Table 1.
Results of Xpert MTB/RIF according to the source and MTBC culture of the samples
| Clinical specimen | No. of specimens witha: |
Total no. of specimens | Sensitivity | Specificity | ||||
|---|---|---|---|---|---|---|---|---|
| Positive MTBC culture |
Negative MTBC culture |
|||||||
| GX+ | GX− | GX+ | GX− | GX IND | ||||
| Sterile fluids | ||||||||
| Pleural fluid | 7 | 19 | 0 | 5 | 0 | 31 | 40.5% | 100% |
| Cerebrospinal fluid | 2 | 0 | 0 | 12 | 0 | 14 | ||
| Joint fluid | 5 | 2 | 0 | 0 | 0 | 7 | ||
| Ascitic fluid | 0 | 1 | 0 | 2 | 0 | 3 | ||
| Pericardial fluid | 1 | 0 | 0 | 2 | 0 | 3 | ||
| Nonsterile fluids | ||||||||
| Gastric aspirate | 2 | 1 | 0 | 3 | 2b | 8 | 66.7% | 100% |
| Urine | 2 | 1 | 0 | 1 | 0 | 4 | ||
| Lymph nodes | 24 | 10 | 0 | 4 | 0 | 38 | 70.6% | 100% |
| Abscess aspirates | ||||||||
| Knee abscess | 1 | 0 | 0 | 0 | 0 | 1 | 76.5% | 100% |
| Cervical abscess | 3 | 2 | 0 | 1 | 0 | 6 | ||
| Skin abscess | 3 | 1 | 0 | 0 | 0 | 4 | ||
| Osteitis pus | 4 | 1 | 0 | 0 | 0 | 5 | ||
| Empyema | 2 | 0 | 0 | 1 | 0 | 3 | ||
| Tissues | ||||||||
| Pelvic biopsy | 0 | 0 | 0 | 1 | 0 | 1 | 41.7% | 100% |
| Testicular biopsy | 1 | 0 | 0 | 0 | 0 | 1 | ||
| Colon biopsy | 0 | 0 | 0 | 2 | 0 | 2 | ||
| Vertebral disc biopsy | 0 | 0 | 0 | 1 | 0 | 1 | ||
| Spondylodiscitis puncture | 0 | 0 | 0 | 1 | 0 | 1 | ||
| Pericardial biopsy | 0 | 0 | 0 | 1 | 0 | 1 | ||
| Bone biopsy | 1 | 2 | 0 | 0 | 0 | 3 | ||
| Bone marrow biopsy | 0 | 0 | 0 | 1 | 0 | 1 | ||
| Synovial biopsy | 0 | 2 | 0 | 0 | 0 | 2 | ||
| Mediastinal tissue | 0 | 1 | 0 | 0 | 0 | 1 | ||
| Skin biopsy | 1 | 1 | 0 | 1 | 0 | 3 | ||
| Larynx biopsy | 0 | 1 | 0 | 0 | 0 | 1 | ||
| Costal cartilage biopsy | 2 | 0 | 0 | 0 | 0 | 2 | ||
| Stool | 2 | 0 | 0 | 0 | 0 | 2 | 100% | 100% |
| Total | 63 | 45 | 0 | 39 | 2 | 149 | 58.3% | 100% |
a
MTBC, Mycobacterium tuberculosis complex; GX, Xpert MTB/RIF; GX IND, Xpert MTB/RIF indeterminate result.
b
The two invalid GX results were not included in the calculation of the specificity.