The Presence of Urinary Nitrites Is a Significant Predictor of Pediatric Urinary Tract Infection Susceptibility to First- and Third-Generation Cephalosporins

Background: Previous studies in adults have refuted the use of nitrites as a predictor of bacterial resistance to both trimethoprim-sulfamethoxazole and cephalosporins. Some centers now consider first-line outpatient therapy with an oral third-generation cephalosporin appropriate 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 complications 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 compare nitrite-negative vs. nitrite-positive UTIs for resistance to third-generation cephalosporins and other empiric antimicrobials. 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 cephalosporins, 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 nitrites is a significant indicator for potential resistance to cephalosporins in pediatric UTIs. Due to low levels of pediatric UTI resistance, cephalosporins continue to represent useful empiric therapy in the general pediatric population. However, in high-risk patients, physicians may opt to alter their empiric choice of antibiotic based on the presence of urinary nitrites.