Comparison of in vitro activity of the nitroimidazoles delamanid and pretomanid against multidrug-resistant and extensively drug-resistant tuberculosis.

Delamanid exhibited greater in vitro potency than pretomanid against multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB) isolates. The pretomanid minimum inhibitory concentration (MIC) values of four MDR-TB isolates were found to be resistant to delamanid ranging from 0.031 to 0.063 mg/L. A novel nonsynonymous mutation within the fbiA gene (Glu249Lys) may be contributing to high-level resistance to delamanid and pretomanid in Mycobacterium tuberculosis.