VIBRIO CHOLERA
Definition Vibrio cholerae is a Gram-negative, facultative anaerobic, curved rod-shaped bacterium that causes cholera.
Causes It is found in contaminated water, food, and environment, especially in areas with poor sanitation and hygiene.
Types There are two types of V. cholerae:
- Classical (El Tor) biotype
- Non-classical (El Tor) biotype
Morphology
- Gram-negative
- Facultative anaerobe
- Curved rod-shaped (comma-shaped)
- 1-4 ฮผm long, 0.5-1 ฮผm wide
- Has a single polar flagellum
- Has a characteristic blue-green pigment (Chromobactin)
Pathogenesis
- Ingestion of contaminated food or water โ โ V. cholerae โ โ small intestine
- Bacteria adhere to intestinal mucosa using flagellum and pili
- Produce cholera toxin (CTX) and hemolysin
- CTX stimulates adenylate cyclase, increasing cAMP levels โ โ secretion of chloride and water โ โ diarrhea
- Diarrhea leads to dehydration, shock, and potentially death
Clinical Features
- Acute watery diarrhea (rice-water stool)
- Vomiting
- Dehydration
- Shock
- Abdominal cramps
- Myalgia
- Fever
Complications
- Dehydration
- Shock
- Hypovolemic shock
- Renal failure
- Cardiac arrest
Laboratory Diagnosis
- Isolation of V. cholerae from stool
- Microscopic examination of stained stool
- Identification using biochemical tests (e.g., fermentation of sucrose, lactose, and maltose)
- Serological tests (e.g., ELISA, agglutination)
- PCR-based methods (e.g., 16S rRNA gene sequencing)
Memory Trick To remember the pathogenesis of V. cholerae, use the following rhyme: "Contaminated food or water's the start, V. cholerae adheres to the gut, a clever art, CTX is produced, cAMP levels rise, Diarrhea ensues, dehydration compromises life's surprise."
Word Trick To remember the morphology of V. cholerae, use the following association: "Curved rod-shaped, a comma's shape, Flagellum's present, it's a bacterial escape."