摘要Objective:To determine the molecular epidemiology of extended-spectrum β-lactamase (ESBL) by testing a cohort of clinicalESBL-producing bacterial isolates that were isolated in the Kingdom of Bahrain.Methods:ESBLproducingEnterobacteriaceae isolates (based on phenotypic tests) were collected from Microbiology Laboratory of the Salmaniya Medical Complex, Bahrain between January-June2006. Antibiotic susceptibility to a panel of antibiotics was performed andblaCTX-M genes were detected by multiplexPCR.Results: A total of230 isolates (Escherichia coli,n=180;Klebsiella pneumoniae,n=50) were studied,98% were CTX-M type. ForEscherichia coli isolates,65 (36.1%)harboredCTXM+TEMcombination and68(37.8%) had CTX-M alone. In contrast, forKlebsiella pneumoniae isolates only 5 (10.0%) harbored the CTX-M combination, and none had CTX-M only. The blaCTX-Mgene was found predominantly in urine isolates (n=145/230; 63.0%). Sensitivity to imipenem and nitrofurantoin was100% and 60%, respectively.CTX-M carriage was associated with the resistance to fluoroquinolones, trimethoprim-sulfamethoxazole and aminoglycosides.Conclusions: Our study documentes high prevalence ofCTX-M ESBL type amongEscherichia coliandKlebsiella from the Kingdom of Bahrain. The apparent dissemination of CTX-Mproducers could represent a substantial barrier in the treatment of community-acquired infections. The use of extended-spectrum cephalosporins, quinolones, and aminoglycosides is compromised, leaving carbapenems as the therapeutic option for severe infections caused byESBL producers.