Pericolonoscopy Antibiotics Associated With Postcolonoscopy Irritable Bowel Syndrome

Experienced colonoscopists have seen occasional patients date the onset of irritable bowel syndrome (IBS) to colonoscopy (and, occasionally, patients who date improvement of digestive symptoms to colonoscopy). The combination of bowel preparation and antibiotics could alter the gut flora, potentially precipitating IBS. 

This study looked at 24,617 patients exposed to antibiotics within 2 weeks of screening colonoscopy, matched to 24,617 individuals not exposed to antibiotics. 

Two outcomes were assessed in patients 195 to 1095 days after index colonoscopy: one was a new diagnosis of IBS, and the other was a composite outcome of a new IBS claim, new prescriptions for IBS, or new claims for potential IBS symptoms (which required abdominal pain and defecatory symptoms that had to develop within 90 days of each other). 

The hazard ratio (HR) for a new diagnosis of IBS was 1.11 for antibiotic exposure, which did not reach significance. When the composite outcome was used, the HR for antibiotic exposure was 1.12, which was significant, and the number needed to harm at 3 years was 94. The only antibiotic class independently associated with the composite outcome was quinolones, with an HR of 1.36.