Resistant phenotype and genotype of extended spectrum β-lactamase (ESBLs) produced in Escherichia coli isolated from urinary infections

AIM: To study the resistant phenotype and genotype of extended spectrum β-lactamase (ESBLs) produced in Escherichia coli isolated from urinary infections. METHODS: Organisms of clinical infection were identified by automatic microbial system (Vitek) and the bacterial susceptibility was tested by Kirby-Bauer (K-B) method as described in NCCLS. ESBLs was detected by disk diffusion confirmatory test and CTX-M or SHV specific PCR were used to determine the genotype of ESBLs. RESULTS: 24.0% of E.coli produced ESBLs. Forty-two of the 62 ESBLs producing strains (67.7%) expressed CTX-M β-lactamase and 9 of the 62 ESBLs producing strains (14.5%) expressed SHV β-lactamase. CONCLUSION: ESBLs producers are mainly resistant to cefotaxime and cefiriaxone and most of them are multi-drug resistant. Cefotaxime resistance is partially due to the production of CTX-M β-lactmase. CTX-M β-lactmase is most prevalent.