Once-daily intramuscular amikacin for outpatient treatment of lower urinary tract infections caused by extended-spectrum beta-lactamase-producing Escherichia coli in children Meltem Polat,1,2 Soner Sertan Kara1 1Pediatric Infectious Diseases Department, Erzurum Research and Training Hospital, Erzurum, 2Pediatric Infectious Diseases Department, Pamukkale University Faculty of Medicine, Denizli, Turkey Background: The rise in community-acquired urinary tract infections (UTIs) with extended-spectrum β-lactamase (ESBL)-producing Escherichia coli strains raises the question of how to treat these infections effectively in pediatric outpatients. Amikacin has shown promising in vitro activity against ESBL-producing urinary isolates of E. coli; however, clinical data are limited. Objective: To investigate the clinical and microbiological outcomes of community-acquired lower UTIs caused by ESBL-producing E. coli treated with outpatient amikacin in children. Materials and methods: A retrospective cohort study was performed on pediatric patients aged ≥2 to 18 years treated as outpatients with intramuscular amikacin (given at a dose of 15 mg/kg/day once daily) for community-acquired lower UTIs caused by ESBL-producing E. coli, between January 2015 and December 2016. Results: A total of 53 pediatric patients (38 females) were enrolled in this study. The median age was 4.7 years (range 3–12 years). All E. coli isolates were susceptible to amikacin with minimum inhibitory concentrations of ≤4 mg/L. The median duration of amikacin treatment was 6 days (range 3–7 days). Favorable clinical and bacteriological responses were observed in 51 of 53 (96%) patients. Development of resistance during treatment with amikacin was seen in only 1 patient (2%), who failed to respond to amikacin treatment and developed acute pyelonephritis with bacteremia. Relapsed lower UTI after initial treatment response occurred in 1 patient (2%) 2 weeks after completion of amikacin treatment. All patients had normal serum creatinine values at baseline, and no significant nephrotoxicity or ototoxicity was observed in any of the patients. Conclusion: Our study suggests that once-daily intramuscular amikacin could be an alternative option for outpatient treatment of community-acquired lower UTIs caused by amikacin-susceptible ESBL-producing E. coli in pediatric patients with normal renal function, when there are no suitable oral antibiotics. Keywords: amikacin, children, community-acquired urinary tract infections, Escherichia coli, extended-spectrum β-lactamase, outpatient