Vibriosis: A Clinical Overview for Healthcare Providers

Vibrio are gram-negative bacteria that live naturally in warm, salty water — salt water and brackish water, where rivers meet the sea. More than 20 species can cause the human illness vibriosis. Most cases are mild, but some species cause infections where prompt, proper treatment is lifesaving.

Image from CDC's clinical overview of vibriosis.

The species

In the United States, vibriosis is most often caused by:

• Vibrio parahaemolyticus
• Vibrio vulnificus
• Vibrio alginolyticus

Illness caused by toxin-producing Vibrio cholerae O1 and O139 is defined by the World Health Organization as cholera, not vibriosis.

V. vulnificus causes especially severe, life-threatening infections. Many patients need intensive care or limb amputation, and about 1 in 5 die — sometimes within a day or two of becoming ill.

Recognizing it

Suspect Vibrio in a patient with watery diarrhea who recently ate raw or undercooked seafood, especially oysters — and in any wound exposed to coastal water, especially in a patient at higher risk. If you suspect a Vibrio wound infection, start treatment immediately. Don't wait for a specialist consult or lab confirmation.

Diagnosis and testing

Vibriosis is diagnosed when Vibrio is found in the stool, wound or blood of a patient with symptoms, either by culture or by culture-independent diagnostic testing (CIDT).

• After a positive CIDT, order culture confirmation when possible: CIDTs don't distinguish among non-cholera Vibrio species, which treatment decisions need.
• For stool cultures, use selective media such as thiosulfate citrate bile-salts (TCBS) agar.
• For wounds, culture the wound or hemorrhagic bullae and send all V. vulnificus isolates to a public health laboratory. Blood cultures are also recommended if the patient has fever, hemorrhagic bullae or signs of sepsis.

Ask the patient or family whether they had an open wound — including from recent surgery, a piercing or a tattoo — that may have touched coastal water or raw or undercooked seafood or its juices, or whether they got a cut or scratch in or around coastal water. The answers guide treatment.

Treatment

Intestinal illness. Mild cases need no treatment beyond plenty of fluids to replace what diarrhea takes. Antibiotics can be lifesaving in severe illness.

Wound infection. Early antibiotics and early surgery improve survival.

• Adults: a third-generation cephalosporin (such as ceftazidime 1–2 g IV/IM every 8 hours) plus doxycycline (100 mg PO/IV twice a day for 7–14 days).
• Children: a third-generation cephalosporin plus doxycycline or a fluoroquinolone — though these two are sometimes avoided in children for their side effects — or an alternative of trimethoprim-sulfamethoxazole plus an aminoglycoside.
• Adjust doses for kidney and liver function, and consult a microbiologist or infectious disease specialist if appropriate.
• Debride necrotic tissue. Severe cases may need aggressive debridement, fasciotomy or amputation of the infected limb.

Sources

Based on "Clinical Overview of Vibriosis," Centers for Disease Control and Prevention; a work of the United States government in the public domain.