杨凌及周边地区零售分割鸡肉中沙门菌污染状况及耐药和分型特征研究

目的研究陕西杨凌及周边地区零售分割鸡肉中沙门菌的污染状况及其药敏性、血清型和基于脉冲场凝胶电泳(PFGE)的基因型,为预警食源性沙门菌疾病暴发提供数据基础。方法采用GB 4789.4—2010《食品安全国家标准食品微生物学检验沙门氏菌检验》对陕西杨凌及周边地区采集的188份零售分割鸡肉中沙门菌进行分离和鉴定,并进行血清学分型。采用PFGE方法确定沙门菌DNA酶切电泳图谱,使用BioNumerics软件聚类分析电泳结果,确定沙门菌基因型。结果 188份零售分割鸡肉中共有34份(18.1%)样品检出沙门菌,农贸市场样品沙门菌检出率(24.6%,29/118)高于超市(7.1%,5/70)。鸡腿、鸡爪、鸡脖和鸡肝样品中沙门菌检出率高于鸡肠和鸡胗。34株沙门菌中共检出10种血清型,其中科瓦利斯沙门菌最为流行,高于德尔卑沙门菌和鼠伤寒沙门菌等,差异有统计学意义(P0.05)。分离株均对磺胺异噁唑、氯霉素、头孢噻呋和环丙沙星耐药,对甲氧苄啶/磺胺甲噁唑、萘啶酮酸、四环素、链霉素、氨苄西林和阿莫西林/克拉维酸的耐药率均在50%以上。34株沙门菌PFGE分型后可被分为11个簇,同一血清型菌株基本聚于同一大簇,同一时间、从相同市场采集的不同样品,其分离株PFGE型相似度均较高,表明分割鸡肉在加工或销售过程可能存在交叉污染。农贸市场分离菌株基因型多样性比较丰富。结论杨凌及周边地区零售分割鸡肉存在沙门菌污染,沙门菌血清型和基因型多样化,耐药菌株比例较高。

Prevalence and characterization of Salmonella in retail raw chicken cuts in Yangling and its surrounding districts

Objective Prevalence of Salmonella in retail raw chicken cuts were collected from Yangling and its surrounding districts, characterizations including antibiotic susceptibility, serotype and genotype based on pulse field gel electrophoresis (PFGE) of Salmonella isolates in these samples were investigated to support basic data for foodborne Salmonella outbreaks prediction. Methods Salmonella was isolated and identified according to procedures of the National Food Safety Standard of Food Microbiological Examination:Salmonella (GB 4789.4-2010), the serotype was determined via serum agglutination method, the genotype was determined via protocol of PFGE, and DNA profiles were clustered by BioNumerics software. Results Thirty-four (18.1%) of 188 retail raw chicken cut samples were positive for Salmonella, the detection rate of Salmonella in farmer''s market (24.6%,29/118) was higher than that in supermarket (7.1%,5/70); the detection rates of Salmonella in chicken leg, chicken feet, chicken neck, chicken liver were higher than those in chicken intestine and gizzard. Ten serotypes were identified from 34 Salmonella isolates, and the most commonly detected serotype was S.Corvallis, which was significantly (P<0.05) more prevalent than other serotypes including S.Typhimurium, S.Derby, and so on. All isolates resisted to sulfamethoxazole, chloramphenicol, ceftiofur and ciprofloxacin; the rates of isolates resisted to trimethoprim-sulfamethoxazole, nalidixic acid, tetracycline, streptomycin, ampicillin, and amoxicillin-clavulanic were above 50%. PFGE profiles of 34 Salmonella isolates could be grouped into 11 clusters, the isolates with the same serotype were commonly grouped into the same cluster. PFGE profiles of isolates with the same serotype and recovered from different samples in same sampling time and marketplace were similar or highly similar, which indicated the retail chickens might be cross-contaminated by Salmonella during processing and/or sale. Genotype of Salmonella isolates from farmer''s market was more diversed than those from supermarkets. Conclusion The retail raw chicken cuts in Yangling and its surrounding districts were contaminated by Salmonella, which not only exhibited diverse serotypes and genotypes, but high frequency of antibiotic resistance.