Vibrio cholera - MegaMicro

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Vibrio cholera

Micro > 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
 
 
 
 
 
Related concepts

Key Words:
Diarrhea
cAMP

Web Resources:
http://www.austincc.edu/microbio/2704u/vc.htm
https://en.wikipedia.org/wiki/Cholera_toxin
http://textbookofbacteriology.net/cholera_3.html
Picture: http://www.slideshare.net/hassanqureshi1/vibrio-cholera
 
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