Simplified microscopy for rapid detection of significant bacteriuria in random urine specimens

Abstract

Simplified urine microscopy, nitrite testing, and dipstick culture were compared with urine loop streak culture colony counts in 219 random voided specimens to determine the accuracy of the three rapid screening techniques. Nitrite testing resulted in 65% false negative results, which could not be significantly improved by incubation at 37 degrees C but which could be improved by adding nitrate substrate before incubation. Dipstick culture could not be quantitated until after 18 h of incubation. A new, simplified microscopy technique, using unspun, unstained urine, resulted in 4% false negative results and 4% false positive results in specimens containing over 10(5) organisms per ml and was the best method Centrifuges, Gram staining reagents, and counting chambers are not necessary for accurate microscopic screening of random urine specimens for the presence of bacteriuria by this technique, and the results are immediately available.