Antimicrobial resistance (AMR) is a major global health concern that benefits from surveillance across human, animal, and environmental interfaces. Wildlife monitoring contributes to a One Health understanding of how resistant bacteria circulate in ecosystems. This study sought bacterial isolates and characterized AMR profiles, including extended-spectrum β-lactamase (ESBL) production, among Escherichia coli recovered from fecal samples of wild felids in a protected Atlantic Forest area in southeastern Brazil.
Researchers collected 22 fecal samples from a protected Atlantic Forest area in southeastern Brazil. Depositor species were identified by trichological analysis of hairs associated with the feces. Identifications included ocelot (Leopardus pardalis, n = 18), jaguar (Panthera onca, n = 1), puma (Puma concolor, n = 1), one Leopardus sp., and one unidentified felid. The study design was noninvasive and did not require handling or capturing live animals.
Bacterial isolation employed eosin methylene blue (EMB) agar and MacConkey agar plates supplemented with either ceftriaxone or meropenem to select for resistant Enterobacterales. Isolates recovered from culture were identified using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS), a rapid proteomic identification method commonly used in clinical and veterinary microbiology.
From culture-positive samples, a subset of 11 Escherichia coli isolates was selected for phenotypic AMR characterization. Those isolates originated from ocelots (n = 9), one jaguar, and one puma. Susceptibility testing was performed using a standardized disk diffusion assay and included a panel of 15 antimicrobials. In addition to the disk diffusion assay, isolates were assessed for production of extended-spectrum β-lactamases (ESBL), an important mechanism conferring resistance to third-generation cephalosporins.
The bacterial assemblage identified in the fecal samples included species beyond E. coli, such as Achromobacter micicolens; Acinetobacter species (A. baumannii, A. nosocomialis, A. vivianii); Enterococcus faecalis; Ochrobactrum intermedium; and Stenotrophomonas maltophilia. Of the Enterobacterales recovered, 11 isolates were confirmed as Escherichia coli and submitted to detailed AMR testing.
All 11 E. coli isolates were susceptible to all 15 antimicrobials tested by disk diffusion. None of the isolates demonstrated evidence of ESBL production. These phenotypic findings indicate an absence of detectable resistance among the tested E. coli population in this sample set.
The complete susceptibility of E. coli isolates and lack of ESBL production in this sample series suggest a low selective pressure for antimicrobial resistance within the sampled protected area at the time of collection. The authors interpret these results as reflective of limited circulation of antimicrobial-resistant bacteria in that environment.
Free-ranging carnivores, such as the felids sampled here, may act as sentinels of environmental microbial change because they integrate microbiota from a range of prey species and habitats. The study provides a baseline dataset for future monitoring of AMR shifts across wild felid populations and their environments in the region.
This report is based on noninvasive fecal sampling of 22 specimens; only 11 E. coli isolates were evaluated in depth. Details such as the specific 15 antimicrobials tested and disk diffusion zone measurements were not reported in the abstract. The study required no invasive procedures and was approved under ICMBio/SISBIO license No. 54218. The authors declared that no Institutional Review Board approval was required because the work did not involve capturing or handling live animals. The authors also declared no competing interests.
In a protected Atlantic Forest area in southeastern Brazil, fecal sampling of wild felids yielded a bacterial assemblage that included Escherichia coli and several other species. Phenotypic antimicrobial susceptibility testing of 11 E. coli isolates showed full susceptibility to a panel of 15 antimicrobials and no evidence of ESBL production. These results may indicate low environmental selective pressure for AMR in the study area and establish a baseline for future One Health surveillance using wild felids as sentinels.
(Report based on: Teixeira MM et al., Vet Res Commun. 2026; abstract and article metadata. Detailed numerical susceptibility data, breakpoints, and the full antimicrobial panel were not reported in the abstract.)