TRENDS IN DRUG-RESISTANT TUBERCULOSIS IN THE UNITED-STATES, 1993-1996

Context.-With the resurgence of tuberculosis (TB) disease in the late 1980s and early 1990s in the United States, multidrug-resistant (MDR) TB emerged as a serious challenge to TB control. In response, the Cent ers for Disease Control and Prevention in 1993 added drug susceptibili ty test results to the information collected for the national surveill ance system to monitor trends in drug resistance. Objective.-To determ ine the extent of drug-resistant tuberculosis (TB) in the United State s. Design.-Descriptive analysis or TB surveillance data. Study Populat ion.-Patients reported to the national TB surveillance system as confi rmed TB cases with culture-positive disease from 1993 through 1996 by the 50 states, New York City, and the District of Columbia (DC). Main Outcome Measure.-Percentage of case patients with culture-positive dis ease whose isolates are resistant to specific anti-TB drugs. Results.- Overall resistance to at least isoniazid was 8.4%; rifampin, 3.0%; bot h isoniazid and rifampin (ie, MDR TB), 2.2%; pyrazinamide, 3.0%; strep tomycin, 6.2%; and ethambutol hydrochloride, 2.2%. Rates of resistance were significantly higher for case patients with a prior TB episode. Among those without prior TB, isoniazid resistance of 4% or more was f ound in 41 states, New York City, and DC. A total of 1457 MDR TB cases were reported from 42 states, New York City, and DC; however, 38% wer e reported from New York City. Rates of isoniazid and streptomycin res istance were higher for cases among US-born compared with foreign-born patients, but rates of rifampin resistance and MDR TB were similar. A mong US-born patients, resistance to first-line drugs, particularly ri fampin mono-resistance, was significantly higher among those with huma n immunodeficiency virus (HIV) infection. Conclusions.-Compared with r ecent US surveys in 1991 and 1992, isoniazid resistance has remained r elatively stable. In addition, the percentage of MDR TB has decreased, although the national trend was significantly influenced by the marke d decrease in New York City. Foreign-born and HIV-positive patients an d those with prior TB have higher rates of resistance. The widespread extent of isoniazid resistance confirms the need for drug susceptibili ty testing to guide optimal treatment of patients with culture-positiv e disease.