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Indian Journal of Microbiology Research

Utility of ADA (Adenosine Deaminase) enzyme assay in diagnosis of tuberculous meningitis

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Author Details: Krupali Kothari, Madhulika A. Mistry, Y.S. Goswami

Volume : 4

Issue : 3

Online ISSN : 2394-5478

Print ISSN : 2394-546X

Article First Page : 320

Article End Page : 324


Introduction: Tuberculous meningitis (TBM) remains one of the leading causes of morbidity and mortality worldwide, including India. Treatment and prevention of TBM is depended on early and quality assured diagnosis. Earlier studies have showed that there is wide delay in diagnosing TBM. ADA is essential for proliferation and differentiation of lymphoid cells, especially T cells. ADA activity increases during activation of the cell, for energy demand to detoxify the toxic metabolites generated. This enzyme increases in TB patients because of delayed hypersensitivity reaction to mycobacterial antigen.
Objective: To evaluate the diagnostic utility of the ADA assay for the diagnosis of tuberculous meningitis and to compare ADA results with results of Ziehl Neelsen stain, routine biochemical tests and cytology.
Materials and Method: Total 86 Cerebrospinal fluid (17 cases of TBM and 69 cases of non-TBM) were studied for ADA levels, ZN stain, routine biochemical tests and cytological evaluation.
Results: Mean level of ADA in TBM is 11.81 U/L and in non-TBM 1.65 U/L. Comparison between different tests for TBM shows: ZN stain is having high specificity of 100% but its sensitivity is 5.88%. Sensitivity of cytological analysis is 88.83% and specificity is 26.87%. Specificity of sugar test is only 34%. Protein estimation is also very less specific, 61%. ADA test is having both sensitivity (64.70%) and specificity (97%) higher than other tests.
Conclusion: As an alternative to subjecting CSF of suspected tuberculous meningitis to various tests (cytology, protein and sugar estimation and ZN stain), subjecting sample for single test, ADA test(very easy, sensitive, specific, cheap and less time consuming: one and half hour) is better option with good results.