Molecular and Phenotypic Characterization of a Multidrug-Resistant Escherichia coli Coproducing OXA-232 and MCR-1.1 in Argentina

The spread of carbapenem-resistant Enterobacterales has raised concern in clinical settings due to the limited therapeutic options available. OXA-48-like enzymes are still sporadic in South America. The aim of this study was to characterize a multidrug-resistant Escherichia coli isolate from a hospitalized patient in Buenos Aires city.The isolate was characterized phenotypically by determination of its susceptibility pattern, synergistic and colorimetric tests, and molecularly, by PCR, whole genome sequencing, and plasmid analysis. It belonged to ST-744, phylogroup A, and serotype O162/O89: H9. It remained susceptible to ceftazidime, meropenem, aminoglycosides, trimethoprim/sulfamethoxazole, and tigecycline. The presence of bla(OXA-232) harbored by a nonconjugative plasmid ColKp3, and bla(CTX-M-14), mcr-1.1, and fosL1 in 2 conjugative plasmids, together with their genetic environment, was revealed. To the best of our knowledge, this is the first report of the coproduction of the enzyme OXA-232 and the mcr-1.1 gene in an E. coli clinical isolate in South America in a patient who had not received colistin therapy.