Care Home Residence and Carbapenemase-Producing Enterobacterales Positivity: A Matched Case-Control Study

Background: Carbapenemase producing Enterobacterales (CPE) remain a major infection prevention and control challenge. Although care home residence is frequently perceived as a risk factor for CPE carriage, its independent association with CPE positivity remains uncertain. Objective: To investigate the relationship between care home residence on admission and CPE positivity among patients undergoing CPE screening. Methods: A retrospective matched case control study was conducted at a single NHS acute hospital in England. Adult patients with laboratory confirmed CPE positivity from screening samples between 1 November 2022 and 1 November 2025 were matched to CPE negative controls at a ratio of up to 1:4 based on ward, specimen year and age no more than 5 years older or younger. Conditional logistic regression was used to assess the association between care home residence and CPE positivity. An adjusted model included previous hospital admission within 12 months. Results: A total of 108 CPE positive cases were successfully matched to 412 controls. Care home residence was identified in 14 (13.0%) cases and 49 (11.9%) controls. In the matched conditional logistic regression model, care home residence was not associated with CPE positivity (OR 1.15, 95% CI 0.58 to 2.28; p=0.690) and remained non-significant after adjustment (aOR 1.32, 95% CI 0.66 to 2.64; p=0.439). Discussion: Care home residence was not independently associated with CPE positivity in this low-prevalence setting. Significance and impact: The findings do not support the use of care home residence alone to guide CPE screening. Further multicentre studies are required to clarify the contribution of care home residence to CPE epidemiology.