Clostridioides difficile infection (CDI) poses an increasing threat to infant and young child health, with detection rates rising annually. This retrospective study aims to explore the epidemiological characteristics, clinical manifestations, and potential biomarkers of CDI in children aged 0-2 years by examining three cohorts: (1) infants diagnosed with CDI, (2) asymptomatic carriers of C. difficile, and (3) healthy controls. Fecal samples from each group will undergo metagenomic sequencing and metabolomic profiling, coupled with questionnaire-based surveys for risk factor assessment. The findings are anticipated to identify key high-risk factors, elucidate the pathogenic mechanisms underlying infant CDI, and support the development of early diagnostic tools and preventive strategies.