Application of bioluminescent urine screens in a tertiary care facility

Two adenosine triphosphate (ATP)-detection systems for quantitating bacteriuria, the LUMAC (noncentrifugation method) and MONOLIGHT (centrifugation method) urine screens, were separately evaluated for their capacity to detect bacteriuria in specimens from patients at a tertiary care teaching hospital. Results of each study were compared with the findings of conventional culture. Indices of test efficacy, sensitivity/predictive value for a negative test, were as follows: at greater than or equal to 10(4) CFU/ml--LUMAC 88%/93% and MONOLIGHT 82%/88%; and at greater than or equal to 10(5) CFU/ml--LUMAC 99%/99% and MONOLIGHT 97%/99%. Both systems were satisfactory urine screens for catheterized and midstream urine specimens when used at the traditional level of significance (greater than or equal to 10(5) CFU/ml). An assessment of the MONOLIGHT noncentrifugation protocol demonstrated efficacy of the system to detect significant bacteriuria at greater than or equal to 10(5) CFU/ml. Decreased numbers of false-positive results compared to the centrifugation method were obtained with this assay. False-positive and false-negative results were attributable to threshold sensitivity of the instruments. The presence of somatic cells and yeasts were associated with false-positive results. False-positive results might stem from the inability of conventional culture to recover selected microorganisms. Time and cost analyses of the LUMAC system indicated that significant savings over conventional methodology were not effected.