Vibrio cholerae
One-Sentence Definition
Vibrio cholerae is a curved, oxidase-positive Gram-negative bacillus of brackish/marine environments; toxigenic O1/O139 strains cause epidemic cholera via cholera toxin–driven secretory diarrhea.
Taxonomy & Morphology
- Vibrionaceae; comma-shaped rods; polar flagellum; grows on TCBS agar
- Serogroups: O1 and O139 — epidemic cholera; non-O1/non-O139 — sporadic gastroenteritis/wound/sepsis
- Biotypes of O1: classical vs El Tor (current pandemic biotype)
Virulence Highlights
- Cholera toxin (CT) — AB₅ toxin; ADP-ribosylates Gs → ↑cAMP → massive Cl⁻/water secretion
- ctx genes on CTXφ prophage (Prophage Detection and Annotation, Transduction)
- TCP (toxin-coregulated pilus) — colonization; also phage receptor
- Regulated by ToxR/ToxT network (Bacterial Operons and Sigma Factors)
Clinical Syndromes
- Profuse watery “rice-water” stool → hypovolemic shock if untreated
- Mild/asymptomatic infections common; severe disease in outbreaks and fragile water systems
- Related species: V. parahaemolyticus, V. vulnificus (seafood/wound — different syndromes)
Diagnosis
- Clinical recognition in outbreaks + dark-field / culture on TCBS
- Rapid antigen / PCR in reference and outbreak settings
- Serogrouping for O1/O139; toxigenicity assays when needed
Treatment Notes (conceptual)
- Rehydration is the therapy (ORS / IV) — antibiotics shorten shedding and severity in severe cases
- Doxycycline, azithromycin, or ciprofloxacin per local resistance — stewardship during epidemics
- Zinc in children; vaccines in outbreak/travel contexts (Vaccination)
AMR
- Tetracycline/fluoroquinolone/macrolide resistance reported in circulating strains
- Plasmid and chromosomal contributions; monitor during outbreak response
- One Health / water sanitation primary control — drugs alone do not stop epidemics
Genomics & Computational Notes
- Seventh pandemic El Tor lineage tracked by Phylodynamics / SNP typing
- Horizontal acquisition of CTXφ and pathogenicity islands is classic teaching
- Environmental reservoirs and climate/water links for surveillance models
Related Notes
- Campylobacter jejuni · Escherichia coli (ETEC toxin analogy) · Gastrointestinal Infections · Infection Prevention and Control
- MOCs: MOC - Bacteriology · MOC - Public Health & Epidemiology · MOC - Clinical Microbiology
Active Recall
- Which serogroups cause epidemic cholera?
- How does cholera toxin produce watery diarrhea?
- What is the single most important treatment intervention?