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

Background: The carbapenemase-encoding genes, 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 and on a single plasmid is a rare occurrence.

Aim And Objective: The purpose of the study was to characterize the plasmids in isolates producing 16S rRNA methyltransferase along with , , and other resistance encoding genes.

Materials And Methods: One-hundred and seventeen clinical isolates which were resistant to aminoglycosides were collected. Polymerase chain reaction-based screening for 16S rRNA methyltransferase genes and ; carbapenamase genes and ; and other resistance genes such as and and determinants was performed. Conjugation experiment was carried out for seven isolates that anchored and 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, was more predominant. and were present in 56 (47.86%) and 22 (18.80%) isolates, respectively. Out of seven isolates which were conjugatively transferable, only four had and on the same plasmid and they belonged to Inc N and A/C replicon. Three isolates co-harbored 16S rRNA methyltransferases and , and out of the them, one isolate harbored two 16S rRNA methyltransferases and on the single-plasmid replicon A/C.

Conclusion: This is the first report revealing the coexistence of and co-harboring two 16S rRNA methylases on a single conjugative plasmid replicon belonging to incompatibility group A/C.