合肥市屠宰生猪卫生现状调查研究

【作者】 李郁；

【导师】 焦新安； 魏建忠；

【作者基本信息】 扬州大学 ， 预防兽医学， 2006， 硕士

【摘要】 菌落总数、大肠菌群和致病菌是食品卫生微生物学检测的三项重要指标。产单核细胞李斯特菌(Listeria monocytogenes，Lm)和沙门氏菌(Salmonella)均为最重要的食源性致病菌，其中Lm可引起人类脑膜炎、脑膜脑炎、孕妇流产以及败血症等严重疾病，致死率高达30％以上：在世界各国的各类细菌性食物中毒中，沙门氏菌引起食物中毒的爆发起数和发病人数常列榜首。本文的研究目的是：通过①市售定点屠宰猪肉中产单核细胞李斯特菌的污染状况调查研究，②定点屠宰场生猪屠宰环节中产单核细胞李斯特菌污染状况调查，③屠宰生猪胴体菌落总数、大肠菌群及沙门氏菌污染状况调查研究，以了解合肥市屠宰生猪的卫生现状，从而为进一步改善合肥市生猪屠宰加工的卫生管理，建立生猪屠宰危害分析和关键控制点(HACCP)体系，加强生猪屠宰加工、贮藏、运输、销售等各环节的卫生监控，提高猪肉产品卫生质量，预防和控制食源性李斯特菌病和沙门氏菌病提供科学依据。一、市售定点屠宰猪肉中产单核细胞李斯特菌的污染状况调查研究应用聚合酶链式反应(PCR)技术对370份市售生猪肉样品进行Lm的检测，分离出4株产单核细胞李斯特菌，阳性检出率为1.08％，表明合肥市市售生猪肉中有一定程度产单核细胞李斯特菌的污染，并且存在李斯特菌病的可能性和食物中毒的潜在危害性。对2株Lm分离菌株的hly基因第190～970位核苷酸序列(780bp)与GenBank中注册的国内外14个参考株进行同源性比较，显示Lm hly基因核苷酸序列差异的距离与地理分布、菌株的样品来源无一定的相关性。二、定点屠宰场生猪屠宰环节中产单核细胞李斯特茵污染状况调查鉴于合肥市市售定点屠宰生猪肉存在产单核细胞李斯特菌的污染，应用PCR技术对合肥市五个定点屠宰场生猪屠宰环节Lm污染状况进行溯源性追踪调查。包括屠宰生猪体表和胴体表面、地面、屠宰污水在内的705份样品中均未检测出Lm，与其他相关报道不相符合。Lm在环境和食品中的数量小于10~2 cfu／ml，易受生产加工诸多因素的损伤影响，同时杂菌数量过多，这些因素可能是造成Lm检测阴性的原因。三、屠宰生猪胴体菌落总数、大肠菌群及沙门氏菌污染状况调查研究应用国标法对700份屠宰生猪胴体体表样品和胴体肉样进行菌落总数、大肠菌群及沙门氏菌污染状况调查。结果显示：生猪胴体肉样菌落总数和大肠菌群的总超标率达47％和22.5％；生猪胴体体表样品和肉样沙门氏菌检出率分别为24.2％和17％，均以B群和E1群为主要菌群，里定沙门氏菌为优势血清型；大肠菌群和沙门氏菌之间呈现正相关。表明合肥市生猪胴体的卫生质量亟待提高，屠宰生产加工水平亟待改善，在肉品生产过程中重视大肠菌群的控制则有利于降低沙门氏菌的污染程度，实施宰前管理和宰前检验是保证病健隔离分宰、减轻对加工环境和产品污染的重要环节。且沙门氏菌优势菌型的分布呈现出一定的区域性。更多还原

【Abstract】 There are three major standards including aerobic bacterial count, Ccoliformbacteria and pathogenic bacteria for microbiological examination of food hygiene.Listeria monocytogenes (Lm) and Salmonella are two of most importantfood-borne pathogens. Lm could even cause meningitis, septicemia and abortionof pregnant women, and the mortality rate could be as high as 30％. All over theworld, Salmonella infection causes the most serious bacterium food poisoning innumber of cases and population.Accordingly, the present study was investigated①the Lm contamination rate in marketing pork,②the Lm contaminationstatus in slaughter process of abattoir, and③aerobic bacterial count andcontamination of Coliform bacteria and Salmonella in pig carcass. This study wasto know the hygienic situation of slaughter pig in Hefei, and consequently,provide a scientific basis for improving the hygienic management of the slaughterprocess, for establishing the pig slaughter Hazard Analysis and Critical ControlPoints (HACCP) system, for strengthening the hygiene monitoring for pigslaughter, processing, storage, transportation, marketing, for improving hygienequality of pork products, and finally, for preventing and controlling food-borneillnesses from Salmonella and Lm.1 Investigation of Lm contamination in marketing porkThe contamination of Listeria monocytogenes in marketing pork wasdetected by polymerase chain reaction (PCR). As a result, four Listeriamonocytogenes strains were isolated in 370 pork samples, and the positive ratewas 1.08％. It indicated that the marketing pork was contaminated by Listeriamonocytogenes with lower level and there was possibility of listeriosis andpotential danger of food poisoning in Hefei. The hly gene of two Lm isolates wassequenced from p190 to p970 nucleotide (DNA, 780 bp) and compared with thesequences of 14 reference strains registered in GenBank. The results showed thatthe difference distance of Lm hly gene nucleotide sequences had no relationshipwith its distribution, origin and source.2 Investigation of Lm contamination in slaughter processBased on the contamination of Lm in marketing pork in Hefei, furtherretrospect survey on the contamination rate of Lm in the slaughter process in 5designated areas was conducted by PCR. Altogether, 750 samples were collectedfrom the slaughtered pig skin and carcass surface, ground and water used inslaughtering. Among them, none was Lm positive, which was not identical withthe previous reports. As for the reason, it might be due to the low concentration insamples (less than 10~2 cfu/ml), the influence of processing factors, andcontamination of many other bacterium. 3 Investigation of aerobic bacterial count, Coliforms bacteria and Salmonellacontamination in slaughtered pig carcassBase on the criteria of national standards, 700 samples from pig carcasssurface and meat were examined for aerobic bacterial count, Coliform bacteriaand Salmonella contamination. The results showed that the overall positive rateof aerobic bacterial count and Coliform bacteria reached 47％and 22.5％respectively, while the overall positive rate of Salmonella in carcass surface andmeat samples was 24.2％and 17％respectively. Among them, the mainserogroups were group B and group E1, and the dominant serotype was S.reading.There was a positive correlation between Coliform bacteria and Salmonellacontamination. It indicates that it is seriously necessary to improve the quality ofpig carcass hygiene and enhance the higiene level of production and processing.It is helpful to reduce the Salmonella contamination if it was paid more attentionon the control of Coliform bacteria. It is also helpful to insure healthy pig andunhealthy pig isolating, reduce the Salmonella contamination to processingsurroundings and products if it was brought into effect on Anti-mortemmanageness and Anti-mortem inspection. Moreover, Salmonella dominant strainsdistribute irregularly in different regions.更多还原