食源性金黄色葡萄球菌肠毒素基因分布、耐药性及分型研究

目的对2017—2021年上海市松江区不同食品来源的金黄色葡萄球菌进行肠毒素基因检测、药敏试验和脉冲场凝胶电泳分子分型,以了解金黄色葡萄球菌病原特征。方法利用PCR方法检测金黄色葡萄球菌肠毒素基因,微量肉汤稀释法进行药物敏感试验,脉冲场凝胶电泳进行基因分型。结果108株食源性金黄色葡萄球菌中有39株检出肠毒素基因,检出率为36.1%,其中sea(28.02%,11/39)、seb(41.0%,16/39)、sec(33.3%,13/39)、sed(12.8%,5/39);药敏试验结果显示氨苄西林(83.3%)、青霉素(80.6%)和红霉素(42.6%)耐药率最高;最低为万古霉素(100.0%)、达托霉素(98.1%)和庆大霉素(94.4%),且有15株耐甲氧西林金黄色葡萄球菌,20株表现出多重耐药,其中1株最高耐受6类抗生素。脉冲场凝胶电泳分子分型结果显示108株金黄色葡萄球菌中有11株不能分型,其他97株共分为19簇,包括77种型别,呈现多样性。结论2017—2021年上海市松江区食源性金黄色葡萄球菌肠毒素基因携带率较高、多重耐药性情况需引起重视,并加强食品中金黄色葡萄球菌的监测,为食品安全风险评估和食源性疾病的预防提供科学依据。

Enterotoxin gene distribution,antimicrobial resistance and molecular typing of foodborne Staphylococcus aureus

Objective To perform enterotoxin gene detection, drug sensitivity test and molecular typing by pulsed-field gel electrophoresis (PFGE) on Staphylococcus aureus (S. aureus) isolates from different foods in Songjiang District of Shanghai from 2017 to 2021, and to understand the etiological characteristics of S. aureus. Methods Enterotoxin genes in S. aureus isolates were detected by PCR. Susceptibility test was performed using the microbroth dilution method recommended by Clinical and Laboratory Standards Institute. PFGE was used for genotyping. Results Enterotoxin genes were detected in 39 of 108 strains of foodborne S. aureus, and the detection rate was 36.1%, including sea (28.02%, 11/39), seb (41.0%, 16/39), sec (33.3%, 13/39), and sed (12.8%, 5/39). The results of drug sensitivity test showed that the drug resistance rates of ampicillin (83.3%), penicillin (80.6%), and erythromycin (42.6%) were the highest, whereas the drug resistance rates of vancomycin (100.0%), daptomycin (98.1%) and gentamicin (94.4%) were the lowest. There were 15 strains of methicillin-resistant S. aureus. 20 strains of S. aureus showed multiple drug resistance, among which one strain was the most resistant to six kinds of antibiotics. The results of PFGE molecular typing revealed that 11 of 108 S. aureus strains could not be typed, and the other 97 strains were divided into 19 clusters, including 77 types, showing diversity. Conclusion From 2017 to 2021, the high carrying rate of enterotoxin gene and multiple drug resistance of foodborne S. aureus in Songjiang District of Shanghai need to be paid attention to, and the monitoring of S. aureus in foods should be strengthened so as to provide a scientific basis for food safety risk assessment and prevention of foodborne diseases.