Co occurrence of two 16S rRNA methyltrasferases along with NDM and OXA 48 like carbapenamases on a single plasmid in Klebsiella pneumoniae.

Abstract: 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 blaNDMand blaOXA-48-likeon 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 blaNDMand blaOXA-48-likealong 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. blaNDMand blaOXA-48-likewere present in 56 (47.86%) and 22 (18.80%) isolates, respectively. Out of seven isolates which were conjugatively transferable, only four had blaNDMand blaOXA-48-likeon 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 blaNDMand blaOXA-48-likeco-harboring two 16S rRNA methylases on a single conjugative plasmid replicon belonging to incompatibility group A/C. [ABSTRACT FROM AUTHOR]