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Microbio exam 3 > Bact GI 3 > Flashcards

Bact GI 3 Flashcards

1
Q

Describe The characteristics of the Vibrio spp.

A
  • Gram-negative, Facultative anaerobes
  • CURVED SHAPED (comma’s)
  • Free-living in water
  • Broad temp. range of growth
  • Broad pH range of growth
  • REQUIRE SODIUM CHLORIDE for growth
  • *SMALL INTESTINE DISEASE**
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2
Q

Describe the clinical manifestations of Vibrio Cholerae

A

Causes Cholera:

  • Ranges from Asymptomatic to SEVERE watery Diarrhea
  • 2 to 3 day incubation
  • lasts up to 7 days
  • *5-25% develop SEVERE Watery diarrhea**
  • ABRUPT onset
  • 150lb person loses 4.5 gallons a day
  • RICE WATER STOOL
  • CAN kill within hours via dehydration
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3
Q

Describe the Pathogenesis of Vibrio Cholerae

A

1) TOXIN co-regulated pilus (TCP) mediates adherence to intestinal epithelial cells
2) Cholera toxin is produced
- AB toxin that activates adenylate cyclase which increase cAMP which causes massive efflux of watery secretions
- NO CELL DAMAGE
- SIMILAR to ETEC LT toxin

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4
Q

Describe the diagnosis and treatment of Vibrio cholerae

A

DIAGNOSIS: culture on differential media
TREATMENT: rehydration therapy via IV and oral
- without rehydration, mortality can be as high as 90%

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5
Q

Describe Vibrio parahaemolyticus

A

INFLAMMATORY SMALL INTESTINE DISEASE
- Explosive watery diarrhea, nausea, vomiting, abdominal cramps, low grade fever
VIRULENCE = Kanagawa hemolysin - induces chloride secretion thus watery diarrhea
EPIDEMIOLOGY = associated with consumption of raw shellfish
TREATMENT/PREVENTION = Self-limiting and proper cooking of shellfish

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6
Q

Describe Yersinia enterocolitica

A
  • Gram negative coccobacilli
    INFLAMMATORY SMALL INTESTINE
  • Due to heat-stable ENTEROTOXIN
  • Fever, abdominal cramps, watery or bloody diarrhea
  • lasts 1-2 weeks
    DIAGNOSIS = Culture of stool
    TREATMENT = self-limiting
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7
Q

Describe the characteristics of Clostridium difficile

A
  • Gram Positive anaerobe
  • NON-invasive
  • SPORE FORMING
  • *INFLAMMATORY LARGE INTESTINE DISEASE**
  • disease and symptoms vary
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8
Q

Describe the clinical manifestations of Clostridium difficile: C. Difficile-associated diarrhea (CHAD)

A

DIARRHEA = watery diarrhea, feval leukocytes, occult blood sometimes seen

  • Nausea, anorexia, fever, malaise, dehydration, leukocytosis with left shift
  • Abdominal distention and tenderness
  • Diffuse or patchy nonspecific colitis in sigmoidoscopic exam
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9
Q

Describe the clinical manifestations of Clostridium difficile: Pseudomembrane colitis

A

DIARRHEA = profuse watery diarrhea, fecal leukocytes, occult blood sometimes seen

  • More severe symptoms than CHAD (same)
  • Marked abdominal distention, tenderness
  • Sigmoidoscopic exam reveals raised, adherent yellow plaques
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10
Q

Describe the clinical manifestations of Clostridium difficile: Fulminant colitis

A

DIARRHEA = severe or diminished

  • lethargy, fever, tachycardia, may observe dilated colon on abdominal film
  • May present as sudden, severe abdominal pain
  • sigmoidoscopic exam is contraindicated
  • surgical consult required.
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11
Q

Describe the pathogenesis of Clostridium difficile

A
  • Toxin A and Toxin B cause damage to mucosa –> disrupts host cell cytoskeleton = diarrhea
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12
Q

Describe the diagnosis and treatment of clostridium difficile

A

DIAGNOSIS: toxin detection in stool (culture NOT helpful)
TREATMENT = oral VANCOMYCIN or METRONIDAZOLE
PREVENTION = fecal transplant

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13
Q

Describe the characteristics of Intestine Enterohemorrhagic E. Coli (EHEC)

A
  • Gram Negative, Facultate anaerobe
  • O157:H7 (binding site)
  • Animal reservoirs = cattle or other ruminants
  • Generally NON-invasive
  • *INFLAMMATORY LARGE INTESTINE DISEASE)
  • associated with contaminated ground beef and vegitables
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14
Q

Describe the Clinical Manifestations of EHEC

A
  • Hemorrhagic colitis = bloody diarrhea
  • NO FEVER, marked abdominal tenderness
  • Sequelae - hemolytic uremic syndrome (HUS) = anemia and kidney failure
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15
Q

Describe the pathogenesis of EHEC

A

1) E. Coli O157:H7 binds to brush border of intestinal mucosa
2) E. Coli O157:H7 produces verotoxin that destroy microvilli
3) Verotoxin enters blooding causing vascular endothelial damage and increasing platelet aggregation
4) platelet-fibrin thrombi form causing ischemic damage to colon, kidney and other tissues (Hemorrhagic colitis and Hemolytic Uremic syndrome)

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16
Q

Describe the Diagnosis and Treatment of EHEC

A

DIAGNOSIS: Presumptive = bloody diarrhea WITHOUT fever
- Culture
- PCR to detect stx gene that encodes toxin
- Rapid diagnostic test kit
TREATMENT: Supportive therapy
- Antibiotic therapy NOT BENEFICIAL due to increasing HUS rate
PREVENTION = properly cook hamburger/ cooking raw vegitables

17
Q

Describe the characteristics of Shigella Spp.

A
  • Gram negative Rods, facultative anaerobe
  • INTRACELLULAR pathogens
  • Dysentery
    • INFLAMMATORY LARGE INTESTINE DISEASE**
  • humans are the only reservoir with transmission through fecal-oral route
  • incidence due to poor sanitation (day care centers, poorly sanitized infrastructure)
  • very little of it needed
18
Q

Describe Clinical manifestations of Shigella Spp.

A

Shigellosis: 1-3 days post ingestion
- Disease is self-limiting (2-5 days post manifestation)
STRAIN SPECIFIC:
- S. Sonneii = Fever, malaise, watery diarrhea (1st world countries)
- S. Flexerni and S. Dysenteriae = Dysentery (fever, malaise, watery diarrhea, abdominal cramps, tenesmus, frequent bloody and pus filled stools) –> 2nd or 3rd world

19
Q

Describe the pathogenesis of Shigella spp.

A
  • Acid Resistant*
    1) adhere selectively to and pass through M-cells
    2) phagocytosis by macrophages
    4) Rapid induction of macrophage apoptosis (programmed cell death)
    6) induce uptake via T3SS (injection of Ipa proteins which induce cytoskeletal rearrangement)
    8) spread to neighboring cells via actin polymerization at a pole (evasion of host defenses
    9) Enterocyte escape/invasion leads to cell death
  • ->ulcers form in infected area
  • -> diarrhea primarily from severe inflammation
  • -> Shiga toxin production (Stx) which inhibits translation and results in cell/tissue death
20
Q

Describe the diagnosis and treatment of Shigella spp.

A

DIAGNOSIS: stool culture using selective media or serological tests to confirm species
TREATMENT: Rehydration therapy
- Antibiotic treatment to shorten duration of illness or limit severity
PREVENTION: NO VACCINE
- improve sanitation and personal hygiene

21
Q

Describe Enteroinvasive E. Coli (EIEC)

A

INFLAMMATORY LARGE INTESTINE DISEASE
- watery to bloody/pus diarrhea
- similar to shigella spp. but no shiga toxin
- FEVER, fecal leukocytes
VERY UNCOMMON

Microbio exam 3 (5 decks)

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