Purpose : V. parahaemolyticus is frequently detected in oysters and fish in Korea, and is the fifth most frequent cause of foodborne infection. In this study, V. parahaemolyticus isolated from oysters collected in September to November, 2022 asides in Jeollabukdo were used to detect toxR and tlh genes, and to determine antimicrobial susceptibility with the aim to improve diagnosis and treatment of the infection.
Method : V. parahaemolyticus detection rate was determined using oysters collected at seasides in Jeollanamdo in September to November, 2022. Accuracy of species identification by tests of phenotype, API 20E and Vitek 2 systems were compared, and in addition presence of toxR and tlh genes in the species was tested and susceptibility of the isolates to antimicrobial agents was determined.
Result : V. parahaemolyticus was detected in all 23 samples collected in September when the seawater temperature was 25°C or above, but none were detected in 67 samples collected in October and November when the temperature was 10-17°C All 23 isolates of V. parahaemolyticus were identified by conventional phenotypic tests and all were Kanagawa phenomenon positive. Accuracy of identification by API 20E and Vitek 2 systems were 98-99%. toxR and tlh gene were detected by PCR in all V. parahaemolyticus isolates, but one isolate was not identified by the nucleotide sequence analysis of the amplicon. All isolates were resistant to colistin, but were susceptible to tetracycline and tigecycline with MIC90of ≤0.5 ㎍/ml.
Conclusion : V. parahemolyticus was detected in all oyster samples collected at the seasides in the Junllabukdo in September when seawater temperature was 25°C or above. All isolates were accurately identified by tests of conventional phenotype, API 20E and Vitek 2 systems, and toxR and tlh gene detection, and sequence analysis of the amplicons were more rapid, and all isolates were resistant to colistin, but were susceptible to tetracycline and tigecycline with MIC90 of ≤0.5 ㎍/ml.