Abstract:Vibrio parahaemolyticus is a common food-borne pathogen. The work attempted to evaluate the genetic diversity of V. parahaemolyticus strains isolated from food and clinical samples in the Pearl River Delta (PRD) district. In total, fifty four V. parahaemolyticus strains were included in the study. Biochemical reaction tests were performed with the API20E system and antibiotic susceptibility was examined for eight common antibiotics: nalidixic acid (NAL), streptomycin (STR), cephalothin (CEP), ampicillin (AMP), ciprofloxacin (CIP), tetracyclin (TCY), chloramphenicol (CHL), and aztreonam (ATM). O-serotypes and prevalence of tdh and trh were determined using PCR methods. Enterobacterial repetitive intergenic consensus (ERIC)-PCR assays were performed for molecular typing. The 54 V. parahaemolyticus strains were grouped into six biochemical clusters, and Biochem-A was the dominant cluster. None of the strains was resistant to NAL, CIP, or CHL, while 48 strains (88%) were resistant to AMP. Nine O-serotypes (O1, O2, O3, O4, O5, O6, O8, O10, and O11) were detected; O2 was the main serotype and O3 was the main clinical serotype. Forty-seven genotypes were found by ERIC-PCR molecular typing and 12 clusters with a similarity of 0.80 were established, but none was dominant. Twelve strains (22%), including ten clinical isolates and two isolates derived from food sources, were tdh-positive. Only two strains (4%) from food samples were trh-positive. Dramatic genetic diversity of V. parahaemolyticus strains from the PRD district was confirmed in this study.
