Gorelik Y, Freilich S, Gerassy-Vainberg S, et al. - In this first large scale study, the production of anti-drug antibodies (ADA) is linked to microbial composition. Avoiding cephalosporins and penicillins with β-lactamase inhibitors (penicillin-BLI), as well as treatment with fluoroquinolones or macrolides, may reduce the risk of ADA development during anti-tumour necrosis factor therapy.

• Data were analyzed from the epi-IIRN (epidemiology group of the Israeli IBD research nucleus), a nationwide registry of all patients with IBD in Israel.

• With a median follow-up of 651 days from the start of therapy, 363 of the 1,946 eligible patients had positive ADA.

• The Cox proportional hazard model revealed that patients who took cephalosporins or penicillin-BLI had a higher risk of developing ADA, on the other hand, patients who took macrolides or fluoroquinolones had a lower risk.

• Infliximab significantly increased ADA production in cephalosporin-treated mice when compared with macrolide-pretreated mice. Germ-free mice did not produce any ADA.