Multidrug-resistant Raoultella ornithinolytica misidentified as Klebsiella oxytoca carrying blaOXA β-lactamases: antimicrobial profile and genomic characterization

Class D beta-lactamases OXA-232 and OXA-48 hydrolyze penicillin, cephalosporins and carbapenems, limiting the pharmacological therapeutics in bacteraemia. OXA producer microorganisms are considered a great emergent threat, especially in nosocomial environments. To determine the resistance profile and genomic characterization of two isolates initially identified as potential carbapenemase-producer Klebsiella oxytoca in a third level hospital. Automated platform BD Phoenix-100 System was used to identify and to biochemically characterize both isolates. Furthermore, the resistance profile was determined through CLSI methods and the whole genome sequences were obtained using Next-Generation Sequencing. Resistance genes were analyzed, and the virtual fingerprinting was determined to corroborate the similarity with related bacteria. Both strains correspond to Raoultella ornithinolytica carrying OXA 232 and OXA-48 genes, confirming the class D beta-lactamases assay results. Here, we present the genetic and phenotypic analysis of multidrug resistance R. ornithinolytica, representing the first report in Mexico.

Automated summary

Class D beta-lactamases OXA-232 and OXA-48 were found to hydrolyze penicillin, cephalosporins, and carbapenems, limiting therapeutic options for bacteraemia. The study identified Raoultella ornithinolytica carrying OXA 232 and OXA-48 genes, confirming the results of the beta-lactamases assay. This represents the first report of multidrug resistance R. ornithinolytica in Mexico, highlighting the emergence of OXA producer microorganisms as a significant threat.