Molecular epidemiology and characterization of Clostridioides difficile isolates by multilocus sequence typing in Iran

Objectives: Clostridioides difficile infection (CDI) is a major cause of healthcare-associated diarrhea and colitis worldwide. C. difficile exhibits extensive genetic diversity among different lineages. This study aimed to identify sequence types (STs) and clades of C. difficile isolates using multilocus sequence typing (MLST) in Iran. Methods: A total of 37 C. difficile isolates untyped by capillary electrophoresis PCR ribotyping from our previous study were included in this work. The presence of toxin-encoding and accessory genes within the pathogenicity locus was determined by PCR. MLST was conducted using seven housekeeping genes to assess the genetic diversity of isolates. Results: Among isolates, 33 distinct STs were identified, including 28 previously unreported STs. ST3 was the most dominant, followed by ST725, ST48, and ST237. The goeBURST analysis grouped 23 STs in clade 1 and 14 STs in singleton. The STs in both clade 1 and singletons were more frequently associated with community-acquired CDI (13/23, 56.5% and 11/14, 78.6%, respectively). Recurrent CDI was observed in 15/23 (56.4%) isolates from clade 1 and 14/14 (100%) from singletons. No significant difference was found relating to demographic and clinical characteristics in clade 1 and singletons, except for CDI severity (P value = 0.002) and antibiotic-associated diarrhea (P value = 0.02), which were associated with singletons. Conclusion: This study demonstrates a high degree of genetic heterogeneity among C. difficile isolates from Iranian CDI patients, with ST3 as the dominant type. Stringent molecular surveillance is essential to understand the epidemiological dynamics and population structure of C. difficile in Iran.