Phylogenetic analysis and virulence determinant of the host-adapted Staphylococcus aureus lineage ST188 in China

Staphylococcus aureus (S. aureus) is an important pathogen of humans and livestock species, but an understanding of the clonal distribution of S. aureus causing different host-species infections in the same geographical environment and within the same period is lacking. By characterizing infections caused by S. aureus in bovine, pediatric, and adult patients in Shanghai, China, between 2012 and 2014, we identified methicillin-sensitive S. aureus (MSSA) ST188 as the major lineage causing infections in multiple host species. Whole-genome sequencing and phenotypic analyses demonstrated that ST188 might evolve from livestock, and there was no significant genomic or virulence difference between ST188 isolated from livestock and humans. The virulence of ST188 is related to its adhesion and nasal colonization ability. This result is in accord with the strong epithelial cell adhesion and biofilm formation properties of ST188. Furthermore, the adhesion- and biofilm-formation-related genes are present in multiple copies and exhibit significantly increased expression in ST188. In conclusion, S. aureus ST188 is the major lineage causing human and livestock infections in Shanghai, China. Due to its high expression of the factors associated with bacterial adhesion and biofilm formation, ST188 has the ability to colonize and infect different host species.

金黄色葡萄球菌（Staphylococcus aureus，简称S. aureus）是人类与畜禽物种的重要致病菌，但目前学界对同一地理环境、同一时期内引发不同宿主物种感染的S. aureus克隆分布情况仍缺乏充分认知。本研究针对2012至2014年中国上海地区牛类、儿科及成人患者感染的S. aureus展开系统表征分析，鉴定出甲氧西林敏感金黄色葡萄球菌（methicillin-sensitive S. aureus，简称MSSA）ST188是引发多宿主物种感染的主要谱系。全基因组测序与表型分析结果表明，ST188可能起源于畜禽宿主；从畜禽与人类体内分离得到的ST188菌株，在基因组特征与毒力表型上均无显著差异。ST188的毒力与其黏附能力及鼻腔定植能力密切相关，这一结论与该菌株表现出的较强上皮细胞黏附与生物膜形成特性相符。此外，与黏附及生物膜形成相关的基因在ST188中存在多拷贝现象，且其表达水平显著上调。综上，S. aureus ST188是中国上海地区引发人类与畜禽感染的主要谱系。由于其高表达细菌黏附与生物膜形成相关因子，ST188具备定植并感染不同宿主物种的能力。