Potential utility of BCG test in excluding tuberculosis in adults

In developing countries, many sputum-negative suspects of pulmonary tuberculosis (PTB) are given antituberculous medication just because tuberculosis (TB) could not be excluded in them. Many studies have shown that BCG test is nearly 100% sensitive, except in those with severe malnutrition, steroid therapy and other causes of immunosuppression. The aim of the present study was to find out the proportion of PTB suspects in whom BCG test may be useful in excluding diagnosis of TB. The study was carried out on adult subjects attending District Tuberculosis Clinic (DTC), Pali, Rajasthan, India. Out of 104 subjects studied, all 18 sputum-positive subjects showed a positive BCG test indicating 100% sensitivity of the test. The result of BCG test was negative in 16.28% of 86 sputum-negative suspects of TB. The BCG test did not show any adverse reactions among these cases except for adenitis of axillary or cervical lymph nodes in 6.7% subjects. The study raises the possibility that BCG test may be useful in excluding diagnosis of tuberculosis in a proportion of adult sputum negative-suspects of PTB in developing countries like India. More studies are needed in this direction.