Molecular characteristics of vibrio parahaemolyticus isolated from food-poisoning events in Guangdong Province,2008

Objective To understand the molecular characteristics and serotype distribution of vibrio parahaemolyticus from food-poisoning events in Guangdong Province in 2008.Methods A total of 90 clinical and 9 food isolates from 14 food-poisoning events were sero-typed and tested by PCR for three virulence genes: thermolabile hemolysin(tlh),thermostable direct hemolysin(tdh),and thermostable related hemolysin(trh).Molecular characterization of dominant serotypes(O3∶K6 and O4∶K8) in isolates was analyzed by ERIC-PCR.Results The main serotypes of the 90 clinical isolates were O3∶K6(62.2%) and O4∶K8(14.4%),while the serotypes of the 9 food isolates presented diversity.The serotype differed between cases and food type in 3 out of the 4 events where isolates from both sources were obtained.All isolates were positive for tlh,but negative for trh.However,tdh was detected in only one food isolate(11.1%),but in 96.7% of the 90 clinical isolates.Eight ERIC-PCR patterns were observed in the clinical isolates tested,including 22 isolates of serotype O3∶K6 and 10 of O4∶K8.Two clusters were formed among these patterns,and the similarity value between them was 54.7%.The ERIC-PCR patterns of the same serotype(O3∶K6 or O4∶K8) from the same event presented diversity,while patterns with 100% similarity can be seen in isolates from different events.Conclusion The isolates of vibrio parahaemolyticus from food-poisoning events in Guangdong presented various serotypes,and the same serotype might show genetic diversity.A group of genetically related isolates,negative for trh,positive for tdh,and of serotype O3∶K6 or O4∶K8,composed the dominant isolates.