title: Characteristics of pulmonary Mycobacterium avium complex disease diagnosed later in follow-up after negative mycobacterial study including bronchoscopy.
abstract: BACKGROUND
  We occasionally experience cases suspected of pulmonary Mycobacterium avium complex (MAC) disease without positive bacterial cultures.
  
  
  OBJECTIVE
  To evaluate features of pulmonary MAC cases diagnosed later in the follow-up after negative intensive investigation.
  
  
  METHODS
  We defined and compared three groups; the first study negative (FSN) group, the first study positive (FSP) group, and MAC negative group. The FSN group consisted of patients negative for MAC isolation by bronchial washing performed between 2007 and 2011, but positive later. Patients with positive MAC cultures in the first study were incorporated into the FSP group. MAC negative group consisted of MAC suspects without MAC isolation in the follow-up.
  
  
  RESULTS
  Twenty-four patients were classified as FSN group, 61 as MAC negative group and 265 as FSP group. FSN group exhibited more solitary nodule pattern (n = 7 in FSN, n = 6 in FSP; p < 0.001) and less nodular/bronchiectatic (NB) diseases (n = 17 in FSN, n = 245 in FSP; p < 0.001). When limited to NB type, the FSP group had more cavitations (6% in FSN, 32% in FSP; p = 0.028). Patients with more than three lung lobes involved were more frequent in the FSN group compared with FSP group with negative sputum cultures (65% vs 34%; p = 0.014) and with MAC negative group (65% vs 28%; p = 0.009).
  
  
  CONCLUSIONS
  Patients diagnosed as pulmonary MAC disease in the follow-up duration tend to show solitary nodular pattern or NB pattern without cavitation. In FSN patients with NB pattern, more lung lobes were involved in the first study, suggesting subsequent MAC infection onto the underlying ectatic bronchi.
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: koyamak@tokyo-hosp.jp.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Koyama
authors.affiliation: Asthma and Allergy Center, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Ohshima
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kawashima
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Okuda
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Sato
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nagai
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Matsui
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan; Asthma and Allergy Center, National Hospital Organization Tokyo National Hospital, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Ohta
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle / Q000379:methods; D001987:Bronchiectasis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000382:microbiology; D001999:Bronchoscopy / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D061705:Image-Guided Biopsy / Q000379:methods; D008171:Lung Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000382:microbiology / Q000473:pathology; D018942:Macrolides / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000382:microbiology / Q000473:pathology; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000382:microbiology / Q000473:pathology; D013183:Sputum / Q000382:microbiology; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D018942:Macrolides
keywords: Bronchiectasis; Latent infecction; Mycobacterium avium complex; Prevalence; Solitary nodule