Vibrio parahaemolyticus causes gastroenteritis associated with consumption of seafood. On TCBS (thiosulfate-citrate-bile-salts-sucrose) agar, it forms colonies that are:
- A Yellow (sucrose fermenting)
- B Blue-green (sucrose non-fermenting) ✓
- C Colorless (sucrose non-fermenting on MacConkey but TCBS not used for this species)
- D Black-centered with metallic sheen (hydrogen sulfide production)
Explanation
On TCBS agar: Vibrio cholerae produces yellow colonies (sucrose fermenter); Vibrio parahaemolyticus produces blue-green colonies (sucrose non-fermenter, glucose fermenter only). TCBS is the selective differential medium of choice for all Vibrio species from stool specimens. V. parahaemolyticus is the leading cause of seafood-associated gastroenteritis worldwide, with the Kanagawa phenomenon (beta-hemolysis on Wagatsuma agar by thermostable direct hemolysin, TDH) being the virulence marker for pathogenic strains. V. vulnificus also produces blue-green colonies on TCBS and causes severe necrotizing fasciitis in immunocompromised patients after seafood consumption.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.