EVALUATION OF POLYMERASE CHAIN-REACTION FOR RAPID DIAGNOSIS OF CLINICALLY SUSPECTED TUBERCULOUS MENINGITIS

Setting: Since conventional bacteriological methods rarely detect Myco bacterium tuberculosis in cerebrospinal fluid (CSF) and are of limited use in the diagnosis of tuberculous meningitis (TBM), clinical featur es suggestive of TBM supported by indirect evidence such as CSF examin ation and computerized tomography (CT) of the head have been used for the early diagnosis of TBM. Objective: We evaluated the efficacy of po lymerase chain reaction (PCR) in the diagnosis of TBM. Methods: Coded CSF samples from 40 patients with TBM and from 49 patients with other neurological disorders were processed. In the absence of a reliable se nsitive and specific test for M. tuberculosis in CSF, we used a set of established clinical criteria as the gold standard. Accordingly, the patients were divided into definite, highly probable, probable and pos sible TBM. The samples were decoded only after completion of the labor atory tests. Results: PCR was positive in 2/4, 19/20, 13/16 patients w ith highly probable, probable and possible TBM respectively. None of t he samples were positive by conventional bacteriological methods. Howe ver, 3/49 CSF samples from non-TBM patients were also found positive b y PCR. PCR detected M tuberculosis genomic DNA in the CSF of 85% of cl inically suspected TBM cases and 6.1% of non-tuberculous controls. Con clusion: PCR, along with the suggested clinical criteria, offers a rap id and fairly accurate diagnosis of TBM.