Augmentation in zone of inhibition of cefoperazone/cefoperazone+ sulbactum compares well with the clinical laboratory standard institute standard extended spectrum beta-lactamase detection method as well as the polymerase chain reaction method.

Background: With increased prevalence of extended spectrum beta-lactamase (ESBL) in hospital practice globally, reporting of extended spectrum beta-lactamase along with drug susceptibility test is expected from clinical microbiology laboratory. The aim was to evaluate cefoperazone and cefoperazone+sulbactum disc for phenotypic detection of extended spectrum beta-lactamase among E. coli and Klebsiella spp. isolates.

Methodology: A total of 948 clinical specimens were analysed which included 496 E. coli and 392 Klebsiella pneumoniae. For confirmation of extended spectrum beta-lactamase ceftazidime/ceftazidime+clavulanidc acid and cefotaxime/ cefotaxime+clavulanic acid discs were used as recommended by Clinical Laboratory Standard Institute (CLSI). Simultaneously randomly selected 100 isolates, each of E. coli and Klebsiella spp. were identified for extended spectrum beta-lactamase genes coding for the TEM, SHV and CTX by polymerase chain reaction (PCR). The results were compared with cefoperazone/cefoperazone+sulbactum disc diffusion method.

Result: Phenotypic characterization identified a high extended spectrum beta-lactamase rate. Four hundred out of 496 (80.64%) E. coli and 392 out of 452 Klebsiella spp.(86.7%) were positive for extended spectrum beta-lactamase by the Clinical Laboratory Standard Institute method. The increase in zone size of cefoprazone/cefoperazone+sulbactum (≥ 5 mm) was seen for all the isolates of E. coli and Klebsiella spp. which were confirmed as extended spectrum beta-lactamase by Clinical Laboratory Standard Institute as well as polymerase chain reaction (PCR) method.

Conclusion: cefoperazone/cefoperazone+sulbactum disc diffusion showed 100% concordance with extended spectrum beta-lactamase detection by ceftazidime/ ceftazidime+clavulanidc cefotaxime/cefotaxime+clavulanic acid disc diffusion method and polymerase chain reaction.