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BioMed Research International
Volume 2018 (2018), Article ID 9519718, 14 pages
Review Article

The Growing Genetic and Functional Diversity of Extended Spectrum Beta-Lactamases

1Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
2Abdul Wali Khan University, Garden Campus, Khyber Pakhtunkhwa, Pakistan
3Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Bioscience Block, Chak Shahzad Campus, Park Road, Islamabad, Pakistan
4Department of Animal Nutrition, The University of Agriculture, Peshawar, Pakistan

Correspondence should be addressed to Sadeeq ur Rahman; kp.ude.mukwa@qeedaS and Jian Gao; nc.ude.uac@6102naijoag

Received 2 November 2017; Revised 24 January 2018; Accepted 31 January 2018; Published 26 March 2018

Academic Editor: Yun-Peng Chao

Copyright © 2018 Sadeeq ur Rahman 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.


The β-lactams—a large class of diverse compounds—due to their excellent safety profile and broad antimicrobial spectrum are considered to be the most widely used therapeutic class of antibacterials prescribed in human and veterinary clinical practices. This, unfortunately, has also given rise to a continuous increased resistance globally in health care settings as well as in the community due to their permanent selective force driving diversification of the resistance mechanism. Resistance against β-lactams is increasing rapidly as novel β-lactamases, enzymes that degrade β-lactams, are being discovered each day such as recent emergence of extended spectrum β-lactamases (ESBL) that have the ability to inactivate most of the cephalosporins. The complexity and diversity of ESBL are increasing so rapidly that more than 170 variants have thus far been described for only a single genotype, the -encoding ESBL. This review is to organize all the current updated literature describing genomic features, organization, and mechanism of resistance and mode of dissemination of all known ESBLs.