Abstract

The order Enterobacterales contains a large number of genera which are mainly gut microbiota bearing similar biochemical and genetic characteristics. They are ubiquitous and the members include several that are among important opportunistic human pathogens, which cause infections including urinary tract, bloodstream, respiratory tract, (hospital and health care associated pneumonia), as well as intestinal and intra-abdominal infections. Klebsiella pneumoniae, Escherichia coli, Proteus, Citrobacter, Enterobacter, Hafnia, Morganella, Providencia, and Serratia are some of the genera that cause opportunistic infections. Other members are primary pathogens such as Salmonella, Shigella, and Yersinia. β-lactam antibiotics, which include penicillins, cephalosporins, and carbapenems, are among the most commonly prescribed antibiotics and preferred therapeutic options for infections caused by Enterobacterales. Resistance to these antibiotics is due to inaccessibility of the antibiotics to their target enzymes, modification of target enzymes, and direct deactivation of the antibiotics by β-lactamases. This review explores the common Extended Spectrum β-Lactamase (ESBL) and carbapenemase gene families, which are commonly involved in resistance to the β-lactams in Enterobacterales.