衡阳市生畜肉及熟肉制品中沙门菌血清型、分子分型及耐药性研究

目的了解2021年衡阳市生畜肉及熟肉制品中沙门菌污染状况,分析沙门菌血清型分布、分子分型特征及耐药情况。方法采集衡阳市各县区生畜肉及熟肉制品样品,依照GB4789.4进行沙门菌分离鉴定和血清分型;采用美国临床和实验室标准化协会(Clinical and Laboratory Standards Institute,CLSI)推荐的微量肉汤稀释法进行药物敏感试验;用脉冲场凝胶电泳(pulsed field gel electrophoresis,PFGE)进行分子分型,结果用BioNumerics软件聚类分析。结果从52份生畜肉中检出18株沙门菌,检出率为34.62%(18/52),52份熟肉制品中检出3株沙门菌,检出率为5.77%(3/52);21株沙门菌可分为7个血清型,其中伦敦沙门菌42.86%(9/21)和罗森沙门菌19.05%(4/21)占主要优势;21株沙门菌均对亚胺培南(IPM)和多粘菌素E(CT)敏感,对萘啶酸(NAL)、头孢噻肟(CTX)、头孢西丁(CFX)、头孢他啶(CAZ)敏感度均达90.00%以上,对四环素(TET)、氨苄西林(AMP)、甲氧苄啶/磺胺甲噁唑(SXT)耐药达50.00%以上,多重耐药严重,最常见的耐药谱为四环素-氨苄西林-甲氧苄啶/磺胺甲噁唑(TET-AMP-SXT),耐药率为52.38%;21株沙门菌PFGE聚类分析相似度为48.20%,罗森、伦敦沙门菌带型最为集中,但鼠伤寒沙门菌呈现多样性;各带型与耐药谱之间未见明显相关。结论衡阳市生畜肉及熟肉制品沙门菌污染及耐药问题严重,血清型分布广泛,同一血清型大部分菌株PFGE型可聚集成簇。

Serotype,molecular typing and drug resistance of Salmonella in raw livestock meat and cooked meat products in Hengyang City

Objective To understand the contamination status of Salmonella in raw livestock meat and cooked meat products in Hengyang City in 2021, and to analyze the serotype, molecular typing characteristics and drug resistance ofSalmonella. Methods Samples of raw livestock meat and cooked meat products were collected in all counties and districts of Hengyang City, and Salmonella was isolated, identified and serotyped according to GB4789.4. The micro broth dilution method recommended by Clinical and Laboratory Standards Institute (CLSI) was used for drug sensitivity test. Molecular typing was performed by pulsed field gel electrophoresis (PFGE), and the results were analyzed by BioNumerics software. Results Eighteen strains of Salmonella were detected from 52 samples of raw livestock meat, and the detection rate was 34.62% (18/52). 3 strains of Salmonella were detected from 52 samples of cooked meat products, and the detection rate was 5.77% (3/52). 21 strains of Salmonella were divided into 7 serotypes, of which Salmonella London (42.86%, 9/21) and Salmonella Rissen (19.05%, 4/21) were dominant serotypes. All the 21 strains of Salmonella were sensitive to imipenem (IPM) and polymyxin E (CT). The drug susceptibility rates of the Salmonella strains to nalidixic acid (NAL), cefotaxime (CTX), cefoxitin (CFX) and ceftazidime (CAZ) were more than 90.00%, and those to tetracycline (TET), ampicillin (AMP) and trimethoprim/sulfamethoxazole (SXT) were more than 50.00%. Multidrug resistance was fairly serious. The most common drug resistance spectrum was tetracycline- ampicillin-trimethoprim/sulfamethoxazole (TET-AMP-SXT), and the drug resistance rate was 52.38%. PFGE cluster analysis of the 21 strains of Salmonella showed a similarity of 48.20%. The bands of Rissen and London serotypes were the most concentrated, but Salmonella typhimurium showed diversity. There was no significant correlation between each band pattern and drug resistance spectrum. Conclusion Contamination and drug resistance of Salmonella in raw livestock meat and cooked meat products in Hengyang City are serious, and the serotypes are widely distributed. The PFGE types of most strains of the same serotype can be clustered.