Role of pcr as a diagnostic screening procedure for tuberculous meningitis in pediatric population

Introduction: Diagnosis of tuberculous meningitis in children is generally based on clinical symptoms, CSF findings, CT scans and response to anti tubercular drugs since conventional methods like microscopy and culture are unsatisfactory. Therefore the present study was undertaken to evaluate the efficacy of polymerase chain reaction for diagnosis of tuberculous meningitis in children. Materials and Methods: The CSF samples referred to the pathology laboratory of a tertiary care center from children >6 months of age and with a high index of clinical suspicion of tuberculous meningitis were considered as cases and those with non tuberculous meningitis as controls. CSF examination was done in both the groups including gross appearance, lymphocytic count, protein, sugar, AFB staining and PCR for M. tuberculosis using IS6110 as the target gene. Results: A total of 126 CSF samples from pediatric patients were included in the study of which 77 were cases and 49 were controls. Presence of cobweb and predominant lymphocytosis were significantly higher in the tuberculous meningitis group than the control group. AFB and TB PCR were positive in 7 (9.1%) and 18 (23.4%) cases respectively and in none and one controls respectively (p value= 0.04 for AFB positivity and 0.0007 for TB PCR positivity). TB PCR (23.4%) was 2.5 times more sensitive than AFB stain (9.1%) for diagnosing M. tuberculosis. Conclusions: Though PCR is a good tool for confirming tuberculous meningitis in children, better gene targets should be looked for, to make it an ideal screening test.