Evaluation of Novel Chip Based Test - Truenat with Traditional Genexpert for Detection of Tubercular Meningitis

Background: TRUENAT is a novel chip based test developed in India. Its use for pulmonary samples has been approved by World Health Organisation. Government of India has recently approved it for Extrapulmonary cases. Aim: To study the role of TRUENAT in diagnosis of Tubercular Meningitis(TBM) and the co-relation between TRUENAT and GeneXpert. Study Design: Prospective study. Subjects and Methods: 75 Children and adolescents with strongly suggestive TBM as per NTEP guidelines [1] were enrolled. Clinical, Radiological and Cerebrospinal fluid(CSF) analysis were carried out. CSF was tested by TRUENAT and GeneXpert. Results: TRUENAT detected 13/75 cases in comparison to GeneXpert which detected 16/75 cases. Out of these, in only 4 samples MTB was detected by both these tests. Concordance between the two tests was 72%. Cohen kappa (k-0.105) analysis showed slight agreement between the two tests. Higher CSF count(>10cell) was associated with higher chances of positivity in GeneXpert as well as TRUENAT. Conclusion: TBM diagnosis requires a combination of clinical, radiological and biochemical parameters. Molecular tests alone cannot detect bacilli in many cases. A single molecular test which targets additional genes could provide higher detection.