预包装熟肉制品生产加工过程沙门菌污染状况及病原学特征研究

Analysis of contamination and pathogenic characteristics of Salmonella in the processing of prepacked cooked meat products

目的了解预包装熟肉制品生产加工过程各环节中沙门菌污染状况,并分析分离株的分子特征及耐药性。方法按照国家《熟肉制品(预包装)生产加工过程监测工作手册》采样要求,2015—2017年在德州某预包装熟肉制品厂采集环境样品和熟肉样品共460份,依据现行有效的GB 4789.4—2016进行沙门菌分离鉴定;用血清凝集法对沙门菌进行血清分型;用脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)法对沙门菌进行分子分型分析;采用微量肉汤稀释法对15种抗生素进行耐药性检测。结果460份样品中沙门菌检出率为5.65%(26/460),2016年沙门菌的检出率最高(7.65%,14/183),不同年份沙门菌检出率差异无统计学意义(χ^(2)=2.82,P>0.05);中间产品中沙门菌的检出率最高,不同样品属性沙门菌检出率差异有统计学意义(χ^(2)=64.16,P<0.05);仅在生制品加工车间检出沙门菌,不同车间沙门菌检出率差异有统计学意义(χ^(2)=78.08,P<0.05)。26株沙门菌共分为6个血清型,肠炎沙门菌最多,占53.85%(14/26)。26株沙门菌经PFGE分型后获得12种带型,以S4型为主;经MLST分型共获得5种ST型,ST11为优势型别。26株分离株中有22株对不同的抗生素有耐药性,耐药率最高的是氨苄西林,为73.08%(19/26),多重耐药率(耐3种及以上抗生素)为73.08%。结论熟肉制品加工过程中沙门菌污染主要集中在加工过程的原辅料和中间产品环节,产品蒸煮后污染状况可被有效控制。

Objective To analyze the molecular characteristics and antibiotic susceptibility of Salmonella isolates and investigate the contamination of Salmonella in pre-packed cooked meat products during food processing.Methods According to the sampling requirements of the national“Manual for Monitoring the Production and Processing of Cooked Meat Products(Pre-packed)”,460 environmental and cooked meat samples were collected from a pre-packed cooked meat product factory in Dezhou from 2015 to 2017.Salmonella isolation and identification were performed per the currently effective GB 4789.4—2016 protocol.Salmonella serotypes were determined based on serum agglutination.Pulsed field gel electrophoresis(PFGE)and multilocus sequence typing(MLST)were employed to determine the molecular types of Salmonella isolates.Resistance tests for 15 antibiotics were performed using the broth microdilution susceptibility test.Results The detection rate of Salmonella in 460 samples was 5.65%(26/460).The detection rate in 2016 was the highest(7.65%,14/183),and the difference among samples from different years was not statistically significant(χ^(2)=2.82,P>0.05).The detection rate in intermediate products was the highest,and the difference among samples from different samples was statistically significant(χ^(2)=64.16,P<0.05).Salmonella was detected only in the raw product workshop,and the difference among samples from different workshops was statistically significant(χ^(2)=78.08,P<0.05).Twenty-six strains of Salmonella were divided into six serotypes,with Salmonella enteritidis being the most prevalent,accounting for 53.85%(14/26).Twenty-six isolates were subtyped into 12 PFGE types,with type S4 predominantly dominating.The 26 Salmonella strains were divided into five types based on MLST typing.ST11 was the major ST type.Of these 26 isolates,22 were resistant to various antibiotics.The highest antibiotic resistance rate was for ampicillin,at 73.08%(19/26),and the multiple antibiotic resistance rate(resistance to three or more antibiotics)was 73.08%.Conclusion During the processing of cooked meat products,Salmonella contamination is concentrated mainly in raw materials and intermediate products.The contamination status of the products after steaming was effectively controlled.