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Despite the availability of many investigational methods, diagnosis of Tuberculous meningitis (TBM) is extremely difficult. Polymerase chain reaction (PCR), using specific primers for Mycobacterium tuberculosis (MTB), shows variable sensitivity and specificity. In this study, we assessed the usefulness of the PCR assay for TBM diagnosis and compared it to our in-house enzyme-linked immunosorbent assay (ELISA) based on antigen 85 complex detection.Cerebrospinal fluid (CSF) samples were obtained from 189 patients in 3 different groups: confirmed TBM (n=13), clinically suspected TBM (n=37), and non-TBM (n=139). A PCR assay was performed using a specific pair of primers designed to amplify the insertion sequence IS6110 in the MTB genome, and it was compared to ELISA, using monoclonal antibodies against the purified Ag 85 complex, to analyze CSF samples and diagnose TBM.The PCR assay yielded sensitivity and specificity values of 80% and 84%, which are slightly less, but comfortable to the values obtained for the ELISA method (84% and 91%). Interestingly, a combinatorial approach using both methods provided sensitivity and specificity of 88% and 93%.The PCR assay was found to be as sensitive and specific as the well-established in-house ELISA technique, suggesting that it can be used for TBM diagnosis.

Diagnosing tuberculous meningitis (TBM) remains problematic despite many new advanced diagnostic methods. Adenosine deaminase (ADA) assays have emerged as novel alternatives to other costly and time-consuming methods for TBM diagnosis. In the present study the usefulness of the ADA method was assessed for the diagnosis of TBM and compared with an in-house developed ELISA method for detecting the antigen 85 (Ag 85) complex of M. tuberculosis in cerebrospinal fluid (CSF) samples of suspected and culture-confirmed TBM patients.ADA activity in CSF was determined at 37 degrees C according to the method of Guisti and Galanti. ELISA, employing monoclonal antibodies against the purified Ag 85 complex, was used to demonstrate Ag 85 complex in CSF from TBM patients. CSF samples were obtained from 153 patients in three different groups: confirmed TBM (n=27), clinically suspected TBM (n=39), and non-TBM (n=87).The ADA method yielded sensitivity and specificity of 83% and 86%, which are similar to those of the ELISA method (89% and 90%). The correlation between the Ag 85 complex activity in absorbance by ELISA and the ADA activity obtained in units per liter per minute (U/l/min) was also positive and significant. (Pearson's correlation coefficient r=0.3234, 95%CI: 0.1621-0.4679, p0.001).This study suggests that the ADA method can be performed for TBM diagnosis in low-income TB-affected regions where more sophisticated facilities are generally not available.

Tuberculous meningitis (TBM) is a serious central nervous system infection, which is seen in clinical practice fairly frequently in developing and underdeveloped countries. Our study was intended to develop a reliable and rapid diagnostic methodology for detecting mycobacterium tuberculous bacilli (MTB) in cerebrospinal fluid (CSF). Dot Enzyme Linked Immunosorbent assay (Dot ELISA) has been standardized to detect MTB antigens and antibodies against MTB in the CSF of TBM patients.CSF samples were collected from 156 registered patients suffering from various neurological disorders, including 56 cases of TBM. Polyclonal antibodies to Culture Filtrate Protein (CFP), H37Rv strain, an MTB antigen, obtained from Colorado State University (USA), were used to detect MTB antigen in the CSF of TBM patients using the Dot ELISA method.The methodology yielded a positive reaction to MTB antigens in 48 CSF samples (86%) obtained from all 56 cases of suspected TBM. The sensitivity achieved through the developed methodology could give reactivity with an antigen level 10ng/dl and above. Dot ELISA for MTB antigen was positive in only 5 out of 100 (5%) of the other neurological disorders, mainly pyogenic meningitis.This rapid methodology for the detection of MTB antigen in CSF is very simple, sensitive, specific, and cost effective. This technique can be easily and routinely employed in the pathology laboratory to support the clinical diagnosis.

Tuberculous meningitis (TBM) is still a serious cause of morbidity and mortality in developing nations, and the timing of treatment is the most crucial factor affecting the ultimate outcome. To establish a rapid diagnosis, we used Single Radial Immuno-Diffusion (SRID) to detect circulating mycobacterium antigen in the CSF of patients with clinically suspected TBM.Single radial immunodiffusion is the simplest of all immunotechniques for the quantitative determination of antigen or antibody. CSF was collected by standard lumbar puncture. Antiserum was raised against CSF from clinically suspected TBM patients by standard Immunization procedures.The developed protocol was tested with 73 CSF samples collected over a period of one year. The assay gave 94% sensitivity for the detection of mycobacterium antigen in the CSF of patients with clinically suspected TBM.This study suggests that single radial immunodiffusion is useful for quantitative as well as qualitative determination of mycobacterium antigen. The developed technique is of potential value in the laboratory diagnosis of TBM.