Etiology of a Vibrio parahemolyticus caused foodborne-disease outbreak

Objective To analyze the etiological characteristics of a Vibrio parahemolyticus caused foodborne-disease outbreak in Ningbo in summer,2016.Methods The V.parahemolyticus strains isolated in a foodborne-disease outbreak were serotyped and their susceptibilities to 10 antibiotics were detected.Real time fluorescence quantitative PCR was used to detect the tdh,trh and tlh genes.The cluster analysis of the 8 V.parahemolyticus strains were performed by using pulsed-field gel electrophoresis (PFGE).Results A total of 8 V.parahemolyticus strains were isolated from the stool samples of diarrhea patients.Serological analysis of O and K antigens indicated that 2 strains were identified as O3:K6,and 6 strains were identified as O4:KUT.The 8 V.parahemolyticus strains were subtyped into 4 PFGE patterns by NotⅠ digestion or 3 PFGE patterns by SfiⅠ digestion.Subtype VPAN11.ZJNB002(VPAS12.ZJNB002) was predominant,including 4 strains.All the strains were sensitive to piperacillin/tazobactam,ceftriaxone,cefepime,aztreonam,imipenem,amikacin,gentamicin,ciprofloxacin,levofloxacin and SMZ.Conclusion This foodborne-disease outbreak was caused by polyclone V.parahemolyticus strains,including at least 2 serotypes or 4 PFGE patterns.Close attention should be paid to the co-infection with polyclone V.parahemolyticus to avoid missed detection.No antibiotic resistance was found in drug susceptibility test of the 8 strains.