Information for Health Professionals & Laboratorians
Etiologic agent
Vibrio are gram-negative bacteria that are naturally found in warm, salty marine environments, such as salt water and brackish water.
Brackish water is a mix of fresh water and salt water, such as where the river meets the sea.
More than 20 Vibrio species can cause the human illness vibriosis.
- The most common species causing vibriosis in the United States are Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus.
- Illnesses caused by Vibrio cholerae O1 and O139 strains that produce cholera toxin are defined by the World Health Organization as cholera.
Image of oblong-shaped, Vibrio parahaemolyticus bacteria
Clinical features
Vibriosis is typically characterized by watery diarrhea, usually with abdominal cramping, nausea, vomiting, and fever. Vibrio bacteria can also cause wound or soft tissue infections. In people with underlying medical conditions, especially liver disease, Vibrio bacteria can cause bloodstream infections characterized by fever, chills, dangerously low blood pressure, blistering skin lesions, and sometimes death.
Diagnosis
Vibriosis should be considered if a patient has watery diarrhea and has recently eaten raw or undercooked seafood, especially oysters, or when a wound infection occurs after exposure to seawater. Infection is diagnosed when Vibrio bacteria are found in the stool, wound, or blood of a patient who has symptoms of vibriosis.
Diagnosis of Vibrio vulnificus wound infections
Consider V. vulnificus as a possible cause of infection in wounds that were exposed to coastal waters, especially in patients at higher risk for Vibrio infection.
If V. vulnificus infection is suspected
- Obtain wound or hemorrhagic bullae cultures and send all V. vulnificus isolates to a public health laboratory.
- Blood cultures are also recommended if the patient is febrile, has hemorrhagic bullae, or has signs of sepsis.
- Ask the patient or family about relevant exposures, including whether they entered coastal water with an open wound; acquired a scratch or a cut while in coastal water; or had open-wound contact with raw or undercooked seafood.
Treatment
Management of mild cases of vibriosis
Treatment is not necessary in mild cases, but patients should drink plenty of liquids to replace fluids lost through diarrhea. Antibiotics can be lifesaving in severe illnesses.
Initiate treatment promptly. Do not wait for consultation with an infectious disease specialist or laboratory confirmation of V. vulnificus infection. Early antibiotic therapy and early surgical intervention improve survival.
- Antibiotic therapy
- A third-generation cephalosporin (e.g., ceftazidime 1–2g IV/IM every 8 hours) plus doxycycline (100mg PO/IV twice a day for 7–14 days) is recommended.1
- Alternate regimens include a third-generation cephalosporin with a fluoroquinolone (e.g., 500mg ciprofloxacin PO twice a day) or a fluoroquinolone given alone.2, 3
- Children may also be treated with a third-generation cephalosporin plus doxycycline or a fluoroquinolone. However, doxycycline and fluoroquinolones are sometimes avoided in children due to concerns about side effects. Children may be treated with an alternative regimen of trimethoprim-sulfamethoxazole plus an aminoglycoside.4
- Doses should be appropriately adjusted for renal and hepatic function.
- If appropriate, consult a microbiologist or infectious disease specialist.
- Give careful attention to the wound site. Necrotic tissue should be debrided. Severe cases might require aggressive debridement, fasciotomy, or amputation of the infected limb.
- Prognostic factors and antibiotics in Vibrio vulnificus DOI
Liu JW, Lee IK, Tang HJ, et al. Arch Intern Med. 2006 Oct; 166(19): 2117–23. - Outcomes of Third-Generation Cephalosporin Plus Ciprofloxacin or Doxycycline Therapy in Patients with Vibrio vulnificus Septicemia: A Propensity Score-Matched Analysis. DOI
Kim SE, Shin SU, Oh TH, et al. PLoS Negl Trop Dis. 2019 Jun; 13(6): e0007478. - Antibiotic therapy for necrotizing fasciitis caused by Vibrio vulnificus: retrospective analysis of an 8 year period. DOI
Chen SC, Lee YT, Tsai SJ, et al. J Antimicrob Chemother. 2012 Feb; 67(2): 488–93. - Other Vibrio In: Red Book: 2021–2024 Report of the Committee on Infectious Diseases, 32nd ed. AAP
American Academy of Pediatrics. 2021 January. Itasca, IL.
Sequelae
Most people with mild illness recover after about 3 days and suffer no long-term consequences.
However, people with V. vulnificus infection can get seriously ill and sometimes need intensive care or limb amputation. About 1 in 5 people with this type of infection die, sometimes within a day or two of becoming ill.
Transmission
Most people with vibriosis develop it after eating raw or undercooked shellfish, particularly oysters. Others develop it after a wound or soft tissue is exposed to salt water, brackish water, raw seafood, or juice or drippings from raw seafood. Although infections occur throughout the year, about 80% occur from May through October when water temperatures are warmer.
Risk groups
Anyone can get vibriosis. People more likely to get an infection or serious complications:
- Have liver disease, cancer, diabetes, HIV, or thalassemia
- Receive immune-suppressing therapy
- Take medicine to decrease stomach acid levels or had part of the stomach removed
Laboratory Guidance
Vibrio bacteria can be detected by culture-independent diagnostic testing (CIDT) or isolated by culture from a clinical specimen. If a culture is performed, CDC recommends the use of selective media, such as thiosulfate citrate bile-salts (TCBS) agar, for examining stool specimens if Vibrio illness is considered possible.
CDC recommends culture confirmation of CIDT positive specimens, when possible, because specific performance characteristics (such as sensitivity, specificity, and positive predictive value) of CIDTs are currently unknown and CIDTs do not differentiate between non-cholera Vibrio – which is necessary to decide on treatment and follow-up.
