Studies in South Africa and Vietnam also indicate 6 months of treatment with an oral antibiotic could help prevent development of MDR-TB in children and adults.
Under an agreement with TB Alliance, Indian pharmaceutical company Macleods will supply pretomanid for low- and middle-income countries.
Health officials are screening people who were exposed and monitoring the sick patient's treatment.
The latest Global Tuberculosis Report shows an increase in the number of people diagnosed with TB, which means more patients are getting the treatment and services they need.
The authors say the study underscores the importance of adequate drug-susceptibility testing capacity.
The decision means generic versions of the drug, which is a critical part of shorter regimens for drug-resistant TB, can be made and sold in 134 low- and middle-income countries.
Although progress has stalled, world leaders at today's UN high-level meeting will commit to new targets aimed at reducing TB incidence and deaths.
The deal is expected to make 5 million more tests available, improving access for lower- and middle-income countries.
The authors said the case report provides a cautionary example for health providers in areas with low TB incidence.
The price cut for bedaquiline will enable low- and middle-income countries to buy more WHO-recommended treatment regimens for drug-resistant TB.