Introduction: Production of extended-spectrum beta-lactamase (ESBL) is one of the most important resistance mechanisms. Today, community-acquired infections caused by ESBL-producing isolates are mentioned as well as nosocomial infections. Theaim of this study was to assess in vitro activity of various antimicrobials against 75 ESBL-producing Escherichia coli isolates obtained from urine samples which were determined in patients with the diagnosis of urinary tract infections. Patients and Methods: In this study, all the 75 ESBL-producing E. Coli isolates obtained from urine samples between September 2011 and February 2012 were included. ESBL production of the isolates was detected by double disk synergy test. The minimum inhibitory concentrations (MICs) of antibiotics (ertapenem, imipenem, doripenem, and cefoperazone-sulbactam) were determined by broth microdilution method according to CLSI (Clinical and Laboratory Standards Institute) guidelines. Results: While MIC50-MIC90 values were 0.125-0.25 μg/mL for ertapenem, 0.5-0.5 μg/mL for imipenem, and 0.06-0.06 μg/mL for doripenem against nosocomial E. Coli isolates (n= 57), MIC50-MIC90 values were 0.06-0.125 μg/mL for ertapenem, 0.25-0.5 μg/mL for imipenem, and 0.06-0.06 μg/mL for doripenem against community-acquired E. Coli isolates (n= 18). Statistically, no difference was determined between these two groups (p> 0.05). Cefoperazone-sulbactam MIC50-MIC90 values were 8-64 μg/mL against both nosocomial and community-acquired E. Coli isolates. Conclusion: Ertapenem, imipenem, and doripenem were more effective as in vitro than cefaperazone-sulbactam and they are antimicrobials that could be used safely in the treatment of infections caused by ESBL-producing isolates.