ANTITUBERCULOSIS DRUG-RESISTANCE IN IMMIGRANTS TO ALBERTA, CANADA, WITH TUBERCULOSIS, 1982-1994

SETTING: Provincial Tuberculosis Service, Alberta, Canada. OBJECTIVE: To estimate resistance rates of Mycobacterium tuberculosis to antitube rculosis drugs in relation to previous treatment, country of origin, a ge and duration of residence in Canada. DESIGN: Retrospective chart re view of all culture-positive tuberculosis diagnosed between 1982 and 1 994 in immigrants to Alberta. RESULTS: A total of 753 immigrants with culture-positive tuberculosis were studied; 131 patients (17.4%, 95% C onfidence Interval [CI] 14.7, 20.1) had strains resistant to one or mo re of the first-line medications (isoniazid [INH], rifampin [RIF], eth ambutol [EMB], pyrazinamide [PZA], and streptomycin [SM]). Initial and secondary resistance rates were 16.4% and 30.3%, respectively (P = 0. 003, Odds ratio [OR] 2.2, 95% CI 1.3, 3.8). Resistance occurred in 22. 2% of patients 40 years of age and under, and in 13.8% of those over 4 0 years of age (P = 0.005, OR 1.8, 95% CI 1.2, 2.6). Resistant M. tube rculosis was isolated from 20.4% of those who had lived in Canada for less than 15 years, and in 9.0% of those who had immigrated to Canada more than 15 years before diagnosis (P < 0.001; OR 2.4, 95% CI 1.3, 4. 2). Resistance rates to individual medications in all immigrants were as follows: INH 9.9% (95% CI 7.8, 12.0), RIF 0.8% (95% CI 0.2, 1.4), E MB 1.9% (95% CI 1.0, 2.8), PZA 1.9% (95% CI 0.3, 3.5), and SM 12.9% (9 5% CI 10.4, 15.4). Immigrants from Vietnam, China, and the Philippines had tuberculosis strains that were resistant to one or more of the fi rst line medications in 30.2%, 21.8%, and 15.5% of cases, respectively (P = 0.04). CONCLUSION: In industrialized countries such as Canada wh ere most cases of tuberculosis are diagnosed among the foreign-born, d rug resistance surveys continue to be an important part of an effectiv e tuberculosis control program.