Serological diagnosis of childhood tuberculosis by estimation of mycobacterial antigen 60-specific immunoglobulins in the serum.
METHODS
An ELISA assay based on mycobacterial antigen 60 (A60) for the estimation of specific immunoglobulins in the serum has been used successfully for the rapid diagnosis of tuberculosis in studies done predominantly in Western countries. In a recent Indian study, encouraging results were reported in adult tuberculosis.


OBJECTIVE
To evaluate the utility of this ELISA test for rapid diagnosis of different clinical forms of tuberculosis in Indian children.


METHODS
ELISA test based on mycobacterial A60 was used to estimate specific IgM, IgA and IgG antibodies in the sera obtained from 452 cases of tuberculosis and 161 controls in the paediatric population of Delhi, India.


RESULTS
Of the 161 controls, only 7.4% were positive for IgM, 4.3% for IgG, 3.7% for IgA and 8% when a combination of IgM and IgA was considered. Of 58 cases of definite pulmonary tuberculosis, 55.2% were positive for IgM, 32.7% for IgG, 36.2% for IgA and a high positivity of 72.4% was seen when IgA and IgM estimations were combined. The corresponding figures in 150 cases of definite extrapulmonary tuberculosis were 57.3%, 36.6%, 38% and 76.6%. A relatively weak serology was observed in 244 cases of probable tuberculosis. A very high positivity (95%) was seen in acid-fast bacilli-positive cases of tuberculosis.


CONCLUSIONS
Our findings point to a very good specificity (92%) and a reasonably good sensitivity (75.5%) of the test when combined IgM and IgA antibody titres are considered in the diagnosis of childhood tuberculosis.
Department of Microbiology, National Institute of Communicable Diseases, Delhi, India.
S
S
Gupta
R
R
Bhatia
K K
KK
Datta
D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood*; D007223:Infant; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D015415:Biomarkers; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C055539:mycobacterial A60 antigen