Etiologic characteristics of Vibrio parahaemolyticus strains causing outbreaks and sporadic cases in Guangdong, 2009

Abstract

To study the serotypes, virulence features and molecular characteristics of Vibrio parahaemolyticus isolated in food poisoning cases and surveillance program on diarrhea patients in Guangdong, 2009. 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. 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. 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.