Section of Infectious Diseases and Immunity, Department of Medicine, Imperial College London, London, United Kingdom.
PLoS One. 2013 Apr 25;8(4):e61655. doi: 10.1371/journal.pone.0061655. Print 2013.
Streptococcus pyogenes is a leading cause of pharyngeal infection, with an estimated 616 million cases per year. The human nasopharynx represents the major reservoir for all S. pyogenes infection, including severe invasive disease. To investigate bacterial and host factors that influence S. pyogenes infection, we have devised an improved murine model of nasopharyngeal colonization, with an optimized dosing volume to avoid fulminant infections and a sensitive host strain. In addition we have utilized a refined technique for longitudinal monitoring of bacterial burden that is non-invasive thereby reducing the numbers of animals required. The model was used to demonstrate that the two component regulatory system, CovR/S, is required for optimum infection and transmission from the nasopharynx. There is a fitness cost conferred by covR/S mutation that is specific to the nasopharynx. This may explain why S. pyogenes with altered covR/S have not become prevalent in community infections despite possessing a selective advantage in invasive infection.
化脓链球菌是咽峡炎的主要致病菌，估计每年有 6.16 亿例病例。人类鼻咽部是所有化脓链球菌感染的主要储存库，包括严重的侵袭性疾病。为了研究影响化脓链球菌感染的细菌和宿主因素，我们设计了一种改良的鼻咽定植的小鼠模型，优化了剂量体积以避免暴发性感染和敏感的宿主株。此外，我们还利用了一种改良的纵向监测细菌负荷的技术，该技术是非侵入性的，从而减少了所需动物的数量。该模型用于证明双组分调控系统 CovR/S 是从鼻咽部进行最佳感染和传播所必需的。covR/S 突变赋予了一种特定于鼻咽部的适应性代价。这可能解释了为什么尽管具有侵袭性感染的选择性优势，但改变 covR/S 的化脓链球菌在社区感染中并未普遍存在。
