Occurrence of Acquired 16S rRNA Methyltransferase-Mediated Aminoglycoside Resistance in Clinical Isolates of Enterobacteriaceae within a Tertiary Referral Hospital of Northeast India.
The methylation of a ribosomal target leads to a high level of resistance to all clinically relevant aminoglycoside antibiotics, so early detection of these resistance determinants will help to reduce the incidence of treatment failures as well as lessen the dissemination rate. Here, we characterized different 16S rRNA methyltransferases responsible for aminoglycoside resistance and their epidemiological background in clinical isolates ofEnterobacteriaceaein a tertiary referral hospital in India. All aminoglycoside-resistant isolates were screened for different 16S rRNA methyltransferases by PCR assay, and incompatibility typing of the conjugable plasmid harboring resistance genes was performed by PCR-based replicon typing. An assay for the stability and elimination of these resistance plasmids was performed. The coexistence of extended-spectrum β-lactamases and metallo-β-lactamases was also detected, and the heterogeneity of these isolates was determined by enterobacterial repetitive intergenic consensus PCR. The PCR assay revealed the presence ofarmA,rmtA,rmtB,rmtC, andrmtDin single and multiple combinations, and these were carried by a diverse group of Inc plasmids. Plasmids harboring these resistance determinants were highly stable and maintained until the 55th serial passage, but SDS treatment could easily eliminate the plasmids harboring the resistance determinants. The coexistence ofblaTEM,blaPER,blaGES, andblaSHV, as well asblaVIMandblaNDM, within these isolates was also detected. Strains with different clonal patterns of aminoglycoside resistance were found to spread in this hospital setting. We observed that the 16S rRNA methyltransferase genes were encoded within different Inc plasmid types, suggesting diverse origins and sources of acquisition. Therefore, the present study is of epidemiological importance and can have a role in infection control policy in hospital settings.
Department of Microbiology, Assam University, Silchar, India.
Jayalaxmi
J
Wangkheimayum
Department of Microbiology, Assam University, Silchar, India.
Deepjyoti
D
Paul
Department of Microbiology, Silchar Medical College and Hospital, Silchar, India.
Debadatta
D
Dhar
Department of Microbiology, Assam University, Silchar, India.
Rajlakshmi
R
Nepram
Department of Microbiology, Assam University, Silchar, India.
Shiela
S
Chetri
Department of Microbiology, Assam University, Silchar, India.
Deepshikha
D
Bhowmik
Department of Microbiology, Silchar Medical College and Hospital, Silchar, India.
Atanu
A
Chakravarty
Department of Microbiology, Assam University, Silchar, India ab0404@gmail.com.
Amitabha
A
Bhattacharjee
D000617:Aminoglycosides / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics*; D007194:India; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D062606:Tertiary Care Centers / Q000706:statistics & numerical data
D000617:Aminoglycosides; D012336:RNA, Ribosomal, 16S
16S rRNA methyltransferase; Enterobacteriaceae; aminoglycoside; stability