Micro 17 Flashcards

Most cell wall–active antibiotics belong to which class?

A. Aminoglycosides

B. β-lactams

C. Macrolides

D. Fluoroquinolones

Which drug group contains β-lactam antibiotics?

A. Penicillins, cephalosporins, carbapenems, monobactams

B. Glycopeptides, lipopeptides, polymyxins, rifamycins

C. Macrolides, tetracyclines, aminoglycosides, oxazolidinones

D. Sulfonamides, trimethoprim, quinolones, nitroimidazoles

What is most bacterial cell walls’ major component?

A. Lipopolysaccharide

B. Teichoic acid

C. Peptidoglycan

D. Mycolic acid

Peptidoglycan contains alternating NAG and what?

A. N-acetylmuramic acid

B. Lipid A

C. Teichoic acid

D. Arabinogalactan

NAG stands for which molecule?

A. N-acetylmuramic acid

B. N-acetylglucosamine

C. N-formylmethionine

D. N-acetylgalactosamine

β-lactams primarily target which bacterial proteins?

A. Ribosomal proteins

B. DNA gyrases

C. Penicillin-binding proteins

D. Folate enzymes

PBPs primarily perform which cell-wall function?

A. Peptidoglycan cross-linking

B. Lipopolysaccharide synthesis

C. Mycolic acid synthesis

D. Protein translation

β-lactam antibiotics are generally what?

A. Bacteriostatic

B. Fungicidal

C. Virustatic

D. Bactericidal

Which bacteria possess an outer membrane?

In Gram-negative bacteria, the outer membrane lies where?

A. Beneath cytoplasmic membrane

B. Within peptidoglycan

C. Outside peptidoglycan

D. Inside nucleoid

What does minimum inhibitory concentration (MIC) represent?

A. Lowest growth-inhibiting concentration

B. Lowest lethal serum concentration

C. Highest tolerated drug concentration

D. Peak bactericidal concentration

What does minimum bactericidal concentration (MBC) represent?

A. Lowest concentration preventing division

B. Highest concentration permitting growth

C. Lowest concentration killing 99.9%

D. Median inhibitory drug concentration

Which β-lactamase class includes TEM-1?

Which β-lactamase class includes SHV-1?

TEM-1 and SHV-1 primarily function as what?

A. Carbapenemases

B. Penicillinases

C. Cephalosporinases

D. Metalloenzymes

TEM-1 and SHV-1 commonly occur in what?

_____-_____ _____

Which organisms commonly harbor TEM-1 or SHV-1?

A. Escherichia and Klebsiella

B. Staphylococcus and Streptococcus

C. Bacillus and Clostridium

D. Mycoplasma and Chlamydia

Typical TEM-1 and SHV-1 have what cephalosporin activity?

A. Extensive

B. Minimal

C. Exclusive

D. Irreversible

Which β-lactamases require zinc?

Class B β-lactamases are also called what?

A. Penicillinases

B. Metallo-β-lactamases

C. Cephalosporinases

D. Serine carbapenemases

Which β-lactamases commonly hydrolyze carbapenems?

A. Class B enzymes

B Class A enzymes

C. Only TEM-1 enzymes

D. Only SHV-1 enzymes

Which β-lactamase class is primarily cephalosporinase?

A. Class D

B. Class A

C. Class C

D. Class B

Class C β-lactamases are commonly encoded where?

A. Plasmid

B. Bacterial chromosome

C. Viral genome

D. Mitochondrial DNA

Class C enzymes can hydrolyze which drugs?

A. Expanded-spectrum cephalosporins

B. Aminoglycosides

C. Fluoroquinolones

D. Glycopeptides

Class C β-lactamase expression is usually what?

A. Maximally constitutive

B. Completely absent

C. Generally repressed

D. Permanently induced

Exposure to certain beta-lactam antibiotics can induce the expression of which resistance mechanism in bacteria?

A. Ribosomal mutation

B. AmpC beta-lactamase enzyme production

C. Cell membrane depolarization

D. Folate synthesis pathway inhibition

Mutations regulating class C enzymes may cause what?

A. Increased enzyme expression

B. Loss of peptidoglycan

C. Reduced chromosome replication

D. Decreased porin synthesis

Which β-lactamase class contains many penicillinases?

A. Class B

B. Class C

C. Class D

D. None

Class D β-lactamases occur mainly in what?

____-____ ____

Penicillins inhibit cell-wall synthesis by binding what?

A. PBPs

B. Ribosomes

C. DNA gyrase

D. RNA polymerase

Cephalosporins primarily inhibit which process?

A. Protein elongation

B. Folate synthesis

C. Peptidoglycan synthesis

D. DNA replication

Carbapenems act primarily through what target?

A. PBPs

B. Topoisomerases

C. Ribosomal RNA

D. Ergosterol

Monobactams primarily inhibit what?

A. Mycolic acid formation

B. Peptidoglycan synthesis

C. Protein translation

D. Folate metabolism

β-lactamase inhibitors primarily prevent what?

A. Ribosomal inhibition

B. Membrane depolarization

C. Enzymatic β-lactam destruction

D. Folate synthesis

Vancomycin inhibits which bacterial structure?

A. Peptidoglycan cell wall

B. Outer membrane LPS

C. Cytoplasmic ribosomes

D. DNA gyrase

Vancomycin ultimately prevents which process?

A. DNA supercoiling

B. Peptidoglycan cross-linking

C. Ribosomal translocation

D. Mycolic acid oxidation

Daptomycin primarily targets which structure?

A. Cell wall peptidoglycan

B. Cytoplasmic membrane

C. Bacterial ribosome

D. Folate pathway

Daptomycin killing results from disruption of what?

A. Ionic concentration gradients

B. DNA nucleotide pools

C. Peptide cross-links

D. Folate intermediates

Which drug blocks transport of peptidoglycan precursors?

A. Vancomycin

B. Daptomycin

C. Bacitracin

D. Ethambutol

Bacitracin interferes with which carrier process?

A. Peptidoglycan precursor movement

B. Ribosomal peptide transfer

C. DNA strand separation

D. Folate precursor uptake

Polymyxins primarily disrupt which bacterial structure?

A. Ribosomes

B. Membranes

C. Peptidoglycan

D. Nucleoid

Which drugs inhibit mycolic acid synthesis?

A. Isoniazid and ethionamide

B. Ethambutol and rifampin

C. Vancomycin and bacitracin

D. Daptomycin and polymyxin

Isoniazid primarily inhibits synthesis of what?

A. Arabinogalactan

B. Peptidoglycan

C. Mycolic acids

D. Lipopolysaccharide

Ethambutol primarily inhibits synthesis of what?

A. Mycolic acids

B. Arabinogalactan

C. Peptidoglycan

D. Lipid A

Which antibiotic inhibits early peptidoglycan precursor synthesis?

A. Cycloserine

B. Rifampin

C. Dapsone

D. Clindamycin

Cycloserine ultimately interferes with synthesis of what?

A. Mycolic acid

B. Peptidoglycan

C. Folic acid

D. Lipopolysaccharide

Aminoglycosides primarily bind which ribosomal subunit?

Which effect is associated with aminoglycoside binding?

A. Premature peptide termination

B. Folate pathway inhibition

C. DNA strand breakage

D. Cell-wall cross-linking

Tetracyclines inhibit protein synthesis at which subunit?

Tetracyclines prevent protein synthesis by blocking what?

A. Transcription initiation

B. DNA supercoiling

C. Polypeptide elongation

D. Peptidoglycan cross-linking

Glycylcyclines bind which bacterial ribosomal subunit?

A. 30S

B. 50S

C. 40S

D. 60S

Glycylcyclines primarily interfere with which process?

A. DNA replication

B. Peptide elongation

C. Cell-wall synthesis

D. RNA transcription

Oxazolidinones act primarily at which subunit?

Oxazolidinones inhibit which stage of translation?

A. Initiation

B. Elongation

C. Termination

D. Translocation

Which drugs inhibit elongation at 50S?

A. Tetracyclines and aminoglycosides

B. Macrolides and clindamycin

C. Quinolones and rifamycins

D. Sulfonamides and trimethoprim

Which group acts primarily on the 50S subunit?

A. Aminoglycosides, tetracyclines, glycylcyclines

B. Quinolones, rifamycins, metronidazole

C. Macrolides, ketolides, streptogramins

D. Sulfonamides, dapsone, trimethoprim

Quinolones primarily inhibit which bacterial enzyme?

A. RNA polymerase

B. DNA gyrase

C. Transpeptidase

D. Dihydrofolate reductase

Quinolones interact with which DNA gyrase subunit?

A. Alpha subunit

B. Beta subunit

C. Gamma subunit

D. Delta subunit

Rifampin inhibits which bacterial process?

A. Translation

B. Transcription

C. Transpeptidation

D. Folate synthesis

Rifampin and rifabutin bind which enzyme?

A. DNA gyrase

B. Topoisomerase IV

C. DNA-dependent RNA polymerase

D. Dihydrofolate reductase

Metronidazole exerts antimicrobial activity by damaging what?

A. Ribosomal RNA

B. Cytoplasmic membrane

C. Peptidoglycan

D. Bacterial DNA

Which enzyme is inhibited by sulfonamides?

A. Dihydropteroate synthase

B. Dihydrofolate reductase

C. DNA gyrase

D. RNA polymerase

Sulfonamides disrupt synthesis of which compound?

A. Mycolic acid

B. Folic acid

C. Peptidoglycan

D. Arabinogalactan

Dapsone inhibits which enzyme?

A. DNA gyrase

B. RNA polymerase

C. Dihydropteroate synthase

D. Dihydrofolate reductase

Trimethoprim inhibits which enzyme?

A. Dihydrofolate reductase

B. Dihydropteroate synthase

C. DNA gyrase

D. Transpeptidase

Trimethoprim ultimately disrupts synthesis of what?

A. Mycolic acid

B. Folic acid

C. Peptidoglycan

D. Lipid A

Which drugs sequentially inhibit bacterial folate metabolism?

A. Dapsone and rifampin

B. Tetracycline and trimethoprim

C. Sulfonamide and trimethoprim

D. Quinolone and sulfonamide

The β-lactam ring of penicillins is fused to what?

A. Dihydrothiazine ring

B. Thiazolidine ring

C. Imidazole ring

D. Pyrimidine ring

Which structure forms the penicillin nucleus?

A. 6-aminopenicillanic acid

B. 7-aminocephalosporanic acid

C. Dihydrofolic acid

D. N-acetylmuramic acid

Which natural penicillin is acid-labile?

A. Penicillin V

B. Oxacillin

C. Penicillin G

D. Methicillin

Why is penicillin G poorly suited for oral use?

A. Rapid renal clearance

B. Gastric acid inactivation

C. Hepatic first-pass metabolism

D. Poor tissue distribution

Which penicillin is relatively acid stable?

A. Penicillin V

B. Penicillin G

C. Methicillin

D. Nafcillin

Which penicillin is preferred orally for susceptible infections?

A. Penicillin G

B. Oxacillin

C. Penicillin V

D. Methicillin

Which drugs are penicillinase-resistant penicillins?

A. Ampicillin and amoxicillin

B. Methicillin and oxacillin

C. Penicillin G and V

D. Piperacillin and ticarcillin

Penicillinase-resistant penicillins primarily target susceptible what? ______

What is the primary rationale for co-administering a beta-lactamase inhibitor with a penicillin-class antibiotic?

A. To prevent enzymatic hydrolysis of the beta-lactam ring

B. To enhance antibiotic binding affinity to 30S bacterial ribosomes

C. To inhibit bacterial folate synthesis pathways

D. To induce rapid cell membrane depolarization

Which structure forms the cephalosporin nucleus?

A. 6-aminopenicillanic acid

B. 7-aminocephalosporanic acid

C. N-acetylmuramic acid

D. Dihydrofolic acid

The β-lactam ring of cephalosporins is fused to what?

A. Thiazolidine ring

B. Pyridine ring

C. Dihydrothiazine ring

D. Imidazole ring

Cephamycins differ structurally from cephalosporins by containing what?

A. Oxygen substitution

B. Zinc substitution

C. Nitrogen substitution

D. Phosphate substitution

The cephamycin structural modification increases resistance to what?

A. Ribosomal degradation

B. β-lactamase hydrolysis

C. Renal elimination

D. Gastric acid secretion

Cephalosporins share their mechanism with which drugs?

A. Quinolones

B. Aminoglycosides

C. Penicillins

D. Sulfonamides

Cephalosporins and penicillins primarily inhibit what?

A. Peptidoglycan synthesis

B. Protein translation

C. DNA replication

D. Folate metabolism

Compared with penicillins, many cephalosporins generally have what?

A. Narrower antibacterial spectra

B. Wider antibacterial spectra

C. Greater acid instability

D. Less β-lactamase resistance

Cephalosporins commonly show improved resistance to what?

A. DNA gyrase mutations

B. Ribosomal methylation

C. Many β-lactamases

D. Folate antagonists

Compared with penicillins, cephalosporins generally have greater activity against what?

Gram-______ bacteria

First-generation cephalosporins cover which gram-negative trio?

____ ____, ____, ____

First-generation cephalosporins also cover susceptible what?

_____-_____ _____

Which Proteus species is classically first-generation susceptible?

A. Proteus vulgaris

B. Proteus penneri

C. Proteus mirabilis

D. Providencia stuartii

Which cephalosporin generation expands H. influenzae coverage?

A. First

B. Third

C. Fourth

D. Second

Second-generation cephalosporins may cover which organisms?

______, ______, ______

Which second-generation subgroup adds Bacteroides fragilis coverage?

A. Carbapenems

B. Cephamycins

C. Monobactams

D. Glycopeptides

Which cephalosporin generations have broad Enterobacteriaceae activity?

A. First and second

B. Second and third

C. Third and fourth

D. First and fourth

Which third-generation cephalosporin covers Pseudomonas?

A. Ceftriaxone

B. Cefotaxime

C. Cefixime

D. Ceftazidime

Which fourth-generation cephalosporin covers Pseudomonas?

A. Cefepime

B. Cefazolin

C. Cefoxitin

D. Cefuroxime

How are carbapenems generally classified?

A. Narrow-spectrum

B. Broad-spectrum

C. Antifungal

D. Bacteriostatic

Monobactams primarily cover which organisms?

______ gram-______ bacteria

Monobactams generally lack activity against what?

Gram-_______ and _______ organisms

Which carbapenemase class includes KPC enzymes?

Which carbapenemase class contains metallo-β-lactamases?

Class B carbapenemases require which cofactor?

Metallo-β-lactamases are widely distributed among what?

A. Gram-positive cocci

B. Acid-fast bacilli

C. Spirochetes

D. Gram-negative bacteria

Class D carbapenemases are especially associated with what?

A. Acinetobacter

B. Streptococcus

C. Enterococcus

D. Clostridium

Vancomycin binds which peptidoglycan terminus?

A. D-Ala-D-Lac

B. D-Ala-D-Ala

C. NAG-NAM

D. L-Ala-D-Glu

Vancomycin binding primarily prevents what?

A. DNA replication

B. Protein translation

C. Peptidoglycan cross-linking

D. Folate synthesis

Why is vancomycin ineffective against gram-negative bacteria?

A. Rapid drug efflux only

B. Target lacks D-alanine

C. Drug destroyed by porins

D. Cannot cross outer membrane

Which structure prevents vancomycin reaching its target?

A. Outer membrane

B. Cytoplasmic ribosome

C. Bacterial capsule

D. Flagellar sheath

Why are gram-negative bacteria intrinsically daptomycin resistant?

A. They lack cytoplasmic membranes

B. Drug cannot reach membrane

C. They destroy calcium

D. They lack phospholipids

Daptomycin is active against resistant forms of what?

_____-_____ _____

Which organisms are typically daptomycin susceptible?

A. Staphylococci, streptococci, enterococci

B. Neisseria, Pseudomonas, Bacteroides

C. Mycoplasma, Chlamydia, Legionella

D. Salmonella, Shigella, Campylobacter

Daptomycin can treat strains resistant to what?

_____

Which antibiotic is commonly used topically?

A. Cefepime

B. Daptomycin

C. Bacitracin

D. Meropenem

Topical bacitracin primarily targets which organisms?

A. Gram-negative bacilli

B. Acid-fast bacilli

C. Anaerobic spirochetes

D. Gram-positive bacteria

Bacitracin is especially active against which pathogens?

A. Staphylococci and group A streptococci

B. Pseudomonas and Acinetobacter

C. Neisseria and Moraxella

D. Bacteroides and Prevotella

Bacitracin inhibits recycling of which molecule?

A. Ribosomal protein

B. Lipid carrier

C. Folate carrier

D. DNA helicase

The bacitracin-sensitive lipid carrier transports what?

A. Amino acids into ribosomes

B. DNA fragments into cells

C. Peptidoglycan precursors across membrane

D. Folate into cytoplasm

Bacitracin inhibits which lipid-carrier step?

A. Dephosphorylation and recycling

B. Glycosylation and cleavage

C. Acetylation and secretion

D. Oxidation and reduction

Which polymyxin is also called colistin?

A. Polymyxin A

B. Polymyxin E

C. Polymyxin C

D. Polymyxin D

Which serious toxicity is associated with polymyxins?

A. Nephrotoxicity

B. Hepatotoxicity

C. Cardiotoxicity

D. Retinotoxicity

Polymyxins exert antibacterial activity primarily by disrupting what?

A. Ribosomes

B. Folate synthesis

C. Bacterial membranes

D. DNA replication

Polymyxins interact with which outer-membrane components?

A. Peptidoglycan and teichoic acid

B. LPS and phospholipids

C. Mycolic acid and arabinogalactan

D. Porins and flagellin

Polymyxin insertion produces which cellular consequence?

A. Reduced membrane permeability

B. Inhibited folate uptake

C. Increased membrane permeability

D. Blocked ribosomal assembly

What is the most common aminoglycoside resistance mechanism?

A. Target methylation

B. Active drug efflux

C. Enzymatic drug modification

D. Reduced folate synthesis

Mutation of which porin can reduce tetracycline entry?

A. OmpF

B. OmpA

C. PhoP

D. TolC

What is the most common tetracycline resistance mechanism?

A. Ribosomal destruction

B. Drug acetylation

C. Active drug efflux

D. Folate overproduction

Which drug blocks formation of the translation initiation complex?

A. Linezolid

B. Clindamycin

C. Doxycycline

D. Gentamicin

Linezolid acts primarily at which ribosomal subunit?

Linezolid prevents assembly involving which components?

A. DNA, helicase, polymerase

B. tRNA, mRNA, ribosome

C. NAG, NAM, transpeptidase

D. PABA, folate, reductase

Which broad-spectrum antibiotic can cause aplastic anemia?

A. Azithromycin

B. Chloramphenicol

C. Doxycycline

D. Linezolid

Why is chloramphenicol rarely used systemically in the United States?

A. Severe marrow toxicity

B. Universal bacterial resistance

C. Poor oral absorption

D. Rapid renal elimination

Which rRNA modification commonly causes macrolide resistance?

A. 16S acetylation

B. 23S methylation

C. 5S phosphorylation

D. 18S hydroxylation

23S rRNA methylation causes macrolide resistance by doing what?

A. Increasing drug degradation

B. Blocking antibiotic binding

C. Enhancing drug uptake

D. Destroying ribosomal RNA

Most gram-negative bacteria have limited susceptibility to which class?

A. Macrolides

B. Carbapenems

C. Aminoglycosides

D. Polymyxins

Which resistance mechanism also commonly affects clindamycin?

A. 23S rRNA methylation

B. DNA gyrase mutation

C. β-lactamase production

D. Porin overexpression

Quinupristin-dalfopristin is especially useful against which organism?

A. Vancomycin-resistant E. faecalis

B. Methicillin-resistant S. aureus

C. Vancomycin-resistant E. faecium

D. Penicillin-resistant S. pneumoniae

What is the main quinolone target in gram-negative bacteria?

A. Topoisomerase I

B. DNA gyrase A

C. RNA polymerase

D. Topoisomerase IV

What is the main quinolone target in gram-positive bacteria?

A. DNA gyrase B

B. RNA polymerase

C. Topoisomerase IV

D. Dihydrofolate reductase

Quinolone resistance commonly involves mutations in which genes?

A. PBPs and porins

B. Gyrase and topoisomerase IV

C. Ribosomes and transpeptidases

D. Folate and RNA polymerase

Reduced uptake limits rifampin activity against many what?

gram-_____ bacteria

Rifabutin is particularly active against which organism?

A. M. leprae

B. M. avium

C. M. kansasii

D. M. marinum

Sulfonamides competitively inhibit utilization of what substrate?

A. D-alanine

B. PABA

C. Arginine

D. Glutamine

Sulfonamides ultimately interfere with synthesis of what?

A. Peptidoglycan

B. Mycolic acid

C. Folic acid

D. Lipopolysaccharide

Which antimicrobial is a key component of multidrug leprosy therapy?

A. Clofazimine

B. Pyrazinamide

C. Rifabutin

D. Ethionamide

Clofazimine has important activity against which pathogen?

A. M. avium

B. M. leprae

C. M. kansasii

D. M. marinum

Which tuberculosis drug works especially well at acidic pH?

A. Rifampin

B. Ethambutol

C. Pyrazinamide

D. Streptomycin

Pyrazinamide is particularly active in which intracellular environment?

A. Neutral cytosol

B. Acidic phagolysosomes

C. Alkaline mitochondria

D. Extracellular plasma

Which drug’s activity is enhanced within acidic phagolysosomes?

A. Pyrazinamide

B. Rifabutin

C. Clofazimine

D. Dapsone