ABSTRACT
Objective To study the serotypes,virulence features and molecular characteristics of Vibrio parahaemaolyticus isolated in food poisoning cases and surveillance program on diarrhea patients in Guangdong,2009.Methods 95 Vibrio parahaemolyticus strains from food poisoning cases and 15 strains from surveillance program on diarrhea patients were serotyped and detected for tdh(thermostable direct hemolysin,tdh)and trh(tdh-related hemolysin gene,trh)by PCR.81 sero-variant Vibrio parahaemolyticus strains were selected through PFGE subtyping.Results There were 15 Vibrio parahaemolyticus strains isolated from surveillance program on diarrhea patients and 95 strains were isolated from 11 Vibrio parahaemolyticus-caused food poisoning cases in 2009.Among these strains,O3:K6(46.67％ and 44.21％)and O4:K8(33.33％ and 28.42％)were the dominant serotypes,but not the 7 food-borne strains.There were 93(84.54％)tdh +trh-,13(11.81％)tdh-trh-,and 3(3.65％)tdh+ trh + strains.The similarity value was between 57.7％ to 100.0％ of the 81 strains after PFGE sub-typing method and 36 PFGE subtypes were identified.PFGE001 and PFGE029 appeared to be the dominant subtypes.Conclusion O3:K6 and O4:K8 were the most dominant serotypes in Vibrio parahaemolyticus-caused diarrhea and food poisoning cases in Guangdong and tdh were detected in most of the strains.Dominant PFGE subtypes were causing both sporadic and outbreak cases in different areas in Guangdong province.
ABSTRACT
Objective To understand the phenotypic characteristics of foodbome Vibrio parahaemolyticus in Guangdong province through carrying out a comprehensive comparison including pulse field gel electrophoresis,ribotyping and serotyping.Methods 74 different Vibrio parahaemolyticus strains isolated from seafood and cases due to food poisoning in Guangdong province were under serotyping and susceptibility testing,in addition to the testing of direct heat hemolysin(tdh)and the heat hemolysin-related hemolysin hormone(trh)via PCR.Ribosomal genotyping(ribotyping)with EcoR Ⅰ restriction enzyme was utilized on 74 different Vibrio parahaemolyticus isolates,whereas pulsed-field gel electrophoresis(PFGE)with the Not Ⅰ restriction enzyme was used on 74 different Vibrio parahaemolyticus isolates.BioNumerics software was used to compare the isolates from different sources,times and places in order to elicit the correlation between different strains.Results Although Vibrio parahaemolyticus was 100.00％ sensitive to chloramphenicol,it still presented different levels of resistance against 13 other antibiotics.Among the 74 different strains of Vibrio parahaemolyticus under testing,24.32％ showed positive for the tdh virulence gene,whereas 4.05％ positive for trh.74 different Vibrio parahaemolyticus strains were found to belong to 26 serotypes,where the O5:K17 and O2:K28 serotypes were dominant in those isolates that causing seafood-poisoning.The O3:K6 serotype was found to be the dominant of those isolates that causing food-poisoning.Based on ribosomal genotyping,the 74 Vibrio parahaemolyticus isolates were divided into 62 different ribotypes,whereas the 74 strains of Vibrio parahaemolyticus were divided into 67 different PFGE types,thus exhibiting considerable genetic diversities of the strains.Conclusion Majority of the isolates causing food-poisoning carried tdh virulence gene.PFGE was shown to have the highest resolution,followed by ribotyping with serotyping being the lowest,where the combination of the three could improve the resolution.