Mupirocin calcium Imp. B (EP): 9-[[(2E)-4-[(2S,3R,4R,5S)-3,4-dihydroxy-5-[(2E,4R,5S)-5-hydroxy-4-methylhex-2-enyl]tetrahydro-2H-pyran-2-yl]-3-methylbut-2-enoyl]oxy]nonanoic acid (pseudomonic acid C).