6种食源性致病菌质控考核结果分析

目的对承担食品安全风险监测任务的全国各级疾病预防控制中心开展微生物质量控制考核,以评价其对6种食源性致病菌的检验能力。方法 6种质控考核菌株包括单核细胞增生李斯特菌、蜡样芽胞杆菌、阪崎肠杆菌、大肠埃希菌、沙门菌以及金黄色葡萄球菌。按照2011和2012年设计的组合,将新鲜培养的致病菌增菌液混合后滴加于灭菌奶粉载体中制成样品。2011年考核制备了6种样品(I~VI),2012年为10种样品(A~J)。运用点分数法对两年结果分别进行满意率评价,率的比较用Pearsonx~2检验或对数似然比x~2检验。结果 2011和2012年考核总体满意率分别为86.5%(268/310)和84.3%(375/445),2011年样品满意率最低的是空白样品VI(68.0%,17/25),2012年满意率最低的是G样品(0.0%,0/8)。2011和2012年考核结果主要漏检的是大肠埃希菌,其中2012年大肠埃希菌漏检率占漏检总数的85.7%(60/70)。2011年非考核菌中漏检最多的是金黄色葡萄球菌和蜡样芽胞杆菌。2012年考核结果主要多检的是金黄色葡萄球菌,占多检总数的36.8%(7/19)。两年的结果均显示大肠埃希菌和阪崎肠杆菌组合样品中,大肠埃希菌的漏检率明显增高。沙门菌和大肠埃希菌的血清分型正确率较低,分别为41.5%(95/229)和45.1%(105/233)。单核细胞增生李斯特菌易错误鉴别成英诺克李斯特菌,蜡样芽胞杆菌易错误鉴别成蕈状芽胞杆菌,阪崎肠杆菌易错误鉴别成河生肠杆菌。结论 80%以上的疾病预防控制中心对6种致病菌的定性检验能力较好,可以满足食品安全风险监测的需求。其中对沙门菌的检验能力最高;金黄色葡萄球菌漏检率较低但易出现多检;大肠埃希菌的检验能力有待提高;阪崎肠杆菌的检验水平较2010年结果有明显提升。

Analysis on quality control results of six foodborne pathogenic bacteria

The microbiological quality control test for the centers for disease control and prevention was conducted at the provincial, municipal and county level, and the detection capability against six foodborne pathogenic bacteria was evaluate. Methods Six bacteria under test were Listeria monocytogenes, Bacillus cereus, Enterobacter sakazakii, Escherichia coli, Salmonella and Staphylococcus aureus. According to the bacterium combination designed in 2011 and 2012, the samples were prepared by adding the fresh blended culture of pathogenic bacteria into radiation-sterilized milk powder carrier. Six samples of I-VI were prepared in 2011 while ten sample of A-J in 2012. The results of qualification were evaluated using the point-score method. The rate of detection was analyzed with Pearson ² or likelihood ratio². Results The overall qualification rate of 2011 and 2012 were 86.5%(268/310)and 84.3%(375/445), respectively. The lowest qualification rate in 2011 was blank sample VI(68.0%,17/25), while the lowest in 2012 was sample G(0.0%,0/8). In both 2011 and 2012, Escherichia coli was the main false negative bacterium and accounted for 85.7%(60/70)of total false negatives in 2012. The most frequent false positive results among in 2011 were Staphylococcus aureus and Bacillus cereus which were not accounted for the evaluation. In 2012, the highest false positive result was Staphylococcus aureus which accounted for 36.8%(7/19)of the total. In Enterobacter sakazakii and Escherichia coli composite samples of the two years both showed that the false negative rate of Escherichia coli increased significantly. The serotyping accuracy of Salmonella and Escherichia coli were as low as 41.5%(95/229)and 45.1%(105/233), respectively. The false identification occurred on Listeria monocytogenes versus Listeria innocua, Bacillus cereus versus Bacillus mycoides, and Enterobacter sakazakii versus Enterobacter amnigenus. Conclusion More than 80% of the centers possessed qualified detection capability against six foodborne pathogenic bacteria, which satisfied the requirements of food safety risk surveillance. The highest detection capability was toward Salmonella. Staphylococcus aureus had lower false negative results but was easy to produce false positives. The detection capability of Enterobacter sakazakii had improved significantly comparing with the results of 2010.