Abstract
BackgroundTuberculous meningitis (TBM) is the commonest form of neurotuberculosis caused by Mycobacterium tuberculosis bacilli (MTB). The diagnosis of TBM is often difficult. A reliable, cost-effective and rapid diagnostic test, which can be performed in any standard pathology laboratory, could be of help in the diagnosis of TBM. In the present study we measured the adenosine deaminase (ADA) activity in cerebrospinal fluid (CSF) of TBM and non-TBM patients.MethodADA activity in CSF was determined according to a method based on the Berthlot reaction, which is the formation of a colored indophenol complex from ammonia liberated from adenosine, and quantified spectrophotometrically.ResultsThe CSF ADA activity from TBM patients was compared with CSF ADA from non-TBM infectious meningitis patients, and from patients with non-infectious neurological disorders. The mean CSF ADA activity was found to be significantly higher in CSF of TBM patients, 14.31 ± 3.87 (2.99–26.94), mean ± SD with range, than in the CSF from non-TBM infectious meningitis, 9.25 ± 2.14 (4.99–13.96) and from the non-infectious neurological disorders group, 2.71 ± 1.96 (0.00–7.68), P < 0.0001 for both comparisons. A cut-off value of 11.39 U/L/min for the TBM patients was calculated from the mean + SD of the non-TBM patients. The ADA test gave a sensitivity of 82% and a specificity of 83% for infectious TBM when this cut-off value was used.ConclusionThis study demonstrated that ADA activity in the CSF of TBM patients, using a cut-off value 11.39 U/L/min, can be useful for the early differential diagnosis of TBM. This test can be performed in any pathology laboratory where more sophisticated methods are not available.
Highlights
Tuberculous meningitis (TBM) is the commonest form of neurotuberculosis caused by Mycobacterium tuberculosis bacilli (MTB)
This study demonstrated that adenosine deaminase (ADA) activity in the cerebrospinal fluid (CSF) of TBM patients, using a cutoff value 11.39 units per litre per minute (U/L/min), can be useful for the early differential diagnosis of TBM
Box plots of the ADA activity in the CSF of culture positive and clinically suspected TBM patients, non-TBM infectious meningitis and non-infectious neurological disorders groups are shown in Figure 1, together with the 90th percentile range, 75th and 25th percentiles
Summary
Tuberculous meningitis (TBM) is the commonest form of neurotuberculosis caused by Mycobacterium tuberculosis bacilli (MTB). The diagnosis of TBM is often difficult. In the present study we measured the adenosine deaminase (ADA) activity in cerebrospinal fluid (CSF) of TBM and non-TBM patients. Tuberculous meningitis (TBM) is the infection of the meninges caused by Mycobacterium tuberculosis (MTB). The diagnosis of TBM is complicated as it causes various clinical manifestations, which overlap with those of other chronic diseases of the central nervous system (CNS) such as viral and pyogenic meningitis [1]. The initiation of antiTB medication in suspected TBM patients can often be (page number not for citation purposes). 2. Non TBM infectious meningitis (n = 60) Pyogenic meningitis (n = 41) Viral meningitis (n = 19).
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