Tuberculosis in Calgary, Canada, 1995-2002: site of disease and drug susceptibility

A centre managing all tuberculosis (TB) cases in the population of the Calgary region in Canada.

To facilitate the diagnosis and management of TB by examining the distribution of TB by site of disease and the prevalence and pattern of drug-resistant Mycobacterium tuberculosis in a north American setting.

A retrospective analysis of data collected at the time of diagnosis of all TB cases recorded during the 8-year period 1995-2002. Data collected included demographic information, site of disease, method of diagnosis and M. tuberculosis drug susceptibility.

During the 8-year period, 435 cases of TB were diagnosed: 49% had exclusively extra-pulmonary disease. Lymph node disease (usually cervical) accounted for 44% of the extra-pulmonary cases. A culture of M. tuberculosis resistant to at least one first-line anti-tuberculosis drug was detected in 16% of the initial isolates. All of the resistant strains were found in foreign-born patients and resistance was more common in patients from Asia (19%) and in previously treated patients (26%).

Extra-pulmonary TB is common in the foreign-born population in the Calgary region, and this pattern may be more widespread than is realised. Drug-resistant strains of TB were more common in foreign-born and previously treated patients.