Multidrug-resistant tuberculosis in Alberta and British Columbia, 1989 to 1998.
OBJECTIVE
To describe the extent of the problem of multidrug-resistant tuberculosis (MDR-TB) in Alberta and British Columbia from 1989 to 1998.


METHODS
A retrospective, population-based descriptive study of all notified MDR-TB cases in the context of all notified TB cases, all notified culture-positive TB cases and all notified drug-resistant TB cases.


METHODS
Provinces of Alberta and British Columbia, and their TB registries.


METHODS
All people with TB reported to the TB registries of Alberta and British Columbia between January 1, 1989 and June 30, 1998.


METHODS
Drug susceptibility testing was performed in all cases of culture-positive TB. Demographic, clinical and laboratory data on all cases of MDR-TB were recorded.


RESULTS
Of 4606 notified cases of TB, 3553 (77.1%) were culture positive. Of these, 365 (10.3%) were drug resistant; of the drug-resistant cases, 24 (6.6%) were MDR. Most MDR-TB patients were foreign-born; of the four Canadian-born patients, two were infected while travelling abroad. Although foreign-born patients were significantly more likely to harbour drug-resistant strains, 14.3% versus 4.8%, respectively (P<0.001), among those who were harbouring a drug-resistant strain, the proportion of Canadian-born versus foreign-born patients with an MDR strain was the same (6.7% versus 6. 6%, respectively). From 1994 to 1998 versus 1989 to 1993, the proportion of all drug-resistant strains that were MDR was greater (9.0% versus 4.3%, respectively), but the difference was not statistically significant. Isolates from 16 of the 24 MDR-TB cases had been archived. Each of these was fingerprinted and found to be unique. Most MDR-TB cases (88%) were respiratory. Of those tested for human immunodeficiency virus (n=17), only one was seropositive. MDR-TB was 'acquired' in 67% and 'primary' in 33% of cases. Eight (33%) of the MDR-TB cases received curative courses of treatment, six (25%) are still being treated, and the remainder have either died (five, 21%), transferred out (four, 17%) or become 'chronic' (one, 4%). No secondary case of MDR-TB has been identified in Alberta and British Columbia.


CONCLUSIONS
Most MDR-TB in Alberta and British Columbia is imported. The proportion of all drug-resistant cases that are MDR appears to be increasing, but not because of disease acquired from recent contact with MDR-TB in Canada.
D000328:Adult; D000416:Alberta / Q000453:epidemiology; D000995:Antitubercular Agents / Q000627:therapeutic use; D001955:British Columbia / Q000453:epidemiology; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D018563:Disease Notification; D004641:Emigration and Immigration / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006679:HIV Seropositivity / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000235:genetics; D011159:Population Surveillance; D012042:Registries; D012189:Retrospective Studies; D015996:Survival Rate; D014195:Travel; D016896:Treatment Outcome; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy / Q000453:epidemiology*; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000453:epidemiology*