Vibrio cholera

Categorization
Cell Wall: Gram Negative Shape: Curved Rod
Metabolism: Facultative Anaerobe
Transmission
  • Vibrio are highly tolerant to salt and are endemic in coastal salty or brackish water. Importantly, vibrio can proliferate and grow on their own in salty water independent of human infection. Epidemic and pandemic spread is usually by fecal-oral transmission in areas of poor sanitation although large infective doses are required for disease.
Virulence Factors
  • Cholera Toxin:
    • V. cholera exotoxin is an enterotoxin of the A-B toxin family similar to LT toxin of Enterotoxigenic E. coli. The B Subunit binds to enterocytes and mediates internalization of the toxin complex. The A Subunit activates adenylyl cyclase which increases intracellular levels of cAMP. This in turn causes enterocytes to reduce their sodium resorption and increases their chloride excretion. Consequently, GI water and electrolyte absorption is impaired and a large-volume, watery diarrhea ensues.
Clinical Consequences
  • V. cholera infection is characterized by a high-volume, non-bloody, watery infectious diarrhea that is clouded by some mucous and thus traditionally described as "Rice-water Stools". The diarrhea usually has an incubation of 1-2 days and is not accompanied by fever but may involve vomiting. Bouts of cholera are self-limited and are of concern only due to complications associated with potentially severe dehydration, volume depletion, and electrolyte imbalances can occur.
Treatment
  • With proper supportive care and replacement of water and electrolytes 99% of individuals recover spontaneously.