426-430 RK Singh-

The present study includes 50 patients symptomatic for tuberculous meningitis and 15 patients with meningitis other than tuberculosis The CSF specimens were subjected for ADA titer estimation, AFB smear preparation and molecular characterization by Nested-PCR for IS6110 gene. Out of 50 specimens 2 came AFB smear positive whereas 29 specimens came positive for Tuberculosis (TB) PCR and 21were negative for TB PCR. 17 specimens came positive by both the targets IS6110 and mpb-64 gene but 9 specimens came positive only by IS6110 gene, but negative for mpb64 gene. 3 specimens came positive for mpb-64 gene and the same were negative for IS6110 gene. 29 specimens came positive for Multiplex PCR. ADA activity >10 (U/L) was found in 33 specimens. The positive signals obtained in these CSF specimens were higher with IS6110 system 26/50 (52%) than with mpb-64 system 20/50 (40%). PCR gave a sensitivity of (58%) and specificity of (93.3%), Positive predictive value of (96.6%) and Negative predictive value of (40%) for the diagnosis of TBM in 50 patients who were strongly suspected for Tuberculosis meningitis. ADA activity in the CSF had limited value when using a cut-off value of 10 U/L for the diagnosis of tuberculous meningitis. In actual clinical practice, the diagnosis of CNS tuberculosis requires not a screening examination but rather a definitive molecular procedure like IS6110 and mpb-64 gene characterization for accurate and confirm diagnosis of tubercular meningitis.