Click to enlarge
Vibrio is a gram-negative rod that is typically found in warm saltwater, although it has been isolated in waters as cold as 17°C. Vibrio infections can rapidly progress to septicemia and death and often require major amputation in patients who survive. A 51-year-old surgeon lacerated his left ring finger near the volar distal interphalangeal joint with a fillet knife while cleaning fish after a late summer day of fishing in coastal New England seawaters. Twelve hours later, he awoke with throbbing pain in his fingertip. A new Clinical Problem-Solving article summarizes the case.
• What are the clinical signs of infectious flexor tenosynovitis?
The four so-called Kanavel signs for infectious flexor tenosynovitis include flexor-sheath tenderness, circumferential swelling (a “sausage digit”), pain with passive stretch, and flexed posture. All these signs are not necessarily present in patients with tenosynovitis, particularly in those who present early.
• What are some of the pathogens to consider when soft-tissue infection develops in a wound that has been exposed to seawater?
The potential inoculation of seawater necessitates special consideration. Streptococcus iniae, which has been linked to exposure to fish, is a potential pathogen. Waterborne pathogens including aeromonas species and Mycobacterium marinum are associated with skin and soft-tissue infections. Aeromonas can cause severe infection with systemic symptoms; aeromonas is most commonly isolated from fresh or brackish water. M. marinum infection typically manifests as a more subacute or chronic infection rather than as a fulminant infection with systemic symptoms. In contrast, vibrio species, particularly Vibrio vulnificus, can cause rapidly progressive infections.
Morning Report Questions
Q: Which vibrio species are associated with soft-tissue infection, and what patient factors increase the risk of death from such infections?
A: V. vulnificus and V. parahaemolyticus species are most frequently associated with soft-tissue infection. V. vulnificus species account for most severe vibrio infections and the majority of deaths that are attributed to these infections in the United States. V. vulnificus infections can rapidly become fatal, progressing from an initial presentation of cellulitis, tenosynovitis, or necrotizing fasciitis to septicemia and death within 48 to 72 hours. Signs and symptoms of vibrio sepsis and necrotizing fasciitis include fevers and chills, localized severe swelling, rapidly painful cellulitis, purpura, and hemorrhagic bullae. According to CDC epidemiologic surveillance data, the mortality rate is 50% among patients presenting with V. vulnificus septicemia and 15% among those with wound infection without septicemia. Underlying immunosuppression, chronic illness, and liver disease are frequently cited risk factors for poor outcomes with vibrio infection, with liver disease in particular conferring a significant increase in the risk of death from wound infection.
Q: What antibiotics are used to treat V. vulnificus infection?
A: There are no definitive data from humans to guide appropriate antimicrobial therapy for V. vulnificus infection, but in vitro data and data from studies in mice have both shown efficacy with fluoroquinolones and synergistic effects of tetracycline derivatives with third-generation cephalosporins. Ampicillin–sulbactam does not provide adequate coverage for V. vulnificus.