Changes in Morphology of an Avirulent Strain of Mycobacterium tuberculosis under the influence of Non-ionic Surface-active Agents

Abstract

H37Ra, an avirulent- variant strain of human Mycobacterium tuberculosis, was studied after repeated subculture in liquid medium containing 0.001 -.002% of Triton A "20 or other non-ionic surface-active agents. The degree and rate of change in.morph. varies, but usually after 10 subcultues the amorphous growth character-istic of avirulent strains is replaced by well-defined cord formation, which is quite stable. The induced cord-forming strain is resistant to D4, a surface-active polyoxyethylene ether which is inhibitory to most avirulent strains. Virulence and cytochemical tests with the cord-forming strains were negative.