Antibiotics Risk in GI Disorders

December 16, 2013

In case primary care physicians need another reason to pay attention to the overuse of antibiotics for nonbacterial illnesses.

Antibiotics and Risk of New Onset Inflammatory Bowel Disease: A Clinical Oral Presentation at AIBD 2013. Presenter: Ryan Ungaro, Icahn School of Medicine, Mt. Sinai

In case primary care physicians need another reason to pay attention to the overuse of antibiotics for nonbacterial illnesses, here’s yet another reason: There may be an association between antibiotics use and the development of inflammatory bowel disease (IBD) (although no association was seen for ulcerative colitis).

Earlier AIBD conferences have covered putative mechanisms of action that could explain such a relationship. Basic scientists are asking whether antibiotic disruption of normal GI flora and subsequent changes in mucosal barrier function could allow for inappropriate intestinal immunological exposure and responses.

This study begs the question of whether these connections are plausible from a basic science standpoint-it’s just a retrospective analysis looking at correlation and can’t be generalized to causation. Nonetheless...

Twelve observational studies were reviewed in this meta-analysis (9 case-control and 3 cohort), covering 8297 patients diagnosed with IBD. In all studies, the incidence of ulcerative colitis, Crohn disease, or a composite was reported as a primary outcome occurring any time after antibiotic prescription. Odds ratio for IBD among those exposed to any antibiotic was 1.62 (they were 62% more likely to develop IBD).

Statistically, all of the association was accounted for by Crohn disease (odds ratio [OR], 1.85). There was no statistically significant relationship between antibiotic exposure and ulcerative colitis (OR, 1.08). Exposure to metronidazole or quinolones was most strongly associated (OR, 5.01 and 1.79, respectively). Penicillin was not significantly associated (OR, 1.12), but all other antibiotics were.

There are other explanations for these associations. Prediagnosis, the future IBD cohort may present more often than healthy persons when they have diarrhea or other GI complaints, with subsequent antibiotic prescription in some percentage of those visits, creating a spurious relationship.

We’ll await further study of the biologic plausibility of this relationship, but meanwhile: Hold the antibiotics unless there’s clearly a bacterial infection.

As always.