title: Clinical significance of a first positive nontuberculous mycobacteria culture in cystic fibrosis.
abstract: BACKGROUND
  Little is known about outcomes of infection with nontuberculous mycobacteria (NTM) in cystic fibrosis (CF) or about the significance of a positive NTM culture. Determining which patients are at risk for active NTM disease is clinically valuable.
  
  
  OBJECTIVE
  To examine the clinical course of subjects with CF with an initial positive NTM culture and identify characteristics associated with active NTM disease.
  
  
  METHODS
  We performed a retrospective study of pediatric and adult subjects with CF with at least one positive NTM culture at the Colorado CF Center from 2000 to 2010.
  
  
  RESULTS
  Mycobacterium avium complex was the first identified NTM in the majority of subjects (73%). The frequency of growing a second NTM species was 26% at 5 years. Clinical characteristics and distribution of NTM species between pediatric and adult subjects were similar except for differences in baseline FEV1 (89% vs. 71%; P < 0.001) and coinfection with Pseudomonas aeruginosa (33% vs. 55%; P = 0.04). Over 60% of subjects had transient or persistent infection but not active NTM disease. Subjects who developed active NTM disease were distinguished from those with transient or persistent infection, respectively, by FEV1 at the time of first positive NTM culture (72% vs. 84 or 86%; P = 0.02) and FEV1 decline in the prior year (-5.8%/yr vs. -0.7%/yr [P = 0.009] or -0.4%/yr [P = 0.001]).
  
  
  CONCLUSIONS
  The majority of patients with CF with a first positive NTM culture do not progress to active disease. Lower lung function and accelerated lung function decline appear to be indicators of the significance of an initial positive NTM culture.
authors.affiliation: 1 Department of Pediatrics, Children's Hospital Colorado and University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Martiniano
authors.forename: Marci K
authors.initials: MK
authors.lastname: Sontag
authors.forename: Charles L
authors.initials: CL
authors.lastname: Daley
authors.forename: Jerry A
authors.initials: JA
authors.lastname: Nick
authors.forename: Scott D
authors.initials: SD
authors.lastname: Sagel
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D015331:Cohort Studies; D060085:Coinfection; D003550:Cystic Fibrosis / Q000150:complications / Q000382:microbiology* / Q000503:physiopathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D009165:Mycobacterium Infections, Nontuberculous / Q000150:complications / Q000175:diagnosis; D015269:Mycobacterium avium Complex / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000150:complications / Q000175:diagnosis*; D009170:Nontuberculous Mycobacteria / Q000302:isolation & purification; D011552:Pseudomonas Infections / Q000150:complications; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000175:diagnosis*; D055815:Young Adult