Abstract: Methods for treating diseases involving pyrazinamide-resistant mycobacteria comprise administering to a mammal in need of treatment a therapeutically effective amount of a combination of rifamycin and a compound of formula I: wherein R1 is hydrogen haloalkyl, or lower alkyl; R2 and R3 are independently chosen from alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, alkylaryl and substituted alkylaryl, or R2 and R3 taken together form a five- or six-membered heterocyclic or substituted heterocyclic ring; and X is hydrogen, halogen, or lower alkyl; or a pharmaceutically acceptable salt thereof.