Microbiology · Other clinically important bacteria
Vibrio vulnificus and Vibrio parahaemolyticus !
- Bacterium
- Gram-negative
- For completeness
Seawater vibrios: diarrhoea from raw shellfish and wound infections that can kill people with liver disease.
Updated 2026-11-01
Also called: non-cholera vibrios
At a glance
- Gram
- Gram-negative
- Shape
- Curved (comma-shaped) rod
- Oxygen
- Facultative anaerobe
- Family
- Vibrionaceae
- Stain
- Curved, motile Gram-negative rods
Morphology
- Curved rod with one polar flagellum
- Halophilic: needs salt to grow
- Oxidase positive; grows on TCBS agar
Transmission
- Eating raw or undercooked shellfish, above all oysters
- Wounds exposed to salt or brackish water, or to raw seafood
- Not spread from person to person
Reservoir: Warm salty and brackish coastal waters; more abundant in the hot months
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- V. vulnificus: polysaccharide capsule that blocks phagocytosis
- Toxins and enzymes that destroy tissue and cause bullae and necrosis
- Free iron boosts its growth, so cirrhosis and haemochromatosis raise the risk
- V. parahaemolyticus: haemolysins that damage the intestinal epithelium
Diseases it causes
- Primary septicaemia from V. vulnificus after eating raw oysters Sepsis and septic shock →
- Seafood-associated gastroenteritis (mostly V. parahaemolyticus) Acute (viral) gastroenteritis →
- Wound infection with necrotising fasciitis from V. vulnificus
Clinical picture
- Fever, shock and haemorrhagic bullae on the legs in a person with cirrhosis
- Watery diarrhoea with cramps after eating shellfish
- Wound infection progresses within hours; amputation may be needed
Diagnosis
- Blood culture and culture of bulla fluid or the wound
- Stool culture on TCBS agar: tell the laboratory if Vibrio is suspected
- A history of raw shellfish or seawater is the key clue
Treatment
Severe V. vulnificus infection: tetracyclines (doxycycline) together with a third-generation cephalosporin (ceftriaxone), or a fluoroquinolone, plus urgent surgical debridement. Mild gastroenteritis usually settles with hydration.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Avoid raw oysters and shellfish, above all with liver disease or immunosuppression
- Cover wounds or stay out of the sea with open wounds
- Wash hands and surfaces after handling raw seafood
Test yourself
Think of the answer, then tap the question to see it.
Which patient is at highest risk of Vibrio vulnificus septicaemia?
Someone with chronic liver disease such as cirrhosis, or with iron overload, who eats raw oysters.
Which selective culture medium is used for vibrios?
TCBS agar (thiosulfate-citrate-bile salts-sucrose).
Which severe skin infection can V. vulnificus cause?
A wound infection with bullae and necrotising fasciitis that progresses within hours.
Which non-cholera vibrio most often causes seafood gastroenteritis?
Vibrio parahaemolyticus.
Related
Related conditions
← Back to the group: Other clinically important bacteria
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: About Vibrio Infection | Vibrio Infection | CDC (CDC, 2024); Jawetz, Melnick & Adelberg's Medical Microbiology, 26th ed., chapter 17: Vibrios, Campylobacters, Helicobacter, and Associated Bacteria (McGraw-Hill, 2013).
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Representative model, for educational purposes only.