Use of Roche AMPLICOR Mycobacterium tuberculosis PCR in early diagnosis of tuberculous meningitis

Several nucleic acid-based amplification tests are available for the detection of Mycobacterium tuberculosis, but few data are available on their use in the diagnosis of tuberculous meningitis (TBM). We performed a prospective study to assess the Roche AMPLICOR Mycobacterium tuberculosis PCR test (TB AMPLICOR) for use in the diagnosis of TBM and compared it with direct Ziehl-Neelsen staining of smears, radiometric culture for M. tuberculosis, and clinical and cerebrospinal fluid (CSF) findings. Eighty-three CSF specimens collected from 69 patients with suspected meningitis in South Africa were tested by TB AMPLICOR. On the basis of clinical and laboratory findings, 40 of these patients were treated for TBM and 29 patients were not treated for TBM. Ten CSF samples from 10 patients were positive by TB AMPLICOR. Seven of these 10 patients were classified as having definite TBM, 2 were classified as having probable TBM, and 1 was classified as having possible TBM. The sensitivity of TB AMPLICOR for detecting cases of definite and probable TBM in patients from whom CSF specimens had been collected less than 10 days into antituberculosis treatment was 60.0%. Specimens from all 29 patients not treated for TBM were negative by the TB AMPLICOR, giving a 100% specificity, TB AMPLICOR is therefore more sensitive than the combination of Ziehl-Neelsen staining of smears and radiometric culture for M. tuberculosis and is a rapid and highly specific diagnostic test for TBM.