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Evaluation of two commercial tests for the serodiagnosis of pulmonary tuberculosis

Abstract:

Two commercial serological tests, Pathozyme- TB complex plus™ and Pathozyme-Myco IgG™, were evaluated for their sensitivity and specificity in HIV negative patients with serum samples from pulmonary tuberculosis (TB) patients and tuberculin positive, healthy controls. The sensitivity for the two tests was 50 and 80% respectively and the specificity 95 and 80%. With a prevalence of pulmonary TB of 10% in symptomatic patients who consult our laboratory, the positive pbkp_redictive values (PPV) for the two ELISA tests were 92 and 80%, and the negative pbkp_redictive values (NPV) 98 and 80% respectively. In the same patient group, the AFB smear has a PPV of 100% and a NPV of 97%. We conclude that AFB smear is a better mass screening tool than ELISA in symptomatic patients who consult our laboratory. The test could be useful as a complementary test in excluding or confirming TB in selected, smear negative, symptomatic patients with high degree of clinical suspicion of active TB.