OXA-244-producing Escherichia coli isolated from a dog in Portugal.

The emergence and spread of extended-spectrum beta-lactamases (ESBL), plasmid-mediated AmpC (pAmpC), and carbapenemases pose a critical threat to animals, humans, and environmental health, highlighting the urgent need for surveillance strategies. In this study, fecal swab samples were collected from dogs and cats (n = 64) that underwent planned clean orthopedic surgery. Samples were screened for ESBL/pAmpC- and carbapenemase-producing Enterobacterales. In total, 20.0% (13/64) of the animals carried ESBL/pAmpC strains. Whole-genome sequencing (WGS) was performed for the carbapenemase-producing strain. In one dog, a multidrug-resistant, carbapenemase-producing Escherichia coli strain was isolated. WGS of this E. coli strain identified multiple virulence genes (aslA, csgA, fdeC, fyuA, gad, hha, hlyE, irp2, iss, nlpI, shiA, terC, tia, yehA, yehB, yehC, yehD) and antimicrobial resistance genes (aadA1, blaCTX−M−15, blaOXA−244, qnrS1, sul3). This represents the first report of an OXA-244-producing E. coli in healthy companion animals from Europe and the first detection of this variant in sequence type ST4981, belonging to O101:H9. The strain also carried the qacL gene, conferring resistance to quaternary ammonium compounds, raising concerns regarding the efficacy of common antiseptics such as chlorhexidine in clinical settings. Genomic surveillance provided deeper insights into microorganisms’ biology and pathogenicity. These findings indicate that healthy dogs can act as reservoirs for commensal strains harboring resistance and virulence factors, posing a potential threat to the One Health concept.