Molecular epidemiology and clinical risk factors for rifaximin-non-susceptible Clostridioides difficile infection in South Korea: a prospective, multicentre, observational study

Objectives: This study was designed to investigate the molecular epidemiology of Clostridioides difficile isolates in South Korea and to evaluate risk factors for rifaximin-non-susceptible C. difficile infection (CDI). Methods: A total of 413 patients with CDI from two sentinel hospitals in South Korea were enrolled in this study. Putative clinical risk factors for CDI were identified using digital medical records of the patients. Pathogen profiles, including antimicrobial susceptibility, toxin production and ribotype, were evaluated for each of the causative C. difficile isolates. Results: Of the 413 C. difficile isolates, 81 (19.6%) were shown to be rifaximin-non-susceptible, with the most common ribotypes being 018 (56.8%; 46/81), 017 (16.0%; 13/81) and 027 (6.2%; 5/81). Rifaximin-non-susceptible C. difficile isolates exhibited higher non-susceptibility rates to most of the other drugs tested in this study compared with rifaximin-susceptible isolates. Previous history of pulmonary tuberculosis and prior rifaximin treatment were shown to be associated with the occurrence of rifaximin-non-susceptible CDI compared with susceptible CDI. Conclusion: Non-susceptibility rates to rifaximin for the C. difficile isolates identified in this study were reasonably high with most of the resistant strains belonging to either ribotype 018 or 017. Widespread dissemination of these clones may be the result of antimicrobial selection pressure introduced by the widespread use of rifaximin. These results suggest that a sustainable surveillance programme for CDI and C. difficile resistance is needed in order to better control CDIs and to improve therapeutic efficacy.