Use of oleic acid-albumin agar medium for the study of streptomycin resistance of Mycobacterium tuberculosis

The oleic acid – albumin agar, proposed by Dubos and Middlebrook as a diagnostic medium for the isolation of Mycobacterium tuberculosis, proved useful for determining streptomycin resistance. By growing cultures of M. tuberculosis on this translucent substrate, containing graded amounts of streptomycin, a close correlation was found between the observed streptomycin resistance and that determined in fluid tween-albumin medium. The initial presence of a few organisms, showing a slight resistance to streptomycin, was found not to be an exclusive characteristic of cultures developing drug resistance in the course of streptomycin therapy. Cultures not developing resistance may also contain such resistant cells.