Virulence of Mycobacterium tuberculosis and susceptibility to peroxidative killing systems.

At sub-bactericidal concentrations of hydrogen peroxide, Mycobacterium tuberculosis was killed by hydrogen peroxide/peroxidase/halide microbicidal systems. The halide cofactor could be either iodide or, with much lower efficiency, chloride. Omission of any one of the reactants eliminated the tuberculocidal effect. Differences in susceptibility between different strains of M. tuberculosis did not correlate with virulence differences. The observations are discussed in the context of host defence mechanisms against tuberculosis.