title: Etiology and Outcome of Diffuse Acute Infectious Bronchiolitis in Adults.
abstract: BACKGROUND
  The etiology and outcome of diffuse acute infectious bronchiolitis (DAIB) in adults is not well known.
  
  
  OBJECTIVE
  To retrospectively review adult patients with DAIB without pneumonia, document the etiologies and outcomes, and assess the relation between DAIB and postinfectious bronchiolitis obliterans.
  
  
  METHODS
  We retrospectively analyzed medical records of 1,664 patients with lower respiratory tract infections admitted to our institution in Saitama, Japan. DAIB was diagnosed when patients developed acute feverish lower respiratory tract infection and chest computed tomography demonstrated mainly multiple centrilobular nodules in four or more lobes. Pneumonia was diagnosed when patients developed acute feverish lower respiratory tract infection and chest computed tomography demonstrated consolidation and/or ground-glass opacities with or without centrilobular nodules.
  
  
  RESULTS
  Of the 1,664 patients, 20 (1.2%) and 1,644 (98.8%) patients were diagnosed as having DAIB and pneumonia, respectively. Of the 20 patients with DAIB, the etiology was determined in 16 (80%): 13 (65.0%) had a single pathogen and 3 (15.0%) had two pathogens. Detected organisms included Mycoplasma pneumoniae in eight (40.0%) patients, influenza virus in two (10.0%), influenza virus and Streptococcus pneumoniae in two (10.0%), Haemophilus influenzae in three (15.0%), and respiratory syncytial virus and rhinovirus in one (5.0%) patient. All patients improved and none developed postinfectious bronchiolitis obliterans.
  
  
  CONCLUSIONS
  The three most common etiologies of DAIB in the studied adults were M. pneumoniae, influenza virus, and H. influenzae. None of the patients with DAIB developed postinfectious bronchiolitis obliterans.
authors.affiliation: 1 Department of Respiratory Medicine and.
authors.forename: Kai
authors.initials: K
authors.lastname: Ryu
authors.affiliation: 1 Department of Respiratory Medicine and.
authors.forename: Noboru
authors.initials: N
authors.lastname: Takayanagi
authors.affiliation: 1 Department of Respiratory Medicine and.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishiguro
authors.affiliation: 2 Department of Radiology, Saitama Cardiovascular and Respiratory Center, Saitama, Japan.
authors.forename: Tetsu
authors.initials: T
authors.lastname: Kanauchi
authors.affiliation: 1 Department of Respiratory Medicine and.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kawate
authors.affiliation: 1 Department of Respiratory Medicine and.
authors.forename: Naho
authors.initials: N
authors.lastname: Kagiyama
authors.affiliation: 1 Department of Respiratory Medicine and.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sugita
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001988:Bronchiolitis / Q000453:epidemiology / Q000209:etiology*; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012141:Respiratory Tract Infections / Q000150:complications* / Q000453:epidemiology; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: adult; bronchiolitis; etiology; outcome; postinfectious bronchiolitis obliterans