Among the six most frequently prescribed antibiotic classes, patients who used BL-BLIs or nitroimidazoles during 12 months prior to the last ADA test in our study showed an increased risk of ADA development in IBD patients treated with anti-TNF drugs (BL-BLIs: p = 0.002, nitroimidazoles: p = 0.006) (Figures 2B, D). Here, TNF is linked to inflammatory bowel disease.