Purpose: Toxins produced by Clostridioides difficile infection (CDI) can cause enteritis and diarrhea. Although the number of pediatric CDI cases is increasing, the clinical management of pediatric CDI, including patient characteristics and prognosis, remains unclear. This study aimed to elucidate the background and clinical course of patients with CDI and evaluate the reliability of diagnostic tests in a tertiary pediatric hospital in Japan. Methods: We retrospectively analyzed the clinical data of children diagnosed with CDI between 2011 and 2021 at the Saitama Children’s Medical Center in Saitama, Japan. Results: During the study period, 1,252 C. difficile antigen/toxin tests were performed, and 37 patients were diagnosed with CDI. The main underlying diseases among the patients were hematological and malignant disorders and gastrointestinal diseases, including inflammatory bowel disease (IBD) (59.4%). Two patients (5.4%) had an unremarkable medical history. Among the 37 patients, 27 (73.0%) were immunocompromised, 25 (67.6%) had a history of antibiotic use within the past two months, and 6 (16.2%) were negative on the initial test but were positive on the second test. Finally, 28 patients (75.7%) required primary antibiotic therapy only, and two patients with IBD required additional antibiotic therapy as secondary treatment. Conclusion The number of pediatric patients with CDI is increasing. Both a comprehensive interview, including underlying diseases and history of antibiotic use, and an understanding of the features of clinical examinations should be emphasized to appropriately diagnose and treat CDI.

Background/Aims: There are few published registry studies from Asia on pediatric inflammatory bowel disease (IBD). Registry network data enable comparisons among ethnic groups. This study examined the characteristics of IBD in Japanese children and compared them with those in European children. Methods: This was a cross-sectional multicenter registry study of newly diagnosed Japanese pediatric IBD patients. The Paris classification was used to categorize IBD features, and results were compared with published EUROKIDS data. Results: A total of 265 pediatric IBD patients were initially registered, with 22 later excluded for having incomplete demographic data. For the analysis, 91 Crohn’s disease (CD), 146 ulcerative colitis (UC), and 6 IBD-unclassified cases were eligible. For age at diagnosis, 20.9% of CD, 21.9% of UC, and 83.3% of IBD-unclassified cases were diagnosed before age 10 years. For CD location, 18.7%, 13.2%, 64.8%, 47.3%, and 20.9% were classified as involving L1 (ileocecum), L2 (colon), L3 (ileocolon), L4a (esophagus/stomach/duodenum), and L4b (jejunum/proximal ileum), respectively. For UC extent, 76% were classified as E4 (pancolitis). For CD behavior, B1 (non-stricturingon-penetrating), B2 (stricturing), B3 (penetrating), and B2B3 were seen in 83.5%, 11.0%, 3.3%, and 2.2%, respectively. A comparison between Japanese and European children showed less L2 involvement (13.2% vs. 27.3%, P< 0.01) but more L4a (47.3% vs. 29.6%, P< 0.01) and L3 (64.8% vs. 52.7%, P< 0.05) involvement in Japanese CD children. Pediatric perianal CD was more prevalent in Japanese children (34.1% vs. 9.7%, P< 0.01). Conclusions Upper gastrointestinal and perianal CD lesions are more common in Japanese children than in European children.