Table 3.
Cumulative sensitivity (incremental yield) of serial sputum specimens from patients with culture confirmed pulmonary TB.
| Specimen | N | Smear microscopy | MGIT culture | MODS culture | MODS + MGIT culture | Xpert MTB/RIF | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Test + (%) | Cum. yield* | Test + (%) | Cum. yield* | Test + (%) | Cum. yield* | Test + (%) | Cum. yield* | Test + (%) | Cum. yield* | ||
| 1st specimen | 51 | 13 (25%) | 25% | 40 (78%) | 78% | 33 (65%) | 65% | 43 (84%) | 84% | 33 (65%) | 65% |
| 2nd specimen | 32 | 10 (31%) | 33% | 22 (69%) | 82% | 15 (68%) | 73% | 24 (75%) | 90% | 18 (56%) | 69% |
| 3rd specimen | 23 | 7 (30%) | 33% | 14 (61%) | 84% | 13 (57%) | 75% | 15 (65%) | 92% | 13 (57%) | 71% |
*Cum. yield = cumulative sensitivity of serial sputum specimens. In 4 (8%) cases of culture-confirmed pulmonary TB, culture confirmation was obtained from a subsequent specimen (n = 1) or from a specimen excluded from the analysis because MODS culture was not performed (n = 3).