Abstract
Objective: To estimate the prevalence of resistance of Mycobacterium tuberculosis to first-line antituberculosis drugs in Canada.
Methods: M. tuberculosis isolates from one third of all culture-positive tuberculosis (TB) cases diagnosed between February 1, 1993 to January 31, 1994 in Canada were collected prospectively. Proportion of drug-resistant isolates and the factors related to drug resistance were measured.
Results: Of 458 study cases, 40 (8.7%) had resistance to at least one first-line antituberculosis drug, of which 5–9% had mono-resistance, 0.7% had multidrug-resistance(MDR-TB) — i.e., resistance to at least isoniazid and rifampin — and 2.2% had other patterns. The overall prevalence of resistance among the foreign-born cases was 10.6% with the highest level among those who resided in Canada for less than four years (15.5%).
Conclusions: Canada has a relatively low prevalence of antituberculosis drug resistance and a very low prevalence of MDR-TB. Some new immigrants to Canada may be at higher risk for drug resistance and their initial treatment needs to be tailored accordingly.
Résumé
Objectif: Évaluer la prévalence de la résistance du mycobacterium tuberculosis contre le médicament antituberculeux de première ligne au Canada.
Méthodes: Le mycobacterium tuberculosis repère un tiers de tous les cas de cultures tuberculosis qui ont fait l’objet d’un diagnostic positif entre le 1er février 1993 et le 31 janvier 1994 au Canada; ces données ont été collectées de manière prospective. On a mesuré la proportion de repère des médicaments résistants et les facteurs reliés à la résistance du médicament.
Résultats: Sur 458 cas étudiés, 40 (8,7 %) se sont avérés résistants à au moins un médicament antituberculeux de première ligne dont 5,9 % se sont avérés résistants à un seul médicament et 0,7 % ont une résistance à plusieurs médicaments (MDR-TB) — c.-à-d. résistants à au moins deux médicaments: l’isoniazid et le rifampin — et 2,2 % avaient d’autres caractéristiques. La prévalence globale de la résistance parmi les cas venus de l’étranger était de 10,6 % dont le niveau le plus élevé a résidé au Canada pendant moins de quatre ans (15,5 %).
Conclusions: Au Canada, la prévalence de la résistance des médicaments antituberculeux est relativement faible. Certains nouveaux arrivants peuvent présenter un risque plus élevé de résistance aux médicaments et leur traitement initial doit être personnalisé en conséquence.
Footnotes
Formerly, TB epidemiologist, Division of Tuberculosis Prevention and Control, LCDC, Ottawa
Formerly, Director, Division of Tuberculosis Control, Ministry of Health, British Columbia, Vancouver
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