Limitation of Double Disc Diffusion Method as a phenotypic confirmatory method for ESBL producing organisms in Clinical Microbiology Laboratory

In the recent years, Extended Spectrum β-lactamase (ESBL) producing gram negative bacteria are increasingly being reported worldwide .1 Extended spectrum β-lactamases are capable of conferring bacterial resistance to the penicillins, first, second, and third generation cephalosporins, and aztreonam (but not the cephamycins or carbapenems) by hydrolysis of these antibiotics. 2 Many Clinical Microbiology laboratories use double disc diffusion method to document ESBLs, which are subsequently reported to the clinicians. Performing genotypic tests for ESBLs in a routine microbiology laboratory is not feasible.