Role of IS6110 uniplex PCR in the diagnosis of tuberculous meningitis: experience at a tertiary neurocentre.

SETTING

Tuberculous meningitis (TBM) is the commonest form of neurotuberculosis in the Indian subcontinent. Rapid laboratory confirmation of TBM is important for the institution of early treatment and to avoid associated morbidity and mortality. The polymerase chain reaction (PCR) is the most widely applied alternative rapid diagnostic technique for TBM.

OBJECTIVE

To evaluate the efficacy of an in-house developed IS6110 uniplex PCR (uPCR) in the diagnosis of TBM.

DESIGN

A prospective, blinded study was conducted in a large sample base of 677 cerebrospinal fluid samples from 677 patients with clinically suspected TBM.

RESULTS

All culture-positive samples (n = 136) were positive (100%) by the PCR assay. The assay was found to be positive in 70% (n = 541) of the samples with a clinical diagnosis of TBM. The assay had an observed sensitivity of 76.37% (negative predictive value 59.90%) and a specificity of 89.18% (positive predictive value 94.69%). A diagnostic accuracy of 80% (kappa 0.57) was seen in patients with a clinical diagnosis of TBM. Statistical significance was observed, as patients with a clinical diagnosis of TBM were found to be 9.38 times more likely to be PCR-positive (OR 9.38, chi2 = 149.94, P < 0.001).

CONCLUSION

The performance of the in-house IS6110 uPCR assay merits its use as a sensitive and specific tool for the rapid diagnosis of TBM.