The University of Western Australia, School of Biomedical Sciences, Western Australia, Australia; PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Western Australia, Australia.
Murdoch University, Medical, Molecular and Forensic Sciences, Western Australia, Australia.
Anaerobe. 2019 Dec;60:102083. doi: 10.1016/j.anaerobe.2019.102083. Epub 2019 Aug 1.
The relevance of large clostridial toxin-negative, binary toxin-producing (ABCDT) Clostridium difficile strains in human infection is still controversial. In this study, we investigated putative virulence traits that may contribute to the role of ABCDTC. difficile strains in idiopathic diarrhea. Phenotypic assays were conducted on 148 strains of C. difficile comprising 10 different ABCDTC. difficile ribotypes (RTs): 033, 238, 239, 288, 585, 586, QX143, QX444, QX521 and QX629. A subset of these isolates (n = 53) was whole-genome sequenced to identify genetic loci associated with virulence and survival. Motility studies showed that with the exception of RT 239 all RTs tested were non-motile. C. difficile RTs 033 and 288 had deletions in the F2 and F3 regions of their flagella operon while the F2 region was absent from strains of RTs 238, 585, 586, QX143, QX444, QX521 and QX629. The flagellin and flagella cap genes, fliC and fliD, respectively, involved in adherence and host colonization, were conserved in all strains, including reference strains. All ABCDTC. difficile strains produced at least three extracellular enzymes (deoxyribonuclease, esterase and mucinase) indicating that these are important extracellular proteins. The toxicity of ABCDTC. difficile strains in Vero cells was confirmed, however, pathogenicity was not demonstrated in a mouse model of disease. Despite successful colonization by most strains, there was no evidence of disease in mice. This study provides the first in-depth analysis of ABCDTC. difficile strains and contributes to the current limited knowledge of these strains as a cause of C. difficile infection.
大梭菌毒素阴性、二元毒素产生（ABCDT）艰难梭菌菌株在人类感染中的相关性仍存在争议。在这项研究中，我们研究了可能有助于 ABCDTC 的毒力特征。艰难梭菌菌株在特发性腹泻中的作用。对 148 株艰难梭菌进行了表型分析，其中包括 10 种不同的 ABCDTC。艰难梭菌核糖体分型（RT）：033、238、239、288、585、586、QX143、QX444、QX521 和 QX629。这些分离株的一部分（n=53）进行了全基因组测序，以鉴定与毒力和存活相关的遗传基因座。运动性研究表明，除 RT 239 外，所有测试的 RT 均无运动性。艰难梭菌 RT 033 和 288 的鞭毛操纵子 F2 和 F3 区域缺失，而 RT 238、585、586、QX143、QX444、QX521 和 QX629 的菌株则缺失 F2 区域。与粘附和宿主定植相关的鞭毛蛋白和鞭毛帽基因 fliC 和 fliD 在所有菌株中均保持不变，包括参考菌株。所有 ABCDTC。艰难梭菌菌株至少产生三种细胞外酶（脱氧核糖核酸酶、酯酶和粘蛋白酶），表明这些是重要的细胞外蛋白。证实了 ABCDTC 的毒性。艰难梭菌菌株在 Vero 细胞中的作用，但在疾病的小鼠模型中未证明其致病性。尽管大多数菌株成功定植，但在小鼠中没有疾病的证据。本研究首次对 ABCDTC 进行了深入分析。艰难梭菌菌株，并有助于当前对这些菌株作为艰难梭菌感染病因的有限认识。
