Original Article Causative pathogens and antibiotic resistance in children hospitalized for urinary tract infection Mesut Koçak, 1 Bahar Büyükkaragöz, 2 Asli Çelebi Tayfur, 2 Aysun Çaltik, 2 Adem Yasin Köksoy, 1 Zeynep Çizmeci 3 and Sacit Günbey 1 Departments of 1 Pediatrics, 2 Pediatric Nephrology and 3 Microbiology, Keçiören Training and Research Hospital, Ankara, Turkey Abstract Background: Urinary tract infections (UTI) are one of the most common bacterial infections in children and a major cause of hospitalization. In this study we investigated the clinical characteristics, causative uropathogens; their antibiotic suscep- tibility and resistance patterns, treatment modalities and efficacy in children hospitalized for UTI in a tertiary care setting. Methods: Patients hospitalized for an upper UTI between March 2009 and July 2014 were enrolled. The urine culture– antibiogram results and accompanying urinary tract abnormalities were recorded retrospectively. Results: A total of 142 patients (104 girls, 73.2%; 38 boys, 26.8%) were enrolled. Mean patient age was 32.6 ± 4.1 months. History of recurrent UTI was present in 45.8% (n = 65), with prior hospitalization in 12.0% (n = 17). Frequency of vesicoureteral reflux was 18.3% (n = 26). Gram-negative enteric microorganisms yielded growth in all culture-positive UTI and the most common microorganism was Escherichia coli (n = 114, 80.3%). Extended spectrum beta-lactamase- producing (ESBL (+)) bacterial strains were detected in 49.3% (n = 70), with third-generation cephalosporin resistance in all and increased duration of hospitalization. Conclusions: The prevalence of UTI with ESBL (+) bacterial strains with multi-drug resistance is increasing in the hospi- talized pediatric population, therefore rational use of antibiotics is essential. Key words antibiotic resistance, children, extended spectrum beta-lactamase, hospitalization, urinary tract infection. Urinary tract infections (UTI) are one of the most common bacte- rial infections in children and a major cause of hospitalization. 1,2 Clinical presentation of UTI and the choice of therapy vary depend- ing upon the site of infection, patient age, features of toxemia, and presence of comorbid urinary tract anomalies (most commonly vesicoureteral reflux; VUR). 3–5 A systematic review found that renal parenchymal defects are identified in 3–15% of children within 1–2 years of their first di- agnosed UTI. For this reason prompt diagnosis and appropriate treatment for UTI are required to ensure optimal clinical outcome and prevention of long-term morbidity associated with renal scarring such as hypertension and chronic renal failure. 6,7 There is growing concern, however, about the antibiotic resistance of uropathogens due to improper and extensive use of antibiotics. Resistance to trimethoprim-sulfamethoxazole (TMP-SMX) and cephalosporins, which are primarily preferred in empiric treatment, is rapidly increasing. 8–12 It is also of concern that the prevalence of UTI with extended spectrum beta-lactamase-producing (ESBL (+)) enteric bacteria also has been increasing worldwide. 1,13 As a result, changes in the char- acteristics and causative pathogens of UTI and antibiotic susceptibility of pediatric uropathogens in hospital-treated children are continuously being reported. 2 Extended-spectrum beta lactamases are enzymes that mediate resistance to some of the beta-lactams, including penicillins and cephalosporins. 1 Data on clinical outcomes indicate that ESBL are clinically significant and an appropriate antibiotic regimen should be initiated promptly. Given that ceftriaxone, (a third-generation cephalosporin most preferred for treatment of pyelonephritis), is inactivated by ESBL (+) microorganisms, resulting in treatment failure, 14 the use of broader-spectrum antibiotics (such as carbapenems) becomes inevitable. Thus, the number of available drugs decrease, and the necessity of hospital stay increases. To date, there are a large number of studies evaluating the community-acquired etiologies of UTI and their treatment. Studies focusing on these parameters in hospitalized children, however, are still scarce. Herein, we investigated the clinical characteristics, causative uropathogens, antibiotic susceptibility and resistance patterns, treatment modalities and efficacy in hospitalized children with the diagnosis of UTI. Methods Patient selection Patients hospitalized for UTI between March 2009 and July 2014 in the Pediatric Clinics of Keçiören Research and Training Hospital were enrolled. Inclusion criteria for inpatient treatment consisted of Correspondence: Bahar Büyükkaragöz, MD, Department of Pediatric Nephrology, Keçiören Training and Research Hospital, Sanatoryum Cad. Ardahan Sok. No: 25, 06380, Ankara, Turkey. Email: karamanbahar@yahoo.com Received 19 May 2015; revised 31 August 2015; accepted 26 October 2015. © 2015 Japan Pediatric Society Pediatrics International (2016) 58, 467–471 doi: 10.1111/ped.12842