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.coli
ST4410, 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.