title: Predictors of the pathogenicity of methicillin-resistant Staphylococcus aureus nosocomial pneumonia.
abstract: OBJECTIVE
  The clinical characteristics of patients with nosocomial pneumonia (NP) associated with methicillin-resistant Staphylococcus aureus (MRSA) infection are not well characterized.
  
  
  METHODS
  Three hundred and thirty-seven consecutive patients with MRSA isolation from respiratory specimens who attended our hospital between April 2007 and March 2011 were enrolled. Patients characteristics diagnosed with 'true' MRSA-NP were described with regards to clinical, microbiological features, radiological features and genetic characteristics of the isolates. The diagnosis of 'true' MRSA-NP was confirmed by anti-MRSA treatment effects, Gram-staining or bronchoalveolar lavage fluid culture.
  
  
  RESULTS
  Thirty-six patients were diagnosed with 'true' MRSA-NP, whereas 34 were diagnosed with NP with MRSA colonization. Patients with a MRSA-NP had a Pneumonia Patient Outcomes Research Team score of 5 (58.3% vs 23.5%), single cultivation of MRSA (83.3% vs 38.2%), MRSA quantitative cultivation yielding more than 10(6) CFU/mL (80.6% vs 47.1%), radiological findings other than lobar pneumonia (66.7% vs 26.5%), and a history of head, neck, oesophageal or stomach surgery (30.6% vs 11.8%). These factors were shown to be independent predictors of the pathogenicity of 'true' MRSA-NP by multivariate analysis (P < 0.05).
  
  
  CONCLUSIONS
  'True' MRSA-NP shows distinct clinical and radiological features from NP with MRSA colonization.
authors.affiliation: Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; Second Department of Internal Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; First Department of Internal Medicine, Hokkaido University Hospital, Hokkaido, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nagaoka
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Harada
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamada
authors.forename: Yohei
authors.initials: Y
authors.lastname: Migiyama
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Morinaga
authors.forename: Koichi
authors.initials: K
authors.lastname: Izumikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kakeya
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nishimura
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kohno
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000145:classification / Q000627:therapeutic use; D016022:Case-Control Studies; D003428:Cross Infection / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology; D004352:Drug Resistance, Microbial; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity; D008875:Middle Aged; D011023:Pneumonia, Staphylococcal / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology; D015995:Prevalence; D011379:Prognosis; D011859:Radiography; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents
keywords: hospital-acquired pneumonia; methicillin-resistant Staphylococcus aureus; pathogenicity; pneumonia