Isolation and typing of Vibrio parahaemolyticus that causes food poisoning

Objective To test for and serotype Vibrio parahaemolyticus that causes food poisoning and to provide grounds for diagnosis of the pathogen responsible for food poisoning by PCR detection of the thermostable direct hemolysin(TDH) gene and TDH-related hemolysin(TRH) genes of different serotypes of Vibrio parahaemolyticus.MethodsSuspected food sources were collected at sites of food poisoning and samples of patient feces,anal swabs,vomit,swabs of the hands of cooks,and swabs of the food preparation room were subjected to pathogen testing and serotyping.PCR was used to detect TDH and TRH from 45 strains of Vibrio parahaemolyticus.Results There were 48 instances of food poisoning from 1978 to 2004;of these,43(89.58%) were caused by bacteria.There were 27 instances of food poisoning from 2005 to 2007;of these,16(59.26%) were caused by Vibrio parahaemolyticus,7(25.93%) were caused by Staphylococcus aureus,and 4(14.81%) were caused by two or more pathogens.In all,88 strains of Vibrio parahaemolyticus were detected with 6 serotypes;of these,23 strains(26.14%) were O1,1(1.14%) was O2,37(42.05%) were O3,25(28.41%) were O4,and 1 was O5(1.14%),and 1(1.14%) was O10.PCR was used to detect TDH and TRH from 45 strains of different serotypes of Vibrio parahaemolyticus.Of 16 strains with the O1 serotype,15 were positive for TDH and 1 was negative for TDH.Of 9 strains with the O3 serotype,all were positive for TDH.Of 20 strains with the O4 serotype,17 were positive for TDH and 3 were negative for TDH.The 45 strains were all negative for TRH1 and TRH2.Conclusion Food poisoning caused by bacteria was caused mainly by Vibrio parahaemolyticus serotypes O1,O2,O3,O4,O5,and O10.