title: Clinical impact of methicillin-resistant staphylococcus aureus on bacterial pneumonia: cultivation and 16S ribosomal RNA gene analysis of bronchoalveolar lavage fluid.
abstract: BACKGROUND
  Determining whether methicillin-resistant Staphylococcus aureus (MRSA) is a true causative pathogen or reflective of colonization when MRSA is cultured from the respiratory tract remains important in treating patients with pneumonia.
  
  
  METHODS
  We evaluated the bacterial microbiota in bronchoalveolar lavage fluid (BALF) using the clone library method with a 16S ribosomal RNA (rRNA) gene analysis in 42 patients from a pneumonia registry who had MRSA cultured from their sputum or BALF samples. Patients were divided into two groups: those treated with (Group A) or without (Group B) anti-MRSA agents, and their clinical features were compared.
  
  
  RESULTS
  Among 248 patients with pneumonia, 42 patients who had MRSA cultured from the respiratory tract were analyzed (Group A: 13 patients, Group B: 29 patients). No clones of S. aureus were detected in the BALF of 20 out of 42 patients. Twenty-eight of 29 patients in Group B showed favorable clinical outcomes, indicating that these patients had non-MRSA pneumonia. Using a microflora analysis of the BALF, the S. aureus phylotype was predominant in 5 of 28 (17.9%) patients among the detected bacterial phylotypes, but a minor population (the percentage of clones ≤ 10%) in 19 (67.9%) of 28 patients. A statistical analysis revealed no positive relationship between the percentage of clones of the S. aureus phylotype and risk factors of MRSA pneumonia.
  
  
  CONCLUSIONS
  The molecular method using BALF specimens suggests that conventional cultivation method results may mislead true causative pathogens, especially in patients with MRSA pneumonia. Further studies are necessary to elucidate these clinically important issues.
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Kawanami
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan. yatera@med.uoeh-u.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yatera
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Yamasaki
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Noguchi
authors.affiliation: Department of Microbiology, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Fukuda
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Kentarou
authors.initials: K
authors.lastname: Akata
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Naito
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kido
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishimoto
authors.affiliation: Department of Microbiology, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Hatsumi
authors.initials: H
authors.lastname: Taniguchi
authors.affiliation: Department of Respiratory Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka, 807-8555, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mukae
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification; D008875:Middle Aged; D016017:Odds Ratio; D011014:Pneumonia / Q000175:diagnosis* / Q000382:microbiology; D018410:Pneumonia, Bacterial / Q000175:diagnosis / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000032:analysis* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013183:Sputum / Q000382:microbiology
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: 16S rRNA gene; Bronchoalveolar lavage, BALF; Clone library; Contamination; Methicillin-resistant Staphylococcus aureus, MRSA; Pneumonia