Halophilic gram-negative rods causing massive secretory diarrhea (cholera) or fulminant wound/septic infection (V. vulnificus) after seawater or shellfish exposure.
Also known as: cholera, Vibrio cholerae, Vibrio vulnificus, Vibrio parahaemolyticus, seafood poisoning
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Risk factors
- Ingestion of contaminated water or undercooked shellfish (oysters in particular)
- Travel to cholera-endemic regions or refugee settings
- Saltwater or brackish water exposure with broken skin (V. vulnificus wound infection)
- Chronic liver disease, hemochromatosis, immunocompromise — V. vulnificus septicemia
- Achlorhydria or PPI use
Pathophysiology
V. cholerae colonizes the small intestine and secretes cholera toxin, which ADP-ribosylates the Gs alpha subunit → constitutive adenylyl cyclase activation → massive chloride and water secretion into the gut lumen with little inflammation, producing isotonic 'rice water' stools. V. vulnificus expresses a polysaccharide capsule and iron-scavenging siderophores; iron overload states accelerate growth, producing rapidly progressive bacteremia and hemorrhagic bullous cellulitis. V. parahaemolyticus produces a thermostable direct hemolysin causing inflammatory diarrhea.
Clinical presentation
Symptoms
- Cholera: sudden painless watery diarrhea progressing to 'rice water' stools, up to 1 L/h, with vomiting and rapid dehydration
- V. parahaemolyticus: watery diarrhea, abdominal cramps, low-grade fever 24 h after raw oyster ingestion
- V. vulnificus gastroenteritis: severe diarrhea after raw oyster ingestion, especially in cirrhotics
- V. vulnificus wound or sepsis: rapidly expanding cellulitis with hemorrhagic bullae, fever, hypotension within hours of seawater exposure
Signs / physical exam
- Severe volume depletion: sunken eyes, tenting skin, hypotension, tachycardia, anuria (cholera)
- Washerwoman hands (skin wrinkling from severe dehydration)
- Hemorrhagic bullae and necrotic skin in V. vulnificus septicemia
- Cool, mottled extremities and septic shock
Classic findings
Rice-water stools (cholera) and hemorrhagic bullae with septic shock in a cirrhotic patient after raw oysters (V. vulnificus).
Differential diagnosis
- Enterotoxigenic E. coli (ETEC) — Travelers' diarrhea, also watery and toxin-mediated, but less voluminous than cholera
- Norovirus — Vomiting predominant, brief duration, outbreaks on cruise ships and in institutions
- Necrotizing fasciitis (Group A strep, polymicrobial) — Rapid progression and disproportionate pain, but lacks the saltwater exposure and hemorrhagic bullae characteristic of V. vulnificus
- Aeromonas wound infection — Freshwater exposure rather than salt; similar clinical picture, doxycycline still active
- Ciguatera or scombroid poisoning — Neurologic or histamine-like symptoms after reef fish ingestion, not diarrhea-predominant
Diagnostic workup
Diagnostic criteria
Clinical picture plus positive culture (TCBS for stool, blood/wound for invasive disease).
Labs
- Stool culture on selective TCBS agar (yellow colonies = V. cholerae; green = V. parahaemolyticus, V. vulnificus)
- BMP for electrolytes; metabolic acidosis from bicarbonate loss is classic in cholera
- Blood cultures in suspected V. vulnificus sepsis
- Wound cultures from bullae or debridement specimens
- CBC: leukocytosis or leukopenia in V. vulnificus sepsis
Imaging
- Not routinely required
- CT or MRI for soft tissue involvement to evaluate fascia and abscess
Treatment
First-line
- Cholera: aggressive oral rehydration solution (ORS) per WHO formula — backbone of therapy; IV Ringer's lactate if severe dehydration
- Cholera antibiotics shorten illness and reduce transmission: doxycycline single dose (adults), azithromycin (pregnancy, children), or ciprofloxacin
- V. parahaemolyticus: supportive care; antibiotics only if severe or prolonged
- V. vulnificus: doxycycline PLUS a third-generation cephalosporin (ceftriaxone or cefotaxime) — the standard double-coverage regimen
- Surgical: aggressive and early debridement for V. vulnificus wound infections
V. cholerae
- WHO ORS until losses stop; IV LR for grade III dehydration
- Doxycycline 300 mg PO once (adult)
- Azithromycin 1 g PO once if pregnant or pediatric
V. vulnificus (wound or sepsis)
- Doxycycline + ceftriaxone (or cefotaxime); alternative fluoroquinolone monotherapy in adults
- Aggressive surgical debridement
- ICU-level resuscitation
Second-line / adjunct
- Oral cholera vaccines (Vaxchora, Dukoral) for travelers to endemic regions
- Public health reporting required
Complications
- Hypovolemic shock and death within hours (cholera)
- Hypoglycemia, especially in children with cholera
- Necrotizing fasciitis, limb amputation (V. vulnificus)
- Septic shock and DIC (V. vulnificus)
- Renal failure
PANCE pearls
- Rice-water stools after travel = V. cholerae; treat the dehydration first, antibiotics are adjunctive.
- Cirrhotic + raw oysters + hemorrhagic bullae = V. vulnificus until proven otherwise. Start doxycycline + ceftriaxone immediately.
- Doxycycline is the unifying drug across Vibrio species (and most marine pathogens).
- TCBS agar selectively isolates Vibrio.
- Counsel patients with chronic liver disease to avoid raw shellfish — single highest-yield prevention pearl.
References
- CDC — CDC Vibrio Illness and Cholera Surveillance Reports
- WHO — WHO Global Task Force on Cholera Control — case management guidelines
- IDSA 2017 — IDSA Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea
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