33-21: Infections Caused by Other Vibrio Species

Vibrios other than V cholerae that cause human disease are Vibrio parahaemolyticus, V vulnificus, and V alginolyticus. All are halophilic marine organisms. Infection is acquired by exposure to organisms in contaminated, undercooked, or raw crustaceans or shellfish and warm (greater than 20°C [82.4°F]) ocean waters and estuaries. Infections are more common during the summer months from regions along the Atlantic coast and the Gulf of Mexico in the United States and from tropical waters around the world. Oysters are implicated in up to 90% of food-related cases. V parahaemolyticus causes an acute watery diarrhea with crampy abdominal pain and fever, typically occurring within 24 hours after ingestion of contaminated shellfish. The disease is self-limited, and antimicrobial therapy is usually not necessary. V parahaemolyticus may also cause cellulitis and sepsis, though these findings are more characteristic of V vulnificus infection.

V vulnificus and V alginolyticus—neither of which is associated with diarrheal illness—are important causes of cellulitis, wound infections, and primary bacteremia following exposure to sea water or ingestion of contaminated shellfish. Cellulitis with or without sepsis may be accompanied by bulla formation and necrosis with extensive soft tissue destruction, at times requiring debridement and amputation. The infection can be rapidly progressive and is particularly severe in immunocompromised individuals—especially those with cirrhosis—with death rates as high as 50%. Patients with chronic liver disease and those who are immunocompromised should be cautioned to avoid eating raw oysters.

Doxycycline 100 mg orally twice daily plus ceftriaxone for 7–10 days is the drug of choice for treatment of suspected or documented primary bacteremia or cellulitis caused by Vibrio species. V vulnificus is susceptible in vitro to penicillin, ampicillin, cephalosporins, chloramphenicol, aminoglycosides, and fluoroquinolones, and these agents may also be effective. V parahaemolyticus and V alginolyticus produce beta-lactamase and therefore are resistant to penicillin and ampicillin, but susceptibilities otherwise are similar to those listed for V vulnificus.