Inflammatory Bowel Disease such as Ulcerative Colitis and Crohn’s blight people’s lives and restrict their functionality. The formative years of our lives represents the time when microbiological partnerships are being formed to provide lifelong co-dependence on each other. The role of the microbiota in immune tolerance in the gut and elsewhere is increasingly understood but is still an area rich for investigation.
In this study of Danish children a nationwide cohort study was conducted of all Danish singleton children born from 1995 to 2003 (N=577,627) with individual-level information on filled antibiotic prescriptions, IBD and potential confounding variables. Using Poisson regression, rate ratios (RRs) of IBD were calculated according to antibiotic use. Antibiotic use was classified according to time since use, type, number of courses used and age at use.
IBD was diagnosed in 117 children during 3,173,117 person-years of follow-up. The RR of IBD was 1.84 (95% CI 1.08 to 3.15) for antibiotic users compared with non-users. This association appeared to be an effect on Crohn`s disease (CD) alone (RR 3.41) and was strongest in the first 3 months following use (RR 4.43) and among children with >/=7 courses of antibiotics (RR 7.32).
Antibiotic use is common in childhood and it’s potential as an environmental risk factor for IBD warrants scrutiny. This is the first prospective study to show a strong association between antibiotic use and CD in childhood. However, as with any observational study, causality cannot be inferred from our results and confounding by indication–in particular, prescribing of antibiotics to children with intestinal symptoms of as yet undiagnosed CD–should also be considered as a possible explanation.
Antibiotic use can alter the commensal intestinal microflora both in the short and long term, and such alterations may be accompanied by overgrowth with potentially pathogenic microorganisms that may directly trigger IBD in susceptible individuals. A further consequence of a changed intestinal microflora is the potential indirect effects on the intestinal immune system. The removal of beneficial populations of bacteria could interfere with immune system maturation and balance leading to immune dysfunction, manifesting in reduced tolerance to microorganisms and triggering IBD in susceptible individuals. If our finding of an increased CD risk shortly after an antibiotic course reflects a causal influence of antibiotic use, it would be more easily compatible with an IBD-triggering effect of a sudden change in the bowel microflora than with some as yet uncharacterised long-term immune dysfunction.
 Hviid A, Svanström H, Frisch M. Antibiotic use and inflammatory bowel diseases in childhood. Gut. 2011 Jan;60(1):49-54. Epub 2010 Oct 21. View Abstract