ANALYSES OF THE FLASHTRACK DNA PROBE AND UTISCREEN BIOLUMINESCENCE TESTS FOR BACTERIURIA

Five hundred urine specimens were selected at random and screened for bacteriuria by a DNA probe method, Flash Track (Gen-Probe, San Diego, Calif.), and an automated bioluminescence method, UTIscreen (Los Alamos Diagnostics, Los Alamos, N.M.), and the results were compared with those of the semiquantitative plate culture method. The performance of each test versus culturing was evaluated at colony counts of greater-than-or-equal-to 10(4), greater-than-or-equal-to 5 x 10(4), and greater-than-or-equal-to 10(5) CFU/ml. Since the interpretive breakpoint of each test was user selectable, the results were reported as receiver operator characteristic curves. Optimum interpretive breakpoints were determined for each test at each colony count by calculating a performance index that emphasized sensitivity over specificity in a 70:30 ratio. Although both tests had less-than-optimal sensitivities and specificities, the performance of Flash Track was significantly better than that of UTIscreen at two of the three colony counts (10(4) and 10(5) CFU/ml); however, Flash Track costs more and is a labor-intensive procedure. Neither method was evaluated for the detection of colony counts of < 10(4) CFU/ml.