title: Association between polyclonal and mixed mycobacterial Mycobacterium avium complex infection and environmental exposure.
abstract: BACKGROUND
  Polyclonal and mixed mycobacterial Mycobacterium avium complex (MAC) infection is observed in pulmonary MAC disease. Human living environments contain multiple species or genotypes of nontuberculous mycobacterial strains and are considered sources of infection.
  
  
  OBJECTIVE
  To investigate the association of environmental exposure with polyclonal and mixed mycobacterial infection in pulmonary MAC disease after adjustments for potential confounding diseases and conditions and radiographic findings.
  
  
  METHODS
  We collected two separate sputum samples from 102 patients and single sputum samples from 18 patients in whom the second MAC strain was not isolated in our prospective cohort of pulmonary MAC disease. MAC isolates from sputum samples and patients' residential soils were used for variable number of tandem repeats (VNTR) analyses. Polyclonal and mixed mycobacterial MAC infections were defined as having different VNTR genotypes and other mycobacterial species, respectively. Monoclonal MAC infection was defined as all isolates showing a single VNTR genotype. Associations of the type of infection with clinical and radiographic findings and environmental exposure were measured.
  
  
  RESULTS
  Polyclonal and mixed mycobacterial MAC and monoclonal infections were observed in 42 and 78 patients, respectively. By stepwise regression analysis, patients with polyclonal and mixed mycobacterial MAC infections were associated with history of asthma (odds ratio [OR], 11.56; 95% confidence interval [CI], 1.41-255.77; P = 0.021), high soil exposure (≥2 h/wk; OR, 4.31; 95% CI, 1.72-11.45; P < 0.01), shower use in a bathroom (OR, 4.57; 95% CI, 1.28-23.23; P = 0.018), and swimming in a pool (OR, 9.69; 95% CI, 1.21-206.92; P < 0.01).
  
  
  CONCLUSIONS
  Environmental exposure was associated with polyclonal and mixed mycobacterial MAC infection in pulmonary MAC disease.
authors.affiliation: 1 Department of Respiratory Medicine.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ito
authors.forename: Toyohiro
authors.initials: T
authors.lastname: Hirai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
authors.forename: Koichi
authors.initials: K
authors.lastname: Maekawa
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ichiyama
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
mesh_terms: D000368:Aged; D001249:Asthma / Q000150:complications; D015331:Cohort Studies; D060085:Coinfection / Q000000981:diagnostic imaging / Q000382:microbiology*; D004781:Environmental Exposure; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D018598:Minisatellite Repeats / Q000235:genetics*; D015269:Mycobacterium avium Complex / Q000235:genetics*; D015270:Mycobacterium avium-intracellulare Infection / Q000150:complications / Q000000981:diagnostic imaging / Q000382:microbiology*; D011446:Prospective Studies; D011859:Radiography; D012044:Regression Analysis; D012988:Soil Microbiology; D013183:Sputum / Q000382:microbiology; D013551:Swimming Pools; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000000981:diagnostic imaging / Q000382:microbiology*