The Vexed Relationship Between Clostridium Difficile and Inflammatory Bowel Disease: An Assessment of Carriage in an Outpatient Setting Among Patients in Remission

OBJECTIVES: Comorbidity with Clostridium difficile may cause diagnostic delay in newly presenting inflammatory bowel disease (IBD) patients, trigger relapse in established disease, confound therapies, and serve as an indicator of an underlying defect in innate immunity. Retrospective analyses have suggested community acquisition; to address this we conducted a prospective analysis of C. difficile carriage in IBD patients using molecular methods specifically in an outpatient setting. METHODS: Recruited participants had long-standing diagnoses of ulcerative colitis (n = 64) and Crohn's disease (n = 58), were in clinical remission, and had no recent exposure to antibiotics, corticosteroids, immunomodulatory drugs or recent hospitalization. Isolates were cultured from stools and confirmed by 16S sequencing. The antibiotic susceptibilities of the isolates were tested followed by further strain characterization by toxinotyping, ribotyping, and pulsed-field gel electrophoresis (PFGE). RESULTS: The frequency of toxigenic C. difficile was higher in IBD patients than in healthy volunteers at 8.2 and 1.0%, respectively (P = 0.02 Fisher's exact test). All strains belonged to toxinotype 0 with rare subtypes of this group noted in five isolates and represented by an altered repressor genotype. Patients harbored a diverse range of toxigenic ribotype groups, including those previously associated with C. difficile-associated disease (CDAD) (R015, R005, and R020) and the rarer types R062, R050, and R003. Interestingly, common nosocomial groups were not identified. The considerable nonclonal distribution of distinct strains was further demonstrated by PFGE genomic fingerprinting. None of the study subjects experienced a clinical episode of CDAD during a 6-month period of follow-up. CONCLUSIONS: Detection of C. difficile is increased in IBD outpatients in remission, and strain diversity is consistent with community acquisition from a multitude of sources.