Wild felids as sentinels of antimicrobial resistance: susceptible Escherichia coli isolates from a protected area in southeastern Brazil

Antimicrobial resistance (AMR) is a major global health concern, and its monitoring in wildlife is essential from a One Health perspective. Here, we obtained bacterial isolates and assessed the AMR profiles and extended-spectrum β-lactamase (ESBL) production of Escherichia coli isolated from fecal samples of wild felids in a protected Atlantic Forest area in southeastern Brazil. We collected 22 fecal samples and identified depositor species through trichological analysis (ocelot, Leopardus pardalis = 18; jaguar, Panthera onca = 1; puma, Puma concolor = 1; Leopardus sp. = 1; unidentified felid = 1). Bacterial isolation was performed using EMB agar and MacConkey agar supplemented with ceftriaxone or meropenem, and isolates were identified by MALDI-TOF MS. From these, 11 E. coli isolates (ocelot = 9; jaguar = 1; puma = 1) were selected to assess AMR using a standardized disk diffusion assay with 15 antimicrobials and to test for ESBL production. In addition to E. coli, the detected bacterial assemblage included Achromobacter micicolens, Acinetobacter baumannii, Acinetobacter nosocomialis, Acinetobacter vivianii, Enterococcus faecalis, Ochrobactrum intermedium and Stenotrophomonas maltophilia. All E. coli isolates were susceptible to all tested antimicrobials, and none showed evidence of ESBL production. These findings may suggest low selective pressure for AMR in the study area, reflecting limited circulation of antimicrobial-resistant bacteria. As free-ranging carnivores may act as sentinels of environmental change and integrate microbiota from prey, this study provides a baseline for monitoring AMR shifts across populations.