Objectives: To evaluate the prevalence of resistance of the various urinary tract infection (UTI) pathogens obtained from patients in an urban pediatric emergency department (PED), and to identify risk factors for infection with resistant strains.
Methods: The data were collected retrospectively in an urban, academic PED in northeastern Florida. The microbiology-computerized database was used to identify all positive urine cultures from October 1999 through June 2000. All patients aged 17 years or less, whose urine specimen was collected in the ED and grew cultures with greater than 10,000 colony forming units (CFU) per milliliter of a single organism on Maconkey or blood agar, were included. The medical records of the patients were reviewed and selective demographic and clinical data were collected. Patients were excluded if their charts were unavailable for review or if the pathogen that grew in culture was a suspected contaminant. All patients lacking clinical symptoms of UTI (frequency, dysuria, abdominal pain, fever, or urgency) and whose urine was collected by clean-catch were excluded if their culture grew between 10,000 and 100,000 CFU. Resistance to trimethoprim-sulfamethoxazole (T-S) was estimated for the subset of gram-negative pathogens. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to compare rates of resistance among patients with and without the following risk factors: age greater than 4 years; current or recent antibiotic use; day care attendance; and previous UTI.
Results: A total of 126 urine cultures were identified for inclusion. Of these, 45 patients were excluded, leaving 81 who met the study criteria. The majority of isolated organisms were Escherichia coli, accounting for 89% of the patients (n = 72). Other organisms identified were Klebsiella 3.7%, Proteus 1.2%, Citrobacter 1.2%, Staphylococcus 1.2%, and Enterococcus 3.7% (all in children < 4 years old). The resistance to T-S was 6.5% (95% CI = 0.9% to 12.1%) for gram-negative pathogens. Overall, 48% of gram-negative isolates were resistant to one or more antibiotics, any resistance (95% CI = 36.5% to 59.5%). T-S resistance was nominally higher for older children and for those with a history of antibiotic use, although not to a significant degree. Children less than age 4 were more likely to have any resistance (OR 2.6; 95% CI = 1.0 to 6.7).
Conclusions: The resistance to T-S in this study was 6.7% for gram-negative pathogens. These rates are lower than rates reported in adult populations, international pediatric studies, and the authors' hospital antibiograms, demonstrating the importance of local, population-specific data in selecting antibiotics. This study did not identify any statistically significant risk factors for resistance to T-S, but suggests that those with a recent history of antibiotic use may be at highest risk. While children less than 4 years old with gram-negative pathogens have nominally lower rates of T-S resistance, they are at higher risk for resistance to one or more antibiotics (any resistance) and are at risk for UTI caused by enterococcus (uniformly nonsusceptible to T-S). Prospective studies are needed to validate these results and to identify predisposing factors for urinary pathogens with antibiotic resistance.