To determine the clinical utility of the
tuberculin purified
protein derivative (
PPD) skin test in patients suspected of having
tuberculous meningitis (TBM), the test was applied on admission to 180 patients suspected of having
tuberculous meningitis and to 50 patients with proven
bacterial meningitis admitted to the Abbassia
Fever Hospital, Cairo, Egypt, during the period 1987 to 1989. Admission
tuberculin positivity in evaluated groups revealed the following: overall suspect TBM cases--17% (31/180), culture-confirmed TBM cases--19% (16/83), and culture-confirmed acute
bacterial meningitis cases--14% (7/50). Repeat
PPD skin test at 60 days in surviving presumptive/confirmed TBM cases revealed a significant increase in
tuberculin positivity to 62% (58/93) from admission (p < 0.001). Evaluation of
PPD positivity by clinical stage of TBM revealed 36% positivity in alert patients as compared to 12% positivity in
comatose patients (p = 0.01). Admission
tuberculin skin testing as a diagnostic aid for clinical management of
tuberculous meningitis is of limited utility in our study population because of the high prevalence of
tuberculin positivity in the Egyptian population (potential false positive correlation with the acute presentation) and the advanced stage of TBM at presentation to Egyptian public hospitals (potential false negative correlation).