Etiology and molecular epidemiology of Vibrio parahaemolyticus in Pudong, Shanghai

Objective To understand the etiological and molecular epidemiological characteristics of Vibrio parahaemolyticus in Pudong new district. Methods Serotyping was conducted for 505 V. parahaemolyticus isolates by using slide serum agglutination test. The drug susceptibility of the isolates to 12 antibiotics was performed by using K-B method. PFGE molecular subtyping was done after the genome DNA digested by restriction enzyme NotI. PFGE pattern clustering analysis was conducted by using BioNumerics Version 6.64. Results The serotyping of 117 of 505 isolates failed. Serotype O3:K6 was predominant in isolates from food poisoning samples (69.14%) and samples from sporadic infection cases (61.87%). No predominant serotype was detected in food samples collected in routine surveillance. In these isolates, 502 (99.41%) were resistant to ampicillin. And in these isolates, 221 PFGE patterns were detected, the PFGE typing failed for 26 isolates. No predominant PFGE pattern was detected in food samples from routine surveillance and the PFGE patterns of these isolates differed with those of the isolates from food poisoning samples and sporadic infection samples. The isolates from food poisoning samples and sporadic infection samples shared the same predominant PFGE patterns. The PFGE patterns of the isolates which were resistant to ≥2 antibiotics differed with those of other isolates. The isolates with same PFGE pattern shared same serotype. Same PFGE patterns were detected in different time or at different surveillance sites. Conclusion No multi-drug resistant isolate of V. parahaemolyticus was detected in Pudong. There were clustering of the infection, but the isolates from these infections had far genetic distance with the isolates from routine surveillance.