Discrepancy between the tuberculin skin test and the levels of serum interferon-gamma in the diagnosis of tubercular infection in contacts.
OBJECTIVE
Our aim was to compare the tuberculin skin test (TST) results and the level of serum IFN-gamma in the diagnosis of TB infection among contact of smear positive tuberculosis.


METHODS
Chest x ray, tuberculin skin test and serum level of interferon-gamma (IFN-gamma) by ELISA were performed to 30 sputum positive tuberculosis patients, their 118 household contacts and 31 healthy controls.


RESULTS
The serum level of IFN-gamma was significantly elevated in index cases than in contacts and control groups. There was no statically significant difference in serum level of IFN-gamma between vaccinated and unvaccinated contacts. There was no significant correlation between IFN-gamma level and tuberculin reaction or induration diameter in vaccinated contacts. There was significant correlation between IFN-gamma level and tuberculin reaction or induration diameter in BCG unvaccinated contacts.


CONCLUSIONS
The serum IFN-gamma is a better indicator of the risk of mycobacterial infection than TST in BCG-vaccinated contacts.
Shalabi
Nesrien M
NM
Chest Medicine Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt.
Houssen
Maha E
ME
D000328:Adult; D016022:Case-Control Studies; D016358:Contact Tracing; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D014374:Tuberculin Test; D014376:Tuberculosis / Q000097:blood / Q000175:diagnosis*
D007371:Interferon-gamma