What to know
Despite the increase in overall tuberculosis (TB) disease case counts in 2023, the number and percentage of isoniazid-resistant TB cases were lower than prepandemic levels reported in 2019. The number and percentage of multidrug-resistant (MDR) TB cases have remained relatively consistent for a decade.
Introduction
Resistance to anti-TB drugs is a concern in the United States and globally. Drug-resistant TB disease is caused by TB bacteria that are resistant to at least one of the most effective TB medicines used in treatment regimens.
Resistance to isoniazid can be a precursor to MDR TB disease. MDR TB disease is caused by TB bacteria that are resistant to two or more of the main TB medicines: isoniazid and rifampin.
Two more serious forms of MDR TB are called pre-extensively drug-resistant TB (pre-XDR TB) and extensively drug-resistant TB (XDR TB). Pre-XDR and XDR TB are rare types of TB disease that are resistant to nearly all medicines used to treat TB disease.
Key findings
During 2023, resistance to at least isoniazid at initial diagnosis was reported for 589 (8.5%) TB cases in the United States, including 100 (1.4%) MDR TB disease cases.
- Among U.S.-born persons, 87 (5.8%) cases were isoniazid-resistant TB, including 6 (0.4%) cases of MDR TB.
- Among non-U.S.–born persons, 501 (9.2%) cases were isoniazid-resistant TB, including 94 (1.7%) cases of MDR TB.
Recommended TB treatment plans for drug-resistant TB disease include a fluoroquinolone. In 2023, among cases with susceptibility results for isoniazid and rifampin, 45 (0.6%) cases were reported as resistant to at least one fluoroquinolone.
Pre-XDR TB disease and XDR TB disease continue to be rare in the United States. In 2023, there were 15 (0.2%) cases of pre-XDR TB disease and one (0.0%) case of XDR TB disease reported. The low percentages of cases with pre-XDR and XDR TB disease have been consistent over time. Stringent guidelines for TB disease treatment in the United States, including diligent follow-up efforts by public health personnel, greatly reduce the risk of developing drug-resistant TB disease.