Table 1. Microbiological tests available for the diagnosis of intrathoracic tuberculosis in children.
| Principle | Limit of Detection (CFU/mL) | Delay to Positive Results (Negative If #) | Sensitivity in Children MRS (%) |
Sensitivity in Children CRS (%) |
WHO Recommendation | Type of Facility Where Usually Available in Resource-Limited Settings | |
|---|---|---|---|---|---|---|---|
| Smear microscopy | Microscopic detection of MTB following Zeilh Neelsen or Auramine staining | 1,000 to 10,000 | Minutes | 15–30 | 5–15 | To be replaced as the initial diagnostic test by WRDs | Primary health centre with microscopy capacity |
| Solid culture | Phenotypic | 10 to 100 | 3 to 4 weeks (8 weeks) | 82 | 20–40 | Monitoring of patient’s response to treatment. | National/regional level reference laboratory |
| Liquid culture | Phenotypic | <10 | 10 to 21 days (6 weeks) | 85 | 20–40 | Monitoring of patient’s response to treatment. | National/regional level reference laboratory |
| Xpert MTB/RIF ** | Molecular detection of MTB and RIF resistance (rpoB gene) using GeneXpert system | 131 112 |
2 h | 62–66 | 25–35 | Initial tests in children with signs and symptoms of pulmonary TB (strong recommendation) | Regional and district hospital * |
| Xpert MTB/RIF Ultra ** | Molecular detection of MTB and RIF resistance (rpoB gene + IS6110) using GeneXpert system | 38 15 |
90 min | 64–75 | 45 | Initial tests in children with signs and symptoms of pulmonary TB (strong recommendation) | Regional and district hospital * |
| TrueNAT ** | MTB and RIF resistance detection using chip-based Real-Time (RT) micro-PCR on automated system | 100 | <1 h | No data in children | No data in children | Initial tests in children with signs and symptoms of pulmonary TB (conditional recommendation) | District hospital laboratory |
| Loop-Mediated Isothermal Amplification (LAMP) | MTB detection using amplification at a fixed temperature (without thermocycler) and simple visual detection | 100 | 2 h | 84 (1 study) | No data | Recommended only in adult as initial test so far | District hospital laboratory |
| Alere LAM | Detection of mycobacterial cell-wall glycolipid lipoarabinomannan in urine by immunocapture | No data | 30 min | 43 to 50 (HIV+) | No data | HIV-positive children with presumptive TB or advanced HIV disease or who are seriously ill or irrespective of TB suggestive signs if they have CD4 count <200 cells/mm3 (inpatients) or CD4 < 100 cells/mm3 (outpatients) | Point-of-Care, no need of laboratory. |
| FUJILAM Silvamp | Detection of mycobacterial cell-wall glycolipid lipoarabinomannan in urine by immunocapture | No data | 60 min | 42 to 65 (any children); 60 (HIV) | No data | Under review | Point-of-Care, no need of laboratory. |