The ddn Trp20Stop Mutation and Its Association with Lineage 4.5 and Resistance to Delamanid and Pretomanid in Mycobacterium tuberculosis.

High-confidence resistance mutations for new and repurposed anti-TB drugs, such as delamanid (DLM) and pretomanid (Pa), are rare and more data are needed in order to correctly interpret the results generated by genotypic drug susceptibility testing. In this study performed on clinical Mycobacterium tuberculosis complex isolates, we report that in the Swedish strain collection the ddn mutation Trp20Stop is found exclusively among DLM and Pa resistant (Pa MIC >16 mg/L) isolates assigned to lineage 4.5.