A Multicentre Study of Wastewater and Antibiotic Resistance in Care Homes.

Extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) are now endemic in France, complicating the management of infections. In parallel, carbapenemase-producing Enterobacterales (CPE) are exhibiting rapid growth, necessitating enhanced surveillance systems and preventive measures across the healthcare network. Current antimicrobial resistance (AMR) surveillance systems, which rely primarily on clinical samples, underestimate the dissemination of commensal bacteria and therefore limit the ability to anticipate epidemic events. Transmission of ESBL-PE and CPE has been documented in long-term care facilities (LTCFs), where they may play a significant role in amplifying and maintaining outbreaks within the healthcare network. However, no dedicated surveillance system currently exists in these facilities. The current French national strategy is based on standard precautions, but improved detection and identification of ESBL-PE and CPE in LTCFs could enable more effective prevention of transmission and reduce control-related costs. The primary objective of this study is to model the relationship between the prevalence of ESBL-PE and CPE carriage among LTCF residents and their respective concentrations in facility wastewater effluents. The primary outcome measure will be the fit and predictive performance of the model for estimating the prevalence of ESBL-PE/CPE carriage among LTCF residents. Carriage prevalence will be assessed through stool sampling or, when unavailable, rectal swabbing. The explanatory variable will be the quantification of ESBL-PE/CPE or resistance genes in wastewater effluents discharged from the LTCF during the corresponding study period.