Determination of polymerase chain reaction efficiency for diagnosis of tuberculous meningitis in Chelex-100 extracted DNA samples.

Polymerase chain reaction (PCR) offers great promise for the rapid, sensitive and specific diagnosis of tuberculous meningitis (TBM). However, the isolation of DNA of high quantity and quality from cerebrospinal fluid (CSF) samples is critical for successful PCR assays. To develop and use a single-tube method for the isolation of PCR-compatible DNA from Mycobacterium tuberculosis using Chelex-100 chelating resin, which does not require organic solvents or detergents. The study focused on the standardisation of a suitable Chelex protocol and its evaluation in 32 CSF samples from TBM and non-TBM subjects. A simultaneous comparison was made with the conventional phenol/chloroform extraction method. PCR was found to be more sensitive, more rapid and less technically demanding with the Chelex protocol than the conventional phenol/chloroform extraction method (sensitivity 84.2% vs. 73.6%). The single-tube method and the simplicity of the procedure permits early and reliable diagnosis of TBM and makes it an attractive method for routine laboratory assays.