成都市从养殖到餐桌环节耐甲氧西林金黄色葡萄球菌污染状况调查

目的 为控制耐甲氧西林金黄色葡萄球菌的播散、防控食源性疾病和食品安全风险评估提供科学依据。方法 从成都市各区县采集猪肉、牛肉、鸡肉、鸭肉等市售食品，从成都市部分学校食堂、养殖场及屠宰场采集加工环节涂抹样本。采用平板法分离鉴定金黄色葡萄球菌，纸片扩散法进行青霉素、氨苄西林、苯唑西林、头孢西丁、头孢唑林、红霉素、庆大霉素、环丙沙星、氯霉素、万古霉素的药敏试验，PCR法检测mecA基因鉴定耐甲氧西林金黄色葡萄球菌，酶联荧光免疫分析测定金黄色葡萄球菌肠毒素。结果 452份样品中分离出的83株金黄色葡萄球菌，其中送检速冻面制品中金黄色葡萄球菌分离率100%。耐药率居前三位的抗菌药物分别是青霉素（66/83）、氨苄西林（65/83）、红霉素（42/83）。其中多重耐药株29株，耐3药17株，耐4药6株，耐5药3株，耐6药3株。83株金黄色葡萄球菌中，15株mecA基因阳性，9株多重耐药，其中5株耐3药，1株耐4药，2株耐5药，1株耐6药。15株耐甲氧西林金黄色葡萄球菌中，3株肠毒素阳性，其中2株为来自超市的生鸡肉样品，1株为某单位送检样品。结论 从成都市养殖、生产、加工和销售环节均检出MRSA，速冻食品中MRSA肠毒素阳性风险较高。建议将MRSA纳入食源性致病菌耐药监测系统。

Investigation on contamination status of methicillin resistant Staphylococcus aureus from farm to table in Chengdu

To provide a scientific basis for controlling the spread of methicillin-resistant Staphylococcus aureus(MRSA), preventing and controlling foodborne diseases and food safety risk assessment. Methods Food samples(pork, beef,chicken and duck meat) and samples from food processing were collected from supermarkets, fairs, school canteens, farms and slaughterhouses in Chengdu from July 2017 to January 2018. Staphylococcus aureus was detected using disk diffusion testing. The K-B method was used for antimicrobial susceptibility test. Mec A gene was detected with PCR to identify methicillin-resistant Staphylococcus aureus. Staphylococcus aureus enterotoxin was detected by enzyme-linked fluorescence immunoassay. Results A total of 83 strains of Staphylococcus aureus were isolated from 452 samples, and the isolation rate of Staphylococcus aureus in the frozen instant products was 100%. The top three drugs with highest antimicrobial resistance rates were penicillin(66/83), ampicillin(65/83) and erythromycin(42/83). Among them, 29 strains were multi-drug resistant, 17 strains were resistant to three antibiotics, six strains were resistant to four antibiotics, three strains were resistant to five antibiotics, and three strains were resistant to six antibiotics. Among 83 strains of Staphylococcus aureus, 15 strains were mec A positive, and nine of them were multi-drug resistant, of which five strains were resistant to three antibiotics, one to four antibiotics,two to five antibiotics, and one to six antibiotics. Among 15 strains of MRSA, three strains were enterotoxin-positive, two of which from raw chicken samples from supermarkets, and one from frozen instant product. Conclusion MRSA is detected from the breeding, manufacturing, processing and marketing chain in Chengdu. There is a higher risk of positive MRSA enterotoxin in frozen foods. It is suggested that MRSA be included in the foodborne pathogen resistance monitoring system.