NDM-1 Metallo-β-Lactamase and ArmA 16S rRNA methylase producing Providencia rettgeri clinical isolates in Nepal

Background: Drug-resistant Providencia rettgeri producing metallo-beta-lactamase and 16S rRNA methylase has been reported in several countries. We analyzed P. rettgeri clinical isolates with resistance to carbapenems and aminoglycosides in a hospital in Nepal. Methods: Five clinical isolates of multidrug-resistant P. rettgeri were obtained in a hospital in Nepal. Antimicrobial susceptibilities were determined using the microdilution method and entire genomes were sequenced to determine drug-resistant genes. Epidemiological analysis was performed by pulsed-field gel electrophoresis. Results: Four of the 5 isolates were resistant to carbapenems (imipenem and meropenem), with MICs >= 16 mg/L, with the remaining isolate showing intermediate resistance to imipenem, with an MIC of 2 mg/L and susceptibility to meropenem with an MIC <= 1 mg/L. All 5 isolates had bla(VEB-1). Of the 4 carbapenem-resistant strains, 3 had bla(NDM-1) and 1 had bla(OXA-72). All isolates were highly resistant to aminoglycosides (MICs >= 1,024 mg/L) and harbored armA. As the result of pulsed-field gel electrophoresis pattern analysis in the 5 P. rettgeri isolates, 4 had identical PFGE patterns and the fifth showed 95.7% similarity. Conclusions: This is the first report describing multidrug-resistant P. rettgeri strains harboring bla(NDM-1) or bla(OXA-72) and armA isolated from patients in Nepal.