FIG. 1.

Mycobacterial ASN susceptibility assays. Mycobacterial isolates were incubated for 16 h in 7H9 medium (pH 5.3) and then plated onto 7H11 agar. CFU were determined at 21 and 50 days of incubation. (A) Isolates were incubated at 37°C in 7H9 broth at pH 5.3 without NaNO₂, and CFU were quantified at day 21 (shaded bars) and day 50 (hatched bars). The results are expressed as the CFU ± the standard error of the mean (SEM). (B) Isolates were exposed to 3 mM (day 21 [black diamonds] and day 50 [solid squares]) and 6 mM NaNO₂ (day 21 [gray triangles] and day 50 [gray circles]). The results are expressed as the percent survival based on the CFU recovered from ASN-exposed strains relative to the CFU of unexposed strains ± the SEM. Both graphs are representative of triplicate experiments and show mean values of triplicate cultures for each strain.