TB’s Weaknesses Revealed by Genes

NIAID Now | August 11, 2017

In recent years, multidrug-resistant (MDR) and extensively-drug-resistant (XDR) tuberculosis (TB) has become increasingly common—and difficult to treat. A new study funded by NIAID reveals that by unravelling the TB bacteria’s DNA and testing it for certain mutations, researchers were able to estimate to what extent the bacteria are resistant to fluoroquinolones, a class of powerful antibiotics typically used to treat TB that includes ciprofloxacin, levofloxacin, and moxifloxacin.

In the new study, published on August 3rd in Clinical Infectious Diseases, researchers from Harvard Medical School, Boston University School of Medicine, and University of Massachusetts Medical School sequenced the gyr genes of Mycobacterium tuberculosis, collected from the sputum of 669 TB patients in Peru. They generated predictions for how well the patients would respond to fluoroquinolones, then compared them with how well the patients actually fared.

Historically, researchers have had difficulty determining to what extent bacteria are resistant to antibiotics by looking at their genetic mutations only. In this study, the researchers found that certain mutations in the gyr gene resulted in greater resistance and poorer outcomes for patients. These tests performed at least as well as traditional culture testing. Since molecular testing is becoming more and more common, the researchers say, a reliable way to quickly test for fluoroquinolone resistance will be essential for healthcare providers in the future.

Content last reviewed on August 11, 2017