Abstract
BackgroundThis 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.MethodsA 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.ResultsA 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 blaCTX-M-15, whereas combination of genes were observed in three isolates (blaVEB+ blaCTX-M-15 in 2 isolates and blaPER + blaCTX-M-15 in 1 isolate). blaNDM and blaOXA-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.ConclusionThe 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.
Highlights
This study aimed to identify ten different 16S rRNA methyltransferase genes and their coexisting Extended Spectrum Beta-lactamase (ESBL) and carbapenemase with the emergence of three E.coli clones within a single study centre
The study was approved by Institutional ethical committee of both Silchar Medical College and Assam University, Antimicrobial susceptibility testing Minimum inhibitory concentration (MICs) of isolates against aminoglycoside antibiotics namely; kanamycin, tobramycin, gentamicin, netilmicin, amikacin and streptomycin (Hi,Media,India) were determined by agar dilution method
Horizontal transferability All the resistance genes detected were conjugatively transferable and transformants carrying the 16SrRNAmethyl transferase genes along with ESBLs and carbapenemases could be selected in the media containing kanamycin
Summary
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. In India there are multiple reports of 16S rRNAmethyltrasferase genes (armA,rmtA, rmtB, rmtC, rmtD and rmtF) as published in various studies [2,3,4] These enzymes are responsible for alteration of A site of 16S rRNA and reported across the globe [5,6,7,8,9,10]. These genes are often associated with horizontal transmission and expansion of aminoglycoside resistance in hospital settings along with other resistance determinants [11]. In the present study we have investigated the presence of acquired 16 s rRNA rmehyltransferase genes along with other co-resistance determinants in the clinical isolate of E. coli in a tertiary referral hospital of northeastern part of India
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