Bacteriophage susceptibility and cultural characteristics of BCG and other tubercle bacilli.

In the course of investigations on the colonial morphology of different strains of mycobacteria,1 their susceptibility to recently isolated bacteriophages2 and physiological properties associated with pathogenicity, it was observed that several strains of BCG in the Olive View culture collection showed some differences from each other by the various technics employed. In order to determine if these or other variations were of frequent occurrence, a larger number of cultures of BCG was therefore obtained for further investigation from laboratories known to be working with this organism in various parts of the world. The source and history of all cultures are recorded in Table I. The wellknown pathogenic human organism, H37 Rv, and its non-pathogenic variant, H37 Ra, the so-called “moderately virulent” human isolate, Ri Rv, and a pathogenic organism of bovine origin, Corper, were also included in these studies as controls of technics and pathogenicity.