['Clinical studies have suggested that patients with inflammatory bowel disease (IBD) are at greater risk for developing Clostridium difficile infection (CDI). The purpose of this study was to identify single-nucleotide polymorphisms (SNPs) associated with CDI among IBD patients.', 'This retrospective cohort study used our biobank to compare patients with IBD who developed CDI (IBD-CDI) with those who had never contracted CDI (IBD-nCDI). Patients were genotyped for 384 IBD-associated SNPs by microarray. Student t, chi-square, and Fisher exact tests were used. Multivariate logistic regression with Bonferroni correction was used for genotype analysis.', 'Twenty IBD-CDI (14 with Crohn disease; 6 with ulcerative colitis) and 152 IBD-nCDI (47 CD/105 UC) patients were identified. The interleukin-4-associated SNP rs2243250 was associated with the development of CDI (raw P\xa0=\xa0.00005/corrected P\xa0=\xa0.02), with 15 of 20 (75%) CDI-IBD patients harboring the at-risk "A" allele versus 52 of 152 (34%) of IBD-nCDI. When we compared Crohn disease and ulcerative colitis patients separately, rs2243250 initially was associated with CDI in both groups, although clinical relevance was lost after Bonferroni correction.'] Is an interleukin-4 polymorphism associated with susceptibility to Clostridium difficile infection in patients with inflammatory bowel disease : results of a retrospective cohort study?