Abstract
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.
Highlights
Clostridioides difficile is the main cause of healthcare-associated diarrhea worldwide
The main goal of the present study was to investigate the toxinotypes and genetic diversity of tcdC gene in a collection of C. difficile tcdA+B+ isolates with known ribotype derived from hospitalized patients in Tehran healthcare settings
Fifteen (30%) patients had a history of inflammatory bowel disease (IBD) and 11/50 (22%) patients suffered from diarrhea at the time of admission
Summary
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. Clostridioides (formerly Clostridium) difficile is the leading cause of hospital-acquired diarrhea (HAD) with notable morbidity and mortality worldwide [1, 2]. This bacterial pathogen causes toxin-mediated diseases ranging from self-limited diarrhea to severe pseudomembranous colitis (PMC) [3]. PaLoc encodes three accessory genes; positive and negative regulators (tcdR and tcdC, respectively) and a holinlike gene (tcdE) that has been shown to be involved in toxin release from C. difficile cells [10, 11]. It was suggested that TcdE might be associated with early toxin release, since the TcdE-
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