ANTITUBERCULOUS DRUG-RESISTANCE IN MANITOBA FROM 1980 TO 1989

Objectives: To estimate the magnitude of antituberculous drug resistan ce and identify the risk factors for its development in tuberculosis p atients in Manitoba over a 10-year period. As well, to examine the cli nical course of the patients whose initial or subsequent isolates of M ycobacterium tuberculosis were resistant to one or more drugs. Design: Comparison of drug-resistant and non-drug-resistant cases of tubercul osis. Setting: Manitoba. Patients: All people with tuberculosis report ed to the Central Tuberculosis Registry of Manitoba between Jan. 1, 19 80, and Dec. 31, 1989. Main outcome measures: Of 1478 cases of active tuberculosis 1086 were culture positive, and drug susceptibility testi ng was performed in these cases. The clinical course, including outcom e of treatment, of all drug-resistant cases was described. Results: Of 1086 culture-positive cases of tuberculosis 77 (7.1%) were drug resis tant. Odds ratios suggested that the risk of drug resistance was signi ficantly higher among the immigrants than among the other Canadians. C ompared with the other Canadians the risk of drug resistance was 9.9 t imes greater among the immigrants in whom tuberculosis developed withi n the first year after arrival in Canada and 5.4 times greater among t he immigrants in whom it developed 2 to 5 years after arrival in Canad a. Of the 71 patients with drug-resistant disease whose type of resist ance was known 62% had never taken antituberculous drugs before and 38 % had. Most (91%) of the 77 cases of drug-resistant disease were resis tant to first-line drugs, especially isoniazid and streptomycin. Thirt y-two (42%) of the 77 cases were resistant to two or more first-line d rugs. Of patients with drug-resistant disease a subgroup of 10 had dis ease that became resistant to several drugs over the 10-year period. T he outcome of treatment in these individuals was poor, and they presen ted a particular public health problem. Conclusion: Resistance to one or more first-line antituberculous drugs continues to complicate the t reatment of tuberculosis and may facilitate the spread of the disease.