Methods for the Phenotypic Detection of Extended Spectrum Beta Lactamase (ESBL)-Producing Bacteria

Extended Spectrum Beta Lactamases (ESBLs) are first reported in Klebsiella pneumonia in 1983. These enzymes possess the ability to inactivate susceptible β-lactam antibiotics i.e. penicillins, first, second and third generation cephalosporins and aztreonam, but not cephamycins and carbapenems . Their mode of action is by hydrolyzing the β-lactam ring. Even before the first β-lactam antibiotic (penicillin) was developed, resistance to β-lactam antibiotics was observed . ESBL genes are plasmidsand transposonsmediated, as such, can be spread easily to other species of bacteria. Resistance of ESBLproducing bacteria to the β-lactam antibiotics is a continuing cause of public health problems , it is increasingly being observed in community and nosocomial acquired infections. Detection and identification of these ESBLs in the laboratory is of prime importance for the selection of appropriate antibiotics to be used in the treatment of infections caused by ESBLproducing bacteria. The aim of this review is to explain in detail , several phenotypic methods used in the detection and confirmation of extended spectrum β lactamases.