The relationship between the gut microbiota and Clostridioides difficile, and its role in the severity of C. difficile infection in humans is an area of active research. Intestinal carriage of toxigenic and non-toxigenic C. difficile strains, with and without clinical signs, is reported in animals, however few studies have looked at the risk factors associated with C. difficile carriage and the role of the host gut microbiota. Here, we isolated and characterized C. difficile strains from different animal species (predominantly canines (dogs), felines (cats), and equines (horses)) that were brought in for tertiary care at North Carolina State University Veterinary Hospital. C. difficile strains were characterized by toxin gene profiling, fluorescent PCR ribotyping, and antimicrobial susceptibility testing. 16S rRNA gene sequencing was done on animal feces to investigate the relationship between the presence of C. difficile and the gut microbiota in different hosts. Here, we show that C. difficile was recovered from 20.9% of samples (42/201), which included 33 canines, 2 felines, and 7 equines. Over 69% (29/42) of the isolates were toxigenic and belonged to 14 different ribotypes including ones known to cause CDI in humans. The presence of C. difficile results in a shift in the fecal microbial community structure in both canines and equines. Commensal Clostridium hiranonis was negatively associated with C. difficile in canines. Further experimentation showed a clear antagonistic relationship between the two strains in vitro, suggesting that commensal Clostridia might play a role in colonization resistance against C. difficile in different hosts.

肠道微生物群和艰难梭菌之间的关系，以及它在人类艰难梭菌感染严重程度中的作用，是一个活跃的研究领域。有和没有临床症状的产毒和非产毒艰难梭菌菌株的肠道携带在动物中有报道，但很少有研究关注与艰难梭菌携带相关的危险因素和宿主肠道微生物群的作用。在这里，我们分离并鉴定了来自不同动物物种（主要是犬科动物（狗）、猫科动物（猫）和马科动物（马））的艰难梭菌菌株，这些动物被带到北卡罗来纳州立大学兽医医院进行三级护理。艰难梭菌通过毒素基因谱分析、荧光 PCR 核糖分型和抗菌药物敏感性测试对菌株进行了表征。对动物粪便进行了 16S rRNA 基因测序，以研究艰难梭菌的存在与不同宿主肠道微生物群之间的关系。在这里，我们表明从 20.9% (42/201) 的样本中回收了艰难梭菌，其中包括 33 只犬科动物、2 只猫科动物和 7 只马科动物。超过 69% (29/42) 的分离株是产毒的，属于 14 种不同的核糖体型，包括已知会导致人类 CDI 的核糖体型。艰难梭菌的存在导致犬科动物和马科动物的粪便微生物群落结构发生变化。共生梭状芽孢杆菌与犬齿艰难梭菌。进一步的实验表明，这两种菌株在体外存在明显的拮抗关系，表明共生梭状芽孢杆菌可能在不同宿主中对艰难梭菌的定植抵抗中发挥作用。