Prevalence, antibiotic resistance, virulence and plasmid profiles of Vibrio parahaemolyticus from a tropical estuary and adjoining traditional prawn farm along the southwest coast of India

Vibrio parahaemolyticus, autochthonous to estuarine, marine, and coastal environments throughout the world, is a leading cause of foodborne gastroenteritis in Asia as well as in other countries. Considering their role in disease outbreaks, water and sediment samples from two different environments along the southwest coast of India, such as the Cochin estuary, which is a tourist hot spot and a traditional prawn farm, were examined for the detection of V. parahaemolyticus. A total of 120 presumptive vibrios were further screened using a chromogenic medium. The isolates producing the specific colour for V. parahaemolyticus on the chromogenic medium were confirmed by molecular methods. Using a PCR assay targeting the species-specific tlh gene, 75 isolates were confirmed as V. parahaemolyticus. The incidence of V. parahaemolyticus was found to be 71.6 % in the Cochin estuary and 53.3 % in the shrimp farm. The virulence genes tdh and trh were detected in two isolates from the Cochin estuary by multiplex PCR. Using 16S rRNA sequence analysis, our isolate exhibited 100 % similarity to the V. parahaemolyticus O3:K6 pandemic clone. The isolates were evaluated for their susceptibility towards 16 different antibiotics. All the isolates exhibited multiple antibiotic resistance (MAR). The MAR index of the isolates from the Cochin estuary ranged from 0.312 to 0.75 and that from the shrimp farm ranged from 0.1875 to 0.5. The plasmid profiles of the isolates were also checked. About 50.6 % of the isolates harboured plasmids and ten different profiles were observed. No correlation was observed between the antibiotic resistance patterns and plasmid profiles.