上海地区生牛乳中金黄色葡萄球菌污染状况及耐药性分析

Contamination and drug resistance of Staphylococcus aureus in raw milk in Shanghai

【目的】了解上海地区生牛乳中金黄色葡萄球菌污染状况,产肠毒素特性及细菌耐药性。【方法】采集上海地区4家奶牛场共计306份生牛乳,按照GB4789.10《食品安全国家标准食品微生物学检验金黄色葡萄球菌检验》进行金黄色葡萄球菌的分离鉴定及毒素测定,并对检出的金黄色葡萄球菌根据临床与实验室标准化协会(CLSI)推荐的微量肉汤稀释法进行药敏试验,定量测定最低抑菌药物浓度(MIC)。【结果】共检出金黄色葡萄球菌32株,检出率为10.5%;其中17株产肠毒素阳性,阳性率为53.1%;对上述金黄色葡萄球菌株进行12种抗生素的耐药检测,其中耐药最严重的是青霉素、氨苄西林、红霉素、四环素,耐药率分别达78.1%、65.6%、53.1%、21.9%,并表现出多种耐药谱。【结论】上海地区生牛乳中金黄色葡萄球菌污染及其肠毒素产毒能力较强,耐药情况严重,这与奶牛养殖过程中抗生素暴露有关,建议上海地区奶牛场扩大对奶牛乳腺炎治疗的药物筛选范围,根据药物敏感实验结果合理选择抗菌药物。

[Objective]To investigate the contamination and characteristics of enterotoxins and drug resistance of Staphylococcus aureus in raw milk in shanghai.[Methods]A total of 306 raw milk were collected from 4 dairy farms in Shanghai.The isolation and identification of Staphylococcus aureus and determination of toxin were performed according to GB4789.10.The detected Staphylococcus aureus was treated according to the CLSI recommended microdilution method for sensitive test,quantitative determination of the minimum inhibitory concentration(MIC).[Results]A total of 32 strains of Staphylococcus aureus were detected,with a detection rate of 10.5%.Among them,17 strains were positive for enterotoxigenicity with a positive rate of 53.1%,then drug resistance was tested in 12 antibiotics.The most serious resistance was penicillin,ampicillin,erythromycin and tetracycline,and the resistant rates were 78.1%,65.6%,53.1%and 21.9%respectively,showing a variety of resistance spectrum.[Conclusion]The Staphylococcus aureus contamination,enterotoxigenic ability,and their drug resistance in raw milk in Shanghai are serious,which is related to the process of dairy cattle breeding antibiotic exposure.It is recommended to expand the drug screening range for treatment of cow mastitis in Shanghai.According to the results of drug-sensitive test should be made the reasonable choice of antimicrobial drugs for the treatment of cows′mastadenitis.