CTX-M ESBL enzyme in Escherichia coli from urology patients in Rawalpindi, Pakistan.

Objective: To detect CTX-M phenotype utilizing disc diffusion and MIC testing in Escherichia coli isolated from a tertiary care urology setting.
Methods: Fifty single, non duplicate ESBL producing isolates from a tertiary care urology hospital were evaluated for the presence of CTX-M phenotype. Initially all the urinary isolates were tested for ESBL production. The isolates were identified by using API 20E galleries and screened for ESBL production by combination disc methods. Representative 4 ESBL isolates were sent to Antibiotic Resistance Monitoring and Reference Laboratory (ARMRL), Health Protection Agency, Colindale, London, UK where those were further subjected to MIC testing by agar dilution and E-test strips.
Results: A total of 4 ESBL producing E. coli isolates were characterized to be CTX-M on phenotypic characterization. The overall yield of CTX-M phenotypes was 75%.
Conclusion: The emergence of CTX-M from Pakistan is alarming; however, further studies are required to study the epidemiology and genetic characterization of CTX-M types of ESBLs.