Bats, wild rodents, and marsupials as ecosentinels of antimicrobial resistance: a systematized narrative review of resistance genes, mobile genetic elements, and One Health implications

Abstract

Abstract Antimicrobial resistance (AMR) is a major One Health challenge, yet wildlife remains underrepresented in surveillance systems. This systematized narrative review synthesized studies published between 2011 and 2025 on antimicrobial-resistant bacteria in bats, wild rodents, and marsupials, aiming to evaluate their role as reservoirs, disseminators, and ecosentinels of environmental AMR. The search was conducted in PubMed, SciELO, MEDLINE, and Scopus, and original studies reporting bacterial identification and phenotypic or genotypic resistance data were included. A total of 110 studies met the inclusion criteria, comprising rodents ( n = 56), bats ( n = 37), and marsupials ( n = 17). The most frequently reported bacterial groups included Escherichia coli , Staphylococcus spp., Klebsiella pneumoniae , Enterococcus spp., and Salmonella spp. Rodents frequently harbored multidrug-resistant Enterobacterales, including ESBL-producing E. coli and resistance genes associated with last-line antimicrobials, reflecting exposure to urban, agricultural, and waste-contaminated environments. Bats were prominent reservoirs of resistant Staphylococcus spp., including methicillin-resistant strains, and carried clinically relevant Gram-negative bacteria, likely influenced by mobility, diet, colony behavior, and anthropogenic landscape exposure. Marsupials generally showed lower AMR burdens in free-ranging conditions, but captive and rehabilitated individuals exhibited increased resistance, suggesting human-mediated acquisition and amplification. Across host groups, the detection of mobile genetic elements and resistance determinants shared with clinical contexts supports the occurrence of cross-ecosystem exchange. These findings reinforce the need to integrate wildlife into AMR monitoring frameworks as early-warning indicators of environmental contamination and resistance dissemination.