Table I.
Tests used for detection of Mycobacterium tuberculosis (MTB) in cerebrospinal fluid and identifying drug resistance
| Phenotypic tests |
| Smear microscopy |
| Ziehl-Neelsen stains |
| AFB auramine O or auramine-rhodamine stains fluorescence microscopy |
| Culture |
| Solid culture L-J medium |
| Liquid culture system like Mycobacteria Growth Indicator Tube (BACTEC™ MGIT 960™ TB System) |
| (The liquid culture systems are more rapid than conventional solid culture system) |
| Genotypic tests |
| IS6110 PCR12 |
| IS6110 is highly conserved part of M. tuberculosis complex genome and is specific for MTB complex |
| Simple PCR |
| Real-time PCR |
| Multiplex PCR |
| Multitargeted (LAMP)13,14 |
| GeneXpert MTB/RIF assay15,16 |
| Cartridge-based technology that simultaneously detects MTB complex and RIF resistance |
| GeneXpert Ultra (Ultra)17,18 |
| Xpert MTB/RIF Ultra is a new technology for faster detection of MTB complex and RIF resistance |
| Molecular line probe assays19 |
| Line probe assays are strip-based technology meant for rapid detection of MTB complex and RIF and INH resistance |
| Commercial line probe assay system |
| INNO-LiPA RIF TB (Innogenetics, Ghent Belgium) |
| The GenoType MTBDR (Hain Life Sciences, Gmbh, Nehren Germany) |
| Other tests |
| The IGRAs20,21 |
| IGRAs are not recommended for diagnosis of tuberculous meningitis |
| Commercial IGRAs |
| An ELISPOT evaluates the release of IFN-γ from T lymphocytes following stimulation of the cells with MTB-specific antigens |
| QuantiFERON® TB Gold test (Cellestis Ltd., Carnegie, Victoria, Australia) and the T-SPOT® TB IGRAs (Oxford Immunotec, Oxford, United Kingdom) are other commercially available IGRAs |
| LAM lateral flow assay22 |
| This test has a very low sensitivity in the CSF |
L-J, Löwenstein-Jensen; PCR, polymerase chain reaction; LAMP, loop-mediated isothermal amplification; IGRAs, interferon-gamma release assays; ELISPOT, enzyme-linked immunospot test; IFN-γ, interferon-γ; LAM, lipoarabinomannan; CSF, cerebrospinal fluid; RIF, rifampicin; INH, Isoniazid; MTBDR, Mycobacterium tuberculosis drug-resistant; AFB, acid-fast bacilli