四川省动物性食品中金黄色葡萄球菌的分离鉴定及污染分析

Isolation,Identification and Contamination Analysis of Staphylococcus aureus in Animal Food in Sichuan

目的:为分析四川省动物性食品源金黄色葡萄球菌(Staphylococcus aureus,简称SA)的耐药性,收集菌株,同时分析动物性食品中SA的污染情况。方法:本实验自2006年12月至2007年9月从四川省各地采集猪源、牛源、鸡源动物性食品样品共2560份,利用选择性培养基和生化实验等常规方法分离鉴定SA。结果:用Baird-Parker平板初步筛出疑似SA118株,结合国标中规定的涂片染色镜检,溶血现象和血浆凝固酶实验结果,判定SA有108株,而科玛嘉金黄色葡萄球菌显色平板和TH-16S中的双歧索引鉴定结果均判定SA有113株;依据TH-16S中的16项生化实验结果,118株疑似SA仅有64%(76株)的菌株鉴定为SA。依据国标判定结果,2560份样品中SA的分离率为4.21%,其中生牛奶中SA的分离率最高(10.54%),其次是猪肉(7.11%),鲜鸡蛋中SA的分离率为零。结论:四川地区动物性食品源SA的生化表型复杂且存在一定差异,常规的表型分析具有一定缺陷。各个地方各类样品中SA污染情况有一定差异,与其他报道相比,四川省生肉、生奶和鲜蛋中SA的分离率较低。

Objective： To investigate the drug resistance of Staphylococcus aureus in animal food in Sichuan, and analyze the Staphylococcus aureus contamination situation. Methods： 2560 samples of animal food （from pig, cattle and chicken ） were collected from December 2006 to September 2007 in Sichuan, then the isolation and identification of Staphylococcus aureus were conducted using selective medium and biochemical test. Results： 118 doubtful strains were isolated according to the growth characteristics on Baird-Parker plate. Among them, 108 strains were regarded as Staphylococcus aureus based on the results of Gram staining, hemolytic crisis and coagulase experiments stipulated in the GB （Chinese national standard）, but 113 strains were regarded as Staphylococcus aureus by CHROMagar chromogenic medium and fork index identification stipulated in the TH- 16S, whereas only 76 strains, 64% of 118 doubtful strains were further identified as Staphylococcus aureus by 16 biochemical experiments stipulated in the TH- 16S. According to GB, the positive rate of SA in 2560 samples was 4.21%, in which, the positive rate of Staphylococcus aureus in raw milk was the highest （10.54%）, followed by the pork （7.11%）, and that in fresh eggs was zero. Conclusion： The biochemical phenotype of Staphylococcus aureus in Sichuan animal food is complicated, which indicates defects of the conventional phenotypic analysis. The contamination of Staphylococcus aureus in various places shows certain differences. Compared to other reports, the positive rates of Staphylococcus aureus in Sichuan animal foods is relatively low.