BACKGROUND: Antibiotic resistance poses a worldwide threat and knowledge concerning risk factors for colonization with multiresistant bacteria (MRB) is limited.
OBJECTIVES: To examine the impact of prior antibiotic consumption on MRB colonization, with focus on type of antibiotic and timeline between antibiotic prescription and MRB colonization.
METHODS: A nationwide case-control study was conducted and adults visiting emergency departments were invited to participate. All patients were swabbed in the throat, nose and rectum, and analysed for colonization with ESBL-producing Enterobacteriaceae (ESBL-E), MRSA, carbapenemase-producing enterobacteria and VRE. Antibiotic history 2 years prior to enrolment was collected at an individual level through a national register. Multivariate analyses were performed to examine the association between antibiotic consumption and MRB status. A subgroup analysis of ESBL-E-colonized cases was made.
RESULTS: We included 256 patients colonized with MRB and 4763 controls. In the 2 years prior to study inclusion, 77% of cases and 68% of controls had at least one antibiotic prescription (P = 0.002). We found a significant increase in risk of colonization with ESBL-E if penicillins (OR = 1.58-1.65) or fluoroquinolones (OR = 2.25-6.15) were prescribed. The analysis of all MRB-colonized patients showed similar results. An assessment of the timeline showed a significant increase in risk of colonization up to 2 years after exposure to penicillins, fluoroquinolones and macrolides.
CONCLUSIONS: The prevalence of ESBL-E colonization was related to fluoroquinolone, macrolide and penicillin consumption for at least 2 years after antibiotic treatment.