西宁市食品中金黄色葡萄球菌污染状况及其肠毒素基因型分布研究

Investigation on the contamination and enterotoxin genetypes of staphylococcus aureus from food in Xining

为了掌握金黄色葡萄球菌在西宁地区食品中的分布规律,了解不同来源、不同种类食品中金黄色葡萄球菌的污染状况及其5种肠毒素基因型(A、B、C、D、E)的分布状况。在西宁市地区采集108份食品样品,按食品微生物学(GB 4789.10-2010)金黄色葡萄球菌检验方法结合Baird-Parker氏鉴别培养基筛选金黄色葡萄球菌,通过对金黄色葡萄球菌耐热核酸酶(nuc)基因的PCR扩增以及基质辅助激光解吸电离飞行时间质谱技术(Matrix assisted laser desorption ionization time of flight mass spectrometry,MALDI-TOF-MS)对疑似菌落进行鉴定;同时利用PCR技术对金黄色葡萄球菌的5种肠毒素基因型进行分型检测。经分离及生化鉴定,从108份样品中得到60株疑似金黄色葡萄球菌、PCR方法及MALDI-TOF MS结果,确认为金黄色葡萄球菌,检出率为55. 56%;同时60株金黄色葡萄球菌分别检出A型6株、B型34株和D型2株,共检测到42株,检出率为70%,C型和E型未被检测到。表明西宁市食品中金黄色葡萄球菌的污染处于一个相对较高水平,因食品来源与种类不同,金黄色葡萄球菌的污染情况和毒素基因的分布情况也各不相同,对西宁市食品质量安全控制具有参考意义。

In order to grasp the distribution regularities of staphylococcus aureus(S.aureus)in foods in xining,and know the contamination status of S.aureus and the distribution status of five S.aureus enterotoxin genetypes(A、B、C、D、E)in food from different sources and species.108 food samples in Xining,using the method of food microbiology(GB 4789.10 2010)combined with Baird-Parker differential culture medium to screen out S.aureus,and by the amplification of PCR for nuc and mass spectrometry to identify suspected colonies.The method of PCR for five S.aureus enterotoxin genotypes to parting detection.Results showed that 60 suspected strains of S.aureus were isolated from 108 samples after separation and biochemical identification,the gene specific fragment of 279 bp(nuc)was amplified by PCR also sequencing and the results of MALDI-TOF MS shown that the score was between 2.445 and 2.451,and the score was very creditable to the level of the bacteria,confirmed as S.aureus ultimately and the detection rate was 55.56%.Respectively detected A type 6 strains、B type 34 strains and D type 2 strains from 60 strains S.aureus,and the detection rate was 70%.C type and E type were not detected.The contamination of S.aureus from food in Xining is at a relatively high level.The contamination of S.aureus and the distribution status of S.aureus enterotoxin gene varies from food sources and species.These results can provide a reference for food quality and safety control in Xining.