Table 3. Performance of Ziehl-Neelsen staining, culture, and polymerase chain reaction dot-blot assays, according to the history of anti-tuberculosis treatment, in human immunodeficiency virus-seronegative individuals.
| Laboratory results and performance of methods | ||||||
|---|---|---|---|---|---|---|
| All groups N=203 |
Non-treated TB group N=156 |
Past-TB group N=47 |
||||
| TB | Non-TB | TB | Non-TB | TB | Non-TB | |
| N=88 | N=115 | N=77 | N=79 | N=11 | N=36 | |
| ZN | ||||||
| Positive | 60 | 1 | 54 | 0 | 6 | 1 |
| Negative | 28 | 114 | 23 | 79 | 5 | 35 |
| SE | SP | SE | SP | SE | SP | |
| 68% | 99% | 70% | 100% | 54% | 97% | |
| LR+ | LR− | LR+ | LR− | LR+ | LR− | |
| 68 | 0.32 | 70 | 0.30 | 18 | 0.47 | |
| Culture | ||||||
| Positive | 75 | 0 | 67 | 0 | 8 | 0 |
| Negative | 13 | 115 | 10 | 79 | 3 | 36 |
| SE | SP | SE | SP | SE | SP | |
| 85% | 100% | 87% | 100% | 73% | 100% | |
| LR+ | LR− | LR+ | LR− | LR+ | LR− | |
| 85 | 0.15 | 87 | 0.13 | 73 | 0.27 | |
| PCR dot-blot | ||||||
| Positive | 66 | 17 | 60 | 11 | 6 | 6 |
| Negative | 22 | 98 | 17 | 68 | 5 | 30 |
| SE | SP | SE | SP | SE | SP | |
| 75% | 85% | 78% | 86% | 54% | 83% | |
| LR+ | LR− | LR+ | LR− | LR+ | LR− | |
| 5 | 0.29 | 5.8 | 0.25 | 3.17 | 0.55 | |
| Performance of methods used in parallel | ||||||
|---|---|---|---|---|---|---|
| ZN in parallel with | SE | SP | SE | SP | SE | SP |
| Culture | 95% | 99% | 96% | 99% | 91% | 99% |
| ZN in parallel with | SE | SP | SE | SP | SE | SP |
| PCR dot -blot | 92% | 84% | 93% | 85% | 85% | 82% |
SE, sensitivity; LR+, positive likelihood ratio; SP, specificity; LR−, negative likelihood ratio.