基于全基因组测序的阪崎克罗诺杆菌婴幼儿食品分离株分子特征研究

Molecular characterization of Cronobacter sakazakii from infant foods using whole genome sequencing

目的研究婴幼儿食品中分离的阪崎克罗诺杆菌(C.sakazakii)分子生物学特征。方法对婴幼儿食品中C.sakazakii进行分离鉴定、药物敏感性试验和全基因组测序,利用BioNumerics软件对全基因组数据进行拼接组装,对组装基因组开展多位点序列分型(MLST)、核心基因组多位点序列分型(cgMLST)、毒力基因和耐药基因分析,并与PubMLST数据库中ST型进行比较分析。结果本研究中分离的9株C.sakazakii共分为5个ST型,ST1和ST64型为主要型别,同时也是PubMLST数据库中C.sakazakii的主要型别。3株C.sakazakii携带mcr-9耐药基因,但药敏结果显示所有菌株对包括多粘菌素B和多粘菌素E在内的12种抗生素均敏感。除携带共同毒力基因谱外,ST1、ST64和ST458型携带脂多糖基因gtrB。cgMLST聚类分析显示,9株C.sakazakii呈高度多样性。结论与临床分离株相关的ST1和ST64型是本研究食品分离株中的主要型别,提示C.sakazakii具有潜在的致病性,有必要对婴幼儿食品中C.sakazakii开展连续监测,为预防控制由其引起的食源性疾病提供依据。

Objective To study the molecular characterization of Cronobacter sakazakii(C.sakazakii) from infant foods. Methods The C.sakazakii isolates were characterized using antibiotic susceptibility tests and whole genome sequencing(WGS). BioNumerics software was used to analyze and assemble WGS data. Then, the multilocus sequence typing(MLST), core-genome multi-locus sequence typing(cgMLST), virulence genes profiles were performed using assembled genome sequences. The resistance genes profiles and antimicrobial susceptibility were investigated. Furthermore, STs of C.sakazakii in this study were compared with those from PubMLST database. Results In this study, nine C.sakazakii isolates were detected and subtyped into five STs. ST1 and ST64 were the predominant STs, which were also the predominant STs of C.sakazakii in PubMLST database. Three C.sakazakii isolates were found to carry the mcr-9 gene. However, all C.sakazakii isolates were sensitive to 12 antibiotics including polymyxin B and E. ST1, ST64 and ST458 carried gtrB in addition to the common virulence genes. The nine C.sakazakii isolates showed highly genomic diversity according to cgMLST results. Conclusion ST1 and ST64 were predominant STs in this study, which were also predominant STs in clinical isolates in PubMLST database. These results suggested the potential pathogenicity of C.sakazakii. Our data underscored the importance of continuous surveillance of C.sakazakii in infant foods for prevention of foodborne disease caused by C.sakazakii.