Expansion of acquired 16S rRNA methytransferases along with CTX-M-15, NDM and OXA-48 within three sequence types of Escherichia coli from northeast India

Abstract

Background: This study aimed to identify ten different 16S rRNA methyltransferase genes (rmtA, rmtB, rmtC, rmtD, armA, rmtF, npmA, rmtH, rmtE and rmtG) and their coexisting ESBL and carbapenemase with the emergence of three E.coli clones within a single study centre. Methods: A total of 329 non-duplicate E.coli isolates were studied to detect the presence of 16S rRNA methyltransferases along with β-lactamases (TEM, SHV, OXA, VEB, GES, PER,CTX-M types, NDM, OXA-48,VIM, IMP and KPC) using PCR assay. Horizontal transferability were validated by transformation and conjugation analysis. Plasmid incompatibility typing and MLST analysis was also performed. Results: A total of 117 isolates were found to be resistant to at least one of the aminoglycoside antibiotics. It was observed that 77 (65.8%) were positive for 16S rRNA methyltransferases. Among them thirty nine isolates were found to harbour only bla CTX-M-15, whereas combination of genes were observed in three isolates (bla VEB+ bla CTX-M-15 in 2 isolates and bla PER + bla CTX-M-15 in 1 isolate). bla NDM and bla OXA-48 like genes were found in 23 and 9 isolates, respectively. All the resistance genes were conjugatively transferable, and incompatibility typing showed multiple 16S rRNA methyltransferase genes were originated from a single Inc. I1 group. MLST analysis detected 3 clones of E.coliST4410, ST1341 and ST3906. Conclusion: The present study identified emergence of three clones of E.coli, resistant to aminoglycoside -cephalosporin- carbapenem. This warrants immediate measures to trace their transmission dynamics in order to slow down their spread in clinical setting.