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BioMed Research International
Volume 2013, Article ID 783540, 11 pages
Research Article

Molecular Characterization and In Silico Analysis of Naturally Occurring TEM Beta-Lactamase Variants among Pathogenic Enterobacteriaceae Infecting Indian Patients

Department of Biochemistry and Medical Biotechnology, Calcutta School of Tropical Medicine, 108 C. R. Avenue, Kolkata 700073, India

Received 24 April 2013; Accepted 9 September 2013

Academic Editor: Veeranoot Nissapatorn

Copyright © 2013 Lena Dhara et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cephalosporin resistance, particularly due to encoded -lactamases, among Enterobacteriaceae is, though, an increasing public health problem in India; their circulating genetic variants remain unknown. The present study deals with determination of variants among 134 pathogenic Enterobacteriaceae of Indian origin. Their resistance profile against 3rd generation cephalosporins was determined. The presence of variants among the bacterial plasmids was characterized by PCR followed by sequencing. Intergenic relations among the variants was determined by phylogenetic analysis. protein were modeled by Modeller9v5 and verified. The catalytic pockets were characterized, and their interaction with cephalosporins was analyzed using AutoDock tools. More than 87% of isolates showed cephalosporin resistance with ESBL production among 57.8% of Escherichia coli and 50.6% of klebsiella pneumoniae. (84.21%), like (3.94%), (3.94%), (3.94%), (3.94%), and (7.89%) were detected in 76 isolates. Four variants, namely, like, , , and , coexisted in 3 isolates. The largest catalytic pocket of explained its expanded activity towards -lactam- -lactamase inhibitor combinations. Molecular docking indicated differential resistance pattern of variants.