Long-term Risk of Infection Among Patients Colonized With Antimicrobial-Resistant Pathogens: A Population-wide Cohort Study

Abstract

Background Antimicrobial resistant (AMR) pathogens represent an ongoing global health burden. Colonization is often a pre-requisite for infection, but the risk of infection after AMR-colonization is not well understood. Using population-level health administrative data, we sought to investigate the risk of infection with the same AMR organism after detection of colonization. Methods We conducted a retrospective population-wide cohort study among residents of Ontario, Canada over a 5-year period to determine the risk of infection after detection of colonization with the following AMR pathogens: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum beta-lactamase producing Enterobacterales (ESBL), and carbapenemase-producing Enterobacterales (CPE). We also examined the effects of age, sex, and healthcare setting of colonization detection on subsequent infection risk. Results There were 69,998 individuals with a positive AMR pathogen surveillance test during the study period, 15.6% of which subsequently developed a sterile or non-sterile site infection, within a median of 57 (IQR 11-228) days. Infection rates varied between organisms: 18.3% for MRSA within a median of 57 (IQR 10-239) days, 2.8% for VRE within a median of 37 (IQR 11-119) days, 21.5% for ESBL within a median of 71 (IQR 18-231) days, and 20.3% for CPE within a median of 10 (3-42) days. A positive surveillance test detected in hospital was associated with increased infection risk after colonization compared with the community setting. Conclusions The overall infection rate after colonization with an AMR pathogen was high for most organisms, highlighting the importance of detecting colonization from both an infection control and empiric antibiotic selection perspective.