Although IBD patients are known to have increased risk of acquiring CDI and of severe, complicated infections,4 routine screening for active CDI is not currently recommended, due to the inability to confidently distinguish colonization from disease.5 In our cohorts, there was no clinical history of CDI, and all but 1 patient that provided a stool sample tested negative for CDI by tcdB PCR; however both CD and UC patients had increased circulating TcdB-specific CD4+ T cells. This evidence concerns the gene CD4 and inflammatory bowel disease.