Vibrio cholera - MegaMicro

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Vibrio cholera

Microbiology > Bacteriology > Gram-negative bacteria > Gram-negative bacilli > Vibrio
·    Biology
o   Gram negative, comma-shaped bacterium
o   Natural habitat: salty water
§  Flourish in waters with shellfish
o   Can undergo respiratory & fermentative metabolism
o   Subdivided based on O antigens
·     Virulence factors
o   Pathogenicity genes code proteins involved in virulence (genes on bacteriophage)
o   Cholera toxin – AB5 toxin
§  Protein
§  Causes “rice water stool” (watery diarrhea)
§  Toxin ribosylates Gs à ↑[cAMP] à ↑Cl- secretion à Osmotic loss of water à Watery diarrhea and dehydration à Untreated à Hypovolemic shock and death
o   TCP: toxin co-regulated pilus
o   Some strains may produce additional toxins
o   Flagella for motility
o   2nd leading cause of death for children under 5
·     Symptoms of infection
o   Can range from asymptomatic to profuse diarrhea
o   Abrupt onset
o   Occasional vomiting & abdominal cramps
o   May lead to: dehydration, thirst, hypotension, tachycardia, tachypnea, renal failure, seizure, death
·      Epidemiology
o   Spread by contaminated food and water, fecal-oral
o   Estimated 3-5 million cases/year & 100,000 deaths
o   Requires high inoculum so person to person spread is unusual
o   Seen in areas with poor contamination
o   Humans are primary reservoirs
·      Treatment
o   Fluid & electrolyte replacement
o   Antibiotics such as azithromycin reduce bacteria & toxin production
o   Mortality rate if untreated = 60%
o   Prevention
§  Water treatment
§  Sanitation, hygiene, & safe food prep
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