Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.
Department of Pediatrics, University of Chicago, Chicago, Illinois, USA.
Infect Immun. 2015 Nov;83(11):4383-91. doi: 10.1128/IAI.00145-15. Epub 2015 Aug 31.
Clostridium difficile infection (CDI) is a major cause of health care-associated disease. CDI initiates with ingestion of C. difficile spores, germination in the gastrointestinal (GI) tract, and then colonization of the large intestine. The interactions between C. difficile cells and other bacteria and with host mucosa during CDI remain poorly understood. Here, we addressed the hypothesis that, in a mouse model of CDI, C. difficile resides in multicellular communities (biofilms) in association with host mucosa. To do this, we paraffin embedded and then sectioned the GI tracts of infected mice at various days postinfection (p.i.). We then used fluorescent in situ hybridization (FISH) with 16S rRNA probes targeting most bacteria as well as C. difficile specifically. The results revealed that C. difficile is present as a minority member of communities in the outer (loose) mucus layer, in the cecum and colon, starting at day 1 p.i. To generate FISH probes that identify bacteria within mucus-associated communities harboring C. difficile, we characterized bacterial populations in the infected mouse GI tract using 16S rRNA gene sequence analysis of bacterial DNA prepared from intestinal content. This analysis revealed the presence of genera of several families belonging to Bacteroidetes and Firmicutes. These data suggest that formation of multispecies communities associated with the mucus of the cecum and colon is an important early step in GI tract colonization. They raise the possibility that other bacterial species in these communities modulate the ability of C. difficile to successfully colonize and, thereby, cause disease.
艰难梭菌感染（CDI）是一种主要的医疗保健相关疾病。CDI 始于摄入艰难梭菌孢子，在胃肠道（GI）中发芽，然后在大肠中定植。在 CDI 期间，艰难梭菌细胞与其他细菌以及与宿主粘膜之间的相互作用仍知之甚少。在这里，我们提出了一个假设，即在 CDI 的小鼠模型中，艰难梭菌与宿主粘膜一起存在于多细胞群落（生物膜）中。为此，我们在感染后不同天数（p.i.）对感染小鼠的 GI 道进行石蜡包埋和切片。然后，我们使用针对大多数细菌以及艰难梭菌特异性的 16S rRNA 探针进行荧光原位杂交（FISH）。结果表明，在 p.i.第 1 天开始，艰难梭菌作为外（疏松）粘液层、盲肠和结肠中群落的少数成员存在。为了生成可识别含有艰难梭菌的粘液相关群落内细菌的 FISH 探针，我们使用从肠道内容物中提取的细菌 DNA 的 16S rRNA 基因序列分析来表征感染小鼠 GI 道中的细菌种群。该分析揭示了属于拟杆菌门和厚壁菌门的几个科的属的存在。这些数据表明，与盲肠和结肠粘液相关的多物种群落的形成是 GI 道定植的一个重要早期步骤。它们提出了这样一种可能性，即这些群落中的其他细菌物种调节艰难梭菌成功定植的能力，并因此引起疾病。
