TB or Tuberculosis seems like one of those diseases that should have gone by the wayside years ago with other “old” diseases like polio and diphtheria. According to the Centers for Disease Control and Prevention, in 2017, 10 Million people were infected worldwide, and more than 9,000 cases were reported in the United States. So why hasn’t TB become one of those diseases we only read about in textbooks? Multidrug resistance. Successful TB treatment is reliant on the Mycobacterium tuberculosis bacteria being susceptible to first-line antibiotics. Unfortunately, a large percentage of new TB cases are antibiotic resistant, and this is one of the leading reasons that Tuberculosis is still a major concern across the globe. The proclivity for TB strains to be multidrug resistance is also why researchers are harnessing technologies such as next-generation sequencing to help find a solution.
Traditional microbiology techniques in strain identification are too slow and whole-genome sequencing requires too much raw input. This is where targeted sequencing comes into play. If you know what you’re looking for and where to look, why would you look anywhere else? This is the thought process behind targeted sequencing. Researchers are continuing to develop targeted sequencing assay panels that target known and suspected tb-resistant loci. By opting for targeted sequencing vs. whole genome sequencing, researchers are not only able to reduce time of analysis, but they are also able to increase sequencing depth. Combining targeted sequencing methodology with deep sequencing instruments such as the Illumina NovaSeq and the PacBio Sequel, the scientific community is able to increase their capability of identifying antibiotic resistant TB strains in a fraction of the time that was once required. As knowledge of the multidrug resistance of Mycobacterium tuberculosis increases and time of analysis continues to decrease, hopefully in the not so distant future, TB will be one of those diseases that becomes a global afterthought thanks in large part no doubt to NGS-based targeted sequencing.