Environmental and animal reservoirs of methicillin-resistant Staphylococcus aureus (MRSA): a One Health challenge.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is among the most prevalent nosocomial pathogens. However, in recent decades, infections were reported in communities, infecting individuals without previous hospitalization, and in livestock. Given this public health concern, this systematic review aimed to analyze studies that isolated MRSA from environmental and animal matrices, with an emphasis on the implications of this pathogen's presence from a One Health perspective. A total of 183 articles were selected between 2005 and 2025. These investigations were conducted in 43 countries, with 44% in Europe and 5% in North America. In South America, only studies from Brazil were identified, indicating a lack of data from other countries in the region. The animal matrix was the most extensively investigated source of MRSA, comprising 153 studies (85%) across a range of wild, domestic, and farm species. In the environmental context, MRSA was primarily identified in water (65.8%), followed by soil (21%), and air (13.2%). The predominance of MRSA isolation in the aquatic environment indicates that water is a critical reservoir for the spread of antimicrobial resistance (AMR). The MRSA isolates exhibited a multidrug resistance profile. Resistance was most frequent to tetracycline (11.51%) and erythromycin (11.51%), followed by clindamycin (9.04%) and penicillin (7.67%). Further, some studies have identified MRSA in foods of animal origin, representing a potential route of transmission to humans. Finally, this study indicates that the MRSA contamination cycle, which involves hospitals, the community, environment, and animals, is a growing One Health problem that necessitates a global multisectoral approach.