Prevalence and predictors of MRSA, ESBL, and VRE colonization in the ambulatory IBD population.

BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) patients may be at increased risk of acquiring antibiotic-resistant organisms (ARO). We sought to determine the prevalence of colonization of methicillin-resistant Staphylococcus aureus (MRSA), Enterobacteriaceae containing extended spectrum beta-lactamases (ESBL), and vancomycin-resistant enterococi (VRE) among ambulatory IBD patients.

METHODS: We recruited consecutive IBD patients from clinics (n=306) and 3 groups of non-IBD controls from our colon cancer screening program (n=67), the family medicine clinic (n=190); and the emergency department (n=428) from the same medical center in Toronto. We obtained nasal and rectal swabs for MRSA, ESBL, and VRE and ascertained risk factors for colonization.

RESULTS: Compared to non-IBD controls, IBD patients had similar prevalence of colonization with MRSA (1.5% vs. 1.6%), VRE (0% vs. 0%), and ESBL (9.0 vs. 11.1%). Antibiotic use in the prior 3 months was a risk factor for MRSA (OR, 3.07; 95% CI: 1.10-8.54), particularly metronidazole. Moreover, gastric acid suppression was associated with increased risk of MRSA colonization (adjusted OR, 7.12; 95% CI: 1.07-47.4). Predictive risk factors for ESBL included hospitalization in the past 12 months (OR, 2.04, 95% CI: 1.05-3.95); treatment with antibiotics it the past 3 months (OR, 2.66; 95% CI: 1.37-5.18), particularly prior treatment with vancomycin or cephalosporins.

CONCLUSIONS: Ambulatory IBD patients have similar prevalence of MRSA, ESBL and VRE compared to non-IBD controls. This finding suggests that the increased MRSA and VRE prevalence observed in hospitalized IBD patients is acquired in-hospital rather than in the outpatient setting.