主要食源性致病菌的PCR检测方法优化及在冷鲜猪肉病原污染调查中的应用

为优化针对主要食源性致病菌的PCR鉴定体系,以及了解猪肉制品中主要食源性致病菌的污染状况,对文献中报道的沙门氏菌属(鼠伤寒沙门氏菌及肠炎沙门氏菌)的5套PCR体系及大肠杆菌O157:H7的6套PCR体系进行比较分析,结果筛选出2套最优体系。基于这两套体系以及本实验室研究人员建立的单增李斯特菌的特异性检测方法,对从杭州市场上采集的50份常温鲜猪肉及150份冷鲜猪肉中单增李斯特菌、沙门氏菌及大肠杆菌O157:H7的污染状况进行调查。调查结果显示,200份样品中致病菌总检出率为21%。冷鲜猪肉中的致病菌检出率(24.7%)明显高于常温鲜猪肉(10%)。单增李斯特菌在常温鲜猪肉中的检出率为2%,而在冷鲜猪肉中检出率达14.7%;沙门氏菌在冷鲜猪肉中的检出率(11.3%)亦高于常温鲜猪肉(8.0%);大肠杆菌O157:H7均未检出。在检出的沙门氏菌中,有4株为鼠伤寒沙门氏菌,均来自冷鲜猪肉。本研究结果提示,市场上冷鲜猪肉存在微生物性安全隐患,这可能是由于其较为复杂的生产流通环节受到污染所致。

Optimization of PCR Assays of Major Foodborne Pathogens and Their Application in Investigation of Pathogen Contamination in Chilled Pork

To optimize the PCR identification systems of major foodborne pathogens for investigating into their prevalence in chilled pork,we compared 5 assay formats of Salmonella spp(including S.typhimurium and S.enteritidis) and 6 assay formats of Escherichia coli O157:H7 reported in the literature.With two optimized assay formats,one for S.typhimurium and S.eneritidis and the other for E.coli,and with the PCR method set up in our laboratory for Listeria monocytogenes,we investigated the prevalence of L.monocytogenes,Salmonella spp and E.coli O157:H7 in 50 fresh pork samples and 150 chilled pork samples collected from Hangzhou markets.The results showed that the overall rate of pathogen contamination in the 200 samples was 21%.The incidence in chilled pork samples was higher than that in fresh pork samples(24.7% vs 10%).The incidence of L.monocytogenes was 2% in fresh pork samples and 14.7% in chilled pork samples.The incidence of Salmonella spp in chilled pork samples was also higher than that in fresh pork samples(11.3% vs 8.0%);No strain of E.coli O157:H7 was found.There were 4 strains of S.typhimurium,all from chilled pork samples.This research suggests the potential risk of major foodborne pathogens in chilled pork,probably due to contamination of the production line.