LAUSR

Objective The aim of this study was to analyze the genetic characteristics of three Enterobacteriaceae strains (one strain of Escherichia coli and two strains of Klebsiella pneumoniae) that produce both the NDM-5 and OXA-181 carbapenemases in pediatric patients. Methods Carbapenem-resistant Enterobacteriaceae (CRE) strains were collected from the Children’s Hospital Affiliated to Nanjing Medical University in 2022. Resistance genes were detected by PCR. CRE strains that produced both the blaNDM-5 and blaOXA-181 genes were further characterized by antimicrobial susceptibility testing, multilocus sequence typing (MLST), plasmid conjugation assay, S1 nuclease-PFGE, Southern blotting and whole-genome sequencing. Results Three Enterobacteriaceae strains carrying both the blaNDM-5 and blaOXA-181 resistance genes were screened. MLST results showed that the strain of Escherichia coli carrying both blaNDM-5 and blaOXA-181 was ST410; the two strains of Klebsiella pneumoniae with both blaNDM-5 and blaOXA-181 were ST2601 and ST759. Conjugation assays showed that the plasmids harboring the blaNDM-5 and blaOXA-181 genes were self-transmissible. S1-PFGE and Southern blotting showed that the blaNDM-5 and blaOXA-181 genes were located on the plasmid with the size of about 60kb~. The genotyping results showed that the plasmid types were ColKP3 and IncX3. Conclusion This is the first report of Enterobacteriaceae strains that produce both NDM-5 and OXA-181 isolated from pediatric patients in China. Active infection control measures are urgently needed to prevent the spread of bacteria in children.