温州市食品中金黄色葡萄球菌污染状况及分子流行病学特征研究

目的了解温州市食品中金黄色葡萄球菌的污染状况,分析分离的金黄色葡萄球菌的耐药性、毒力基因分布及脉冲场凝胶电泳(PFGE)分子分型特征。方法依据GB 4789.10—2010《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》进行菌株分离鉴定,采用纸片法进行药敏试验,mini-VIDAS法和聚合酶链式反应(PCR)法分别进行肠毒素及其基因的检测,PFGE法进行分子分型。结果 4类食品388份样品中有16份样品检出金黄色葡萄球菌,检出率为4.12%,其中生畜肉和生禽肉检出率较高,分别为13.89%(5/36)和11.11%(4/36)。所有菌株均有不同程度的耐药,对青霉素耐药率最高(100.00%,16/16),其次为红霉素(56.25%,9/16),多重耐药率为18.75%(3/16),未检出对甲氧西林耐药的金黄色葡萄球菌。金黄色葡萄球菌肠毒素及其基因检测阳性率均为56.25%(9/16),其中seb、seg基因检出率较高,均为37.50%(6/16)。PFGE图谱分为12种PFGE带型。结论金黄色葡萄球菌在温州市食品中存在一定的污染率,且具有分子多态性、产肠毒素率及毒素基因携带率较高的特征,提示存在潜在的食品安全隐患。

Contamination and molecular epidemiology of Staphylococcus aureus in food in Wenzhou

Objective To investigate Staphylococcus aureus contamination in food in Wenzhou, and to analyze the drug resistance, enterotoxin genes distribution and pulsed-field gel electophroresis(PFGE) patterns. Methods According to GB 4789.10-2010 National Food Safety Standard Food Microbiological Examination:Staphylococcus aureus, the strains were isolated and identified. The Kirby-Bauer method was used in drug sensitivity test. Mini-VIDAS and polymerase chain reaction(PCR)were used to detect the Staphylococcus aureus enterotoxin and its genes. All strains were subtyped by PFGE. Results Four categories of 388 samples were collected. Sixteen Staphylococcus aureus strains were isolated with a positive rate of 4.12% and livestock meat and poultry meat got the highest detection rate as 13.89%(5/36)and 11.11%(4/36), respectively. All strains were antibiotic-resistant to at least one drug, and the resistant rate to penicillin was the highest(100.00%,16/16), followed by erythromycin(56.25%,9/16), and 18.75%(3/16)strains displayed multi-drug resistance. No methicillin-resistant Staphylococcus aureus(MRSA) was detected. The prevalence rates were 56.25%(9/16)in enterotoxin and its genes, among which seb and seg gene were more frequently found 37.50%(6/16). The 16 isolates were divided into 12 PFGE patterns. Conclusion The food was contaminated by Staphylococcus aureus to some degree in Wenzhou. Foodborne Staphylococcus aureus isolated in Wenzhou showed molecular polymorphism and strong enterotoxin-producing ability. The prevalence rates of enterotoxin gene was high, which may result in potential risks to food safety.