市售生鲜肉食品中金黄色葡萄球菌基因分型与毒素基因检测

Genotyping and toxin gene detection of Staphylococcus aureus isolated from market fresh meat

【目的】了解市售生鲜肉中金黄色葡萄球菌的污染、群体遗传多样性和毒素基因携带规律,为金黄色葡萄球菌的污染防控提供依据。【方法】按照GB4789.10—2016对金黄色葡萄球菌进行分离鉴定,采用多位点序列分型方法(MLST)进行分子分型,利用PCR方法检测11种毒素基因的携带情况。【结果】148份样品中有56份检出金黄色葡萄球菌,污染率为30.1%,分离到56株菌。56株菌可分成11种序列型(STs),其中ST7(28.6%)是主要流行的序列型,其他优势序列型分别为ST188(23.2%),ST1(8.93%)和ST88(8.93%)。6种毒素基因在27株菌(48.2%)中检出阳性结果,其中杀白细胞素基因pvl(26.8%)检出率最高,其次为肠毒素基因sec(12.5%),seh(10.7%),sea(7.1%)和sed(5.4%)。【结论】金黄色葡萄球菌在市售生鲜肉中具有较高的污染率,丰富的遗传多样性表明菌株污染来源广泛,与食物中毒和临床感染相关的毒素基因具有较高的分布比例,应加强对生鲜食品中金黄色葡萄球菌的监控。

[Objective]To investigate the contamination situation,molecular diversity and virulence gene distribution of Staphylococcus aureus isolated from market fresh meat,providing basis for its prevention and control.[Methods]S.aureus strains were isolated and identified according to GB 4789.10-2016.MLST(multilocus sequence typing)method was used for genotyping these isolates,and the distribution of 11 toxin genes were tested by PCR.[Results]A total of 56 S.aureus-positive samples(30.1%)were found out of 148 samples from market fresh meat,and finally 56 strains were isolated.MLST results showed that these strains could be typed into 11 different sequence types(STs).Among them ST7(28.6%)was dominant,and followed by ST188(23.2%),ST1(8.93%)and ST88(8.93%).Six toxin genes were detected in 27 strains(48.2%),in which the most frequent toxin gene was pvl gene(26.8%),followed by enterotoxin genes sec(12.5%),seh(10.7%),sea(7.1%)and sed(5.4%).[Conclusion]S.aureus has a high pollution rate in raw meat commodities.The high genetic diversity of the strains implies multiple sources of contamination.The toxin genes associated with food poisoning and clinical infection show a high distribution proportion.The monitoring of S.aureus in market fresh meat should be strengthened.