Colonoscopy-based Clostridioides difficile screening for inflammatory bowel disease patients

Patients with IBD have an increased risk for Clostridioides difficile infection, and the significance of asymptomatic colonization is poorly understood. Overlapping symptoms often complicate diagnosis, and there is a lack of validated screening methods. Colonic wash aspirates collected during routine colonoscopies may offer a convenient screening option. We aimed to evaluate culture methods for detecting C. difficile colonization in IBD patients using colonic wash samples. Patients with Crohn's disease or ulcerative colitis undergoing outpatient colonoscopy were enrolled. Clinical characteristics, IBD activity indices, and endoscopic scores were recorded. Colonic wash aspirates were centrifuged and cultured on selective CHROMID® media with and without broth enrichment. Isolates were confirmed by Gram stain and MALDI-TOF. PCR/qPCR identified tcdB gene carriage. Whole-genome sequencing was performed on selected isolates, and associations between clinical factors and colonization were assessed. Of the 121 patients enrolled, 10.7% (13/121) were colonized. Crohn's patients were colonized more frequently than ulcerative colitis patients (13.3% CD, 8.2% UC). Among colonized patients, 53.8% (7/13) had C. difficile with detectable tcdB. Enrichment increased detection compared to direct plating. No clinical predictors of colonization were identified, but wash samples yielded sufficient DNA for sequencing with comparable depth to whole stool. Colonoscopy wash aspirates allow for the detection of asymptomatic C. difficile colonization in IBD. This screening method may provide a useful tool for investigating the prevalence, persistence, and clinical significance of C. difficile colonization in IBD and for informing future studies of CDI prevention.