What is MDR TB?Multidrug-resistant tuberculosis (MDR TB) is defined as TB disease caused by bacteria that are resistant to at least isoniazid and rifampin, two of the most potent first-line anti-TB drugs. According to CDC, extensively drug-resistant TB (XDR TB) means TB resistant to isoniazid, rifampin, a fluoroquinolone, and a second-line injectable, or resistant to isoniazid, rifampin, a fluoroquinolone, and bedaquiline or linezolid. Pre-XDR TB means MDR TB plus resistance to either a fluoroquinolone or a second-line injectable.
Background/NeedDespite a decline in TB incidence in California over the past 30 years, MDR TB remains a challenge to TB control efforts and a threat to communities. On average, 1-2% of California’s patients diagnosed with TB are MDR. Nearly half of those patients have substantial additional resistance (i.e., XDR, pre-XDR, or resistance to all four first-line drugs). Because MDR TB has become more common globally, the proportion of patients with MDR TB in California might increase in future years. During 2016-2020 there were 106 patients diagnosed with MDR TB, more than 20% of all MDR TB cases diagnosed in the United States during this period.
| Consultation with an expert in the management of MDR TB is recommended by CDC. Because of higher morbidity and mortality, potential extended duration and cost of treatment, and overall complexity associated with patients with MDR TB, local health jurisdictions (LHJs) face greater challenges with the management of MDR TB than with drug-sensitive disease. Familiarity and experience with providing care for patients with MDR TB, access to timely drug susceptibility testing, second-line drug procurement, and ability to minimize other case management challenges in the long term have been associated with prompt identification and successful treatment of patients with MDR TB in California. Patients managed through consultation with the MDR Service have good outcomes with more than 90% of patients achieving cure. Additionally, the landscape of treatment and management of patients with MDR TB is now evolving rapidly. With the approval of a new TB drug, pretomanid, and increased use of newer, short-course drug regimens for MDR and XDR TB (e.g., bedaquiline, pretomanid, and linezolid, or BPaL), new research and recommendations continue to develop. California is contributing to CDC’s surveillance of BPaL implementation in the United States and participated in the national BPaL Implementation Group, a community of practice focused on the implementation and outcomes of using a short-course regimen. The CA MDR Service remains a source of up-to-date information on the latest research findings and clinical practice for the LHJs in California.
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