Ch. 21-26

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Microbiology
Chapters 21-26
updated 6 years ago by kjansen01
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1

Normal flora for skin

  • Staphylococci
  • Micrococci
  • Diphtheroids
  • Gram-positive
  • Salt tolerant
2

Two types of bacteria that frequently cause skin disease

Staphylococcus

Streptococcus

3

Folliculitis

Infection of hair follicles

Sty

4

Acne

Most common skin problem (17 million affected)

Occurs when sebum channels are blocked with shed cells

Caused by Propionibacterium acnes

Best drug to treat with - Isotretinoin (serious side fx)

5

Chicken Pox

Transmitted via respiratory route

Pus-filled vesicles

Virus may remain latent in dorsal root ganglia

Much more severe in adults

Caused by Herpes Varicella-zoster virus

6

Smallpox

Extremely serious disease - very deadly in Middle Ages

Starts as respiratory, but leads to pox lesions on skin

Caused by Variola virus

First disease artificially controlled (vaccine)

First eradicated in 1977 in Africa

7

Cutaneous Mycoces

Infects epidermis, hair, nails

Dermatophytes: tineas or ringworm

Metabolizes keratin

Ringworm, jock itch, athlete's foot

Topical or oral treatment

8

Acanthamoeba kerititis

Transmitted from water

Associated with unsanitary contact lenses

9

Microbes can enter the Nervous System by:

  • Trauma (skull or bone fractures)
  • Medical procedures (spinal tap)
  • Along peripheral nerves (inner ear infection)
  • Blood or lymph
10

Meningitis

Inflammation of meninges

11

Encephalitis

Inflammation of the brain

12

Bacterial Meningitis

  • Fever, headache, stiff neck
  • Followed by nausea & vomiting
  • May progress to convulsions and coma
  • Diagnosis by Gram-stain of CSF
  • Treated with cephalosporins
13

Haemophilus influenzae Meningitis

  • Occurs mostly in children (6 mo - 4 yr)
  • Gram-neg aerobic bacteria
  • Normal flora for throat
  • Capsule antigen type B
  • Prevented by Hib vaccine
14

Neisseria Meningitis

  • Neisseria meningitidis
  • Gram neg. aerobic cocci, capsule
  • 10% are carriers of nasopharyngeal
  • Begins as throat infection and rash
  • Caused by endotoxins
  • Antibiotics for treatment
15

Streptococcus pneumoniae Meningitis

  • Gram-posi diplococci
  • 70% are carriers of nasopharyngeal
  • Most common in children (1 mo - 4 yr)
  • Mortality: 30% children, 80% elderly
  • Some antibiotic resistance
16

Listeriosis

  • Listeria monocytogenes
  • Gram-neg aerobic rod
  • Usually food borne (dairy products)
  • Can be transmitted to fetus
  • Reproduce in phagocytes
  • Shed in feces
17

Tetanus

  • Clostridium tetani
  • Gram-posi, endospore-forming, obligate anaerobe
  • Grows in deep wounds
  • Tetanospasmin released from dead cells blocks relaxation pathway in muscles
  • Spastic paralysis, lockjaw
  • Prevented by DTP vaccine and dT (10 years)
18

Botulism

  • Clostridium botulinum
  • Gram-posi, endospore-forming, obligate anaerobe
  • Intoxication due to ingesting botulinal toxin
  • Botulinal toxin blocks release of neurotransmitter causing flaccid paralysis
  • Very heat resistant
  • Nitrites kill, but are very carcinogenic
  • Treatment: supportive care and antitoxin
19

Leprosy

  • Mycobacterium leprae
  • Acid-fast rod that grows best at 30 deg celsius
  • Grows in peripheral nerves & skin cells
  • Transmission requires prolonged contact w/ infected person
20

Leprosy

  • Tuberculoid (neural) form: loss of sensation in skin areas & positive lepromin test
  • Lepromatous (progressive) form: Disfiguring nodules over body, negative lepromin test (hands and nose)
  • Treatment: combination of sulfur drugs
21

Cryptococcus neoformans Meningitis

  • Soil fungus assoc. w/ pigeon & chicken dropping
  • Transmitted by respiratory route
  • Spreads through blood to CNS
  • Mostly occurs in immunosuppressed
  • Treatment: amphotericin B & flucytosine
22

African Trypanosomiasis

  • Protozoan
  • Trypanosoma brucei gambiense is chronic (2 to 4 yr)
  • T.b. rhodesiense is more acute (few mo)
  • From blood to CNS
  • Dullness of mental ability, coma, death
  • Transmitted from animals to humans by tsetse fly
  • Prevention: elimination of the vector
  • Eflornithine blocks an enzyme necessary for the parasite
  • Parasite evades Ab through Ag variation
23

Prions

  • Self-replicating proteins with no detectable nucleic acid
  • Long incubation periods
  • Disease of the CNS that progresses slowly and causes spongiform degeneration
24

Sepsis & Septic Shock

  • Sepsis (septicemia): bacteria growing in blood
  • Severe sepsis: decrease in BP and dysfunction of at least one organ
  • Septic shock: Often occurs with septicemia (inflammation of lymph vessels and nodes)
  • Red streaks under skin
25

Sepsis

  • Gram-neg sepsis
  • E. coli, pseudomonas, enterobacter
  • Endotoxins cause BP decrease
  • Antibiotics can worsen condition by killing bacteria
  • Many are nosocomial (IV, catheter)
26

Sepsis

  • Gram-posi sepsis
  • Nosocomial
  • Staphylococcus areus
  • Streptococcus pyogenes
  • Group B streptococcus
  • Enterococcus faecium and E.faecalis
27

Endocarditis

Inflammation of the endocardium (inner layer)

28

Rheumatic Fever

  • Autoimmune complication of Streptococcus progenies infections
  • Starts as strep throat
  • Arthritis and fever
  • Can cause endocarditis
  • Usually 4-18 yr
29

Tularemia

  • Francisella tularensis, gram-neg rod
  • Transmitted from rabbits and deer by deer flies
  • Usually through skin breaks, aerosol or eat
  • Bacteria reproduce in phagocytes
30

Brucellosis (Undulant fever)

  • Brucella, gram-neg rods that grow in phagocytes
  • B. abortus most common (elk, bison, cows)
  • Undulating fever that spider to 40 deg celsius each evening
  • Transmitted vial milk from infected animals/contact
31

Anthrax

  • Bacillus anthracis, gram-posi, endospore-forming aerobic rod
  • Found in soil
  • Cattle routinely vaccinated
  • Treated w/ ciprofloxacin or doxycycline
  • Death due to exotoxins
32

Cutaneous Anthrax

  • Endospores enter through minor cut
  • 20% mortality
33

GI Anthrax

  • Ingestion of undercooked/contaminated food
  • 50% mortality
34

Inhalational Anthrax

  • Inhalation of endospores
  • 100% mortality
35

Gangrene

  • Ischemia
  • Loss of blood supply to tissue (anaerobic)
  • Necrosis (death of tissue)
  • Death of soft tissue
36

Gas Gangrene

  • Clostridium perfringens, gram-posi, endospore-forming anaerobic rod
  • Grows in necrotic tissue
  • Treatment: surgical removal of dead tissue and/or hyperbaric chamber
37

Lyme Disease

  • Organism - also Borrelia
  • Vector: tick
  • Reservoir: mice
  • Ticks feed on mice & then deer or human
  • Stages: rash, flu-like symptoms, heart problems, nervous signs may appear
38

Typhus

  • Rickettsia, obligate intracellular parasite
  • Causes several diseases
  • Vector: arthropod
  • Infects: endothelial cells of BV
  • Rocky Mtn. Spotted Fever
  • Rash, fever, headache, later kidney & heart failure
39

Infectious Mononucleosis

  • Epstein-Barr virus (HV4)
  • Acquired during childhood
  • Transmitted via saliva
  • Fever, sore throat, swollen lymph nodes
  • Immune to re-infection
  • Remains latent, always a carrier
40

Burkitt's Lymphoma

  • Cancerous tumors of jaw
  • EBV
  • Cancer in immunosuppressed individuals, malaria and AIDS patients
  • Mostly Africa
  • Nasopharyngeal carcinoma
  • Major cause of death in Asia
41

Cytomegalic Inclusion Disease

  • Cytomegalovirus (HV5)
  • Infected cells swell
  • Latent in WBC
  • May be asymptomatic or mild
  • Transmitted across placenta, can cause mental retardation
  • Sexually, blood, transplant can also transmit
  • AIDS patients at risk
42

Dengue Fever

  • Vector: mosquito
  • Also called breakbone fever: severe muscle and joint pain
  • Similar to Yellow Fever but milder
  • Endemic in Caribbean
43

Dengue Hemorrhagic Fever

  • Induces shock and fever
  • Die few hours after infection
  • Southeast Asia
44

Toxoplasmosis

  • Toxoplasma gondii
  • Reservoir: cats
  • Pass oocysts in feces to water or food
  • Uncooked meat, cat feces
  • Congenital damage to unborn fetus via placenta
45

Malaria

  • Plasmodium
  • Transmission: mosquito
  • Enters from mosquito saliva to blood stream and infects and reproduces in the blood cells, all burst open at once - severe fever
  • Treatment: quinine
  • No vaccine
46

Otitis Media

  • Common Cold
  • Rhinovirus
  • We tend to build up immunity to colds, as we get older we get fewer colds
47

Pertussis

  • Bordetella pertussis
  • Violent cough, gasping for air in between coughs, fever
  • Recovery can last for months
  • Severe in children >1 yr
  • Treated with Erythromycin
48

Bacterial pneumonias

  • Inflammation of lungs
  • Most pneumonias are bacterial in origin
49

Pneumonococcal pneumonia

  • Streptococcus pneumoniae
  • Gram-posi encapsulated diplococci
  • High fever, breathing difficulty, chest pain
  • Usually affects people w/ weakened immunity
  • Treated with penicillin
50

Mycoplasmal Pneumonia

  • Mycoplasmal pneumoniae
  • Pleomorphic, wall-less bacteria
  • Mild symptoms
  • Very hard to culture
  • Treated with tetracycline
51

Legionellosis

  • Legionella pneumophila
  • High fever, cough, general symptoms of pneumonia
  • Transmitted by water and AC
  • Treated with Erythromycin
52

Psittacosis (Ornithosis)

  • Chlamydia psittaci
  • Gram-neg, intracellular bacterium
  • Transmitted by elementary bodies from bird droppings to humans
  • Parakeets and parrots
  • Fever, headache, chills, delirium
  • Treated with tetracycline
53

Respiratory Syncytial Virus (RSV)

  • Common in infants
  • Causes cell fusion (syncytium) in cell culture
  • Symptoms: coughing
  • Diagnosis by serologic test for virus and Ab
  • Treated by Ribavirin
54

Influenza

  • Influenzavirus
  • Contains 8 separate RNA segments
  • Chills, fever, headache, general muscular aches
  • No GI symptoms
55

Influenza

  • Hemagglutinin (H) spikes used for attachment to host cells
  • Neuraminidase (N) spikes used to release virus from cell
  • Antigenic shift changes H and N spikes
  • Due to genetic recombination between diff. strains infecting same cells
  • Allows virus to avoid IgA Ab
56

Coccidioidomycosis

  • Coccidioides immitis
  • Transmitted by airborne arthrospores
  • Chest pain, fever, coughing, weight loss
  • Strong resemblance to TB
  • Treated by Amphotericin B
57

Coccidioidomycosis

  • Pneuomocystis Pneumonia
  • Pneumocystis jiroveci (P.carinii) found in healthy human lungs
  • Occurs in newly infected infants and immunosuppressed
58

Dental Caries

  • Streptococcus mutants: worst organism to break down enamel
  • Bacteria convert sucrose into lactic acid and erodes tooth enamel
59

Saliva functions

  • Breakdown CHO
  • Neutralizes acids
  • Washes away bacteria
  • Lubrication
60

Gingivitis

  • Periodontal disease in the gums
  • Symptoms: bleeding gums after brushing
61

Staphylococcal food poisoning

  • Staphylococcus aureus
  • Leading cause of gastroenteritis
  • Can tolerate high osmotic pressure
  • Enterotoxins are superantigens
  • Toxin is durable and can stand reheating once formed
  • Vomiting, cramps, diarrhea
  • Recover in 24 hours
62

Salmonellosis

  • Salmonella enterica- various strains
  • Second most common food poisoning
  • Mortality (<1%) due to septic shock caused by endotoxin
  • High risk foods: meat products, poultry, eggs
  • Also infection from reptiles
  • Incubation: 12-36 hours
  • Abdominal pain and diarrhea
  • Cook food thoroughly to prevent
63

Escherichia coli Gastroenteritis

  • Escherichia coli
  • Occurs as traveler's diarrhea and epidemic diarrhea in nurseries
  • Diarrhea is symptom
  • Enterohorrhagic strains such as E. coli O157 produce Shiga toxin
  • Treatment: Oral rehydration and self-limits
64

Hepatitis B

  • Hepatitis B Virus (HBV)
  • Transmitted by transfusion, IV drug use, sex
  • Incubates for 3 mo
  • Symptoms vary, may be mild - loss of appetite, low fever, joint pain
  • Fever, nausea, jaundice
65

Hepatitis B

  • Most people recover
  • Complications: chronic carrier (10%) and liver cancer
  • Treated by vaccine
66

Hepatits C

  • Hepatits C Virus (HCV)
  • IV drug use most common way to transmit
  • Mild symptoms, 85% of patients develop chronic hepatitis
  • May lead to cirrhosis of liver/ liver cancer
  • Treated with interferons
67

Hepatitis D

  • Hepatitis D Virus (HDV)
  • Person has to be infected with HBV
  • Chronic HBV w/ HDV - superinfection
  • Increases mortality rate
68

Hepatits E

  • Hepatitis E Virus (HEV)
  • Transmitted by fecal-oral route
  • Resembles HAV
  • No chronic cases
  • Treated by self-limiting
69

Norovirus

  • 50% of US Adults have Ab
  • 1-2 day incubation, 1-3 day illness
  • Treated with rehydration
70

Tapeworms

  • Taenia spp.
  • Life cycle w/ three stages
  • Egg: excreted in feces and ingested by animal
  • Cysticerci: in muscle of animal
  • Adult tapeworm
71

Tapeworms

  • Transmitted as cysticerci in undercooked food
  • Diagnosed by observing proglottids and eggs in feces
  • Treated with praziquantel
  • Cysticerci may develop in humans
  • Neruocysticercosis may require surgery
72

Ascariasis

  • Ascaris lumbricoides
  • Lives in human intestines
  • Transmitted by ingesting Ascaris eggs
73

Cystitis

  • Inflammation of urinary bladder
  • Common in females
  • Usually caused by E.coli or S. saprophyticus
  • Painful urination and leukocytes in urine
  • Treated with Ampicillin
74

Gonorrhea

  • Neisseria gonorrhoeae
  • Attaches to oral pharyngeal area, eyes, rectum, urethra, opening of cervix, external genitals by fimbrae
  • Females may be asymptomatic, males have painful urination and pus discharge
  • Treatment with Ab
  • Untreated may result in endocarditis, meningitis, arthritis
  • Can be transmitted to newborn's eyes
75

Nongonococcal Urethritis

  • Chlamydia trachomatis
  • May be transmitted to newborn's eyes
  • Painful urination and watery discharge
  • Symptoms are mild & patients don't know they have it
  • Males: inflammation of epididymis
  • Females: inflammation of uterine tubes
  • Treated with tetracycline
76

Syphilis

  • Treponema pallidum (spirochete)
  • Transmitted by direct contact and can invade intact mucous membranes or penetrate through breaks in skin
  • Primary stage: chancre at site of infection
  • Secondary: skin and mucosal rashes
  • Laten period: no symptoms
  • Tertiary: gummas on many organs
  • Congenital: neurological damage
  • Primary & secondary stages treated with penicillin
77

Genital Herpes

  • Herpes simplex virus 2
  • Lesions appear after incubation period of one week
  • Urination can be painful, walking is uncomfortable, even clothing is uncomfortable
  • Recurrences from virus latent in nerves
  • Triggered by stress, illness or scratching area
  • Suppressed by acyclovir or valacyclovir
78

AIDS

  • Usually sexually transmitted
  • Attacks immune system
  • Lesions from other infections increase spread
  • No cure