EA 4043, USC INRA 'Ecosystème microbien digestif et santé', Faculté de Pharmacie, Université Paris-Sud 11, Châtenay-Malabry, France.
J Med Microbiol. 2011 Aug;60(Pt 8):1155-1161. doi: 10.1099/jmm.0.029553-0. Epub 2011 Feb 24.
Clostridium difficile is a frequent cause of severe, recurrent, post-antibiotic diarrhoea and pseudomembranous colitis. Its pathogenicity is mediated mainly by two toxins, TcdA and TcdB. However, different adhesins have also been described as important colonization factors which are implicated in the first step of the intestinal infection. In this study, we focused our interest on one of these adhesins, fibronectin-binding protein A (FbpA), and on its role in the intestinal colonization process. A mutant of FbpA (CDΔFbpA) was constructed in C. difficile strain 630Δerm by using ClosTron technology. This mutant was characterized in vitro and in vivo and compared to the isogenic wild-type strain. Adhesion of the CDΔFbpA mutant to the human colonic epithelial cell line Caco-2 and to mucus-secreting HT29-MTX cells was examined. Surprisingly, the CDΔFbpA mutant adhered more than the wild-type parental strain. The CDΔFbpA mutant was also analysed in three different mouse models by following the intestinal implantation kinetics (faecal shedding) and caecal colonization (7 days post-challenge). We showed that in monoxenic mice, CDΔFbpA shed C. difficile in faeces at the same rate as that of the isogenic wild-type strain but its colonization of the caecal wall was significantly reduced. In dixenic mice, the shedding rate was slower for the CDΔFbpA mutant than for the isogenic wild-type strain during the first days of infection, but no significant difference was observed in caecal colonization. Similar rates of intestinal implantation and caecal colonization were observed for both strains in assays performed in human microbiota-associated mice. Taken together, our data suggest that FbpA plays a role in intestinal colonization by C. difficile.
艰难梭菌是一种常见的致病菌，可引起严重、反复的抗生素相关性腹泻和伪膜性结肠炎。其致病性主要由两种毒素，TcdA 和 TcdB 介导。然而，不同的黏附素也被描述为重要的定植因子，它们与肠道感染的第一步有关。在这项研究中，我们关注其中一种黏附素，纤维连接蛋白结合蛋白 A（FbpA），及其在肠道定植过程中的作用。我们使用 ClosTron 技术构建了艰难梭菌 630Δerm 株的 FbpA 突变体（CDΔFbpA）。该突变体在体外和体内进行了特征描述，并与同源野生型菌株进行了比较。检测了 CDΔFbpA 突变体与人结肠上皮细胞系 Caco-2 和黏液分泌 HT29-MTX 细胞的黏附。令人惊讶的是，CDΔFbpA 突变体的黏附能力强于野生型亲本菌株。还通过跟踪肠道植入动力学（粪便脱落）和盲肠定植（感染后 7 天），在三种不同的小鼠模型中分析了 CDΔFbpA 突变体。我们表明，在单养小鼠中，CDΔFbpA 以与同源野生型菌株相同的速度在粪便中脱落艰难梭菌，但它在盲肠壁上的定植显著减少。在双养小鼠中，在感染的最初几天，CDΔFbpA 突变体的脱落率比同源野生型菌株慢，但盲肠定植没有明显差异。在人类微生物群相关小鼠的实验中，两种菌株的肠道植入和盲肠定植率相似。综上所述，我们的数据表明 FbpA 在艰难梭菌的肠道定植中发挥作用。
