Analysis of contamination, virulence genes and antimicrobial resistance of Vibrio parahaemolyticus in cultured oysters from the coast in Guangdong province

To investigate the contamination, virulence gene and antimicrobial resistance of Vibrio parahaemolyticus in cultured oysters from the main culture areas along the coast of Guangdong. The results showed that the average detection rate of Vibrio parahaemolyticus was 18.8% among 320 oyster samples. There were significant differences of incidence among different seasons and regions. 60 strains were isolated from the positive samples. All the isolates carried the tlh gene, while the tdh and trh gene were not detected in all isolates. 26 kind of antibiotics were used for drug sensitivity test. The results revealed that most of the isolates were generally resistant to ampicillin, and the resistance rate was 83.3%. Some strains were resistant to 8 antibiotics, such as piperacillin, tetracycline and nitrofurantoin, etc, and the resistance rates were 1.67%～11.7%. All the isolates were sensitive to 12 antibiotics, such as cefpodoxime, imipenem, amikacin, etc. The multi-drug resistance rate of the isolates was 3.33%, and a strain showed multi-drug resistance to 7 antibiotics. The results indicated that there were significant differences of Vibrio parahaemolyticus contamination level among different seasons and regions in cultured oysters along the coast of Guangdong. The isolates had a low risk of disease and showed different degrees of drug resistance. Among the oysters farming areas, Huizhou showed a higher contamination rate and resistance degree than other areas.