Carbapenemase-Producing Enterobacterales (CPE) in Hospital Drains in Southern Ontario, Canada.

Abstract Background Hospital drains may be an important reservoir for carbapenemase-producing Enterobacterales (CPE). Aim To determine prevalence of CPE in hospital drains exposed to in-patients with CPE, relatedness of drain and patient CPE, and risk factors for drain contamination. Methods We cultured sink and shower drains in patient rooms and communal shower rooms exposed to 310 in-patients with CPE colonization/infection at 10 hospitals. Using short- and long-read whole-genome sequencing, in-patient and corresponding drain CPE were compared. Risk factors for drain contamination were assessed using multi-level modelling. Findings Of 1,209 exposed patient room and communal shower room drains, 53 (4%) yielded 62 CPE isolates in 7 (70%) hospitals. Of 49 CPE isolates in patient room drains, 4 (8%) were linked to prior room occupants. Linked drain/room occupant pairs included Citrobacter freundii ST18 isolates separated by 8 single nucleotide variants (SNVs), related blaKPC-containing IncN3-type plasmids (different species), related blaKPC-3-containing IncN-type plasmids (different species), and related blaOXA-48-containing IncL/M-type plasmids (different species). In one hospital, drain isolates from 8 rooms on 2 units were Enterobacter hormaechei separated by 0-6 SNVs. Shower drains were more likely to be CPE-contaminated than hand hygiene (OR 3.45, 95%CI 1.66-7.16) or patient use (OR 13.0, 95%CI 4.29-39.1) sink drains. Hand hygiene sink drains were more likely to be CPE-contaminated than patient use sink drains (OR 3.75, 95%CI 1.17-12.0). Conclusion Drain contamination was uncommon but widely dispersed. Drain CPE unrelated to patient exposure suggests contamination by undetected colonized patients or retrograde (drain-to-drain) contamination. Drain types had different contamination risks.