Table 2 Sensitivity (SENS), specificity (SPEC), positive and negative predictive values (PPV and NPV), and numbers of false negative (FN) and false positive results (FP) when test strips or flow cytometry was used to separate relevant bacteriuria from bacteriuria, contamination or no culture growth of all samples using different cut-off values. Test performances for different definitions of relevant bacteriuria (≥ 105, ≥ 104 and ≥ 103, respectively) are listed. Pos.: positive test strip result
Bacterial growth (CFU/ml) | Method | Test Cut-off | SENS (%) | SPEC (%) | PPV (%) | NPV (%) | FN | FP | |
|---|---|---|---|---|---|---|---|---|---|
≥ 105 | Test strip | Nitrate | pos. | 35.8 | 97.9 | 84.9 | 82.0 | 7662 | 758 |
Leuk. esterase | pos. | 81.5 | 68.1 | 46.1 | 91.7 | 2211 | 11,372 | ||
Flow cytometry | Leukocyte count | 10 | 91.8 | 46.2 | 36.3 | 94.4 | 981 | 19,190 | |
50 | 75.9 | 74.7 | 50.1 | 90.2 | 2876 | 9028 | |||
Bacteria count | 50 | 95.8 | 67.8 | 49.9 | 98.0 | 497 | 11,471 | ||
250 | 87.2 | 85.6 | 66.9 | 95.2 | 1528 | 5137 | |||
≥ 104 | Test strip | Nitrate | pos. | 28.4 | 98.1 | 87.8 | 73.8 | 11,129 | 613 |
Leuk. esterase | pos. | 75.0 | 70.5 | 55.2 | 85.3 | 3892 | 9441 | ||
Flow cytometry | Leukocyte count | 10 | 87.2 | 48.2 | 45.0 | 88.6 | 1986 | 16,583 | |
50 | 68.8 | 76.9 | 59.2 | 83.6 | 4844 | 7384 | |||
Bacteria count | 50 | 86.3 | 70.4 | 58.6 | 91.4 | 2122 | 9484 | ||
250 | 72.4 | 86.6 | 72.4 | 86.6 | 4295 | 4292 | |||
≥ 103 | Test strip | Nitrate | pos. | 27.2 | 98.1 | 88.2 | 72.2 | 11,836 | 592 |
Leuk. esterase | pos. | 74.1 | 71.1 | 57.2 | 84.1 | 4213 | 9034 | ||
Flow cytometry | Leukocyte count | 10 | 86.8 | 48.8 | 46.8 | 87.7 | 2149 | 16,018 | |
50 | 68.1 | 77.6 | 61.2 | 82.4 | 5197 | 7009 | |||
Bacteria count | 50 | 83.8 | 70.4 | 59.6 | 89.3 | 2628 | 9262 | ||
250 | 69.6 | 86.5 | 72.9 | 84.6 | 4949 | 4218 | |||