Download Vibrio cholerae - University of Louisville

D. Hagman F2013
Modified by DYH
Vibrio cholerae
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Gammaproteobacteria
Gram-negative
Comma-shaped
Two circular chromosomes of DNA
– Approximately 4 million base pairs combined
• Single, polar flagella
• Some strains cause cholera
Electron micrograph image of a Vibrio cholerae bacterium by Leodotia
Pope, of the Department of Microbiology at the University of Texas at
Austin
D. Hagman F2013
Modified by DYH
Pathogenicity of V. cholerae
• Enters digestive tract through consumption of contaminated water
or food
– Contaminant usually the feces of a person infected by V. cholerae
• N-methylphenyl-alanine pili allows the bacterium to adhere to
intestinal epithelium
• Embeds itself in the microvilli of intestinal epithelial cells
• Secretes cholera toxin, a type III exotoxin
– Neuraminidase spreading factor is also secreted to help cholera toxin
bind to and penetrate the enterocytes, as it degrades neuraminic acid,
a monosaccharide that holds the intestinal mucosa together
– Cholera toxin stimulates the mucosa of the intestines to rapidly
release fluids, causing vomiting and diarrhea which facilitates the
transmission of the bacteria to other hosts
– LD50 of the toxin is 250 μg/kg body weight
• Untreated, death by dehydration is common