Metronidazole may raise inflammatory bowel disease risk

Exposure to antibiotics other than penicillins, in particular metronidazole and quinolones, was associated with new-onset Crohn’s disease, based on a meta-analysis of observational and case control studies presented at a conference on inflammatory bowel disease.

“Exposure to antibiotics may somehow contribute to alterations in the microbiome and result in dysbiosis, which is known to be part of the pathogenesis that leads to IBD,” said the leahn School of Medicine at Mount Sinai, New York.

Alternatively, antibiotic exposures might just be surrogate markers for an infectious trigger that is actually associated with IBD. The analysis did not detect a link between antibiotic exposure and ulcerative colitis.

They performed a meta-analysis of 11 studies that included the records of 7,208 patients who had been newly diagnosed with IBD after antibiotic exposure: 3,937 had Crohn’s disease, 3,207 had ulcerative colitis, and 64 had unclassified IBD.

Nine of the studies included in the meta-analysis accounted for the potential confounding effect of diagnosed delay, with a range of 4 months to 4 years.

All classes of antibiotics except penicillin were implicated in new-onset lBD, with an odds ratio of 1.55 for the overall risk of new-onset inflammatory bowel disease after antibiotic exposure, Dr. Ungaro said.

Three studies provided data on the use of metronidazole, which proved to have the highest associated risk for new cases of IBD.

Quinolones were accounted for in three of the studies and carried the next-highest associated risk of new IBD.

When stratified by age, the odds ratio for new IBD diagnosis in adults was 1.43 and in children 1.89. The odds ratio for a new diagnosis of Crohn’s disease was 1.56 in adults and 2.7 in children.