| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 107 === Vibrio parahaemolyticus is the most common foodborne pathogen in Taiwan. Gastroenteritis caused by the infection of this microorganism frequently occurs when a person consumes raw or undercooked aquatic products which contained pathogenic V. parahaemolyticus. In the aquaculture, antimicrobials are used not to promote growth but rather to prevent and treat bacterial infections; however, excessive use of antibiotics could lead to increased bacterial antimicrobial resistance. Towards this, the antibiotic susceptibility and pathogenic gene of V. parahaemolyticus isolates from clinical and aquatic products were investigated in this study. Sixteen clinical isolates were obtained from the Center for Disease Control, Department of Health of Taiwan, 16 pathogenic isolates were obtained from the Soochow University, Dr. Wong laboratory, and 88 V. parahaemolyticus strains were isolated from aquatic products. The result showed that the positive rate of V. parahaemolyticus was 81.8% in oysters, one strain of V. parahaemolyticus isolated from aquatic products carried tdh+/trh+, and clinical isolates have tdh or trh. All the strains carried the T3SS1 gene, whereas T3SS2α genes were present in tdh+ isolates, and T3SS2β genes were present only in trh+ isolates. In addition, this study found that 100% of the isolates were resistance to amoxicillin and ampicillin, highly susceptible to doxycycline (100%), flumequine (96%), tetracycline (96%). Furthermore, the multiple antibiotic resistance (MAR) index of the isolates ranged from 0.22 to 0.78, the MAR index of most isolates was 0.33 and 0.44, and the resistance patterns were AML/AMP/OT and AML/AMP/NA/OT, respectively. The β-lactam (blaSHV) resistance genes were detected in the 6 V. parahaemolyticus isolates, thus, the phenotype of resistance to V. parahaemolyticus was considered not related to genotype. Genotyping by enterobacterial repetitive intergenic consensus-polymerase chain reaction showed that all the isolates were classified into seven clusters at a 0.12 similarity and pathogenic isolates were present in clusters C, D, E and F. These findings demonstrated that V. parahaemolyticus is easy to find in aquatic products and possess potential pathogenicity factors and MAR. The occurrence of MAR strains in the environment could be an indication of excessive usage of antibiotics in aquaculture fields; thus, the quality management of aquatic products should be strengthened to reduce the growth of V. parahaemolyticus and decrease its MAR.
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