1. Strains, equipment and procedures

This study was carried out at the Instituto Nacional de Enfermedades Neoplasicas (INEN), Lima, Peru, between March and December 2021. OXA-48-like CPE isolates were detected as part of the routine microbiological study, and clinical data were obtained by reviewing medical records. Conventional and alternative methods are used routinely by the Microbiology Laboratory of INEN. The BD Phoenix automated microbiology system (Becton Dickinson, Diagnostic Systems, Sparks, MD, USA) provides the bacterial identification and antimicrobial susceptibility profile by the dilution method according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI) 2020 [7]. Beta-lactamases such as ESBLs, AmpC, and carbapenemases are evaluated by diffusion disk testing when needed. The Resist-5 O.K.N.V.I column chromatography test (CORIS BioConcept, Gembloux, Belgium) is used to detect carbapenemase enzymes, including OXA-48-like. In addition, minimum inhibitory concentration (MIC) for colistin was determined by broth microdilution (ComASPTM Colistin, Liofilchem, Italy) and the molecular identification of OXA-48-like enzyme was carried out at the Biochemistry and Nutrition Research Center of the Universidad Nacional Mayor de San Marcos, Peru. Bacterial DNA was extracted by heat shock and multiplex polymerase chain reaction (PCR) amplification for the bla_VIM, bla_IMP, bla_NDM, bla_OXA-48-like, and bla_KPC genes following previously established conditions [8].