食源性单核增生性李斯特氏菌毒力基因的分布

Distribution of Virulence Genes in Foodborne Listeria monocytogenes

为探明保定、石家庄及周边地区食源性单增李斯特菌的污染状况以及食源性单增李斯特菌中毒力基因的分布情况,从保定、石家庄及周边地区农贸市场、超市采集七大类食品,共1 288个样品进行单增李斯特菌的污染调查,对鉴定分离出的308株食源性单增李斯特菌的27个毒力基因进行PCR检测。结果表明:七大类食品中单增李斯特菌的平均检出率为23.91%,动物源食品单增李斯特菌污染远高于植物源食品;27个毒力基因的PCR检测发现,inl、plcA、plcB、hpt、hly及fbp等与侵入、感染有关的毒力基因在动物源食品分离株中分布明显高于植物源食品分离株;而iap、ami、dlt、prfA、virR、hfq与粘附、调控有关的毒力基因在动物源食品分离株和在植物源食品分离株中差别不明显;hfq、dltC和iap 3个基因的检出率最高,分别达到94.68%,93.36%和91.03%,可作为该地区食源性单增李斯特氏菌鉴定的参考基因。

In order to know the contamination status of Listeria monocytogenes and the distribution of virulence genes in Listeria monocytogenes, there were 308 wild strains of L. monocytogenes isolated from 1 288 samples of seven kinds of foods which were obtained from Baoding and Shijiazhuang areas of Hebei province, china. Meanwhile, the distribution of 27 virulence genes in 308 strains of Listeria monocytogenes was detected by PCR. The result showed that the total isolation rate of Listeria monocytogenes in seven kinds of foods was 23.91%. The contamination level of raw meat was the most serious in all foods, the isolation rate of Listeria monocytogenes was up to 40.60%, followed by cooked meat products （25.42%） and aquatic products （23.46%）. In comparison, the contamination level of Listeria monocytogenes was higher in the animal food than in garden stuff. The result of the detection of 27 virulence genes indicated that those genes which related to cell infection and intercellular spread were distributed in animal food isolates more than in garden stuff isolates, such as inl,plcA ,plcB,hpt,actA ,hly and fbp. Those genes which related to cell adhesion and regulation, such as iap,ami,dlt,prfA ,virR and hfq were distributed no significant difference both in animal food isolates and in garden stuff isolates. The detection rate of hfq,dltC and lap was up to 94.68%, 93.36%, 91.03% respectively in 308 wild isolates, which suggested that the three gene above could be used as a reference gene in identification of Listeria monocytogenes in this area.