Term
What are the virulence factors for Vibrio cholerae? |
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Definition
1. Cholera toxin 2. Flagella for motility 3. Pili for adherence |
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Term
| Mechanisms of Cholera toxin |
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Definition
| Production of enterotoxin when V. cholerae colonises small intestine, B subunit binds to ganglioside receptor on enterocyte membrane while A subunit crosses membrane & activates adenylate cyclase. This causes an overproduction of cAMP, resulting in active absorption of electrolytes & osmotic reabsorption of water is inhibited. |
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Term
Clinical signs and symptoms of Cholera |
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Definition
Early stages: vomiting. Profuse watery diarrhea ('rice water stools') with fishy odour. Abdominal pain & fever are rare. Morbidity and death due to dehydration & electrolyte imbalance resultin in cardiac and renal failure, acidosis & hypokalemia. |
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Term
| What are the serotypes of V. cholerae involved in disease? |
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Definition
O1 group (according to nature of O cell wall). O139 of V. cholerae is associated with epidemics. El Tor biotype less symptomatic but more common. |
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Term
Describe the management of Cholera |
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Definition
Oral rehydration with fluids containing glucose & salts (IV fluids if serious). Tetracycline/ciprofloxacin to shorten period of pathogen excretion and reduce severity of diarrhea. Type O1 vaccine ineffective, limited duration of protection, for travel to endemic areas >1/12. |
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Term
Oxidase positive bacteria. |
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Definition
Pseudomonas aeruginosa, all Vibrio species, Neisseria meningitidis & gonorrhoeae, Campylobacter spp. All enterobacteriaceae are oxidase negative. |
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