Cost Savings in Microbiology Urine Screening: An Alternative for Routine Culture

Providing cost-effective clinical laboratory tests has never been more important. To this end, we reviewed the recent literature dealing with screening methods for urine submitted for culture. Since 80% of the urine samples received in our microbiology section are negative (less than 100,000 organisms per milliliter), the introduction of a method that would eliminate the supplies and time involved in culturing and would have a high predictive value for negative results (low false-negative rate) would be cost-effective. Using leukocyte esterase and nitrite reagent dipstick, we tested 1,879 urine samples submitted for culture. Of these samples, 1,290 were true negative, 213 were true positive, 321 were false positive, and 55 were false negative. The predictive value of negative results in this study was 96%. We have concluded that this method is an acceptable alternative to routine culturing provided that the urine samples that are negative by this screening are kept refrigerated for 24 hours. This gives the physician the opportunity to request routine culture if still medically justified.