Streptococcus pneumoniae is an important global pathogen that causes bacterial pneumonia, sepsis and meningitis. Beta-lactam antibiotics are the first-line treatment for pneumococcal disease, however, their effectiveness is hampered by beta-lactam resistance facilitated by horizontal genetic transfer (HGT) with closely related species. Although interspecies HGT is known to occur among the species of the genus Streptococcus , the rates and effects of HGT between Streptococcus pneumoniae and its close relatives involving the penicillin binding protein (pbp) genes remain poorly understood. Here we applied the fastGEAR tool to investigate interspecies HGT in pbp genes using a global collection of whole-genome sequences of Streptococcus mitis , Streptococcus oralis and S. pneumoniae . With these data, we established that pneumococcal serotypes 6A, 13, 14, 16F, 19A, 19F, 23F and 35B were the highest-ranking serotypes with acquired pbp fragments. S. mitis was a more frequent pneumococcal donor of pbp fragments and a source of higher pbp nucleotide diversity when compared with S. oralis . Pneumococci that acquired pbp fragments were associated with a higher minimum inhibitory concentration (MIC) for penicillin compared with pneumococci without acquired fragments. Together these data indicate that S. mitis contributes to reduced β-lactam susceptibility among commonly carried pneumococcal serotypes that are associated with long carriage duration and high recombination frequencies. As pneumococcal vaccine programmes mature, placing increasing pressure on the pneumococcal population structure, it will be important to monitor the influence of antimicrobial resistance HGT from commensal streptococci such as S. mitis .

中文翻译：

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经常定植于人鼻咽部的肺炎链球菌血清型是缓症链球菌青霉素结合蛋白基因片段的常见受体

肺炎链球菌 是引起细菌性肺炎、败血症和脑膜炎的重要全球病原体。β-内酰胺类抗生素是肺炎球菌病的一线治疗药物，但其有效性受到与密切相关物种的水平遗传转移 (HGT) 促进的 β-内酰胺类耐药性的阻碍。虽然已知种间 HGT 发生在链球菌属的物种中，但对肺炎链球菌及其涉及青霉素结合蛋白 ( pbp ) 基因的近亲之间的 HGT 发生率和影响仍知之甚少。在这里，我们应用 fastGEAR 工具来研究pbp中的种间 HGT 基因使用链球菌、口腔链球菌和肺炎链球菌的全基因组序列的全球集合。通过这些数据，我们确定肺炎球菌血清型 6A、13、14、16F、19A、19F、23F 和 35B 是获得pbp片段的最高级别的血清型。与口腔链球菌相比， mitis链球菌是更常见的pbp片段供体肺炎球菌和更高pbp核苷酸多样性的来源。获得pbp的肺炎球菌 与没有获得性片段的肺炎球菌相比，片段与更高的青霉素最低抑制浓度 (MIC) 相关。这些数据共同表明，S. mitis有助于降低常见携带的肺炎球菌血清型中的 β-内酰胺敏感性，这些血清型与长携带时间和高重组频率相关。随着肺炎球菌疫苗计划的成熟，对肺炎球菌种群结构的压力越来越大，监测来自共生链球菌（如S. mitis）的抗菌素耐药性 HGT 的影响将变得很重要。