Specific detection of Mycobacterium tuberculosis in radiometric cultures by using an immunoassay for antigen 5.

Abstract

The time required for cultural identification of Mycobacterium tuberculosis has been greatly decreased by the introduction of radiometric techniques capable of recognizing early mycobacterial growth by detecting production of [14C]CO2 [1, 2]. Useful as this method has proven to be, it fails to discriminate among various organisms growing from cultures of clinical specimens. Selective media favor the growth of mycobacteria, but other organisms often grow in these cultures, and species of mycobacteria other than M. tuberculosis grow well in the selective media. Additionally, the requirement for the use of isotopes and expensive laboratory equipment makes radiometric methods unsuitable for use in developing countries, where the prevalence of tuberculosis is often very high. We established an inhibition immunoassay using ELISA techniques to detect M. tuberculosis antigen 5. This antigen has previously been found to be restricted to M. tuberculosis and Mycobacterium bovis [3]. In this report we present data indicating that this immunoassay can be used for the early, specific recognition of M. tuberculosis in radiametric cultures.