Morphology: Gram-negative curved rod (comma-shaped), oxidase-positive, halophilic. Grows on TCBS agar (green colonies, unlike V. cholerae which is yellow).
Typical drugs
- #1Doxycycline— **100 mg PO/IV BID + ceftriaxone** — IDSA preferred combination for V. vulnificus necrotizing infection.
- #2Ceftriaxone— **1–2 g IV daily** — combine with doxycycline. Active against Vibrio.
- #3Ciprofloxacin— Alternative to doxycycline. Monotherapy with cipro acceptable for milder disease in some guidelines.
- #4Meropenem— Severe disease or unclear etiology — covers Vibrio + other GNR + anaerobes.
Empiric therapy when resistant
Treatment failure rare with doxycycline + ceftriaxone if started promptly. Surgical debridement is the cornerstone — antibiotics alone fail in established necrotizing disease.
Resistance mechanisms
intrinsic
Variable resistance to ampicillin and 1st-generation cephalosporins
Example: Empirics should use ceftriaxone-grade or doxycycline, not amp-sulbactam.
Resistance notes
Resistance to first-line agents (doxy, cefotaxime, ceftriaxone, FQ) is rare.
Common syndromes
Pearls
The classic boards vignette: cirrhotic / hemochromatosis / immunocompromised patient eats raw oysters or wades in warm salt water → rapid-onset cellulitis with hemorrhagic bullae → necrotizing fasciitis + septic shock. Mortality 30–50%, even higher if treatment delayed >24 h. Iron overload + immunosuppression are key risk factors. Doxycycline + ceftriaxone + emergent surgical debridement. Aeromonas hydrophila is the freshwater counterpart — similar presentation in freshwater exposure with similar empiric coverage. Notifiable disease.