This study aims to model the relationship between the prevalence of ESBL-E and CPE carriage among nursing home residents and their respective concentrations in wastewater discharged from the facility.

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.

Inclusion Criteria:

• Residents present on the day of sampling (D0 or D+1) in a facility selected during randomization, without criteria regarding length of stay in the facility, and whose health status on the day of the survey permits it;
• Residents who, based on clinical criteria (including an MMSE greater than or equal to 20), are deemed by the nursing home team to be able to understand the issues of the study and to express an informed non-opposition; OR Residents who the nursing home team considers unable to express an informed non-objection but who have a legal representative, a trusted person, or a loved one capable of understanding the information and expressing an informed non-objection.

Residents may be included regardless of the presence of infection, diarrheal stools, antibiotic use or any other treatment, or health status.

Participants in this study may participate in other research projects concurrently.

Exclusion Criteria: Health and medico-social facilities not considered nursing homes (e.g., FAM, MAS, etc.);

• Residents whose health status is incompatible with performing the procedure on the day of the survey (e.g., end-of-life with comfort care);
• Residents with a Mini Mental State Examination (MMSE) score of less than or equal to 20, or without an MMSE score but who, according to nursing home professionals, are unable to provide an informed non-objection and who do not have a legal representative, trusted person, or relative capable of receiving information and providing an informed non-objection;
• Residents, regardless of their MMSE score, who refuse to have the sample taken on the day of the survey even if their legal repre

Nursing home residents located in Loire-Atlantique and Maine-et-Loire, France