Tuberculosis, an infectious disease that killed 1.5 million people in 2020, is most commonly treated with a cocktail of four drugs that must be taken for up to six months. This treatment plan, however, can have the unintended consequence of leading to antibiotic resistance, both because people may not finish the full course of treatment and, more directly, because one of the drugs can act on bacteria other than Mycobacterium tuberculosis, including components of the intestinal microflora that are critical to health and well-being.