title: The incidence of pulmonary non-tuberculous mycobacteria in British Columbia, Canada.
abstract: METHODS
  British Columbia Centre for Disease Control (BCCDC), Vancouver, Canada.
  
  
  OBJECTIVE
  To determine the incidence of non-tuberculous mycobacteria (NTM) and to assess the impact of new laboratory techniques.
  
  
  METHODS
  Population-based study of all subjects with positive cultures for NTM from 1990 to 2006.
  
  
  RESULTS
  Mycobacterium avium complex (MAC) was the most common NTM isolate (77%). The median incidence rates per 100 000 population in the total sample were respectively 6.7, 4.5 and <0.7 for all NTMs, MAC and all non-MAC species; for NTM-treated subjects the rates were respectively 1.6, 1.4 and <0.08; and for the NTM-colonised they were respectively 4.7, 2.7 and <0.5. In the period after the introduction of new laboratory techniques, all NTM isolates, the overall MAC rate and the MAC-colonised rate increased by respectively 24%, 35.4% and 76% (P < 0.05). All NTM isolates and rates for all NTMs, NTM-treated and M. tuberculosis subjects (used as comparison group) decreased over time (P < 0.05).
  
  
  CONCLUSIONS
  The most common NTM species was MAC. Episodic increases in the number of isolates and incidence rates of subjects colonised with MAC are likely to be associated with the implementation of new laboratory techniques, which may represent an artefact. The decrease in rates of NTM-treated subjects is reassuring.
authors.affiliation: Department of TB Control, British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada. eduardo.hernandez@bccdc.ca
authors.forename: E
authors.initials: E
authors.lastname: Hernández-Garduño
authors.forename: M
authors.initials: M
authors.lastname: Rodrigues
authors.forename: R K
authors.initials: RK
authors.lastname: Elwood
mesh_terms: D016477:Artifacts; D001431:Bacteriological Techniques; D001955:British Columbia / Q000453:epidemiology; D006077:Government Agencies; D006801:Humans; D015994:Incidence; D009165:Mycobacterium Infections, Nontuberculous / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D015269:Mycobacterium avium Complex / Q000302:isolation & purification; D015270:Mycobacterium avium-intracellulare Infection / Q000453:epidemiology; D009170:Nontuberculous Mycobacteria / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D013997:Time Factors