Multitargeted loop-mediated isothermal amplification for rapid diagnosis of tuberculous meningitis.

ABSTRACT

SETTING: Rapid and accurate diagnosis of tuberculous meningitis (TBM) is imperative for the optimal management of patients. Loop-mediated isothermal amplification (LAMP) is a promising nucleic-acid amplification assay, especially for resource-poor, endemic countries. OBJECTIVE: Evaluating LAMP assay using insertion sequence (IS) 6110 and MPB64 targets for the Mycobacterium tuberculosis complex (MTC) for the rapid diagnosis of TBM. Results were compared with culture and the composite reference standard. DESIGN: The LAMP assay was performed using six MTC-specific primers each for IS6110 and MPB64 on the cerebrospinal fluid of 150 TBM patients (50 confirmed, 100 suspected) and 100 non-TBM control subjects. RESULTS: Multitargeted LAMP had a sensitivity and specificity of 96% and 100% for confirmed (50 culture-positive) TBM cases. The sensitivity of IS6110 polymerase chain reaction (PCR), IS6110 LAMP and MPB64 LAMP for probable cases was respectively 70 (70%), 78 (78%) and 82 (82%). In a total of 150 TBM patients, the overall sensitivity of microscopy, IS6110 PCR, IS6110 LAMP, MPB64 LAMP and the multitargeted LAMP was respectively 4%, 74.6%, 82.7%, 86.7% and 88%. The specificity for all was 100%. Six cases were missed by IS6110 LAMP and two cases by MPB64 LAMP. CONCLUSION: The LAMP assay using two targets is a promising and accurate technique for the rapid diagnosis of TBM.