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 tcdA⁺B⁺ 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 tcdA⁺B⁺ 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.

艰难梭菌是全球医疗保健相关性腹泻的主要原因。有人提出，某些具有不同致病性基因座 (PaLoc) 变异的艰难梭菌毒素型与疾病严重程度和结果相关。此外，很少有研究描述了常见的艰难梭菌毒素型，而且对伊朗分离株中的tcdC变体也知之甚少。我们对来自伊朗临床艰难梭菌 tcdA ⁺ B ⁺具有已知核糖型 (RT) 分离株的毒素型和tcdC基因型进行了表征。50 个具有已知 RTs 并携带tcdA 的艰难梭菌分离株和分析了tcdB毒素基因。基于对包含 PaLoc 的 19.6 kb 区域的 PCR-RFLP 分析进行毒素分型。tcdC基因的遗传多样性由基因测序确定。在研究的 50 种艰难梭菌分离株中，识别出五种不同的毒素型。毒素型 0 (33/50, 66%) 和 V (11/50, 22%) 是最常见的。毒素型 0 的艰难梭菌分离物主要属于 RT 001 (12/33, 36.4%)，而毒素型 V 由 RT 126 (9/11, 81.8%) 组成。该技合测序显示6点的变体（35/50，70％）; tcdC-sc3 (24%)、tcdC-A (22%)、tcdC-sc9 (18%)、tcdC-B(2%)、tcdC-sc14 (2%) 和tcdC-sc15 (2%)。其余的分离株是tcdC基因的野生型（15/50，30%）。本研究表明，艰难梭菌的大多数临床tcdA ⁺ B ⁺分离株经常带有 tcdC遗传变异。我们还发现 RT 001/toxinotype 0 和 RT 126/toxinotype V 是伊朗分离株中最常见的类型。需要进一步的研究来调查各种tcdC基因型与 CDI 严重程度及其复发之间的假定关联。