Studies on the reliability of diagnosis of atypical mycobacterial infection using the ELISA technique

Six groups of tuberculin-negative guinea-pigs were artificially infected with atypical mycobacterial strains, e.g. M. kansasii, M. scrofulaceum, M. intracellulare and M. fortuitum, and with two standard typical mycobacterial strains, i.e. M. bovis and M. avium. Serum samples were taken and a tuberculin test was carried out during the experiment. At the end of the experiment all the dead animals were subjected to post mortem examination and the strains used for inoculation were reisolated and identified. There were no tuberculin reactions in the infected groups of animals 2 weeks after infection (2 WPI). Animals infected with M. bovis and M. kansasii showed moderate tuberculin reactions with human PPD tuberculin. The Elisa technique was able to defect mycobacterial antibodies early at 2 WPI, and a high titre was observed more frequently in homologous reactions than in heterologous ones. The technique could not, however, differentiate between infections involving different mycobacterial strains. The ELISA test could thus be used as a screening test.