title: Prevalence and risk factors for chronic co-infection in pulmonary Mycobacterium avium complex disease.
abstract: BACKGROUND
  Patients with pulmonary Mycobacterium avium complex (MAC) disease are often co-infected with various pathogenic microorganisms. This study aimed to determine the prevalence of co-infection with non-MAC pathogens and the risk factors associated with co-infection in patients with pulmonary MAC disease.
  
  
  METHODS
  We retrospectively reviewed the patient characteristics, microbiological results and chest CT findings in 275 patients with pulmonary MAC who visited the Kyoto University Hospital from January 2001 to May 2013. We defined chronic pathogenic co-infection as the isolation of non-MAC pathogens from sputum samples taken on more than two visits that occurred at least 3 months apart.
  
  
  RESULTS
  The participants were predominantly female (74.5%) and infected with M. avium (75.6%). Chronic co-infection with any pathogen was observed in 124 patients (45.1%). Methicillin-sensitive Staphylococcus aureus (MSSA; n=64), Pseudomonas aeruginosa (n=35) and Aspergillus spp (n=18) were the most prevalent pathogens. The adjusted factors were chronic obstructive pulmonary disease (COPD; OR=4.2, 95% CI 1.6 to 13.1) and pulmonary M. intracellulare disease (OR=2.2, 95% CI 1.1 to 4.4) in chronic co-infections; COPD (OR=4.2, 95% CI 2.1 to 31.4), long duration of MAC disease (OR=2.2, 95% CI 1.2 to 4.4) and nodules (OR=3.5, 95% CI 1.2 to 13.2) in chronic MSSA co-infection; COPD (OR=7.5, 95% CI 2.1 to 31.4) and lower lobe involvement (OR=9.9, 95% CI 2.0 to 90.6) in chronic P. aeruginosa co-infection; and use of systemic corticosteroids (OR=7.1, 95% CI 1.2 to 50.9) and pulmonary M. intracellulare disease (OR=4.0, 95% CI 1.1 to 14.5) in chronic Aspergillus spp co-infection.
  
  
  CONCLUSIONS
  Patients with pulmonary MAC disease frequently had chronic co-infections with pathogenic microorganisms such as MSSA, P. aeruginosa and Aspergillus. The risk factors for chronic co-infection were COPD and pulmonary M. intracellulare disease.
authors.affiliation: Department of Respiratory Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Respiratory Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Respiratory Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Toyohiro
authors.initials: T
authors.lastname: Hirai
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
authors.affiliation: Department of Clinical Laboratory Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ichiyama
authors.affiliation: Department of Respiratory Medicine , Graduate School of Medicine, Kyoto University , Kyoto , Japan.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
keywords: Atypical Mycobacterial Infection; Bacterial Infection; Bronchiectasis; Respiratory Infection