Molecular Epidemiology and Conjugative Transferability of blaOXA-48/blaNDM-1 Co-Occurrence in Extensively Drug-Resistant Klebsiella pneumoniae from Egyptian Tertiary Care Hospitals

Abstract

Carbapenem-resistant Klebsiella pneumoniae is a major threat to global health, with increasing incidence in developing countries, including Egypt. This study determined carbapenem-resistance prevalence among clinical K. pneumoniae isolates from two Egyptian tertiary hospitals, characterized the major carbapenemase genes, and assessed the transferability of the resistance plasmids. VITEK® 2 and MALDI-TOF MS identified 94 non-duplicate isolates. Susceptibility was determined by Kirby–Bauer diffusion and VITEK® 2. MICs of imipenem, meropenem and colistin were confirmed by broth microdilution. Isolates were classified as multidrug-resistant (MDR), extensively drug-resistant (XDR), or pandrug-resistant (PDR) according to established definitions. Phenotypic (modified Hodge test [MHT], modified carbapenem inactivation method [mCIM], modified Carba NP test [mCNP]) and genotypic (PCR/BlastN) evaluation of carbapenemase production and plasmid transferability by conjugation were carried out in 18 isolates, selected to represent every carbapenemase genotype identified in the collection. All isolates were MDR, and 94.68% were carbapenem-resistant and fulfilled the criteria for XDR, remaining susceptible only to colistin and tigecycline. Carbapenemase production was confirmed phenotypically in 98.9% and genotypically in 97.9% of isolates. blaOXA-48 (94.7%) and blaNDM-1 (69.1%) predominated, with 67.0% co-carriage; blaKPC occurred in 5.3%. Conjugation transferred carbapenemase-encoding plasmids to Escherichia coli J53 from 77.8% (14/18) of donors, conferring carbapenem non-susceptibility in all transconjugants. All isolates were colistin-susceptible by broth microdilution, the reference method. The high XDR prevalence, along with the conjugative transferability of blaOXA-48/blaNDM-1, is consistent with a mobile carbapenemase-encoding plasmid reservoir in Egyptian tertiary care, highlighting the significance of carbapenemase surveillance and stewardship. Plasmid characterization and clonal typing were not performed and are required to define that reservoir fully.