Immunodiagnosis of childhood pulmonary and extrapulmonary tuberculosis using Mycobacterium tuberculosis ES antigen by penicillinase ELISA.

The diagnostic potential for detection of IgG to Mycobacterium tuberculosis excretory secretory (ES) antigen in childhood pulmonary and extrapulmonary tuberculosis was explored. IgG antibody to M. tuberculosis ES antigen was detected by indirect penicillinase ELISA. Twenty (80%) out of 25 pulmonary tuberculosis cases (clinically diagnosed and/or AFB-positive), five of nine tuberculous pleural effusion cases and only six of 69 cases in the control group were positive for IgG antibody to M. tuberculosis ES antigen. All CSF and sera were positive for IgG antibody in 12 cases of clinically diagnosed tuberculous meningitis (TBM). Out of 35 cases in the control group for TBM, all five cases of pyogenic meningitis but none of the 13 cases of viral encephalitis, five cases of enteric encephalopathy and 12 cases with no CNS infection were positive for anti-tubercular IgG antibody in CSF samples. Only two of them, i.e. one case of pyogenic meningitis and the other with no CNS infection, were positive for antibody in sera. The study demonstrated the potential of this assay in the diagnosis of tuberculosis in children where bacteriological confirmation is very difficult.