1株食品源ST45型耐甲氧西林金黄色葡萄球菌的生物学特征和系统发育分析

Biological characteristics and phylogenetic analysis of a foodborne ST45 methicillin-resistant Staphylococcus aureus

中文关键词:  食品链  ST45  耐甲氧西林金黄色葡萄球菌  系统发育分析

英文关键词:food chain  ST45  methicillin-resistant Staphylococcus aureus  phylogenetic analysis

中文摘要:

      目的 对1株食品源ST45型耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus, MRSA)的特征和来源进行分析, 并评估其致病性。方法 本研究对所获得的食品源ST45-MRSA (SAV15)进行抗菌药物敏感性检测、全基因组测序及分析、溶血活性、生物被膜形成能力和大蜡螟致死性检测, 以全面评估其潜在威胁。使用国家生物技术信息中心(National Center for Biotechnology Information, NCBI)数据库收录的金黄色葡萄球菌基因组数据, 构建ST45型金黄色葡萄球菌数据集, 基于单核苷酸多态性分析建立系统发育树, 对食品源SAV15进行溯源。结果 从食品中分到的SAV15对头孢西丁、苯唑西林、青霉素和红霉素耐药, 携带mecA、erm(C)、blaZ等多种耐药基因。SAV15携带hla、hlb、hld等溶血素基因, 还携带clfAB和icaABCDR等黏附因子, 表现出强生物被膜形成能力; 此外, 其对大蜡螟的致死能力与USA300和血流感染菌株无差异(P>0.05)。这些数据表明, 食品源SAV15具有耐药和致病风险。系统发育分析显示, SAV15属于中国ST45-MRSA谱系, 并且携带chp、scn和sak等多个人类免疫逃逸基因簇, 可初步推断本研究中食品源SAV15可能是由带菌者污染食品链造成的水平传播。结论 人源ST45-MRSA可能存在通过污染食品链介导水平传播的风险, 应加强对食品链中MRSA的监测, 可为食品安全和公共卫生政策的制定提供数据支撑。

英文摘要:

      Objective To analyze the characteristics and origin of one food-derived ST45 methicillin-resistant Staphylococcus aureus (MRSA) strain and evaluate its pathogenicity. Methods This study conducted antimicrobial susceptibility testing, whole genome sequencing and analysis, hemolytic activity, biofilm formation ability and the lethality of the food source ST45-MRSA (SAV15) to comprehensively assess its potential threat. Using the genomic data of Staphylococcus aureus included in the National Center for Biotechnology Information database (NCBI), the ST45 Staphylococcus aureus dataset was constructed. A phylogenetic tree was established based on single nucleotide polymorphism analysis to trace the food source SAV15. Results The foodborne SAV15 exhibited resistance to cefoxitin, oxacillin, penicillin and erythromycin, carrying multiple resistance genes including mecA, erm(C) and blaZ. SAV15 harbored hemolysin genes (hla, hlb and hld) and adhesion-related factors (clfAB and icaABCDR), exhibiting strong biofilm formation capacity. Notably, its lethality in Galleria mellonella showed no significant difference compared to the hypervirulent USA300 and bloodstream infection strains (P>0.05). Phylogenetic analysis revealed that SAV15 belongs to the Chinese ST45-MRSA lineage and carries multiple human immune evasion cluster genes, such as chp, scn and sak. These findings suggested that the foodborne SAV15 likely originated from human carriers through contamination of the food chain via horizontal transmission. Conclusion Human-origin ST45-MRSA may be horizontally transmitted through food chain contamination. Strengthening the surveillance of MRSA within the food chain is essential to provide data support for food safety and public health policy-making.