The prevalence and molecular epidemiology of <i>Clostridioides difficile</i> 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 <i>C. difficile</i> in pediatric populations. Among 1,442 stool samples collected, 242 <i>C. difficile</i> isolates were recovered (16.8%), including 188 from asymptomatic carriers (13.0%) and 11 from confirmed <i>C. difficile</i> 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 <i>ermB</i>, while all isolates remained susceptible to metronidazole and vancomycin. Moxifloxacin resistance (10.7%) was associated with <i>gyrA</i> T82I mutations, particularly in toxigenic ST3 strains. Transposon analysis indicated ST-specific carriage of AMR genes, with Tn6218(<i>ermB</i>) prevalent in nontoxigenic ST3 isolates and Tn5801 (<i>tet(M)</i>) 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 <i>C. difficile</i>, maintaining resistant lineages and disseminating AMR, thereby underscoring the need for enhanced surveillance and targeted antimicrobial stewardship in Chinese healthcare settings.本研究于2023年9月至2024年4月间，在国内6家医院开展多中心横断面研究，旨在调查儿童人群中艰难梭菌（<i>C. difficile</i>）的流行情况、分子流行病学特征、抗菌药物耐药性（antimicrobial resistance, AMR）及遗传相关性。本次研究共收集1442份粪便样本，分离获得242株艰难梭菌，分离率为16.8%；其中188株来自无症状携带者（携带率13.0%），11株来自确诊艰难梭菌（<i>C. difficile</i>）感染（CDI）病例（感染率0.98%）。1~2岁儿童的无症状携带率最高，达29.3%。多位点序列分型（Multilocus sequence typing, MLST）鉴定显示，ST3为优势序列型，占比30.6%，其次为ST42、ST54、ST2、ST102及ST110。核心基因组系统发育分析揭示了9个不同的遗传谱系，其中谱系VI在CDI病例中最为流行。研究观察到菌株对克林霉素具有高耐药率（64.5%），该耐药性主要由ermB基因介导；所有分离株均对甲硝唑与万古霉素敏感。莫西沙星耐药率为10.7%，该耐药性与gyrA基因T82I突变相关，尤其在产毒型ST3菌株中更为显著。转座子分析结果显示，耐药基因的携带具有序列型特异性：Tn6218（携带ermB基因）在非产毒型ST3分离株中流行，而Tn5801（携带tet(M)基因）则在ST54分离株中占主导地位。12.0%的无症状携带者间存在基因组相关性（单核苷酸多态性≤2个），多数关联线索指向院内接触，提示存在潜在的传播事件。本研究强调了无症状定植儿童作为艰难梭菌储存宿主的重要性，其可维持耐药谱系并传播抗菌药物耐药性，因此凸显了在中国医疗环境中加强监测与实施针对性抗菌药物管理的必要性。