Objective: To determine antituberculosis drug resistance patterns, geographic distribution, demographic characteristics, and risk factors of reported tuberculosis (TB) patients in the United States.
Design: Survey of reported TB cases in the United States. For culture-positive cases reported to the Centers for Disease Control and Prevention, we asked health departments to provide drug susceptibility test results from initial Mycobacterium tuberculosis isolates.
Study population: Culture-positive TB cases in the United States reported during the first quarter of 1991.
Main outcome measures: Individual TB case reports submitted to the Centers for Disease Control and Prevention and drug susceptibility test results.
Results: Resistance to one or more antituberculosis drugs was found in 14.2% of cases. Resistance to isoniazid and/or rifampin was found in 9.5% of cases whose isolates were tested against one or both drugs; such cases were found in 107 counties in 33 states. Resistance to both isoniazid and rifampin (multidrug-resistant [MDR] TB) was found in 3.5% of cases whose isolates were tested against both drugs; such cases were found in 35 counties in 13 states. New York City accounted for 61.4% of the nation's MDR TB cases. The 3-month population-based incidence rate of MDR TB in New York City was 52.4 times (95% confidence interval [CI], 35.5 to 78.3) that of the rest of the nation (9.559 vs 0.182 cases per million population). Compared with the rate in non-Hispanic whites in the rest of the nation (0.032 cases per million), the relative risk of MDR TB in New York City non-Hispanic whites was 39.0 (95% CI, 8.1 to 164.5), 299.3 (95% CI, 112.5 to 927.1) in Hispanics, 420.9 (95% CI, 121.0 to 1515.8) in Asian/Pacific Islanders, and 701.0 (95% CI, 296.4 to 2018.1) in non-Hispanic blacks.
Conclusions: With nearly 10% of TB patients resistant to isoniazid and/or rifampin, greater use of four-drug regimens and directly observed therapy is indicated. Aggressive intervention to prevent the further spread of MDR TB is needed to find every TB patient and to provide optimal patient management to ensure completion of chemotherapy.