A comparative evaluation of ELISA test employing antigen 85C with ZN staining, culture and PCR in the diagnosis of Tuberculosis in children

Objectives: Childhood tuberculosis is difficult to diagnose. A rapid, simple and relatively inexpensive diagnostic test will be crucial to future control efforts. Therefore, diagnostic potential of secretory antigen 85C in human sera specimen, CSF and other body fluids of Mycobacterium tuberculosis in childhood tuberculosis cases were evaluated using ELISA technique and reactivity was compared with the gold standards (Ziehl Neelsen staining, BACTEC culture) and IS6110 targeted PCR. Methods: In the present study, 73 fresh, untreated childhood tuberculosis (TB) cases under 18 years of age out of these 27 had pulmonary tuberculosis and 46 patient had extra pulmonary tuberculosis. Twenty healthy children were included. Results: ELISA with Antigen 85C in sera was positive in 88.89% and 80.43% of pulmonary and extrapulmonary cases, respectively. Overall sensitivity and specificity were 83.56% and 65%, (p 0.05). PCR targeting IS6110 was positive in 96.30% and 65.22% of pulmonary and extrapulmonary cases, respectively. Overall sensitivity and specificity were 76.71% and 90%, respectively. Conclusions: Our findings demonstrates the potential of Ag 85C in sera in the detection of antibody in childhood TB cases and this antigen showed good concordance with PCR positivity.