Prevalence and distribution of Vibrio parahaemolyticus in finfish from Cochin (south India).

Finfish samples obtained from four retail outlets in Cochin between June 2009 and June 2010 were investigated for the occurrence of Vibrio parahaemolyticus. A total of 182 samples were collected and suspect isolates were identified using standard biochemical tests and were further confirmed by a species-specific tlh gene. V. parahaemolyticus was detected in 45.1% of samples, with demersal fish being more affected than pelagic species. The bacterium was isolated more frequently from the skin and gills of pelagic fish, while the intestine yielded greater numbers of V. parahaemolyticus in demersal fish. The highest incidence of antibiotic resistance was recorded against ampicillin and streptomycin, followed by carbenicillin, cefpodoxime, cephalothin, colistin and amoxycillin; the lowest was against nalidixic acid, tetracycline, chloramphenicol and ciprofloxacin. Multiple drug resistance was prevalent among isolates. Although only a fraction of strains are pathogenic for humans, the time-temperature abuse in markets provides ample scope for these strains to multiply to dangerous levels. The multidrug resistant nature of the strains adds to the gravity of the problem. High V. parahaemolyticus incidence rates in market finfish samples from areas in and around Cochin clearly indicates that control measures should be adopted to reduce post-harvest contamination in seafood and time-temperature abuse in markets to diminish the risk of V. parahaemolyticus infection associated with seafood destined for human consumption.