Genotyping of Mycobacterium tuberculosis Rifampin Resistance-Associated Mutations by Use of Data from Xpert MTB/RIF Ultra Enables Large-Scale Tuberculosis Molecular Epidemiology Studies.

Molecular epidemiology studies of tuberculosis have been empowered in recent years by the availability of whole-genome sequencing, which has allowed a new focus on the adaptive significance of drug resistance mutations. Genome sequencing technology remains expensive, however, limiting the potential for larger studies. Conversely, during this same time the GeneXpert molecular diagnostic method has been deployed globally and now serves as a cornerstone of tuberculosis diagnosis and drug sensitivity testing. In this issue, Y. Cao, H. Parmar, A. M. Simmons, D. Kale, et al. (J Clin Microbiol 57:e00907-19, 2019, https://doi.org/10.1128/JCM.00907-19) report the development of an algorithm that can use high-resolution melting temperature data generated in the course of analysis using the next-generation Xpert MTB/RIF Ultra assay to accurately genotype rifampin resistance-associated mutations. When paired with a system to aggregate data from diagnostic laboratories, this technique has the potential to enable studies on the global scale of the epidemiology of tuberculosis drug resistance.