Abstract
            Introduction: The prevalence of urinary tract infections (UTIs) due to extended-spectrum  beta-lactamase (ESBL)-producing bacteria is rising, which needs more potent antibiotics,  such as carbapenems.  
  Objectives: To evaluate the clinical and laboratory differences between ESBL-positive and  ESBL-negative bacteria in febrile UTI in children between one month to seven years to indicate  prognostic parameters for ESBL+ UTI and to suggest appropriate antibiotic treatment.  
  Patients and Methods: This cross-sectional study investigated 282 patients diagnosed with  the first febrile UTI. The participants were assigned to ESBL-positive and ESBL-negative UTI  groups. The groups were compared based on their clinical and laboratory characteristics and  outcomes; the infant group was assessed separately (with the onset age of <3 months).  
  Results: The ESBL UTI was detected in 10.2% of the cases with a history of more frequent  hospitalization (P=0.002), longer hospitalization (P=0.04), higher recurrence rate (P=0.003),  and more red blood cell count in urine analysis findings (P=0.02). In the antimicrobial  susceptibility assay, the ESBL-positive UTI group indicated resistance to third-generation  cephalosporins; nevertheless, 93.1% of the cases responded clinically. The infant group showed  13% of the patients with ESBL-positive UTI that was correlated with a history of longer preonset hospital stay (P=0.001), elevated C-reactive protein (CRP) concentration (P=0.002),  and elevated recurrence rate (P=0.03), compared to the older group.  
  Conclusion: The ESBL UTI should be further considered due to the resulted recurrence  rate. The antimicrobial sensitivity assay indicated resistance to third-generation  cephalosporins; however, these drugs are applied as the first choice due to the high response  rate. Aminoglycosides are applicable as second choice drugs prior to initiating the use of  carbapenems, if third-generation cephalosporins did not indicate bactericidal impacts on  ESBL UTI.