湖州市市售冷冻即烹类预制菜分离单增李斯特菌基于全基因组序列的分子特征和耐药性分析
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湖州市疾病预防控制中心,浙江 湖州 313000

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纪蕾 女 副主任技师 研究方向为病原微生物 E-mail: 356155762@qq.com

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R155

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浙江省医药卫生科技计划(2023KY1185)


Antimicrobial resistance and genomic characterization of Listeria monocytogenes isolated from frozen prepared dishes from Huzhou City
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Huzhou Center for Disease Control and Prevention, Zhejiang Huzhou 313000, China

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    摘要:

    目的 了解2023—2024年湖州市市售冷冻即烹类预制菜中单增李斯特菌的污染状况,基于全基因组测序(WGS)对冷冻即烹类预制菜中分离的单增李斯特菌株的血清型、基因型、耐药及毒力基因等遗传特征进行分析。方法 2023—2024年随机采集湖州市零售的冷冻即烹预制菜127件,参照食品安全国家标准GB 4789.30—2016对单增李斯特菌进行分离鉴定。利用微量肉汤法测定分离菌株对8种抗生素的最小抑菌浓度(MIC)值,同时进行WGS及生物信息学分析,包括谱系、血清型、序列分析(ST型)、克隆群(CC型)、耐药基因、毒力基因、环境抗性基因的携带情况等。结果 127份冷冻即烹预制菜中,有21份样品检出单增李斯特菌,总检出率为16.54%(21/127),1/2a为优势血清型,占比57.14%(12/21)。21株分离株来自2个谱系(谱系Ⅰ和谱系Ⅱ),包括7个克隆群(CCs)和7个序列型(STs),CC121-ST121(28.57%)、CC8-ST8(23.81%)和CC87-ST87(19.05%)为优势ST型。所有分离株均携带LIPI-1毒力基因和内化素家族成员inlA、inlB、inlC等核心毒力决定因子,inlA基因提前终止突变均发生在谱系Ⅱ。此外1株CC288-ST330型菌株携带LIPI-3相关毒力基因,CC87-ST87型菌株均携带LIPI-4相关毒力基因,具有潜在致病风险。ST5、ST8、ST9、ST155型菌株携带压力生存岛SSI-1相关基因。95.24%(20/21)的分离株对所选抗生素敏感,但有1株显示对一线抗生素青霉素以及广谱抗生素美罗培南耐药。全基因组多位点序列分型(cgMLST)进化分析显示,同一厂家分离的菌株之间具有较近的进化关系,同时发现某厂家连续两年检出疑似同源的ST8型菌株,提示该型别菌株在该厂家生产线的污染持续存在。结论 湖州市冷冻即烹类预制菜中存在一定水平的单增李斯特菌污染,尤其是高毒力的ST87型菌株,且部分菌株对一线抗生素具有耐药性。该研究提示食品生产企业需加强原料管控与生产过程管理,同时提升消费者对预制菜处理和烹饪过程中的食品安全意识,以降低潜在风险。

    Abstract:

    Objective To investigate the contamination status of Listeria monocytogenes in frozen prepared dishes collected from Huzhou City during 2023—2024, and to elucidate the antimicrobial resistance and genetic characteristics of the isolates.Methods A total of 127 retail frozen prepared dish samples were randomly collected in Huzhou City from 2023 to 2024. L. monocytogenes was isolated and identified according to the China national food safety standard GB 4789.30—2016. Minimum inhibitory concentrations (MICs) for 8 antibiotics were determined for 21 L. monocytogenes isolates using the broth microdilution method. Whole genome sequencing and bioinformatics analysis were conducted to analyze isolates lineages, serotypes, sequence types (STs), clonal complexes (CCs), core genome multi locus sequence types (cgMLSTs), resistance genes, virulence genes, and stress response genes.Results L. monocytogenes was detected in 21 of 127 samples, with an overall detection rate of 16.54% (21/127). Serotype 1/2a was dominant, accounting for 57.14% (12/21) of all isolates. The 21 isolates belonged to two lineages (Lineage Ⅰ and Ⅱ), and were classified into 7 CCs and 7 STs. The predominant CC-ST types were CC121-ST121 (28.57%), CC8-ST8 (23.81%), and CC87-ST87 (19.05%). All isolates carried the LIPI-1 pathogenicity island and key internalin family virulence genes such as inlAinlB, and inlC. Premature stop codon (PMSC) mutations in inlA were observed exclusively in Lineage Ⅱ strains. One CC288-ST330 strain carried LIPI-3 associated virulence genes, and all CC87-ST87 strains carried LIPI-4, indicating more pathogenic potentiality. Strains of ST5, ST8, ST9, and ST155 carried stress survival island 1 (SSI-1) genes. In total, 95.24% (20/21) of isolates were sensitive to the tested antibiotics, while one isolate showed resistance to both the first-line antibiotic penicillin (PEN) and the broad-spectrum antibiotic meropenem (MEM). cgMLST phylogenetic analysis revealed close evolutionary relationships among strains isolated from samples with the same manufacturer, and a possible persistence of ST8 strains was observed across two consecutive years in one production facility, suggesting ongoing contamination existed.Conclusion A certain level of L. monocytogenes contamination existed in frozen prepared dishes in Huzhou City, with particular concern for high-virulence ST87 strains and occasional antibiotic resistance. These findings highlight the need for food production enterprises to strengthen raw material control and process management, while also promoting consumer awareness of food safety during handling and cooking of prepared dishes to reduce potential health risks.

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纪蕾,陈莉萍,卢忠豪,吴晓芳,严伟,董芬芬.湖州市市售冷冻即烹类预制菜分离单增李斯特菌基于全基因组序列的分子特征和耐药性分析[J].中国食品卫生杂志,2025,37(10):930-936.

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  • 收稿日期:2025-02-25
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  • 在线发布日期: 2026-03-27
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