Rapid detection of insignificant bacteriuria by concomitant use of Lumac system and Gram's stain

The Lumac system, which assays bacterial ATP by bioluminescence, is a rapid method (less than 1 hour) for detection of bacteriuria. Conventional culture by calibrated loop technic and the Lumac system were compared using 2,000 urine specimens. Interpretation of Gram's stains of uncentrifuged specimens in addition to results of the Lumac system provided a second comparison with culture. Using a criterion of greater than or equal to 10(4) CFU/mL, conventional culture yielded 17% of the 2,000 specimens positive for bacteriuria. By Lumac + smear 27% were positive opposed to 41% positive by the Lumac system alone. The Lumac + smear method produced sensitivity (97%), specificity (88%), positive predictive value (62%), and negative predictive value (99.3%). False negative rates by the Lumac alone and Lumac + smear were 0.65% and 0.5%, respectively.