Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Anaerobe. 2020 Dec;66:102294. doi: 10.1016/j.anaerobe.2020.102294. Epub 2020 Nov 9.
Clostridioides difficile is the main cause of healthcare-associated diarrhea worldwide. It is proposed that certain C. difficile toxinotypes with distinct pathogenicity locus (PaLoc) variants are associated with disease severity and outcomes. Additionally, few studies have described the common C. difficile toxinotypes, and also little is known about the tcdC variants in Iranian isolates. We characterized the toxinotypes and the tcdC genotypes from a collection of Iranian clinical C. difficile tcdAB isolates with known ribotypes (RTs). Fifty C. difficile isolates with known RTs and carrying the tcdA and tcdB toxin genes were analyzed. Toxinotyping was carried out based on a PCR-RFLP analysis of a 19.6 kb region encompassing the PaLoc. Genetic diversity of the tcdC gene was determined by the sequencing of the gene. Of the 50 C. difficile isolates investigated, five distinct toxinotypes were recognized. Toxinotypes 0 (33/50, 66%) and V (11/50, 22%) were the most frequently found. C. difficile isolates of the toxinotype 0 mostly belonged to RT 001 (12/33, 36.4%), whereas toxinotype V consisted of RT 126 (9/11, 81.8%). The tcdC sequencing showed six variants (35/50, 70%); tcdC-sc3 (24%), tcdC-A (22%), tcdC-sc9 (18%), tcdC-B (2%), tcdC-sc14 (2%), and tcdC-sc15 (2%). The remaining isolates were wild-types (15/50, 30%) in the tcdC gene. The present study demonstrates that the majority of clinical tcdAB isolates of C. difficile frequently harbor tcdC genetic variants. We also found that the RT 001/toxinotype 0 and the RT 126/toxinotype V are the most common types among Iranian isolates. Further studies are needed to investigate the putative association of various tcdC genotypes with CDI severity and its recurrence.
艰难梭菌是全球范围内导致医疗保健相关腹泻的主要原因。据推测，某些具有不同毒力基因座（PaLoc）变异的艰难梭菌毒素型与疾病严重程度和结局有关。此外，很少有研究描述了常见的艰难梭菌毒素型，也很少有人了解伊朗分离株中的 tcdC 变异体。我们从具有已知核糖体分型（RT）的伊朗临床艰难梭菌 tcdAB 分离株中鉴定了毒素型和 tcdC 基因型。对 50 株已知 RT 且携带 tcdA 和 tcdB 毒素基因的艰难梭菌分离株进行了分析。基于对包含 PaLoc 的 19.6kb 区域的 PCR-RFLP 分析进行了毒素型分析。通过基因测序确定了 tcdC 基因的遗传多样性。在所研究的 50 株艰难梭菌分离株中，鉴定出了五种不同的毒素型。毒素型 0（33/50，66%）和 V（11/50，22%）是最常见的。毒素型 0 的艰难梭菌分离株主要属于 RT 001（12/33，36.4%），而毒素型 V 由 RT 126 组成（9/11，81.8%）。tcdC 测序显示了六种变体（35/50，70%）；tcdC-sc3（24%）、tcdC-A（22%）、tcdC-sc9（18%）、tcdC-B（2%）、tcdC-sc14（2%）和 tcdC-sc15（2%）。其余分离株在 tcdC 基因中为野生型（15/50，30%）。本研究表明，大多数临床 tcdAB 分离株的艰难梭菌经常携带 tcdC 遗传变异体。我们还发现，RT 001/毒素型 0 和 RT 126/毒素型 V 是伊朗分离株中最常见的类型。需要进一步研究来探讨各种 tcdC 基因型与 CDI 严重程度及其复发的潜在关联。
