Mycobacterium tuberculosis CDC1551 is resistant to reactive nitrogen and oxygen intermediates in vitro

Abstract

Resistance to reactive oxygen intermediates and reactive nitrogen intermediates in vitro of a clinical isolate of Mycobacterium tuberculosis (CDC1551) that caused a large outbreak of tuberculosis was compared to that of M. tuberculosis strains CB3.3, H37Rv, H37Ra, Erdman, RJ2E, C.C. 13, and C.C. 22 as well as M. bovis strains Ravenel and BCG. CDC1551 and CB3.3 were significantly more resistant to both hydrogen peroxide (H(2)O(2)) and acidified sodium nitrite than were the other strains tested. This biological phenotype may serve as an in vitro marker for clinical strains of M. tuberculosis likely to cause a large outbreak of tuberculosis.

FIG. 1.

Effect of H₂O₂ on mycobacterial viability in Middlebrook 7H9 medium at 2 mM (black bars) and 5 mM (gray bars) concentrations. Data shown are representative of triplicate experiments. Results are expressed as percents survival relative to baseline ± standard errors of the means and are mean values of triplicate cultures for each strain.

FIG. 2.

Effect of ASN on mycobacterial viability in Middlebrook 7H9 medium at 3 mM (black bars) and 6 mM (gray bars) concentrations. Data shown are representative of triplicate experiments. Results are expressed as percents survival relative to baseline ± standard errors of the means and are mean values of triplicate cultures for each strain.