• 中文核心期刊
  • CSCD来源期刊
  • 中国科技核心期刊
  • CA、CABI、ZR收录期刊

闽北地区牛乳源金黄色葡萄球菌分子流行特征、耐药谱和进化分析

Molecular Epidemiology, Antimicrobial Resistance, and Phylogenetics of Staphylococcus aureus Isolated from Bovine Raw Milk in Northern Fujian, China

  • 摘要:
    目的 明确闽北地区规模化牧场中牛乳源金黄色葡萄球菌的分子分型组成、耐药谱结构及进化特征。
    方法 对2023—2024年从闽北地区14家牧场分离的59株菌株开展Illumina高通量全基因组测序,进行MLST与spa分型、耐药基因检测及药物敏感性试验;构建基于核心基因组SNP的系统发育树,并结合全球公开数据绘制最小生成树(MST)。
    结果 首次在闽北乳源样本中发现ST59-t437型牲畜相关MRSA(LA-MRSA),并鉴定出区域性新分型ST9784-t189。优势型为ST1-t114(25.4%)和ST9784-t189(20.3%)。菌株总体耐药率为45.8%,其中青霉素与氨苄西林耐药率最高(28.8%),但低于国内其他地区。spa分型在菌株微进化解析中显示出较高分辨力。基于PubMLST数据库全球分离物最小生成树分析,ST398和ST1为跨洲传播双核心型,其他ST型传播受地域限制。MDR菌株耐药基因种类更为丰富,分型与基因型之间存在显著关联。
    结论 福建北部牛乳源金黄色葡萄球菌群体结构呈现多样化特征,整体耐药水平相对较低,但新发现的ST9784及区域首次报道的LA-MRSA ST59-t437可能具备较强的传播风险,应加强跨宿主监测。

     

    Abstract:
    Objective Molecular epidemiology, antimicrobial resistance, and evolutionary characteristics of Staphylococcus aureus strains isolated from bovine raw milk at dairy farms in northern Fujian, China were investigated.
    Methods From the milk samples collected at 14 dairy farms in 2023-2024, 59 pathogen isolates were undergone whole-genome sequencing using the Illumina platform along with molecular MLST and spa typing, antimicrobial susceptibility testing, and resistance gene profiling. Phylogenetic relationship among the isolates was reconstructed based on core genome single-nucleotide polymorphisms (SNPs), and a global minimal spanning tree (MST) analysis conducted using publicly available sequences from the PubMLST database.
    Results Livestock-associated MRSA (LA-MRSA) ST59-t437 was identified for the first time in the dairy specimens from northern Fujian, along with a novel regional clone ST9784-t189. The predominant types of the isolates were ST1-t114 (25.4%) and ST9784-t189 (20.3%). The overall non-susceptibility rate to antimicrobial agent was 45.8% with the highest resistance to penicillin and ampicillin (28.8%), albeit lower than those found in other regions in China. The spa typing had a high discriminatory power for micro-evolutionary analyses. The MST analysis indicated that ST398 and ST1 had dual-core global dissemination lineages, whereas others had geographically limited distributions. The multidrug-resistant (MDR) strains harbored a rich repertoire of resistance genes showing a significant correlation with the molecular type.
    Conclusion S. aureus from the dairy farms in northern Fujian displayed considerable genetic diversity and relatively low overall antimicrobial resistance. Nevertheless, the newly identified ST9784 and the first regional LA-MRSA ST59-t437 might still pose a risk of dissemination which required attentive cross-host surveillance by the involved agencies.

     

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