Antimicrobial exposure leads to an increased risk of colonization and spread of vancomycin-resistant enterococci. Studies have also implicated exposure to nonantimicrobial medications as a potential risk factor for an increased risk of colonization with these pathogens.

A matched case-control study was performed to determine specific nonantimicrobial medications associated with vancomycin-resistant enterococci rectal colonization. Cases and controls were defined as persons who were not exposed to antimicrobials in the preceding 12 months and in whom vancomycin-resistant enterococci rectal colonization was and was not detected at hospital admission, respectively. Matching was performed by the date of admission. Data were extracted from electronic medical records and included patient demographics, clinical data, and exposure to non-antimicrobial medications in the preceding 90 days.

Vancomycin-resistant enterococci colonization was identified among 2,919 (4.8%) patients during their first admission among 59,986 admissions. Among these patients, 27 cases were identified and were matched to 63 controls. Exposure to opioids was the only independent risk factor associated with colonization (adjusted odds ratio 3.8 [95% confidence interval 1.4-10.8], P-value = .01).

Opioid exposure may increase the risk of vancomycin-resistant enterococci colonization. Preventing the acquisition of these pathogens may require infection-prevention efforts targeting persons exposed to opioids.