Improved Diagnosis of Tuberculous Meningitis Using a Combination of Multiplex Antigens and Antibodies Testing Methods

Abstract

Introduction: Various serological assays exists, including Antigen and Antibody detection (IgM and IgG) for diagnosis of Tuberculous Meningitis (TBM) cases. To the best of our knowledge, most of the laboratories either do Antigen detection or IgM or IgG, at a time. As different antigens get expressed in a different stage of infection it may be possible that many cases remain undiagnosed due to one test at a time approach. Aim: To evaluate the combination of Mycobacterium Tuberculosis (MTB) antigen (Ag85 Complex and Rv2623) and antibody (Anti-Ag85, Anti-45kD, Anti-HSP-16, Anti-CFP-10 Anti-GroES and Anti-ESAT-6) immunoassay panels in the Cerebrospinal Fluid (CSF) samples for diagnosis of TBM patient. Materials and Methods: In the present prospective study conducted at Central India Institute of Medical Sciences (CIIMS) from October 2013 to April 2015, a total of 200 CSF samples of different groups {confirmed TBM (n=100) and noninfectious neurological diseases as control (n=100)} were analysed by Enzyme-Linked Immunosorbent Assay (ELISA). A panel of MTB antigens consisting of Ag85B, 45kDa, HSP-16, CFP-10, GroES and ESAT-6 were used for detection of antibodies response, whereas polyclonal antibodies were used for antigen detection of Ag85 complex and Rv2623 in the CSF samples. The comparison of the CSF parameter between TBM and non-TBM patients was performed using a student t-test. A p-value <0.05 was considered statistically significant for all the analyses. Results: The study population has similar age and sex distribution (p>0.05). Symptoms of headache, fever, neck stiffness, vomiting, abnormal behaviour, unconsciousness were more common among the TBM patients as compared to non-TBM patients (p<0.05) (TBM Vs non-TBM). Similarly TBM patients had an increase (p<0.05) Vs non-TBM total cell count, protein, parallel blood sugar and decline in CSF sugar and Parallel blood sugar ratio (p<0.05) (TBM Vs non-TBM). We found diagnostic accuracy of 67% to 76% with either antigen or antibody assay, however, combinations of antigen and antibody immunoassay together increase the diagnostic accuracy of up to 96%. Conclusion: Our study recommends that a combination of antigen and antibody assay should be considered for early and accurate diagnosis of TBM cases.