2010~2011年间从四川省部分牛乳生产企业采集生产环节(生鲜牛乳-车间半成品牛乳-成品牛乳)牛乳样品893份,用GB 4789.10~2010方法结合科玛嘉显色培养基,从中分离鉴定出191株金黄色葡萄球菌,样品总检出率为21.4%(191/893),其中生鲜牛乳检出率(26.4%)高,生产车间半成品牛乳(7.1%)次之,成品牛乳未检测出。利用多重PCR方法对部分金黄色葡萄球菌分离株的肠毒素基因(SEA、SEB、SEC、SED)进行检测。结果显示,22.3%(27/121)菌株携带肠毒素基因,7.4%的菌株携带两种及两种以上肠毒素基因。其中,生鲜牛乳源、中间过程牛乳源及成品牛乳源菌株肠毒素基因携带率分别为23.9%(27株)、0.0%(0株)及0.0%(0株);121株金黄色葡萄球菌SEA、SEB、SEC、SED基因的总检出率分别为13.2%(16株)、10.7%(13株)、5.8%(7株)、3.3%(4株)。研究结果对金黄色葡萄球菌毒力机制研究与乳品质量安全控制具有参考意义。

A total of 191 Staphylococcus aureus isolates were identified from 893 milk samples taken from raw milk,semi-product milk and finished product milk from 2010 to 2011 in Sichuan.The S.aureus isolates were detected by traditional culture method including gram staining,coagulase reaction,together with Chromagar chromogenic media to improve the accuracy.Totally 21.4% of the samples were contaminated with S.aureus,and the prevalence rates of the raw milk,the semi-product milk and finished product milk were 26.4%,7.1% and 0.0%,respectively.After phenotypic characterization,the presence of classical enterotoxin genes as SEA,SEB,SEC and SED were determined by multiplex PCR in the 121 isolates of S.aureus.The results indicated that 22.3% of the isolates harbored enterotoxin genes and 7.4% of the isolates harbored at least two types of the enterotoxin genes.The prevalence rates of enterotoxin genes in the isolates of raw milk,semi-product milk and finished product milk were 23.9%,0.0% and 0.0%,respectively.The most common was SEA gene( 13.2%),followed by SEB gene( 10.7%),SEC gene( 5.8%) and SED gene( 3.3%).This work had increased our knowledge about the contamination status and toxin genes of the S.aureus during the processing of raw milk and provided evidence for the control of the milk quality and safety.