A summary of tuberculosis drug resistance in Canada, 2003-2013.

Background Drug-resistant strains of tuberculosis (TB) pose a serious threat to prevention and control efforts. In response to this growing worldwide concern, the Public Health Agency of Canada (PHAC) established and maintains the Canadian Tuberculosis Laboratory Surveillance System (CTBLSS) in partnership with the Canadian Tuberculosis Laboratory Technical Network (CTLTN) and participating laboratories. Objective To report on national trends and patterns in anti-tuberculosis drug resistance in Canada for the years 2003 to 2013. Method At the beginning of each calendar year, participating laboratories submit to PHAC reports on the results of anti-tuberculosis drug susceptibility testing for all isolates tested during the preceding year. These data are then analyzed by PHAC and the results are validated by supplying laboratories. The results are published annually as the Tuberculosis Drug Resistance in Canada series. Results In 2013, anti-tuberculosis drug susceptibility test results for 1,380 isolates were reported to PHAC. Of these, 762 (54%) were reported as Mycobacterium tuberculosis complex (MTBC) where the species was known. Two thirds (68%) of all the reported isolates originated from the three largest provinces, British Columbia, Ontario and Quebec. Overall, of the laboratory results received, 112 (8.1%) showed resistance to at least one first-line drug and, of these, the majority (93 or 83%) were monoresistant. Conclusion TB drug resistance observed in Canada remains well below the global average. Over the last 10 years, the percentage of isolates with resistance to one or more of the first-line medications has decreased from 10.5% in 2003 to 8.1% in 2013.