Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110.
Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110.
Proc Natl Acad Sci U S A. 2017 Oct 10;114(41):E8721-E8730. doi: 10.1073/pnas.1707572114. Epub 2017 Sep 25.
Methicillin-resistant (MRSA) is an emerging cause of catheter-associated urinary tract infection (CAUTI), which frequently progresses to more serious invasive infections. We adapted a mouse model of CAUTI to investigate how catheterization increases an individual's susceptibility to MRSA UTI. This analysis revealed that catheterization was required for MRSA to achieve high-level, persistent infection in the bladder. As shown previously, catheter placement induced an inflammatory response resulting in the release of the host protein fibrinogen (Fg), which coated the bladder and implant. Following infection, we showed that MRSA attached to the urothelium and implant in patterns that colocalized with deposited Fg. Furthermore, MRSA exacerbated the host inflammatory response to stimulate the additional release and accumulation of Fg in the urinary tract, which facilitated MRSA colonization. Consistent with this model, analysis of catheters from patients with -positive cultures revealed colocalization of Fg, which was deposited on the catheter, with Clumping Factors A and B (ClfA and ClfB) have been shown to contribute to MRSA-Fg interactions in other models of disease. We found that mutants in had significantly greater Fg-binding defects than mutants in in several in vitro assays. Paradoxically, only the ClfB strain was significantly attenuated in the CAUTI model. Together, these data suggest that catheterization alters the urinary tract environment to promote MRSA CAUTI pathogenesis by inducing the release of Fg, which the pathogen enhances to persist in the urinary tract despite the host's robust immune response.
耐甲氧西林金黄色葡萄球菌(MRSA)是导管相关性尿路感染(CAUTI)的一个新兴病因,常进展为更严重的侵袭性感染。我们改造了 CAUTI 小鼠模型,以研究导尿如何增加个体对 MRSA UTI 的易感性。该分析表明,导尿是 MRSA 在膀胱中实现高水平持续感染所必需的。如前所述,导尿管的放置会引起炎症反应,导致宿主蛋白纤维蛋白原(Fg)的释放,纤维蛋白原覆盖在膀胱和植入物上。感染后,我们发现 MRSA 附着在尿路上皮和植入物上的模式与沉积的 Fg 共定位。此外,MRSA 加剧了宿主的炎症反应,刺激了 Fg 在泌尿道中的额外释放和积累,从而促进了 MRSA 的定植。与该模型一致,对阳性培养物患者的导管分析显示,纤维蛋白原与凝结因子 A 和 B(ClfA 和 ClfB)共定位,已在其他疾病模型中表明 ClfA 和 ClfB 有助于 MRSA-Fg 相互作用。我们发现,在几种体外检测中,与 ClfA 相比, ClfB 缺失突变体的纤维蛋白原结合缺陷明显更大。矛盾的是,只有 ClfB 菌株在 CAUTI 模型中明显减弱。这些数据表明,导尿通过诱导纤维蛋白原的释放来改变泌尿道环境,促进 MRSA CAUTI 的发病机制,病原体增强了纤维蛋白原的定植能力,尽管宿主有强烈的免疫反应。