The aim of the investigators' study was to evaluate oral and non carbapenem antimicrobial agents which can be used in outpatient for the treatment of non-bacteremic acute pyelonephritis caused by Extended Spectrum Beta Lactamase Escherichia coli. This study was conducted to compare the clinical and bacteriological outcomes of patients with non-bacteremic acute pyelonephritis caused by Extended Spectrum Beta Lactamase Escherichia coli who were treated with intravenous (IV) carbapenems followed by oral sitafloxacin or IV ertapenem.