doi:10.1016/j.jemermed.2008.01.010 Original Contributions THE PRESENCE OF URINARY NITRITES IS A SIGNIFICANT PREDICTOR OF PEDIATRIC URINARY TRACT INFECTION SUSCEPTIBILITY TO FIRST- AND THIRD-GENERATION CEPHALOSPORINS Dany Weisz, MD, Jamie A. Seabrook, MA, and Rodrick K. Lim, BSC, MD Department of Paediatrics, Children’s Hospital of Western Ontario, London Health Sciences Centre, London, Ontario, Canada Reprint Address: Rodrick Lim, BSc, MD, Department of Paediatrics, Schulich School of Medicine & Dentistry, Children’s Hospital of Western Ontario, 800 Commissioners Rd. E, London, ON N6C 4V5 e Abstract—Background: Previous studies in adults have refuted the use of nitrites as a predictor of bacterial resis- tance to both trimethoprim-sulfamethoxazole and cephalo- sporins. Some centers now consider first-line outpatient therapy with an oral third-generation cephalosporin appro- priate for young children. Objective: The objective of this study was to determine if nitrite-negative pediatric urinary tract infections (UTIs) were more likely than nitrite-positive UTIs to be resistant to cephalosporins. This may enable physicians to adjust antimicrobial therapy before patients leave the Emergency Department (ED) to avoid the com- plications of ineffectively treated pediatric UTIs. Methods: A retrospective chart review examined, over a 9-month period, 173 pediatric patients who were diagnosed with a clinical UTI in the ED and who also had a positive urine culture and a recorded dipstick at the time of visit. The chi-squared test and Fisher’s exact test were used to com- pare nitrite-negative vs. nitrite-positive UTIs for resistance to third-generation cephalosporins and other empiric anti- microbials. Results: For third-generation cephalosporins, 1.4% of nitrite-positive UTIs were resistant, whereas 14.4% of nitrite-negative UTIs were resistant (95% confidence interval [CI] 0.22 to 0.05). For first-generation cepha- losporins, 8.4% were resistant in the nitrite-positive group, compared to 22.2% in the nitrite-negative group (95% CI 0.24 to 0.03). Conclusion: The absence of urinary ni- trites is a significant indicator for potential resistance to cephalosporins in pediatric UTIs. Due to low levels of pe- diatric UTI resistance, cephalosporins continue to repre- sent useful empiric therapy in the general pediatric popu- lation. However, in high-risk patients, physicians may opt to alter their empiric choice of antibiotic based on the presence of urinary nitrites. © 2010 Elsevier Inc. e Keywords— urinary tract infection; pediatrics; urinary nitrites INTRODUCTION Background Urinary tract infections (UTIs) are among the most com- mon pediatric bacterial infections diagnosed in Emergency Departments (ED). Diagnosing UTIs in children is espe- cially important due to the risk of renal scarring and renal insufficiency in some patients. Common empi- ric antimicrobial therapies for pediatric UTIs include trimethoprim-sulfamethoxazole (TMP-SMX), cephalo- sporins, and amoxicillin. However, due to increasing resistance rates, the choice of antibiotics is becoming more challenging (1). In a patient with a presumed UTI, a real-time indicator that identified a higher risk of re- sistance would aid a physician’s empiric choice of antimicrobials. Urine dipstick is a common and inexpensive test, and urine nitrites have a low sensitivity (53%, range 15– 82%) but high specificity (99%, range 90 –100%) for the diagnosis of UTI (2,3). Previous studies in adults have considered and refuted the use of nitrites as a predictor RECEIVED: 30 September 2007; FINAL SUBMISSION RECEIVED: 5 December 2007; ACCEPTED: 8 January 2008 The Journal of Emergency Medicine, Vol. 39, No. 1, pp. 6 –12, 2010 Copyright © 2010 Elsevier Inc. Printed in the USA. All rights reserved 0736-4679/$–see front matter 6