NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection & Immunity, University College London, London, UK. akuzike.kalizang'
Malawi Liverpool Wellcome Programme, Blantyre, Malawi. akuzike.kalizang'
Nat Commun. 2024 Sep 6;15(1):7812. doi: 10.1038/s41467-024-52120-z.
Streptococcus mitis is a leading cause of infective endocarditis (IE). However, our understanding of the genomic epidemiology and pathogenicity of IE-associated S. mitis is hampered by low IE incidence. Here we use whole genome sequencing of 129 S. mitis bloodstream infection (BSI) isolates collected between 2001-2016 from clinically diagnosed IE cases in the UK to investigate genetic diversity, antimicrobial resistance, and pathogenicity. We show high genetic diversity of IE-associated S. mitis with virtually all isolates belonging to distinct lineages indicating no predominance of specific lineages. Additionally, we find a highly variable distribution of known pneumococcal virulence genes among the isolates, some of which are overrepresented in disease when compared to carriage strains. Our findings suggest that S. mitis in patients with clinically diagnosed IE is not primarily caused by specific hypervirulent or antimicrobial resistant lineages, highlighting the accidental pathogenic nature of S. mitis in patients with clinically diagnosed IE.
缓症链球菌是感染性心内膜炎（IE）的主要病因。然而，由于 IE 的发病率较低，我们对与 IE 相关的缓症链球菌的基因组流行病学和致病性的了解受到了阻碍。在这里，我们使用英国在 2001 年至 2016 年间从临床确诊的 IE 病例中采集的 129 株缓症链球菌血流感染（BSI）分离株的全基因组测序，来研究遗传多样性、抗菌药物耐药性和致病性。我们发现，与 IE 相关的缓症链球菌具有很高的遗传多样性，几乎所有的分离株都属于不同的谱系，这表明没有特定谱系的优势。此外，我们发现已知肺炎链球菌毒力基因在分离株中的分布存在高度可变性，其中一些在疾病中的表达高于携带菌株。我们的研究结果表明，在临床确诊的 IE 患者中，缓症链球菌不是由特定的高毒力或抗菌药物耐药谱系引起的，这突出了缓症链球菌在临床确诊的 IE 患者中偶然的致病性。
