TITLE:
Detection of blaNDM-1 and Genetic Relatedness in Clinical Isolates of Escherichia coli Producing Extended Spectrum β-Lactamase from Tertiary Care Centres in South India
AUTHORS:
Nithya Narayanan, Manju Suresh, Jayasree Pullampara Rajamma, Manish Kumar Panickassery Ramakrishnan
KEYWORDS:
ESBL, blaNDM-1, Plasmids, E. coli
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.3,
March
10,
2016
ABSTRACT: Background: Extended spectrum β-lactamases
(ESBL) producing E. coli co-producing other β-lactamases and exhibiting co-resistance to different antibiotic
classes continue to emerge as a threat to clinical field. This study aimed to
analyze the co-production of New Delhi metallo-β-lactamase-1 (blaNDM-1) in ESBL producing plasmid-bearing
clinical isolates collected from two tertiary care centres in Kerala, South
India, and to understand their genetic relatedness. Methods: Antibiotic
resistance phenotypes of 44 clinical isolates were determined by disc-diffusion
method. Plasmid-bearing isolates, detected by the alkaline-lysis method, which
also tested positive for ESBL production, were screened for the presence of blaNDM-1
by polymerase chain reaction. Plasmid, random amplified polymorphic DNA
profiles and blaNDM-1 sequence-based phylogenetic tree were analyzed to
understand the genotypic similarities among the isolates. Results: Beta-lactam
antibiotics, quinolones, cephalosporins, used in this study, and AZM were found
to be ineffective against the isolates as significantly high number of isolates
were resistant to these antibiotics (P blaNDM-1
amplicons were noticed in four (16%) isolates and these DNA sequences showed homology
between them and with similar sequences reported from other countries like
Japan and Korea. Plasmid and RAPD profiles demonstrated that most of the
isolates, including those harbouring blaNDM-1 shared genetic
similarities as well as an apparent geographical distinctiveness. Conclusion: The
predominance of ESBL production and the occurrence of blaNDM-1 in plasmid-bearing
isolates observed in our study corroborate the worldwide drug-resistance scenario.
This study thus warrants the need for constant surveillance in the face of
sparse information available in Kerala State on the emerging drug resistance in
clinical bacteria.