Effect of anti-tuberculosis drugs on the iron-sequestration mechanisms of mycobacteria.

ABSTRACT

The effect of sub-lethal concentrations of isoniazid, ethambutol, rifampicin and pyrazinamide on the growth in vitro and the production of both exochelins and mycobactins by the high virulent and the South Indian low virulent strains of M. tuberculosis was examined under iron-deficient and iron-rich conditions. There was a marked decrease in the growth of both strains in the presence of increasing concentrations of all four drugs, the inhibition being total in the presence of minimal inhibitory concentrations of the drugs. It was also observed that the growth-inhibitory effect of all four drugs was slightly reversed in the presence of high concentration of iron in the medium. A significant increase was observed in the concentrations of both siderophores in the presence of all four drugs, under both iron-deficient (or) iron-rich conditions.