back 55 1. Lipid A (responsible for endotoxin activity) |
front 56 During cell division, the production of 2 daughter bacteria requires growth and extension of the cell wall components followed by the production of a ____ to divide the 2 cells. For streptococci, the growth zone is located ____o from each other and for staphylococci, the growth zone is located ____o from each other | back 56 septum 180 90 |
front 57 The outer coat of a spore contains the protein _____ | back 57 keratin |
front 58 How do spores form? depletion of specific ______ (______) from the ______ medium | back 58 depletion of specific nutrients (alanine) from the growth medium |
front 59 What makes the mycobacterial cell wall unusually waxy and acid-fast? A. Teichoic acid | back 59 B. Mycolic acid |
front 60 In mycobacteria, peptidoglycan is covalently attached to which polymer? A. Arabinogalactan | back 60 A. Arabinogalactan |
front 61 Bacitracin inhibits peptidoglycan synthesis by blocking recycling of: A. D-Ala-D-Ala | back 61 C. Phosphobactoprenol |
front 62 Penicillin acts as a structural analog of which peptidoglycan component? A. NAG-NAM | back 62 B. D-Ala-D-Ala |
front 63 Why does transpeptidase bind penicillin? A. Penicillin resembles D-Ala-D-Ala | back 63 A. Penicillin resembles D-Ala-D-Ala |
front 64 What happens after transpeptidase binds penicillin? A. Peptidoglycan cross-linking increases | back 64 B. Transpeptidase is inactivated |
front 65 The core region of LPS contains which phosphorylated sugar? A. D-alanine | back 65 C. 2-keto-3-deoxy-octanoate |
front 66 Why are Neisseria species more susceptible to host-mediated complement lysis? They lack the ___-antigen portion of ___ | back 66 They lack the O-antigen portion of LPS |
front 67 In Neisseria, lack of O antigen allows LOS aggregates to be shed, which reduces: A. Ribosomal protection | back 67 B. Complement protection |
front 68 What can stimulate germination of a bacterial spore into the vegetative state? ______ of the outer ______-like protein coat | back 68 Disruption of the outer keratin-like protein coat |
front 69 ______ stress or ______ changes can trigger spore germination. | back 69 Mechanical pH |
front 70 About how long does spore germination take? A. 5 minutes | back 70 C. 90 minutes |
front 71 A bacterium has a structure that can be targeted by both the immune system and antibiotics. Which structure is being described? ____ ____ | back 71 Cell wall |
front 72 Gram-positive bacteria have a much thicker cell wall due to increased amounts of what? A. Lipopolysaccharide B. Peptidoglycan C. Sterols D. Mycolic acid | back 72 B. Peptidoglycan |
front 73 Which structure is present in gram-positive bacterial cell walls? A. Lipopolysaccharide B. Lipoteichoic acid C. Outer membrane D. Sterols | back 73 B. Lipoteichoic acid |
front 74 Which bacterium does not Gram stain because it lacks a cell wall? A. Mycoplasma B. Mycobacteria C. Bacillus D. Neisseria | back 74 A. Mycoplasma |
front 75 Mycoplasma lacks a cell wall but maintains membrane stability using what? A. Mycolic acids B. Lipopolysaccharide C. Sterols D. Teichoic acids | back 75 C. Sterols |
front 76 Which bacteria have cell walls containing mycolic acid? A. Mycobacteria B. Mycoplasma C. Neisseria D. Streptococcus | back 76 A. Mycobacteria |
front 77 Mycobacteria are best visualized using which special stain? A. Gram stain B. Capsule stain C. Ziehl-Neelsen acid-fast stain D. India ink stain | back 77 C. Ziehl-Neelsen acid-fast stain |
front 78 Why do mycobacteria require an acid-fast stain instead of a standard Gram stain? A. They lack ribosomes B. Their cell walls contain mycolic acid C. They contain endotoxin D. They have no cell membrane | back 78 B. Their cell walls contain mycolic acid |
front 79 Mycobacteria include organisms that cause which diseases? A. Syphilis and Lyme disease B. Cholera and plague C. Botulism and tetanus D. Tuberculosis and leprosy | back 79 D. Tuberculosis and leprosy |
front 80 Electron transport and oxidative phosphorylation occur on which bacterial structure? | back 80 Cell membrane |
front 81 Gram-negative bacteria can resist some antibiotics because enzymes are located in which space? ______ | back 81 Periplasm |
front 82 β-lactamase in the periplasm of gram-negative bacteria helps resist which type of treatment? A. Antiviral therapy B. Antifungal therapy C. β-lactam antibiotic therapy D. Antiprotozoal therapy | back 82 C. β-lactam antibiotic therapy |
front 83 Which molecule on the surface of gram-negative bacteria drives a strong immune response? A. Lipopolysaccharide B. Sterol C. Teichoic acid D. Peptidoglycan | back 83 A. Lipopolysaccharide |
front 84 Lipopolysaccharide is found on which structure? A. Gram-positive cell wall B. Mycoplasma membrane C. Outer membrane of gram-negative bacteria D. Cytoplasmic membrane of gram-negative bacteria | back 84 C. Outer membrane of gram-negative bacteria |
front 85 Which part of lipopolysaccharide is a major antibody target? A. O antigen B. Lipid A C. Core polysaccharide D. Peptidoglycan | back 85 A. O antigen |
front 86 IgG antibodies bind bacterial capsules and promote phagocytosis through which receptor interaction? A. T-cell receptors B. Fc receptors C. B-cell receptors D. Sterol receptors | back 86 B. Fc receptors |
front 87 IgG binding to a bacterial capsule can also promote which immune pathway? A. Histamine release B. Complement binding C. Viral budding D. Fungal dimorphism | back 87 B. Complement binding |
front 88 Lack of B cells, antibodies, or complement increases susceptibility to which type of bacterial infection? A. Encapsulated bacterial infections B. Intracellular viral infections C. Dimorphic fungal infections D. Spirochetal infections | back 88 A. Encapsulated bacterial infections |
front 89 Asplenia increases the risk of sepsis from which type of bacteria? A. Acid-fast bacteria B. Anaerobic bacteria C. Intracellular bacteria D. Encapsulated bacteria | back 89 D. Encapsulated bacteria |
front 90 Why does asplenia increase susceptibility to encapsulated bacteria? A. Loss of thymic selection B. Loss of neutrophil oxidative burst C. Loss of splenic phagocytes D. Loss of T-cell receptors | back 90 C. Loss of splenic phagocytes |
front 91 Which set contains classic encapsulated organisms remembered by SHiNS? A. Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Salmonella B. Staphylococcus aureus, Helicobacter pylori, Neisseria gonorrhoeae, Shigella C. Streptococcus pyogenes, Histoplasma, Nocardia, Salmonella D. Shigella, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus epidermidis | back 91 A. Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Salmonella |
front 92 Bacterial capsular polysaccharides are the basis for many what? A. Gram stains B. Acid-fast stains C. Antibiotic resistance genes D. Vaccines | back 92 D. Vaccines |
front 93 Which organisms are commonly targeted by polysaccharide capsule-based vaccines? A. Staphylococcus aureus, Helicobacter pylori, Neisseria gonorrhoeae B. Shigella, Salmonella, Bacillus anthracis C. Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis D. Mycoplasma, Mycobacteria, Trichophyton | back 93 C. Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis |
front 94 A bacterium has an irregular, fuzzy outer layer. Which structure is being described? ______ | back 94 Glycocalyx |
front 95 A bacterium has a distinct, firmly attached gelatinous layer. Which structure is being described? ______ | back 95 Capsule |
front 96 Pili or fimbriae in E. coli help cause which infections? A. Meningitis and encephalitis B. Pneumonia and endocarditis C. Syphilis and Lyme disease D. UTIs and pyelonephritis | back 96 D. UTIs and pyelonephritis |
front 97 Small DNA elements within bacteria that replicate independently are called _____. | back 97 Plasmids |
front 98 Which bacterial DNA element can carry genes for antibiotic resistance or toxins? A. Plasmid B. Flagellum C. Capsule D. Lipopolysaccharide | back 98 A. Plasmid |
front 99 Why are plasmids clinically important? They can transfer _____ _____ between bacteria | back 99 They can transfer survival genes between bacteria |
front 100 Some bacteria can enter a dormant survival state called what? | back 100 Spore |
front 101 What is true of bacteria in spore form? A. They are metabolically hyperactive B. They immediately divide C. They replicate viruses D. They can survive long periods in extreme conditions | back 101 D. They can survive long periods in extreme conditions |
front 102 Which conditions can bacterial _____ survive? Lack of nutrients, dehydration, heat, and chemicals | back 102 spores |
front 103 The middle layer, or cortex, of a bacterial spore is made of what? A. Mycolic acid B. Lipopolysaccharide C. Peptidoglycan D. Sterols | back 103 C. Peptidoglycan |
front 104 The core of a bacterial spore contains _____, _____, and _____ enzymes | back 104 DNA, ribosomes, glycolytic |
front 105 Which genera are known as spore-forming bacteria? ____ and ____ | back 105 Bacillus and Clostridium |
front 106 Spore-forming Bacillus and Clostridium are usually classified as what? gram-____ bacteria | back 106 Gram-positive bacteria |
front 107 What substance is present in the core of a bacterial spore? _____ bound to dipicolinic acid | back 107 Ca2+ bound to dipicolinic acid |
front 108 Which bacteria have branched filamentous appearances? A. Neisseria and Streptococcus pneumoniae B. Bacillus and Clostridium C. Nocardia and Actinomyces D. Staphylococcus and E. coli | back 108 C. Nocardia and Actinomyces |
front 109 Which bacteria are classically diplococci? A. Streptococcus pneumoniae and Neisseria B. Nocardia and Actinomyces C. Bacillus and Clostridium D. E. coli and Salmonella | back 109 A. Streptococcus pneumoniae and Neisseria |
front 110 Which bacterium classically forms chains? A. Staphylococcus aureus B. Neisseria meningitidis C. Bacillus anthracis D. Streptococcus pyogenes | back 110 D. Streptococcus pyogenes |
front 111 A spherical bacterium is called what? A. Bacillus B. Coccus C. Spirillum D. Spore | back 111 B. Coccus |
front 112 A rod-shaped bacterium is called what? A. Coccus B. Spirillum C. Bacillus D. Diplococcus | back 112 C. Bacillus |
front 113 A snakelike bacterium is called what? A. Spirillum B. Coccus C. Bacillus D. Spore | back 113 A. Spirillum |
front 114 In the gram-negative outer membrane, what makes up the outer leaflet? _____ | back 114 Endotoxin |
front 115 In the gram-negative outer membrane, what makes up the inner leaflet? _____ | back 115 Phospholipids |
front 116 Which ions help hold the gram-negative outer membrane together by linking phosphates on LPS? ______ and ______ | back 116 Mg2+ and Ca2+ |
front 117 Which interaction helps stabilize the gram-negative outer membrane? ______ interactions between ______ and ______ | back 117 Hydrophobic interactions between LPS and proteins |
front 118 During Gram staining, which stain is applied first? _____ _____ | back 118 Crystal violet |
front 119 During Gram staining, crystal violet is precipitated with which substance? _____ | back 119 Iodine |
front 120 During Gram staining, unbound and excess stain is removed using what? ______-based decolorizer and ______ | back 120 Acetone-based decolorizer and water |
front 121 Serotyping bacteria involves distinguishing bacteria using antibodies against what? A. Ribosomal subunits B. Characteristic antigens C. Mitochondrial proteins D. Host cytokines | back 121 B. Characteristic antigens |
front 122 What is the purpose of safranin in Gram staining? A. To stain decolorized cells red B. To precipitate crystal violet C. To dissolve mycolic acid D. To form spores | back 122 A. To stain decolorized cells red |
front 123 Which process uses antibodies to detect characteristic bacterial antigens? A. Gram staining B. Acid-fast staining C. Serotyping D. Spore staining | back 123 C. Serotyping |
front 124 Which organisms do not contain a peptidoglycan cell wall? A. Bacillus and Clostridium B. Streptococcus and Neisseria C. Staphylococcus and E. coli D. Archaea and mycoplasms | back 124 D. Archaea and mycoplasms |
front 125 Teichoic acids in gram-positive bacteria are what type of molecules? A. Neutral lipid droplets B. Water-soluble anionic polymers of polyol phosphates C. Sterol-rich membrane anchors D. Protein toxins | back 125 B. Water-soluble anionic polymers of polyol phosphates |
front 126 Teichoic acids are covalently linked to which bacterial structure? _____ | back 126 Peptidoglycan |
front 127 Why are teichoic acids important in gram-positive bacteria? They are essential to _____ viability | back 127 They are essential to cell viability |
front 128 Which gram-positive cell wall component is linked to innate immune activation? A. O antigen B. Lipoteichoic acid C. Sterol D. Plasmid | back 128 B. Lipoteichoic acid |
front 129 Which bacterial structure is most associated with antibiotic resistance gene transfer? _____ | back 129 Plasmid |
front 130 Which structure allows bacteria to survive extreme conditions with little to no metabolic activity? _____ | back 130 Spore |
front 131 Do gram-negative bacterial cell walls contain teichoic or lipoteichoic acids? A. Yes, both are present B. Only teichoic acid is present C. Only lipoteichoic acid is present D. No, neither is present | back 131 D. No, neither is present |
front 132 What is one major function of the gram-negative outer membrane? A. Production of ribosomes B. Formation of spores C. Storage of plasmids D. Permeable barrier | back 132 D. Permeable barrier |
front 133 The outer leaflet of the gram-negative outer membrane contains which molecule A. Teichoic acid B. Lipopolysaccharide C. Sterols D. Mycolic acid | back 133 B. Lipopolysaccharide |
front 134 Lipopolysaccharide in gram-negative bacteria stimulates which host response? A. Innate immune response B. Somatic hypermutation C. T-cell receptor rearrangement D. Antibody class switching | back 134 A. Innate immune response |
front 135 A gram-negative bacterium triggers a strong innate immune response through LPS. Where is this LPS located? A. Inner leaflet of cytoplasmic membrane B. Peptidoglycan cortex C. Outer leaflet of outer membrane D. Bacterial chromosome | back 135 C. Outer leaflet of outer membrane |
front 136 Porins in the gram-negative outer membrane allow diffusion of which molecules? A. Hydrophobic molecules B. Large proteins only C. Steroid hormones only D. Hydrophilic molecules | back 136 D. Hydrophilic molecules |
front 137 A small _____ molecule crosses the gram-_____ outer membrane through porin. | back 137 A small hydrophilic molecule crosses the gram-negative outer membrane through porin. |
front 138 The bacterial flagellum is best described as what? A. An external structure used for movement B. A DNA element that carries resistance genes C. A polysaccharide layer used for immune evasion D. A membrane pore for hydrophilic molecules | back 138 A. An external structure used for movement |
front 139 A bacterium living in a biofilm becomes harder for antibiotics and immune cells to eliminate. What is the main advantage of the biofilm? A. Increased oxygen use B. Increased sporulation C. Protection D. Loss of virulence | back 139 C. Protection |
front 140 Which two polysaccharide components make up bacterial peptidoglycan? A. Glucose and fructose B. Ribose and deoxyribose C. N-acetylglucosamine and N-acetylmuramic acid D. Cellulose and glycogen | back 140 C. N-acetylglucosamine and N-acetylmuramic acid |
front 141 Transpeptidases and carboxypeptidases involved in peptidoglycan synthesis are targets of which antibiotics? A. Macrolides and a-lactam antibiotics B. Tetracyclines and a-lactam antibiotics C. Fluoroquinolones and β-lactam antibiotics D. Penicillins and β-lactam antibiotics | back 141 D. Penicillins and β-lactam antibiotics |
front 142 Penicillin and β-lactam antibiotics target enzymes involved in which process? Peptidoglycan ______ | back 142 Peptidoglycan synthesis |
front 143 A bacterium forms spores. It is most likely classified as which Gram stain type? | back 143 Gram-positive |
front 144 A bacterial spore contains how many peptidoglycan layers? | back 144 Two |
front 145 Which structure is part of a bacterial spore? A. Outer membrane with LPS B. Sterol-rich membrane only C. Inner membrane D. Teichoic acid layer | back 145 C. Inner membrane |
front 146 High concentrations of dipicolinic acid in bacterial spores help stabilize contents by binding what? A. Sodium B. Magnesium C. Potassium D. Calcium | back 146 D. Calcium |
front 147 Which spore component helps stabilize the spore contents by binding calcium? A. Peptidoglycan B. Dipicolinic acid C. Lipopolysaccharide D. Porin | back 147 B. Dipicolinic acid |
front 148 Which sequence best describes bacterial cell division? A. Cell wall growth and extension → septum formation → two daughter bacteria B. Septum formation → loss of cell wall → viral budding C. Spore coat formation → LPS release → two daughter bacteria D. Flagellar movement → capsule loss → chromosome deletion | back 148 A. Cell wall growth and extension → septum formation → two daughter bacteria |
front 149 ____ is so important that many bacteria secrete special proteins called ____ to concentrate ____ from dilute solutions | back 149 Iron siderophores iron |
front 150 What organism causes gas gangrene? ____ ____ | back 150 Clostridium Perfringes |
front 151 What are obligate anaerobes? organisms that ____ grow in the presence of ____ (____ ____) | back 151 cannot O2 Clostridium perfringens |
front 152 What are obligate aerobes? organisms that require ____ for metabolism and growth | back 152 O2 |
front 153 What are facultative anaerobes? 1. May use ____ as a terminal ____ ____ to generate ____ 2. Can also use ____ and other ____ -independent pathways | back 153 May use O2 as a terminal electron acceptor to generate ATP Can also use fermentation and other O2-independent pathways |
front 154 Aerobic bacteria produce the following 2 enzymes: 1. _____ _____ 2. _____ | back 154 1. Superoxide dismutase 2. Catalase |
front 155 What are autotrophs? _____ that can rely solely on _____ chemicals for their energy and source of carbon | back 155 bacteria inorganic |
front 156 What are heterotrophs? _____ and _____ cells that require _____ carbon sources | back 156 bacteria and animal cells that require organic carbon sources |
front 157 The _____ species can improve the function of the normal GI flora | back 157 Lactobacillus |
front 158 ______: small molecules are assembled into large ones using energy | back 158 Anabolism |
front 159 ______: substrate breakdown and conversion into usable energy | back 159 Catabolism |
front 160 ______ of the colon can select for and promote the growth of beneficial ______ -producing endogenous bacteria | back 160 Acidification lactate |
front 161 Electrochemical energy is stored by the _____ of _____ to _____ | back 161 reduction NAD NADH |
front 162 What enzyme drives the spinning of flagella and drives the conversion of ADP into ATP? | back 162 ATP synthase |
front 163 1. What is the most efficient way in which bacteria can produce energy from glucose? 2. What is the least efficient way in which bacteria can produce energy from glucose? | back 163 Aeorobic respiration Fermentation |
front 164 Fermentation results in the conversion of _____ into _____ and _____ | back 164 yeast ethanol CO2 |
front 165 Alcoholic fermentation uses the one-step conversion of _____ acid into _____ acid | back 165 pyruvic lactic |
front 166 What is the theoretical yield from each molecule of pyruvate in the TCA cycle? ____ NADH ____ FADH2 ____ CO2 ____ GTP | back 166 3 NADH 1 FADH2 2 CO2 1 GTP |
front 167 Acetyl CoA enters the TCA cycle by combining with _____ to form the molecule _____ | back 167 oxaloacetate citrate |
front 168 What is the most efficient mechanism for the generation of ATP? | back 168 TCA cycle |
front 169 Fermentation produces only _____ ATP molecules per glucose. Aerobic metabolism with ETC and a complete TCA cycle can generate as much as _____ ATP molecules from the same starting material | back 169 2 38 |
front 170 Deamination of glutamic acid yields _______ and deamination of aspartic acid yields _______ | back 170 a-ketoglutarate oxaloacetate |
front 171 The ETC resides in the ____ ____ of bacteria. It uses electrons obtained from ____ and ____ to produce a transmembrane proton electrochemical gradient that drives the ____ ____ and powers transport and flagella | back 171 plasma membrane NADH, FADH2 ATP synthase |
front 172 What is the function of the pentose phosphate pathway (HMP shunt)? 1. Provides _____ _____ precursors 2. Provides a source of _____ | back 172 nucleic acid NADPH |
front 173 The normal flora of our body process complex carbohydrates and releases _____-_____ _____ _____ as products of _____ | back 173 short-chain fatty acids fermentation |
front 174 The bacterial DNA-dependent RNA Polymerase is inhibited by _____ which is an antibiotic often used in the treatment of _____ | back 174 rifampin tuberculosis |
front 175 How does bacterial protein synthesis begin? binding of the: 1. ____ ribosomal subunit and the 2. Special initiator ____ for formyl methionine (____) at the ____ start codon to form the initiation complex | back 175 30s tRNA, f-met, AUG |
front 176 Increased cAMP levels indicate ____ ____ levels | back 176 low glucose |
front 177 The _____ sequence of the tRNA binds to the _____ sequence on the mRNA | back 177 anticodon codon |
front 178 The trigger for biofilm production by Pseudomonas spp. is triggered by a critical concentration of N-acyl homoserine lactone (_____) produced when sufficient numbers of bacteria are present. Activation of biofilm, toxin production, and more virulent behavior by Staphylococcus aureus accompanies the increase in concentration of a _____ _____. | back 178 AHL cyclic peptide |
front 179 What class of drugs are 30s ribosomal subunit inhibitors? 1. _____ (_____ and _____) 2. _____ | back 179 1. Aminoglycosides (streptomycin and gentamicin) 2. Tetracyclines |
front 180 What class of drugs are 50s ribosomal subunit inhibitors? 1. _____ 2. _____ (_____) 3. _____ (_____) 4. _____ | back 180 1. Chloramphenicol 2. Lincosamide (clindamycin) 3. Macrolides (erythromycin) 4. Linezolid |
front 181 _____ peptides are chemotactic and attract neutrophils to the site of infection | back 181 fmet |
front 182 What is the role of a repressor protein? binds to a specific ____ sequence within the ____, blocking ____ ____ from initiating ____ at the ____ sequence | back 182 binds to a specific DNA sequence within the operator, blocking RNA polymerase from initiating transcription at the promoter sequence |
front 183 In the lac operon, what occurs when there is an absence of lactose? repressor protein binds to the _____ sequence | back 183 operator |
front 184 In the lac operon, what occurs when there is an absence of glucose? 1. _____ binds to catabolite activator protein (CAP) 2. CAP-cAMP complex enhances binding of _____ _____ to the promoter = _____ _____ | back 184 1. CAMP binds to catabolite activator protein (CAP) 2. CAP-cAMP complex enhances binding of RNA polymerase to the promoter = increased transcription |
front 185 When are Salmonella pathogenicity islands turned on? 1. High _____ 2. Low _____ These conditions are present in the GI tract/endosomal vesicle within a macrophage | back 185 1. High osmolarity 2. Low O2 |
front 186 What can activate expression of hemolysin in E. coli or diphtheria toxin from Corynebacterium diphtheriae? low ____ levels | back 186 iron |
front 187 for lac operon No _____→ repressor bound → operon _____ | back 187 No allolactose → repressor bound → operon OFF |
front 188 In DNA synthesis, the _____ strand is synthesized _____ whereas the lagging strand is synthesized as many pieces of DNA using _____ _____ , creating _____ fragments | back 188 leading, continously RNA primers, Okazaki |
front 189 The lagging strand DNA must be extended in the ____' to ____' direction as its ____ becomes available. Then, DNA pieces are connected via the enzyme ____ ____ | back 189 5' to 3' template DNA ligase |
front 190 What is the role of DNA topoisomerase? creates ____ in the ____ to add or remove ____ in the ____ | back 190 creates breaks in the helix to add or remove supercoils in the DNA |
front 191 What class of drugs targets topoisomerases in prokaryotes _____ antibiotics | back 191 fluoroquinolone |
front 192 Depletion of metabolites or a buildup of toxic by-products triggers production of chemical ______ | back 192 alarmones |
front 193 When bacteria are added to a new medium, they require time to adapt to the new environment before they begin _____. This phase is known as the _____ _____ of growth. | back 193 dividing lag phase |
front 194 During the ____ ____ phase, the bacteria will grow and divide with a doubling time | back 194 log exponential |
front 195 1. What occurs in a transition base change? ___ to ___ or ___ to ___ 2. What occurs in a transversion base change? ___ to ___ or ___ to ___ | back 195 purine to purine or pyrimidine to pyrimidine purine to pyrimidine or pyrimidine to purine |
front 196 What are the 3 proteins in which the lac operon can be transcribed and translated into? _____- β galactosidase _____- permease _____- acetylase | back 196 LacZ LacY LacA |
front 197 An E. coli cell is exposed to a high intracellular concentration of tryptophan. During transcription of the trp operon leader region, the ribosome moves quickly through the leader peptide. Which RNA hairpin forms? A. Regions 1 and 2 | back 197 C. Regions 3 and 4 |
front 198 In the trp operon, formation of the 3–4 hairpin loop causes which outcome? A. Increased translation of tryptophan biosynthetic
enzymes | back 198 B. Premature termination of transcription |
front 199 An E. coli cell has low intracellular tryptophan levels. The ribosome stalls at the tryptophan codons in the leader peptide. Which hairpin forms, allowing transcription to continue? A. Regions 2 and 3 | back 199 A. Regions 2 and 3 |
front 200 What occurs in a silent mutation? a change at the ____ level that codes for the ____ amino acid | back 200 DNA same |
front 201 What occurs in a missense mutation? 1. Results in a _____ amino acid 2. Called a _____ mutation if _____ amino acid has similar chemical structure | back 201 new conserved, new |
front 202 What occurs in a nonsense mutation? results in an _____ _____ _____ | back 202 early stop codon |
front 203 A small deletion or insertion that is not in multiples of three produces a _____ mutation. This results in a change in the reading frame, usually leading to a useless _____ and premature truncation of the _____. | back 203 frameshift peptide, protein |
front 204 What occurs in a Null mutation? 1. Arise when there is an extensive insertion, deletion, or gross rearrangement of _____ structure 2. Completely destroys _____ function | back 204 chromosome gene |
front 205 Heat can induce mutations by causing ____ of ____ | back 205 deamination nucleotides |
front 206 DNA-reactive chemicals such as ____ ____ act directly on the DNA to change the chemical structure of the base | back 206 nitrous acid |
front 207 A researcher exposes bacterial DNA to 5-bromouracil (5-BrU). Which property of 5-BrU is primarily responsible for its mutagenic effect? It can base-pair with ____ instead of ____ | back 207 guanine adenine |
front 208 5-Bromouracil is classified as which type of mutagen? A. Alkylating agent | back 208 C. Nucleotide-base analog |
front 209 Ethidium bromide causes mutations primarily by which mechanism? _____ between stacked DNA bases | back 209 Inserts |
front 210 What occurs in base excision repair? | back 210 glycoslyase endonuclease Lyase Polymerase, ligase |
front 211 What occurs in recombinational/postreplication repair? replaces a damaged or missing section of DNA with the ____ or ____ sequences that may be present during replication | back 211 same or similar |
front 212 CRISPR/Cas9 is used to protect the bacterial chromosome against integration of ______ and ______ plasmids | back 212 bacteriophages foreign |
front 213 Borrelia burgdorferi possess _____ genomes and _____ . causative agent of _____ disease | back 213 linear, plasmids Lyme |
front 214 What are bacteriophages? bacterial viruses with a _____ or _____ genome usually protected by a _____ or _____ shell | back 214 DNA or RNA membrane, protein |
front 215 What are the 2 ways in which bacteriophages infect? 1. _____ infection- replicate in large numbers and cause the cell to lyse 2. _____ state- integrate into host cell without killing | back 215 Lytic Lysogenic |
front 216 The E. coli bacteriophage ______ remains in a ______ state as long as the repressor protein is synthesized and prevents the phage genome from being excised to replicate and exit the cell | back 216 lambda lysogenic |
front 217 What are transposons? a ____ sequence that can change its ____ within a genome | back 217 DNA position |
front 218 What occurs in transformation? bacteria take up fragments of naked _____ and _____ them into their own genomes | back 218 DNA incorporate |
front 219 The hepatitis B surface antigen is produced by ____ ____ | back 219 Saccharomyces cerevisiae |
front 220 An F⁺ E. coli cell conjugates with an F⁻ cell. Which structure allows the F⁺ cell to attach to the F⁻ cell? A. Flagellum | back 220 B. Sex pilus |
front 221 In standard F⁺ × F⁻ bacterial conjugation, what is transferred to the recipient cell? A. The entire donor chromosome | back 221 D. A single strand of F plasmid DNA |
front 222 Does standard F⁺ × F⁻ conjugation transfer chromosomal DNA? A. No, only plasmid DNA is transferred | back 222 A. No, only plasmid DNA is transferred |
front 223 After successful F⁺ × F⁻ conjugation, what usually happens to the recipient cell? A. It remains F⁻ because plasmids cannot replicate | back 223 C. It becomes F⁺ because it receives the F plasmid |
front 224 The F plasmid contains genes required for which major process? A. Antibiotic degradation | back 224 B. Sex pilus formation and conjugation |
front 225 A bacterium has its F plasmid integrated into the bacterial chromosome. What is this cell called? A. F⁻ cell | back 225 D. HFr cell |
front 226 In an HFr cell, where is the F factor located? A. Integrated into the bacterial chromosome | back 226 A. Integrated into the bacterial chromosome |
front 227 An HFr cell conjugates with an F⁻ cell. Which DNA is most likely transferred first? A. Random fragments of recipient DNA | back 227 C. The leading portion of the integrated F factor followed by nearby chromosomal genes |
front 228 In HFr × F⁻ conjugation, why does the recipient usually remain F⁻? A. The recipient destroys all incoming chromosomal
DNA | back 228 B. The entire F factor usually is not completely transferred |
front 229 Which outcome is most characteristic of HFr × F⁻ conjugation? A. The recipient becomes F⁺ and receives no chromosomal
genes | back 229 D. The recipient may integrate some donor chromosomal genes but usually remains F⁻ |
front 230 What occurs in generalized transduction? incorporation of ____ sequences into phages are random due to a ____ error | back 230 DNA packaging |
front 231 What occurs in specialized transduction? phages transfer _____ genes (not _____) | back 231 particular random |
front 232 Isolates of S. aureus acquired the _____ resistant gene during a mixed infection with _____ _____ | back 232 vancomycin Enterococcus faecalis |
front 233 _____ _____ recognize a specific palindromic sequence and make a staggered cut that generates sticky ends | back 233 Restriction enzymes |
front 234 A researcher adds a plasmid to competent bacteria so the bacteria will take up and replicate the DNA. Which bacterial genetics process is being used? A. Transduction B. Transformation C. Conjugation D. Translation | back 234 B. Transformation — bacteria take up free/exogenous DNA from the environment. |
front 235 A virus that infects bacteria is best described as which of the following? A. Plasmid B. Transposon C. Operon D. Bacteriophage | back 235 D. Bacteriophage — also called a phage. |
front 236 A bacteriophage accidentally carries bacterial DNA from one bacterium to another. What is this process called? A. Transduction B. Transformation C. Conjugation D. Replication | back 236 A. Transduction — DNA transfer between bacteria via a phage. |
front 237 A newborn’s gut microbiome is shaped by complex carbohydrates in breast milk. Which bacterium is selected for? A. Staphylococcus aureus B. Escherichia coli C. Enterococcus faecalis D. Bifidobacterium infantis | back 237 D. Bifidobacterium infantis — it is selected by breast milk carbohydrates. |
front 238 Skin bacteria catabolize keratin, oils, and dead cells in which outer skin layer? A. Stratum corneum B. Stratum basale C. Dermis D. Hypodermis | back 238 A. Stratum corneum — the outer layer containing dead keratinized cells. |
front 239 Which molecules help maintain the structure of the bacterial chromosome? A. Peptidoglycans B. Sterols C. Polyamines D. Porins | back 239 C. Polyamines — examples include spermine and spermidine. |
front 240 Prokaryotes can couple transcription and translation because they lack which structure? A. Cell wall B. Nuclear membrane C. Ribosome D. Plasma membrane | back 240 B. Nuclear membrane — mRNA can be translated while still being transcribed. |
front 241 Bacterial chromosomal replication begins at which specific sequence? | back 241 oriC — the origin of chromosomal replication. |
front 242 A bacterium exposed to UV light develops covalent links between adjacent pyrimidines. What caused this mutation? A. Pyrimidine dimer formation B. Base deamination C. Transposon insertion D. Plasmid loss | back 242 A. Pyrimidine dimer formation — UV exposure causes thymine/pyrimidine dimers. |
front 243 A patient with xeroderma pigmentosum has impaired repair of UV-induced pyrimidine dimers. Which repair pathway is defective? A. Mismatch repair B. Homologous recombination C. Nucleotide excision repair D. Base insertion repair | back 243 C. Nucleotide excision repair — it removes damaged DNA and replaces it. |
front 244 Which group of bacteria is naturally capable of taking up exogenous DNA? A. E coli, Salmonella, Shigella B. S pneumoniae, H influenzae type B, Neisseria C. Mycoplasma, Chlamydia, Rickettsia | back 244 B. Streptococcus pneumoniae, Haemophilus influenzae type B, and Neisseria — these are naturally competent. |
front 245 The bacterial sex pilus is a specialized form of which secretion system? A. Type I B. Type II C. Type III D. Type IV | back 245 D. Type IV — the sex pilus functions as a type IV secretion device. |
front 246 Bacteria break down carbohydrates into sugars and short-chain fatty acids. What is this process called? A. Fermentation B. Transduction C. Conjugation D. Recombination | back 246 A. Fermentation — bacteria metabolize carbohydrates into smaller products such as SCFAs. |
front 247 What is the universal intermediate of cell metabolism? A. Lactate B. Acetyl-CoA C. Pyruvic acid D. Citrate | back 247 C. Pyruvic acid — many metabolic pathways converge on pyruvate. |
front 248 Fermentation occurs under which condition? A. Only with oxygen B. Only in eukaryotes C. Only during replication D. Only without oxygen | back 248 D. Only without oxygen |
front 249 Which statement best describes bacterial genetics? A. Bacteria are haploid and often organize related genes into operons B. Bacteria are diploid and often organize related genes into operons C. Bacteria are haploid and lack gene regulation D. Bacteria are diploid and use introns | back 249 A. Bacteria are haploid and often organize related genes into operons. |
front 250 What is transcription? A. mRNA to protein B. Protein to DNA C. DNA to mRNA D. DNA to protein | back 250 C. DNA to mRNA — RNA polymerase makes an mRNA copy from DNA. |
front 251 What is translation? A. DNA to mRNA B. mRNA to protein C. Protein to DNA D. RNA to DNA | back 251 B. mRNA to protein — ribosomes synthesize proteins from mRNA. |
front 252 Promoters and operators are usually located where relative to the gene/operon they regulate? | back 252 Beginning |
front 253 In negative control, genes are expressed unless turned off by what? A. Repressor protein B. Ribosome C. Helicase D. Primase | back 253 A. Repressor protein — negative control blocks transcription unless repression is removed. |
front 254 Which enzyme unwinds bacterial DNA at the origin during replication? | back 254 Helicase |
front 255 Which enzyme synthesizes primers to start bacterial DNA replication? | back 255 Primase |
front 256 What does semiconservative DNA replication mean? A. Each daughter DNA has one parental strand and one new strand B. Both daughter DNAs are completely new C. One daughter DNA is old and one is new D. DNA is copied without using a template | back 256 A. Each daughter DNA has one parental strand and one new strand. |
front 257 Bacterial DNA synthesis occurs at growing replication forks and proceeds in which pattern? A. Unidirectionally from plasmids B. Only after cell division C. Bidirectionally from the origin D. Randomly across the chromosome | back 257 C. Bidirectionally from the origin — two forks move away from oriC. |
front 258 During bacterial growth, chromosome replication is initiated near which bacterial structure? A. Capsule B. Membrane C. Flagellum D. Ribosome | back 258 B. Membrane — membrane growth helps pull daughter chromosomes apart. |
front 259 Which sequence correctly lists the phases of bacterial growth? A. Death, lag, stationary, exponential B. Stationary, death, lag, exponential C. Exponential, lag, death, stationary D. Lag, exponential, stationary, death | back 259 D. Lag → exponential/log → stationary → death. |
front 260 A repair system removes a damaged section of DNA and inserts a new DNA strand. Which repair type is this? A. Direct repair B. Fermentation C. Excision repair D. Conjugation | back 260 C. Excision repair — damaged DNA is cut out and replaced. |
front 261 What does plasmid copy number measure? A. Ratio of ribosomes to plasmids B. Ratio of plasmid copies to chromosome copies C. Ratio of phages to bacteria D. Ratio of operons to genes | back 261 B. Ratio of plasmid copies to chromosome copies. |
front 262 A mobile genetic element moves DNA from one location to another. What is it called? A. Bacteriophage B. Promoter C. Operator D. Transposon | back 262 D. Transposon — transposons are mobile DNA elements. |
front 263 Which are the 3 main mechanisms of bacterial horizontal gene transfer? A. Transformation, conjugation, transduction B. Transcription, translation, replication C. Lytic, lysogenic, exponential D. Fermentation, respiration, oxidation | back 263 A. Transformation, conjugation, and transduction. |
front 264 A donor bacterium transfers DNA directly to a recipient through a sex pilus. Which process is this? _____ | back 264 Conjugation |
front 265 During transduction, two genes are more likely to be cotransduced when they are located how? A. On different chromosomes B. Closer together C. On separate plasmids D. Farther apart | back 265 B. Closer together — nearby genes fit into the same transferred DNA fragment more easily. |
front 266 Scientists use a DNA carrier to deliver a gene into receptive bacteria. What is this carrier called? A. Repressor B. Operator C. Cloning vector D. Pyrimidine dimer | back 266 C. Cloning vector — it delivers DNA into bacteria for replication or expression. |
front 267 A patient with gram-negative sepsis has fever, hypotension, and inflammatory cytokine release due to a bacterial membrane component. Which toxin is responsible? ______. ______ is part of the gram-negative bacterial ______ membrane. | back 267 Endotoxin — endotoxin is part of the gram-negative bacterial outer membrane. |
front 268 A secreted bacterial toxin is found to be a protein produced by either gram-positive or gram-negative bacteria. What type of toxin is this? ______ | back 268 A. Exotoxin — exotoxins are secreted proteins made by gram-positive or gram-negative bacteria. |
front 269 A researcher isolates a lipopolysaccharide complex from a gram-negative bacterium. Which toxin type is this? | back 269 Endotoxin — endotoxin is composed of LPS. |
front 270 Which part of LPS is mainly responsible for endotoxin toxicity? ____ ____ | back 270 Lipid A — Lipid A is the toxic portion of LPS. |
front 271 The terminal portion of LPS varies among bacterial strains and helps distinguish strains. What is this portion called? ____ ____ | back 271 O antigen — the O antigen is the variable terminal end of LPS. |
front 272 A toxin has an A component that causes toxicity and a B component that binds the host cell. What type of toxin is this? _____ | back 272 Exotoxin — many exotoxins are A-B toxins. |
front 273 In an A-B exotoxin, which component binds to the host cell surface? A. A component B. B component | back 273 B. B component — “B” stands for binding. |
front 274 In an A-B exotoxin, which component performs the toxic activity inside the host cell? A. A component B. B component | back 274 D. A component — “A” stands for active. |
front 275 Endotoxin binds CD14 on macrophages. Which mediators are released? IL-____, IL-____, ____-____, ____ ____ | back 275 IL-1, IL-6, TNF-alpha, and NO — these drive inflammation and shock. |
front 276 A gram-negative infection activates complement through LPS. Which complement fragments are released as anaphylatoxins? ____ and ____ | back 276 C3a and C5a — these promote inflammation and neutrophil chemotaxis. |
front 277 Why is endotoxin generally a poor target for toxoid-style vaccination? A. It is only made by viruses B. It has no toxic activity C. It generates a weak antibody response D. It is rapidly secreted from gram-positive cells | back 277 C. It generates a weak antibody response — endotoxin does not make a strong protective antibody response. |
front 278 A bacterial toxin gene is found on a plasmid or bacteriophage rather than the chromosome. What type of toxin is most likely encoded? _____ | back 278 Exotoxin — exotoxin genes are often carried on plasmids or bacteriophages. |
front 279 Which mobile genetic elements commonly encode exotoxin genes? A. Ribosomes and operons B. Capsules and fimbriae C. Endospores and porins D. Plasmids and bacteriophages | back 279 D. Plasmids and bacteriophages — exotoxin genes are often horizontally transferred. |
front 280 A toxin activates many T cells at once by linking MHC II on an APC to the T-cell receptor. What is this toxin called? ______ | back 280 Superantigen |
front 281 Superantigens differ from normal peptide antigens because they are not processed normally and instead bind _____ _____ and _____ directly | back 281 Not processed normally and instead bind MHC II and TCR directly |
front 282 A patient develops shock after massive cytokine release from T-cell activation. Which toxin mechanism is most likely? A. Botulinum toxin blocking ACh B. Cytolysin destroying membranes C. Superantigen causing massive T-cell activation D. O antigen activating B cells | back 282 C. Superantigen causing massive T-cell activation — cytokine release causes vasodilation, hypotension, and shock. |
front 283 Which two organisms produce superantigens that can cause shock? ______ ______ and ______ ______ | back 283 Staphylococcus aureus and Streptococcus pyogenes |
front 284 Most exotoxins are heat labile. What does this mean? A. They are rapidly destroyed by heat B. They become stronger after heating C. They are made only during fever D. They are identical to LPS | back 284 A. They are rapidly destroyed by heat — many exotoxins are inactivated around 60°C. |
front 285 Which exotoxins are classic exceptions to the “heat-labile exotoxin” rule? ______ ______ and ______ ______ heat-stable toxin | back 285 Staphylococcal enterotoxin and E coli heat-stable toxin — these are heat-stable exceptions. |
front 286 A patient has flaccid paralysis after ingestion of a toxin that prevents acetylcholine release from vesicles. Which toxin is responsible? A. Endotoxin B. Superantigen C. Botulinum toxin D. Cytolysin | back 286 C. Botulinum toxin — it blocks ACh release from presynaptic vesicles. |
front 287 A burn patient develops a wound infection with a blue-green pigment and fruity odor. Which opportunistic pathogen is classically associated with burns? _____ _____ | back 287 Pseudomonas aeruginosa |
front 288 Patients with cystic fibrosis are especially prone to chronic lung colonization by which organisms? _____ _____ and _____ _____ | back 288 Staphylococcus aureus and Pseudomonas aeruginosa — impaired mucociliary clearance promotes colonization. |
front 289 Why do bacteria not express virulence factors all the time? A. Virulence genes cannot be regulated B. They only express them under specific conditions C. All virulence factors are toxic to bacteria D. Virulence factors are only found in viruses | back 289 B. They only express them under specific conditions — expression is often triggered by the environment. |
front 290 Large genetic regions on a chromosome or plasmid that contain multiple virulence genes are called: A. Operons B. Ribosomes C. Pathogenicity islands D. Porins | back 290 C. Pathogenicity islands — they encode coordinated sets of virulence factors. |
front 291 A Salmonella virulence island is activated by acidic pH inside a macrophage phagocytic vesicle. Which pathogenicity island is this? A. SPI-2 B. O antigen island C. MSCRAMM island D. Lipid A island | back 291 A. SPI-2 — Salmonella SPI-2 is activated in the acidic phagocytic vesicle. |
front 292 SPI-2 helps Salmonella survive intracellularly by promoting assembly of which device? A. Type I secretion pump B. Type II pili C. Type IV conjugation pilus D. Type III secretion device | back 292 D. Type III secretion device — it injects bacterial proteins into host cells. |
front 293 A bacterium injects a pore-forming molecule into a host cell, then injects proteins through that pore. Which structure is being used? A. Flagellum B. Type III secretion device C. Capsule D. Ribosome | back 293 B. Type III secretion device — this syringe-like apparatus delivers bacterial proteins into host cells. |
front 294 Many proteins injected by a type III secretion system help bacteria enter host cells by promoting what process? A. Actin polymerization B. Antibody secretion C. Complement inhibition D. Nuclear division | back 294 A. Actin polymerization — rearranging actin helps host cells engulf bacteria. |
front 295 An organism causes disease mainly when host defenses are weakened or tissue barriers are damaged. What is this organism called? A. Superantigen B. Endotoxin C. Opportunistic bacterium D. Anaphylatoxin | back 295 C. Opportunistic bacterium — it takes advantage of preexisting weakness or damage. |
front 296 Patients with AIDS are especially susceptible to intracellular bacteria such as which group? _______ | back 296 Mycobacteria — impaired cell-mediated immunity increases risk. |
front 297 Systemic symptoms during bacterial infection are often caused by bacterial toxins and which host response? A. Keratin production B. Cytokine production C. Lactose fermentation D. Flagellar rotation | back 297 B. Cytokine production — toxins and host cytokines produce systemic responses. |
front 298 S aureus and S epidermidis are normal flora of which site and can cause infection after breaks in the barrier? | back 298 Skin — they can enter through skin breaks. |
front 299 Indwelling catheters and IV lines increase risk of infection by skin flora mainly because they: A. block antibody production B. damage the spleen C. reduce stomach acid D. bypass the skin barrier | back 299 D. Bypass the skin barrier — skin flora can enter deeper tissues or blood. |
front 300 Natural openings such as the mouth, nose, anus, and respiratory/GI/GU tracts are protected by which defenses? A. Mucus, cilia, lysozyme, and IgA B. Lipid A, O antigen, and TNF C. Plasmids, phages, and transposons D. ATP, NADH, and FADH2 | back 300 A. Mucus, cilia, lysozyme, and IgA — these protect exposed mucosal surfaces. |
front 301 E coli remains attached to the urinary or intestinal epithelium instead of being washed away. Which bacterial factor explains this? A. Endotoxin B. Capsule C. Adhesins D. Botulinum toxin | back 301 C. Adhesins — they bind specific receptors on tissue surfaces. |
front 302 Many bacterial adhesins are located on which surface structures? A. Fimbriae B. Ribosomes C. Nucleoids D. Inclusion bodies | back 302 A. Fimbriae — fimbrial adhesins help bacteria bind host tissues. |
front 303 Fimbrial adhesins commonly bind tightly to which host molecules? A. Cytokines B. Lectins C. Antibodies D. Complement proteins | back 303 B. Lectins — fimbriae often mediate lectin-like binding to host surfaces. |
front 304 Which organisms express adhesin proteins that are not located on fimbriae? _____ _____ _____ _____ _____ | back 304 Yersinia, Bordetella pertussis, and Mycoplasma pneumoniae — their adhesins are nonfimbrial. |
front 305 A bacterium moves through the mucous layer toward epithelium. Which structure helps it swim? _____ | back 305 Flagella — flagella provide motility through mucus. |
front 306 Which bacterial enzymes help digest the mucous layer so bacteria can approach epithelial cells? ______ | back 306 Proteases — they break down mucus proteins. |
front 307 C perfringens is normal microbiota but can cause gas gangrene under which condition? ____ oxygen | back 307 Low oxygen — anaerobic conditions favor C perfringens gas gangrene. |
front 308 A patient develops rapid vomiting after eating food containing toxin already produced by bacteria. What type of toxin exposure is this? A. Preformed toxin B. Endotoxin only C. Type III secretion D. Pathogenicity island | back 308 A. Preformed toxin — symptoms occur quickly without needing bacterial growth in the host. |
front 309 Why do preformed toxins cause symptoms quickly? A. They require bacterial replication first B. They are already present before ingestion or exposure C. They only activate complement slowly D. They must integrate into host DNA | back 309 B. They are already present — no time is needed for bacterial growth and toxin production. |
front 310 Exotoxins can include cytolytic enzymes and receptor-binding proteins. What do these toxins do? A. Only form bacterial chromosomes B. Alter cell function or kill cells C. Become part of gram-negative membranes D. Prevent all cytokine release | back 310 B. Alter cell function or kill cells — exotoxins can disrupt host cell activity or viability. |
front 311 A toxin directly breaks down host cell membranes. What type of toxin is this? ______ toxin | back 311 Cytolytic toxin — cytolytic toxins damage membranes. |
front 312 A gram-negative bacterium releases LPS during infection, leading to macrophage activation. Which receptor complex is classically involved in recognizing LPS on macrophages? A. CD14/TLR4 B. CD4/MHC II C. CD8/MHC I D. BCR/IgA | back 312 A. CD14/TLR4 — LPS binding activates macrophages and cytokine release. |
front 313 Nitric oxide released after endotoxin stimulation contributes most directly to which shock finding? A. Bradycardia only B. Vasodilation and hypotension C. Increased platelet production D. Increased gastric acid secretion | back 313 B. Vasodilation and hypotension — NO relaxes vascular smooth muscle. |
front 314 Which toxin type is most likely to be converted into a toxoid vaccine because it is a protein with strong immunogenicity? Endotoxin or Exotoxin? | back 314 Exotoxin |
front 315 Which factor best explains why Pseudomonas can colonize cystic fibrosis lungs? Impaired _____ _____ clearance | back 315 Impaired ciliary mucous clearance — thick mucus and poor clearance allow colonization. |
front 316 A device-associated S epidermidis infection persists despite antibiotics. Which bacterial structure most likely contributes? _____ | back 316 Biofilm — biofilms protect bacteria on catheters and implanted devices. |
front 317 Which bacteria produce endotoxin? A. Gram-positive bacteria only B. Gram-negative bacteria only C. Both gram-positive and gram-negative bacteria D. Anaerobes only | back 317 B. Gram-negative bacteria only — endotoxin refers to lipid A in LPS/LOS. |
front 318 High concentrations of endotoxin can activate which complement pathway? A. Classical pathway B. Lectin pathway C. Alternative pathway D. Terminal-only pathway | back 318 C. Alternative pathway — endotoxin can activate alternative complement. |
front 319 What is a typical bacterial capsule made of? _____ | back 319 Polysaccharide — most bacterial capsules are polysaccharide-based. |
front 320 A heavily encapsulated bacterium survives despite neutrophil exposure. What is the capsule mainly preventing? A. Bacterial replication B. Translation C. Phagocytosis D. Fermentation | back 320 C. Phagocytosis — capsules help bacteria avoid engulfment. |
front 321 Which set lists three ways bacteria evade antibody responses? A. Antigenic variation, antibody inactivation, intracellular growth B. ATP production, fermentation, replication C. Capsule loss, ribosome loss, DNA loss D. Complement fixation, opsonization, phagolysosome fusion | back 321 A. Antigenic variation, antibody inactivation, intracellular growth. |
front 322 A bacterium repeatedly changes its surface antigens so previously made antibodies no longer bind well. Which immune evasion strategy is this? A. Antigenic variation B. Complement activation C. Opsonization D. Chemotaxis | back 322 A. Antigenic variation — changing surface antigens helps evade existing antibodies. |
front 323 A bacterium produces enzymes that destroy or inactivate host antibodies. Which immune response is it evading? A. Antibody-mediated immunity B. Complement-independent killing C. T-cell receptor rearrangement D. Macrophage cytokine release | back 323 A. Antibody-mediated immunity — antibody inactivation prevents effective humoral defense. |
front 324 Why does intracellular bacterial growth help evade antibodies? Antibodies work best _____— intracellular bacteria are _____ from circulating antibodies. | back 324 extracellularly hidden |
front 325 Which bacterial structure limits complement access in gram-positive bacteria? A. Thin LPS layer B. Thick peptidoglycan C. Long O antigen D. Outer membrane porins | back 325 B. Thick peptidoglycan — it can physically limit complement-mediated killing. |
front 326 Which gram-negative structure can limit complement access in most gram-negative bacteria? A. Long O antigen of LPS B. Teichoic acid C. Thick peptidoglycan D. Spore coat | back 326 A. Long O antigen of LPS — it can block complement from reaching the membrane. |
front 327 Why are Neisseria species an important exception when discussing long O antigen protection? A. They lack peptidoglycan B. They have LOS rather than full LPS with long O antigen C. They are gram-positive D. They cannot activate complement | back 327 B. They have LOS rather than full LPS with long O antigen — this gives less protection from complement. |
front 328 Which strategy helps bacteria evade phagocytic cells by directly damaging those cells? A. Producing enzymes that lyse phagocytes B. Activating C3b opsonization C. Increasing IgA binding D. Promoting phagolysosome fusion | back 328 A. Producing enzymes that lyse phagocytes. |
front 329 A bacterium avoids being engulfed by macrophages and neutrophils. Which evasion mechanism is this? A. Inhibition of phagocytic uptake B. Increased antigen presentation C. Complement fixation D. Cytokine neutralization | back 329 A. Inhibition of phagocytic uptake — antiphagocytic factors such as capsules can prevent engulfment. |
front 330 A bacterium is engulfed by a macrophage but survives by preventing phagosome-lysosome fusion. Which evasion strategy is this? A. Blocking intracellular killing B. Antibody class switching C. Alternative complement activation D. Anaphylatoxin release | back 330 A. Blocking intracellular killing — preventing fusion allows survival inside phagocytes. |
front 331 A gram-negative bacterium releases endotoxin, activates macrophages, and triggers complement. Which final clinical outcome is most concerning at high endotoxin levels? A. Hypotension and shock B. Pure flaccid paralysis C. No inflammatory response D. Isolated antibody deficiency | back 331 A. Hypotension and shock — cytokines, NO, and anaphylatoxins can cause severe vasodilation. |
front 332 E coli O157:H7 infection is classically associated with which serious complication? A. Toxic shock syndrome B. Pseudomembranous colitis C. Hemolytic uremic syndrome D. Gas gangrene | back 332 C. Hemolytic uremic syndrome — E coli O157:H7 can cause HUS. |
front 333 The production of type III secretion devices by Shigella flexneri is triggered by which environmental signal? A. Oxygen tension B. Acidic pH C. High temperature D. Bile salts | back 333 A. Oxygen tension — Shigella flexneri type III secretion expression is triggered by oxygen tension. |
front 334 The production of type III secretion devices by Salmonella typhimurium is triggered mainly by which signal? A. IgA binding B. D-mannose binding C. Fibronectin binding D. pH | back 334 D. pH — Salmonella typhimurium type III secretion expression is triggered by pH. |
front 335 The SPI-2 pathogenicity island of Salmonella is activated in which location? Acidic phagocytic vesicle inside a ______ | back 335 Acidic phagocytic vesicle inside a macrophage — SPI-2 promotes intracellular survival. |
front 336 A patient develops pseudomembranous colitis after antibiotic use. Which organism is most likely responsible? ____ ____ | back 336 Clostridium difficile — C difficile causes pseudomembranous colitis. |
front 337 Which organism is inhaled, grows in the lungs, and is not typically spread person-to-person? _____ | back 337 Legionella — it is acquired by inhalation from environmental water sources and does not readily spread between people. |
front 338 In E coli, type 1 fimbriae bind which receptor molecule? A. GM1 ganglioside B. P blood group glycolipid C. D-mannose D. Fibronectin | back 338 C. D-mannose — E coli type 1 fimbriae bind mannose-containing receptors. |
front 339 E coli colonization factor antigen fimbriae bind which host receptor? A. Collagen B. Laminin C. D-mannose D. GM1 ganglioside | back 339 D. GM1 ganglioside — colonization factor antigen fimbriae bind GM1. |
front 340 E coli strains that cause acute pyelonephritis use which adhesin and receptor pair? A. Type 1 fimbriae; D-mannose B. P fimbriae; P blood group glycolipid C. MSCRAMMs; fibronectin D. Colonization factor antigen; GM1 ganglioside | back 340 B. P fimbriae; P blood group glycolipid — P fimbriae help E coli attach to uroepithelial cells. |
front 341 Streptococci and Staphylococcus aureus bind fibronectin, collagen, or laminin using which adhesin molecules? A. MSCRAMMs B. P fimbriae C. Type 1 fimbriae D. Colonization factor antigen | back 341 A. MSCRAMMs — microbial surface components recognizing adhesive matrix molecules bind extracellular matrix proteins. |
front 342 _____ and _____ use fimbriae to bind _____ cells before injecting pathogenic proteins. | back 342 Salmonella Yersinia M cells |
front 343 Many proteins injected by a type III secretion device promote which host-cell process? A. Antibody class switching B. Complement activation C. Sphingomyelin breakdown D. Actin polymerization | back 343 D. Actin polymerization — this helps invasion or movement within and between cells. |
front 344 How does Salmonella promote invasion through the GI tract? _____ tight junctions of _____ cells | back 344 Weakens tight junctions of mucoepithelial cells — this helps Salmonella invade across the intestinal barrier. |
front 345 Rapid food poisoning from a preformed toxin is classically caused by which organisms? ____ ____ ____ ____ | back 345 Staphylococcus aureus and Bacillus cereus — symptoms occur quickly because the toxin is already in the food. |
front 346 Clostridium perfringens produces alpha-toxin. What is alpha-toxin? A. IgA protease B. Superantigen C. Adenylate cyclase activator D. Phospholipase C | back 346 D. Phospholipase C — C perfringens alpha-toxin damages membranes. |
front 347 Clostridium perfringens alpha-toxin breaks down which membrane component? A. Peptidoglycan B. Hyaluronic acid C. Sphingomyelin D. D-mannose | back 347 C. Sphingomyelin — alpha-toxin damages cell membranes by cleaving phospholipids such as sphingomyelin. |
front 348 Cholera toxin increases cAMP by doing which of the following? Permanently activating _____ | back 348 Permanently activating Gs |
front 349 Pertussis toxin increases cAMP by doing which of the following? inactivating _____ | back 349 Inactivating Gi — loss of Gi inhibition increases adenylate cyclase activity. |
front 350 A toxin cross-links the beta region of the T-cell receptor to MHC II on an APC. What type of toxin is this? A. Endotoxin B. Cytolysin C. Superantigen D. IgA protease | back 350 C. Superantigen — it causes massive nonspecific T-cell activation. |
front 351 Toxic shock syndrome causes shock mainly through overwhelming release of which cytokines? A. IL-4, IL-5, IL-13, IgE B. IL-10, TGF-beta, IL-35, IgA C. C3a, C3b, C5b, C9 D. IL-1, IL-2, IFN-gamma, TNF-alpha | back 351 D. IL-1, IL-2, IFN-gamma, TNF-alpha — massive cytokine release causes shock. |
front 352 Corynebacterium diphtheriae causes disease by inactivating which target? ____ ____ ____ | back 352 Elongation factor 2 |
front 353 Tetanospasmin from Clostridium tetani causes disease by which mechanism? Cleaving _____ proteins to block _____ neurotransmitter release | back 353 Cleaving SNARE proteins to block inhibitory neurotransmitter release |
front 354 Which triad best describes the major clinical effects of endotoxin? A. Flaccid paralysis, diplopia, dry mouth B. Fever, shock, DIC C. Pseudomembranes, watery diarrhea, ileus D. Spastic paralysis, lockjaw, opisthotonos | back 354 B. Fever, shock, DIC — endotoxin can trigger systemic inflammation and coagulation. |
front 355 The Streptococcus pyogenes capsule is made of which substance? A. Hyaluronic acid B. Polyribosylribitol phosphate C. Lipid A D. Sphingomyelin | back 355 A. Hyaluronic acid — it mimics human connective tissue. |
front 356 Why is the hyaluronic acid capsule of Streptococcus pyogenes useful for immune evasion? It mimics human _______ tissue — this helps the bacterium _______ from immune recognition. | back 356 It mimics human connective tissue — this helps the bacterium hide from immune recognition. |
front 357 Which organism evades antibodies by antigenic variation and produces an IgA protease? _____ _____ | back 357 Neisseria gonorrhoeae — it changes surface antigens and degrades IgA. |
front 358 Protein A prevents opsonization and phagocytosis by binding which part of IgG? _____ region | back 358 Fc region — Protein A binds Fc so phagocytes cannot recognize IgG normally. |
front 359 Which organism expresses Protein A? _____ _____ | back 359 Staphylococcus aureus |
front 360 Which Streptococcus pyogenes toxin causes cell membrane lysis? A. Tetanospasmin B. Diphtheria toxin C. Streptolysin O D. Cholera toxin | back 360 C. Streptolysin O — it lyses host cell membranes. |
front 361 What is the main role of M protein in Streptococcus pyogenes virulence? A. Prevents phagocytosis B. Blocks acetylcholine release C. Activates adenylate cyclase D. Breaks down sphingomyelin | back 361 A. Prevents phagocytosis — M protein is antiphagocytic. |
front 362 Mycobacterium species survive inside macrophages by blocking which process? A. IgA secretion B. Actin polymerization C. D-mannose binding D. Phagosome-lysosome fusion | back 362 D. Phagosome-lysosome fusion — this prevents exposure to lysosomal killing contents. |
front 363 Listeria monocytogenes escapes macrophage killing by doing which of the following? A. Binding Fc region of IgG B. Lysing the phagosome and escaping into the cytoplasm C. Producing hyaluronic acid capsule D. Activating the alternative complement pathway | back 363 B. Lysing the phagosome and escaping into the cytoplasm — Listeria avoids phagolysosomal killing. |
front 364 Which test result best distinguishes Staphylococcus aureus from Staphylococcus epidermidis? S aureus is _____ _____ | back 364 S aureus is coagulase positive — S epidermidis is coagulase negative. |
front 365 What does coagulase do? Converts _____ into fibrin to form a _____ barrier | back 365 Converts fibrinogen into fibrin to form a clotlike barrier — this helps S aureus wall itself off. |
front 366 Both cholera toxin and pertussis toxin increase cAMP. Which comparison is correct? A. Cholera inactivates Gi; pertussis activates Gs B. Cholera blocks adenylate cyclase; pertussis activates EF-2 C. Cholera cleaves SNARE; pertussis lyses membranes D. Cholera activates Gs; pertussis inactivates Gi | back 366 D. Cholera activates Gs; pertussis inactivates Gi — both increase adenylate cyclase activity and cAMP. |
front 367 A patient has rapid-onset vomiting after eating food left at room temperature. Why do symptoms appear so quickly with S aureus food poisoning? A. The toxin is preformed in the food B. The bacteria must invade macrophages first C. The bacteria must form M protein first D. The toxin requires phagosome-lysosome fusion | back 367 A. The toxin is preformed in the food — bacterial growth inside the host is not required first. |
front 368 Salmonella and Yersinia bind M cells, inject proteins, and stimulate uptake into the host cell. Which bacterial tool makes this injection possible? A. Coagulase B. Type III secretion device C. Protein A D. IgA protease | back 368 B. Type III secretion device — it injects virulence proteins into host cells. |
front 369 Listeria and Shigella use actin polymerization mainly for which purpose? ______ within cells and spread to neighboring cells | back 369 movement |
front 370 A clinician is trying to maximize the yield of a blood culture in a patient with suspected bacteremia. What is the most important factor for success? _____ of blood processed | back 370 Volume of blood processed — larger appropriate blood volume improves blood culture yield. |
front 371 Approximately how much blood should be collected from an adult for each blood culture? A. 1 mL B. 5 mL C. 10 mL D. 20 mL | back 371 D. 20 mL — adult blood cultures require about 20 mL per culture. |
front 372 How much blood should generally be collected per blood culture in children? A. 1-5 mL B. 5-10 mL C. 20-25 mL D. 30-35 mL | back 372 B. 5-10 mL — children require less blood than adults. |
front 373 How much blood should generally be collected per blood culture in neonates? A. 1 mL B. 5 mL C. 10 mL D. 20 mL | back 373 A. 1 mL — neonates require only about 1 mL per culture. |
front 374 A patient with pneumonia has bacteremia that appears only at certain times rather than constantly. What type of septicemia is this? A. Continuous septicemia B. Intermittent septicemia C. Latent septicemia D. Commensal septicemia | back 374 B. Intermittent septicemia — localized infections such as lung, urinary tract, or soft tissue infections can seed blood intermittently. |
front 375 A patient with infective endocarditis or septic thrombophlebitis has persistent bacteria in the blood. What type of septicemia is most likely? A. Intermittent septicemia B. Transient septicemia C. Continuous septicemia D. Localized septicemia | back 375 C. Continuous septicemia — intravascular infections such as endocarditis or septic thrombophlebitis cause continuous bloodstream infection. |
front 376 Most clinically significant blood culture isolates are detected within what time frame? A. 1-2 hours B. 1-2 days C. 5-7 days D. 2-3 weeks | back 376 B. 1-2 days |
front 377 Even though most significant isolates appear early, blood cultures should be incubated for at least how long? A. 12 hours B. 24 hours C. 5-7 days D. 30 days | back 377 C. 5-7 days |
front 378 When CSF is collected from a suspected patient with ______, the specimen is concentrated by ______ and the sediment is used to inoculate bacteriologic media and prepare a ______ stain | back 378 meningitis centrifugation Gram |
front 379 After CSF is centrifuged in suspected meningitis, which part is used to inoculate bacteriologic media and prepare a Gram stain? A. Supernatant B. Sediment C. Serum layer D. Clot | back 379 B. Sediment |
front 380 For routine bacterial culture of CSF, what specimen volume is usually collected? A. 0.1 mL B. 1-5 mL C. 20 mL D. 50 mL | back 380 B. 1-5 mL |
front 381 If mycobacterial meningitis is suspected, how much CSF should be collected? As large a sample as possible — mycobacteria may be _____, so larger volume improves _____. | back 381 sparse detection |
front 382 Most bacterial infections of the pharynx are caused by which organism? _____ _____ _____ | back 382 Group A Streptococcus |
front 383 Which swab types are appropriate for collecting pharyngeal specimens? A. Cotton or dacron B. Wood or dacron C. Dacron or calcium alginate D. Metal or calcium alginate | back 383 C. Dacron or calcium alginate — these are used for throat specimens. |
front 384 Why should saliva contamination be avoided when collecting a throat swab for suspected group A strep? ____ bacteria can ____ growth of group A streptococci | back 384 Saliva inhibit |
front 385 Which specimens should be inoculated onto culture media immediately after collection before transport to the lab? _____ _____ and _____ _____ — these organisms are fragile and require immediate inoculation. | back 385 Bordetella pertussis and Neisseria gonorrhoeae — these organisms are fragile and require immediate inoculation. |
front 386 Group A streptococci can be detected directly from a clinical specimen using which method? _____ for _____ -specific antigen | back 386 Immunoassay for group-specific antigen |
front 387 Which set contains the most common bacterial causes of sinusitis? _____ _____ _____ _____ _____ _____ _____ _____ | back 387 Haemophilus influenzae Streptococcus pneumoniae Moraxella catarrhalis Staphylococcus aureus |
front 388 A respiratory specimen has many squamous epithelial cells on microscopy. What does this suggest? A. Excellent lower respiratory specimen B. Saliva contamination C. Mycobacterial infection D. Bloodstream contamination | back 388 B. Saliva contamination — squamous epithelial cells indicate oral contamination. |
front 389 What procedure is required to make a specific microbiologic diagnosis of a middle ear infection? A. Nasopharyngeal swab B. Tympanocentesis C. Throat culture D. Blood culture | back 389 B. Tympanocentesis — sampling middle ear fluid is needed for a specific diagnosis. |
front 390 An abscess is drained and cultured. Where within the abscess are organisms most commonly replicating? A. Surface crust B. Base of the abscess C. Surrounding normal skin D. Necrotic center only | back 390 B. Base of the abscess — organisms most actively replicate at the base. |
front 391 Clostridium difficile — it is a major cause of antibiotic-associated _____ and _____ | back 391 diarrhea colitis. |
front 392 What is the most sensitive and specific test for diagnosing Clostridium difficile infection? ____ ____ ____ ____ (____) detects C difficile toxin genes. | back 392 nucleic acid amplification testing (NAAT) detects C difficile toxin genes. |
front 393 How long does it usually take to isolate and identify enteric pathogens by traditional methods? A. 1-3 hours B. 12 hours C. 3 days D. 2 weeks | back 393 C. 3 days — enteric pathogen isolation and identification usually takes about 3 days. |
front 394 A lab wants rapid detection of common bacterial, viral, and parasitic enteric pathogens directly from fecal swabs. Which method can detect them in 1-3 hours? A. High-multiplex NAAT B. Broth dilution C. Blood agar hemolysis D. Acid-fast stain | back 394 A. High-multiplex NAAT — it can rapidly detect multiple enteric pathogens directly from fecal swabs. |
front 395 Which factor is required for aminoglycosides to enter bacterial cells? A. Carbon dioxide B. Oxygen C. Capsule D. IgA | back 395 B. Oxygen — aminoglycoside uptake is oxygen-dependent. |
front 396 Why are aminoglycosides generally ineffective against anaerobes? A. Anaerobes destroy all ribosomes B. Anaerobes lack oxygen-dependent drug uptake C. Anaerobes always produce beta-lactamase D. Anaerobes have no cell membrane | back 396 B. Anaerobes lack oxygen-dependent drug uptake |
front 397 What is one advantage of broth dilution antibiotic susceptibility testing? A. It requires no bacteria B. Any antibiotic can be tested C. It only detects viruses D. It gives results without incubation | back 397 B. Any antibiotic can be tested — broth dilution is flexible for different antibiotics. |
front 398 What is one limitation of broth dilution tests? The manufacturer determines the _______ range and limited dilutions are _______. | back 398 The manufacturer determines the antibiotic range and limited dilutions are available. |
front 399 Which organisms are alpha-hemolytic? _____ _____ _____ _____ | back 399 Streptococcus pneumoniae Viridans streptococci |
front 400 Which set contains beta-hemolytic organisms? _____ _____ _____ _____ _____ _____ _____ _____ | back 400 Streptococcus pyogenes Streptococcus agalactiae Staphylococcus aureus Listeria monocytogenes |
front 401 A stool specimen shows gram-negative bacteria arranged in S-shaped pairs. Which organism is most likely? ______ | back 401 Campylobacter |
front 402 A blood agar plate shows a large outer zone of alpha-hemolysis with an inner zone of beta-hemolysis. Which organism classically produces this double zone? _____ _____ | back 402 Clostridium perfringens |
front 403 Which specimen should be sampled from an abscess to maximize recovery of actively growing organisms? _____ base because organisms most commonly _____ there. | back 403 Abscess base — organisms most commonly replicate there. |
front 404 A lab reports the MIC of an antibiotic for a bacterial isolate. What does this value tell the clinician? The ____ drug concentration that stops ____ growth | back 404 The lowest drug concentration that stops visible growth |
front 405 What is the most common pathogen that causes swimmer's ear? | back 405 Pseudomonas aeruginosa |
front 406 What organism is a gram-negative rod that has bipolar staining? _____ | back 406 Enterobacteriaceae |
front 407 What two classes of organisms are best detected using microscopy? 1. ____-____ rods 2. ____-____ cocci | back 407 1. Acid-fast rods 2. Gram-negative cocci |
front 408 A patient with infective endocarditis has persistently positive blood cultures throughout the day. What septicemia pattern is most likely? A. Transient septicemia B. Intermittent septicemia C. Continuous septicemia D. Localized septicemia | back 408 C. Continuous septicemia — intravascular infections cause continuous bacteremia. |
front 409 Intermittent septicemia occurs in patients with _____ infections Continuous septicemia occurs primarily in patients with _____ infections | back 409 localized intravascular |
front 410 To maximize recovery from an adult blood culture, how should the media bottles be inoculated? A. One bottle, 20 mL B. Two bottles, 5 mL each C. Four bottles, 2 mL each D. Two bottles, 10 mL each | back 410 D. Two bottles, 10 mL each — each culture uses two bottles with 10 mL per bottle. |
front 411 After blood culture bottles arrive in the laboratory, at what temperature should they be incubated? A. 25°C B. 37°C C. 4°C D. 60°C | back 411 B. 37°C — blood cultures are incubated at body temperature. |
front 412 A CSF specimen is collected for suspected meningitis. Which handling instruction is most appropriate? A. Freeze before transport B. Refrigerate immediately C. Avoid heat and refrigeration D. Heat before plating | back 412 C. Avoid heat and refrigeration — CSF should not be heated or refrigerated. |
front 413 Which direct test can detect group A strep? A. Immunoassay B. Coagulase test C. Oxidase test D. Acid-fast stain | back 413 A. Immunoassay — group A strep antigen can be detected directly. |
front 414 A clinician sends an oropharyngeal and nasopharyngeal culture to diagnose a lower respiratory infection. Why is this specimen inappropriate? A. It is normally sterile B. It misses oral flora C. It is not useful D. It requires refrigeration | back 414 C. It is not useful — nasopharyngeal or oropharyngeal culture should not be used. |
front 415 A lower respiratory specimen has many squamous epithelial cells on microscopy. What does this indicate? _____ contamination | back 415 Saliva contamination |
front 416 A wound culture is needed, but the surface is covered with colonizing flora. What is the best collection method? A. Surface swab only B. Dried drainage sample C. Deep aspiration D. Surrounding skin swab | back 416 C. Deep aspiration — collect deep in the wound, preferably by aspiration. |
front 417 2 most common genital specimens? _____ _____ _____ _____ | back 417 Neisseria gonorrhoeae Chlamydia trachomatis |
front 418 How should you collect a feces sample? ____ pan not a swab | back 418 Clean |
front 419 Two general forms of antimicrobial susceptibility tests are performed in the clinical laboratory: _____ _____ tests and _____ _____ tests | back 419 broth dilution tests and agar diffusion tests |
front 420 A broth dilution test is one in which an antibiotic is prepared in a _____ medium and then then _____ with a standardized concentration of bacteria. | back 420 nutrient innoculated |
front 421 An agar diffusion test has bacteria spread over a surface, then a _____ with _____ is inserted into the surface. If there is no _____ around the disk it is senstive to the _____ if there are bacteria it is resistant | back 421 disk antibiotics bacteria antibiotic |
front 422 A sputum smear is ordered because the clinician wants direct visualization of organisms often missed by routine Gram stain. Which class is microscopy especially useful for? A. Anaerobic cocci B. Viridans streptococci C. Enteric bacilli D. Acid-fast rods | back 422 D. Acid-fast rods — acid-fast organisms are best detected by microscopy. |
front 423 A urethral discharge specimen is examined directly because the suspected organism is best detected microscopically. Which organism class fits this? A. Gram-positive rods B. Gram-negative cocci C. Anaerobic bacilli D. Spore-forming rods | back 423 B. Gram-negative cocci — microscopy is useful for gram-negative cocci. |
front 424 To maximize recovery from an adult blood culture, how should the media bottles be inoculated? A. One bottle, 20 mL B. Two bottles, 5 mL each C. Four bottles, 2 mL each D. Two bottles, 10 mL each | back 424 D. Two bottles, 10 mL each — each culture uses two bottles with 10 mL per bottle. |
front 425 A clinician wants blood cultures drawn exactly during a fever spike. Which statement is most accurate? A. Timing is essential B. Timing prevents contamination C. Timing detects fungi only D. Timing is less important | back 425 D. Timing is less important — collection timing itself is not very important. |
front 426 A resident asks for a Gram stain directly on blood from a septic patient. Why is this low yield? Too _____ organisms — _____ blood usually has very low organism burden. | back 426 Too few organisms — septic blood usually has very low organism burden. |
front 427 A CSF specimen from suspected meningitis is sitting unprocessed. Why is immediate processing important? A. Some pathogens are labile B. CSF rapidly clots C. NAAT requires freezing D. Anaerobes overgrow quickly | back 427 A. Some pathogens are labile — N meningitidis and S pneumoniae are fragile. |
front 428 Which meningitis pathogens are especially labile in CSF specimens? A. E coli, B fragilis B. S aureus, Listeria C. C difficile, Shigella D. N meningitidis, S pneumoniae | back 428 D. N meningitidis and S pneumoniae — both can degrade quickly. |
front 429 A CSF specimen is sent to detect bacteria, viruses, and fungi. Which method is commonly used? A. Coagulase test B. NAAT C. Oxidase test D. Catalase test | back 429 B. NAAT — nucleic acid amplification tests detect multiple CSF pathogens. |
front 430 A sterile abdominal fluid specimen may contain anaerobes. What handling error should be avoided? A. Oxygen exposure B. Prompt processing C. Sterile collection D. Anaerobic transport | back 430 A. Oxygen exposure — oxygen inhibits anaerobe recovery. |
front 431 Anaerobic culture handling is especially important in which infections? A. Skin and urinary B. Bone and joint C. Intra-abdominal and pulmonary D. Pharyngeal and sinus | back 431 C. Intra-abdominal and pulmonary — these often involve anaerobes. |
front 432 Most bacterial pharyngitis is caused by which organism? ____ ____ Streptococcus | back 432 Group A Streptococcus |
front 433 A pharyngitis culture is ordered for Bordetella pertussis. What should the lab expect? A. Routine recovery B. Special techniques C. Anaerobic transport D. Blood culture only | back 433 B. Special techniques — B pertussis requires special recovery methods. |
front 434 When collecting a throat swab for suspected group A strep, what contamination should be avoided? A. Saliva B. Exudate C. Tonsillar tissue D. Posterior pharynx | back 434 A. Saliva — saliva flora can overgrow or inhibit GAS. |
front 435 Which throat areas should be sampled for suspected bacterial pharyngitis? A. Tongue and cheeks B. Teeth and gums C. Tonsils, posterior pharynx, exudate D. Lips, palate, uvula | back 435 C. Tonsils, posterior pharynx, exudate — include ulcerative areas if present. |
front 436 A rapid group A strep immunoassay is positive. What is the major strength of immunoassays? A. High sensitivity B. Low specificity C. High specificity D. Anaerobe detection | back 436 C. High specificity — GAS immunoassays are highly specific. |
front 437 Current NAATs for group A strep are best described as having what major advantage? A. Low contamination risk B. High sensitivity C. No transport needs D. Detects all anaerobes | back 437 B. High sensitivity — current GAS NAATs are highly sensitive. |
front 438 Which organisms are relatively resistant to drying during throat specimen handling? A. GAS, C diphtheriae B. B pertussis, gonorrhoeae C. S pneumoniae, meningitidis D. H influenzae, Moraxella | back 438 A. Group A strep and C diphtheriae — both resist drying. |
front 439 A child has suspected epiglottitis. Why should epiglottis culture be avoided? A. Causes false negatives B. Requires anaerobic transport C. May obstruct airway D. Detects normal flora only | back 439 C. May obstruct airway — especially dangerous in children. |
front 440 A specific microbiologic diagnosis of sinusitis requires direct aspiration, anaerobic transport, and what else? A. Fever-spike timing B. Saliva dilution C. Blood culture D. Prompt processing | back 440 D. Prompt processing — sinus aspirates need rapid lab processing. |
front 441 A blood culture grows Candida, while another grows E coli. Collectively, these bloodstream infections are called what? A. Cellulitis B. Empyema C. Septicemia D. Abscess | back 441 C. Septicemia — bacteremia and fungemia are collectively septicemia. |
front 442 A septic patient needs blood cultures before therapy. What collection strategy gives optimal yield? A. Two to three samples B. One large syringe C. One aerobic bottle D. Fever-spike sampling | back 442 A. Two to three samples — collect 2–3 blood samples when possible. |
front 443 A patient already received antibiotics before blood cultures. Why is this suboptimal? A. Causes false gram stain B. Inhibits organism recovery C. Causes anaerobe overgrowth D. Dilutes the specimen | back 443 B. Inhibits organism recovery — cultures are best collected before antibiotics. |
front 444 Which organisms should be inoculated onto culture media immediately after collection? A. GAS, C diphtheriae B. S aureus, pneumococcus C. H influenzae, Moraxella D. B pertussis, N gonorrhoeae | back 444 D. B pertussis and N gonorrhoeae — both are fragile. |
front 445 A cavitary lung infection is suspected to be caused by an organism requiring extended incubation. Which organism fits this concern? A. Moraxella catarrhalis B. Streptococcus pneumoniae C. Mycobacteria D. Haemophilus influenzae | back 445 C. Mycobacteria — mycobacteria need extended incubation. |
front 446 A branching, weakly acid-fast pulmonary pathogen is suspected. How should the lab handle incubation? A. Stop at 48 hours B. Extend incubation C. Refrigerate only D. Discard early | back 446 B. Extend incubation — Nocardiae require longer incubation than routine pathogens. |
front 447 A child presents with fever, ear pain, and bulging tympanic membrane. Which set contains the most common otitis media pathogens? A. Pneumococcus, H influenzae, Moraxella B. Pseudomonas, S aureus, Candida C. Gonorrhoeae, Chlamydia, Treponema D. Mycobacteria, Nocardia, Legionella | back 447 A. Pneumococcus, H influenzae, Moraxella — these are classic otitis media pathogens. |
front 448 Otitis externa culture is needed after treatment failure. What is the best specimen? A. Middle-ear aspirate B. Nasal swab C. Ear-area scraping D. First-void urine | back 448 C. Ear-area scraping — culture uses scraping of the involved ear area. |
front 449 A patient has suspected bacterial conjunctivitis. How should the initial eye surface specimen be collected? A. Swab before anesthetic B. Swab after anesthetic C. Direct eye aspiration D. First morning urine | back 449 A. Swab before anesthetic — topical anesthetics can interfere with recovery. |
front 450 A corneal ulcer is suspected after contact lens use. After surface swabbing, what specimen may be needed? A. Corneal scraping B. Midstream urine C. Nasopharyngeal swab D. Blood culture | back 450 A. Corneal scraping — corneal scrapings are used when necessary. |
front 451 Endophthalmitis is suspected after eye surgery. What is the proper intraocular specimen method? A. Surface swab B. Corneal scraping C. Direct aspiration D. Eyelid scraping | back 451 C. Direct aspiration — intraocular specimens are collected by aspirating the eye. |
front 452 Why are ocular infection cultures often difficult to interpret? A. Excessive specimen volume B. Few organisms present C. Constant anaerobe overgrowth D. Routine blood contamination | back 452 B. Few organisms present — ocular samples are small with low organism burden. |
front 453 An ocular specimen may contain Neisseria gonorrhoeae. What special lab need should be considered? A. Specialized culture media B. Extended mycobacterial incubation C. Anaerobic urine preservative D. Biphasic blood bottles | back 453 A. Specialized culture media — N gonorrhoeae requires special media. |
front 454 An ocular infection is suspected to be caused by Chlamydia trachomatis. Which culture approach is needed? A. Blood agar only B. Tissue culture cells C. Anaerobic broth D. Routine urine agar | back 454 B. Tissue culture cells — Chlamydia requires intracellular culture systems. |
front 455 A urine culture is collected for suspected cystitis. Why is the first portion of urine discarded? A. It lacks bladder organisms B. It contains urethral flora C. It kills anaerobes D. It prevents pyuria | back 455 B. It contains urethral flora — the urethra is colonized by bacteria. |
front 456 A urine specimen cannot be plated immediately. What should be done? A. Leave at room temperature B. Warm to 37°C C. Refrigerate or preserve D. Freeze before transport | back 456 C. Refrigerate or preserve — this prevents overgrowth before culture. |
front 457 Why should urine culture transport not be delayed? A. Pathogens grow in urine B. Urine rapidly clots C. NAATs become nonspecific D. Pyuria disappears instantly | back 457 A. Pathogens grow in urine — delay can falsely increase colony counts. |
front 458 A urine culture plate is inoculated with a calibrated loop. What volume is typically used? A. 1–10 µL B. 0.5–1 mL C. 5–10 mL D. 20–30 mL | back 458 A. 1–10 µL — measured inoculation allows colony quantification. |
front 459 Why is a measured urine volume plated for culture? A. Quantify organism burden B. Prevent oxygen exposure C. Detect exotoxin genes D. Remove urethral cells | back 459 A. Quantify organism burden — colony counts help judge significance. |
front 460 A symptomatic patient has pyuria but only low colony counts. How should this be interpreted? A. Always contamination B. Potentially significant C. Reject automatically D. Ignore without testing | back 460 B. Potentially significant — small numbers matter when pyuria is present. |
front 461 Most labs evaluating sexually transmitted urethritis focus on which pathogens? A. Gonorrhoeae and trachomatis B. Pneumococcus and Moraxella C. Mycobacteria and Nocardia D. Pseudomonas and Staph | back 461 A. Gonorrhoeae and trachomatis — NAATs commonly target these organisms. |
front 462 A man has dysuria and urethral discharge. Which urine specimen is preferred for GC/CT NAAT? A. Midstream urine B. First-void urine C. Refrigerated catheter urine D. Discarded first portion | back 462 B. First-void urine — urethritis organisms are captured early. |
front 463 A woman has suspected cystitis rather than urethritis. Which urine collection best reduces urethral contamination? A. First-void urine B. Midstream urine C. Eye aspirate D. Corneal scraping | back 463 B. Midstream urine — cystitis testing avoids urethral contamination. |
front 464 A patient has a painless genital chancre, but the suspected organism cannot be cultured. Which diagnostic approach is appropriate? A. Stool culture B. Darkfield or serology C. Blood agar culture D. Broth dilution | back 464 B. Darkfield or serology — Treponema pallidum cannot be cultured routinely. |
front 465 A spirochete is suspected in a syphilis lesion, but brightfield microscopy is negative. Why can this happen? A. Too thick B. Nonmotile organism C. Intracellular growth D. Too thin | back 465 D. Too thin — Treponema pallidum is too thin for brightfield microscopy. |
front 466 A clinician collects fluid from a suspected syphilitic chancre for microscopy. When should the exam be performed? A. After refrigeration B. After 24 hours C. At collection D. After freezing | back 466 C. At collection — T pallidum dies rapidly with air and drying. |
front 467 A stool specimen for enteric culture sits unprocessed for hours. Which change can harm pathogens such as Shigella? A. Alkaline shift B. Acidic shift C. Oxygen depletion D. Bile dilution | back 467 B. Acidic shift — bacterial metabolism acidifies stool and can kill Shigella. |
front 468 Why should stool specimens be transported promptly for culture? A. Prevent toxic pH changes B. Increase bacterial metabolism C. Preserve urine volume D. Prevent antibody loss | back 468 A. Prevent toxic pH changes — acidic changes can inhibit some enteric pathogens. |
front 469 A rectal swab is submitted for routine stool culture. Why is this specimen poor? A. Too anaerobic B. Too acidic C. Inadequate pathogen recovery D. Excessive stool volume | back 469 C. Inadequate pathogen recovery — rectal swabs are not ideal for stool culture. |
front 470 Transport of a stool specimen will be delayed. Which medium is appropriate? A. Chocolate agar B. Cary-Blair medium C. Thioglycolate broth D. Loeffler medium | back 470 B. Cary-Blair medium — delayed fecal specimens need preservative transport medium. |
front 471 Which preservative can be used for delayed stool transport? A. Phosphate-glycerol buffer B. Sheep blood agar C. Mueller-Hinton agar D. Sabouraud agar | back 471 A. Phosphate-glycerol buffer — phosphate buffer with glycerol helps preserve feces. |
front 472 A patient has rapid vomiting after reheated rice. Stool culture is negative for the causative organism. Why? A. Intracellular infection B. Preformed toxin disease C. Slow anaerobic growth D. Acid-fast organism | back 472 B. Preformed toxin disease — B cereus illness is toxin-mediated before ingestion. |
front 473 Which organisms are not expected in stool because illness is caused by preformed food toxin? A. Shigella, Salmonella B. Vibrio, Campylobacter C. S aureus, B cereus D. Giardia, Cryptosporidium | back 473 C. S aureus, B cereus — disease comes from toxin already in food. |
front 474 A clinician strongly suspects a specific unusual enteric pathogen. What should be done for optimal testing? A. Notify the laboratory B. Delay specimen transport C. Request rectal swab D. Avoid preservatives | back 474 A. Notify the laboratory — special media or tests may be required. |
front 475 Why can culture-based enteric pathogen identification take several days? A. Feces lacks bacteria B. Feces has mixed flora C. Culture is always anaerobic D. NAAT blocks growth | back 475 B. Feces has mixed flora — many normal and pathogenic bacteria are present. |
front 476 Which method is becoming preferred for broad enteric pathogen detection? A. High multiplex NAAT B. Gram stain only C. Blood culture D. Broth dilution | back 476 A. High multiplex NAAT — it is rapid and more sensitive than culture. |
front 477 High multiplex NAAT can detect common enteric pathogens directly from fecal swabs in what time? A. 24–48 hours B. 1–3 hours C. 3–5 days D. 2–4 weeks | back 477 B. 1–3 hours — multiplex NAAT gives results in hours. |
front 478 High multiplex NAAT is especially useful for pathogenic E coli because it can distinguish it from what? A. Normal enteric E coli B. C difficile toxin C. Acid-fast rods D. Anaerobic lung flora | back 478 A. Normal enteric E coli — pathogenic strains may resemble normal flora by culture. |
front 479 In a broth dilution test, antibiotics are prepared how? A. On paper disks B. In dilution series C. On corneal scrapings D. Inside blood bottles | back 479 B. In dilution series — serial antibiotic dilutions are inoculated with bacteria. |
front 480 Broth dilution testing is used to determine which value? A. O antigen B. Toxin titer C. MIC D. Capsule thickness | back 480 C. MIC |