URINALYSIS PREDICTIVE OF URINE CULTURE RESULTS

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 greater than or equal to 2+ bacteriuria (sensitivity, 0.74; specificity, 0.80), or greater than or equal to 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.