ESBLs are β-lactamases capable of conferring bacterial resistance to the penicillins, first, second, and third-generation cephalosporins, and aztreonam (but not the cephamycins or carbapenems) but these are inhibited by-lactamase inhibitors such as clavulanic acid. The ESBLs are typically plasmid-mediated enzymes, mostly produced by Gram negative bacteria. Extended spectrum beta lactamase (ESBLs) enzymes were first reported in Germany in 1983 from Klebsiella pneumonia. ESBL-producing Enterobacteriaceae have been responsible for numerous outbreaks of infection throughout the world and pose challenging infection control issues. Different phenotypic test for ESBL detection have been developed, which are easy to use and cost effective.