Urinalysis predictive of urine culture results.

Abstract

BACKGROUND: Most clinicians treat patients for presumptive urinary tract infections based on urinalysis findings. Which of these findings is the best predictor of infection? METHODS: A retrospective cross-sectional study of 202 serial subjects of all ages was conducted over 8 months in a typical family medicine setting. Urinalysis and culture were performed concurrently. RESULTS: The best predictors for significant bacteriuria (defined as a culture with more than 50,000 colony-forming units) were > or = 2+ bacteriuria (sensitivity, 0.74; specificity, 0.80), or > or = 10 white blood cells per high-power field (sensitivity, 0.816; specificity, 0.651), or a positive nitrite test (sensitivity, 0.395; specificity, 0.929). The optimal combination of any two of the three predictor variables also was determined. CONCLUSIONS: Standard urinalysis results can be highly predictive of infection in typical family practice patients.