Vibriões e curvos

Vibrio parahaemolyticus

Curved Gram-negative bacilli

Identification & Growth

Identification

Oxidase-positive, halophilic (requires NaCl), sucrose-negative
TCBS: green colonies; Kanagawa phenomenon on Wagatsuma agar

Growth Conditions

Media with 1–3% NaCl, 35–37 °C, 18–24 h

Clinical Significance

Gastroenteritis after raw or undercooked seafood; wound infection in salt water

Intrinsic Resistance

Ampicillin has reduced activity in most isolates

Bench Alerts

Grows poorly on salt-free media — the routine stool culture may read 'negative'

Clinical Notes

Clinical presentations

Acute self-limited gastroenteritis with watery diarrhea, cramps and nausea, typically 12–24 h after eating raw or undercooked seafood.
Wound infection and cellulitis after skin exposure to seawater or seafood handling, which can progress to fasciitis in immunocompromised hosts.
Rare primary bacteremia, associated with chronic liver disease and other immunosuppressive conditions.

Specimens and collection

Stool culture on TCBS (thiosulfate-citrate-bile-salts-sucrose) selective agar, where they form green colonies due to non-fermentation of sucrose.
Wound swab and tissue material for soft-tissue infection linked to seawater; note the exposure history on the request form.
Blood culture when systemic signs or underlying liver disease are present, collected before starting antimicrobials whenever possible.

Epidemiology and at-risk populations

Leading bacterial cause of seafood-associated gastroenteritis in many coastal regions, with seasonality in warmer months.
Halophilic organism of brackish and marine water; risk is linked to raw oysters, shrimp and other undercooked seafood.
Strains producing thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) are associated with greater gastrointestinal virulence.

Resistance and therapeutic implications

Gastroenteritis is self-limited and managed with rehydration; antimicrobials are reserved for severe, prolonged or immunocompromised cases.
EUCAST/BrCAST do not publish species-specific breakpoints for Vibrio spp.; when indicated, guide therapy by MIC and discuss with infectious diseases.
Doxycycline or a fluoroquinolone are common options for wound infection or bacteremia, combined with surgical debridement when needed.

Bench and reporting notes

Curved, oxidase-positive Gram-negative rod that is halophilic and requires added NaCl in media for optimal growth.
Differentiate from V. cholerae and V. vulnificus by biochemical testing or MALDI-TOF, since management and notification differ.
Seafood-associated gastroenteritis cases may require notification to local health authorities for outbreak investigation.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Vibrio parahaemolyticus in the lab?

Vibrio parahaemolyticus is identified through oxidase-positive, halophilic (requires nacl), sucrose-negative, tcbs: green colonies; kanagawa phenomenon on wagatsuma agar.

What are the intrinsic resistances of Vibrio parahaemolyticus?

This organism is naturally resistant to ampicillin has reduced activity in most isolates. These drugs should not be reported as susceptible.

Where is Vibrio parahaemolyticus commonly found?

It is typically associated with gastroenteritis after raw or undercooked seafood; wound infection in salt water.

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