title: The changing pattern of clinical Mycobacterium avium isolation in the Netherlands.
abstract: METHODS
  National Mycobacteria Reference Laboratory, The Netherlands.
  
  
  OBJECTIVE
  To assess the role of factors other than laboratory improvements in the increasing frequency of isolation of non-tuberculous mycobacteria (NTM) in the Netherlands; laboratory improvements are often considered key factors in this increase.
  
  
  METHODS
  Laboratory database study. All clinically isolated NTM referred to the national reference laboratory between January 2000 and January 2007 were retrieved from the laboratory database and categorised by species, patient age group and sample origin. Data were compared with national demographic data.
  
  
  RESULTS
  Clinical Mycobacterium avium isolates accounted for most of the increase in referred NTM. The number of respiratory M. avium samples in patients aged >40 years increased over time. This age group increased in size during the study. In this age group, the prevalence of chronic obstructive pulmonary disease (COPD) increased during the study period. M. avium isolation from lymph nodes in children remained stable, whereas extra-pulmonary M. avium isolation in the middle age group, including human immunodeficiency virus associated bloodstream isolates, decreased.
  
  
  CONCLUSIONS
  The increasing NTM notification in the Netherlands is unlikely to have been a result of laboratory improvements alone: the ageing population with an increasing prevalence of COPD is likely as important. Environmental characteristics may specifically favour M.avium.
authors.affiliation: Department of Pulmonary Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. jakko.van.ingen@rivm.nl
authors.forename: J
authors.initials: J
authors.lastname: van Ingen
authors.forename: W
authors.initials: W
authors.lastname: Hoefsloot
authors.forename: P N R
authors.initials: PN
authors.lastname: Dekhuijzen
authors.forename: M J
authors.initials: MJ
authors.lastname: Boeree
authors.forename: D
authors.initials: D
authors.lastname: van Soolingen
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D015658:HIV Infections / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000453:epidemiology; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012189:Retrospective Studies; D055815:Young Adult