Correlation of GeneXpert and cerebrospinal fluid culture in patients of tubercular meningitis

Abstract

Background: Mycobacterium tuberculosis (MTB) remains one of the most common causes of mortality and morbidity in India. Therefore, an apart from an early diagnosis and detection of rifampin (RIF) resistance is also very essential for management. A novel integrated diagnostic device GeneXpert MTB/RIF assay has revolutionized the rapid diagnosis of tuberculosis and along with RIF resistance in patients. However, its use is not been explored in extrapulmonary specimens. Objective: We determined the performance of the GeneXpert MTB/RIF assay for rapid diagnosis of tuberculosis from cerebrospinal fluid (CSF) specimens obtained from possible tubercular meningitis (TBM) cases. Materials and Methods: A cross-sectional study was conducted where CSF sample of suspected TBM patients was evaluated for TB by GeneXpert and liquid culture (mycobacteria growth indicator tube) and compared. Results: Of 53 patients, who were included in the study period, 5 patients were culture positive and 48 were culture negative for M. tuberculosis. GeneXpert MTB/RIF test showed a sensitivity of 60% and specificity is 97.9% for diagnosing TBM, the negative predictive value was 95.9% and positive predictive value was 75%. Conclusion: GeneXpert MTB/RIF test is highly specific and can be used for diagnosis of TBM adjunct to clinical finding, biochemical and radiological features. Its role as sole diagnostic test needs to be studied in larger sample.