CTX-M-2-producing Escherichia Coli ST1266 in a Peri-urban Wild Giant Anteater (Myrmecophaga tridactyla) from Brazil

The emergence of antimicrobial resistance (AMR) is a critical One Health problem, with wildlife increasingly threatened. While captive giant anteaters (Myrmecophaga tridactyla) have been studied for microbiota composition and AMR, wild-living individuals have not yet been investigated. Therefore, this study investigated the Gram-negative aerobic microbiota colonizing 21 wild M. tridactyla individuals and evaluated the phenotypic and genotypic AMR profiles of enterobacteria. Accordingly, 67 enterobacteria and non-fermenting Gram-negative bacilli were identified, with Escherichia coli, Pseudomonas sp., and Achromobacter sp. being observed in all swab types (oral, ocular, and rectal). Among 12 enterobacteria, three E. coli strains were identified as resistant to antimicrobials, with the TMND-VV-15 strain, isolated from a peri-urban specimen, exhibiting multidrug resistance and producing an extended-spectrum β-lactamase (ESBL). Genome sequencing of the TMND-VV-15 strain revealed AMR determinants, including horizontally acquired genes and chromosomal point mutations associated with resistance. The bla_CTX-M-2 gene was harbored in a complex class 1 integron located on its chromosome. Potential virulence genes mainly related to adhesion, invasion, immune evasion, and host cell damage were found. Strain TMND-VV-15 belonged to the sequence type (ST) 1266 and sublineage E-ST1266-H108. Comparative genomic analysis revealed that E-ST1266-H108 strains, including those harboring ESBL genes and classified as putative enteropathogenic E. coli, have been circulating in many countries, but not in Brazil. These findings suggest that the CTX-M-2-producing E. coli strain may be driven by anthropogenic pressures in the area studied. Therefore, continuous microbiological monitoring in free-ranging populations remains necessary to better understand the dynamics of AMR dissemination to the wildlife health framework.