Polymerase chain reaction for the rapid diagnosis of tuberculous meningitis

Polymerase chain reaction (PCR) based on the amplification of a 169 bp DNA fragment specific for the Mycobacterium tuberculosis complex was evaluated for the rapid diagnosis of tuberculous meningitis (TBM). A total of 105 CSF specimens from clinically suspected cases of TBM were studied. Clinical details of the cases and cytochemical parameters of the CSF specimens were recorded. For PCR 10 CSF specimens from cases other than TBM, 4 non-mycobacterial culture isolates (one strain of E coli, one strain of proteus species and 2 strains of salmonella species) and one sample of sterile distilled water were processed as negative controls. For positive control standard culture of Mycobacterium tuberculosis H37Rv was processed with every batch of specimens. Besides PCR, smear for AFB by the Ziehl-Neelsen (ZN) and the fluorochrome method and culture on Lowenstein-Jensen medium was also carried out. By PCR, 31.42% specimens were found positive, whereas by conventional culture on Lowenstein-Jensen medium only 3.8% specimens were positive.