RESUMO
BACKGROUND: The carbapenemase-encoding genes, blaNDM- and blaOXA-48 - like, confer resistance to all the known beta-lactams and are encountered along with other beta-lactamase-encoding genes and/or 16S ribosomal RNA (rRNA)-methylating genes. The co-occurrence of blaNDM and blaOXA-48 - like on a single plasmid is a rare occurrence. AIM AND OBJECTIVE: The purpose of the study was to characterize the plasmids in Klebsiella pneumoniae isolates producing 16S rRNA methyltransferase along with blaNDM , blaOXA-48-like , and other resistance encoding genes. MATERIALS AND METHODS: One-hundred and seventeen K. pneumoniae clinical isolates which were resistant to aminoglycosides were collected. Polymerase chain reaction-based screening for 16S rRNA methyltransferase genes armA, rmtB, and rmtC; carbapenamase genes blaNDM , blaOXA-48-like , blaIMP, blaVIM, and blaKPC ; and other resistance genes such as blaTEM, blaSHV, blaCTX-M, and qnr (A, B, and S) determinants acc (6') Ib-cr was performed. Conjugation experiment was carried out for seven isolates that anchored blaNDM and blaOXA-48-like along with any one of the 16S rRNA methyltransferases. The plasmid-based replicon typing for different plasmid-incompatible (Inc) group was performed on the conjugatively transferable plasmids. RESULTS: Among the 16S rRNA methyltransferases, armA was more predominant. blaNDM and blaOXA-48 -like were present in 56 (47.86%) and 22 (18.80%) isolates, respectively. Out of seven isolates which were conjugatively transferable, only four had blaNDM and blaOXA-48 - like on the same plasmid and they belonged to Inc N and A/C replicon. Three isolates co-harbored 16S rRNA methyltransferases armA, rmtB, and rmtC, and out of the them, one isolate harbored two 16S rRNA methyltransferases armA and rmtB, on the single-plasmid replicon A/C. CONCLUSION: This is the first report revealing the coexistence of blaNDM and blaOXA-48 - like co-harboring two 16S rRNA methylases on a single conjugative plasmid replicon belonging to incompatibility group A/C.