Myxopyronin (Myx) is an alpha-pyrone antibiotic, the first in a new class of inhibitors of bacterial RNA polymerase (RNAP) that target switch 1 and switch 2 of the RNAP "switch region." Rifamycin antibacterial agents, which are first-line treatments for tuberculosis, and lipiarmycin (fidaxomicin, Dificid) also target RNAP, but target different sites in RNAP.