The prevalence and molecular epidemiology of Clostridioides difficile in hospital-based pediatric populations in China.

A multicenter cross-sectional study was conducted across six Chinese hospitals between September 2023 and April 2024 to investigate the prevalence, molecular epidemiology, antimicrobial resistance (AMR) and genetic relatedness of C. difficile in pediatric populations. Among 1,442 stool samples collected, 242 C. difficile isolates were recovered (16.8%), including 188 from asymptomatic carriers (13.0%) and 11 from confirmed C. difficile infection (CDI) cases (0.98%). The highest rate of asymptomatic carriage was observed in children aged 1-2 years (29.3%). Multilocus sequence typing (MLST) identified ST3 as the predominant sequence type (30.6%), followed by ST42, ST54, ST2, ST102, and ST110. Core genome phylogenetic analysis revealed nine distinct genetic lineages, with lineage VI being the most prevalent among CDI cases. High resistance to clindamycin (64.5%) was observed, primarily mediated by ermB, while all isolates remained susceptible to metronidazole and vancomycin. Moxifloxacin resistance (10.7%) was associated with gyrA T82I mutations, particularly in toxigenic ST3 strains. Transposon analysis indicated ST-specific carriage of AMR genes, with Tn6218(ermB) prevalent in nontoxigenic ST3 isolates and Tn5801 (tet(M)) predominant in ST54. Genomic relatedness (≤2 SNPs) was detected in 12.0% of asymptomatic carriers, with most links associated with hospital-wide contact, suggesting possible transmission events. This study highlights the importance of asymptomatic colonized children as a reservoir for C. difficile, maintaining resistant lineages and disseminating AMR, thereby underscoring the need for enhanced surveillance and targeted antimicrobial stewardship in Chinese healthcare settings.