The Study Of Distribution And Internalin Genes Of Listeria Monocytogenes Among Food Samples

Listeria monocytogenes is a kind of important zoonotic disease pathogens, which can cause persons, various livestocks and fowls serious diseases. Listeria monocytogenes has been considered zoonotic disease pathogens in all over the world since 1940s. From the public health point of view, Listeria monocytogenes as one of the most important food-borne pathogen, it has been paid much more attention of the people since 1990s.Many experts and scholars at home and abroad study the biological characteristics, detection technology, pathogenicity gene, virulence factors and epidemiological of Listeria monocytogenes.This paper isolated and identified Listeria monocytogenes by the first step of the physiologic and biochemical tests from 1627 samples. 1627 random samples from 9 sorts of quick-frozen food, aquatic products, resh meat, meat protucts, fruit, vegetables, bean product, raw milk, salted product were collected from supermarkets and peasant-trade mart and some faeces of animal and person. The total detectable rate of Listeria monocytogenes was 14.5%. The results showed that the detectable rate of Listeria monocytogenes were higher. It expressed that pollution level of Listeria monocytogenes in Baoding and circumjacent area was taller. Studying distributing status of Listeria monocytogenes, it was discovered that the able rate of Listeria monocytogenes in resh meat samples was the highest (27.4%). The second rate was 24.7% in salted product. It indicated that the probability of this bacterium to pollute resh meat and salted product were high and we should attach importance to quality problem of these products to avoid breaking out of food-borne diseases. It was very important to defend the pathogen.At present, Listeria monocytogenes internalin genes can be divided into 9 types (inlA, inlB, inlC, inlC2D, inlD, inlE, inlF, inlG and inlH). According to announced literatures, inlA and inlB were in all of Listeria monocytogenes strains. inlC, inlC2D, inlD, inlE, inlF, inlG and inlH were in certain of Listeria monocytogenes strains. Owing to identifying them to genus certainly, these strains were identified by PCR with primers of inlA, inlB, inlC, inlC2D, inlD, inlE, inlF, inlG and inlH. They were special pathogenic genes of L.monocytogenes and these primers were synthesized according to primer sequences in announced literatures. Identified internalin gene of 236 strains which had been isolated, 2 were identified as typeâ… ; 43 were identified as typeâ…¡; 87 were identified as typeâ…¢; There were 104 identified strains neither had inlA, inlB gene family, no complete (inlG, inlC2, inlD, inlE) gene family or (inlG, inlH, inlE) gene family.It is needed that the pollution conditions of Listeria monocytogenes in crowd, livestocks and foods as well as epidemiologic conditions of this pathogen are further investigated for the supervision of Listeria monocytogenes, the examination of explosion and spread as well as tracking to pollrter to providing basis.