title: Emergence of methicillin-resistant Staphylococcus aureus USA300 genotype as a major cause of late-onset nosocomial pneumonia in intensive care patients in the USA.
abstract: OBJECTIVE
  To compare demographic and clinical characteristics, and methicillin-resistant Staphylococcus aureus (MRSA) strain characteristics, in patients with early-onset (EO) and late-onset (LO) MRSA nosocomial pneumonia.
  
  
  METHODS
  This was a retrospective analysis of data from a multicenter observational study of nosocomial pneumonia patients admitted between November 2008 and July 2010. Laboratory analyses performed on MRSA isolates included confirmation of antimicrobial susceptibility and heteroresistance to vancomycin, USA typing, staphylococcal cassette chromosome (SCC) mec typing, and detection of Panton-Valentine leukocidin (PVL) genes.
  
  
  RESULTS
  We identified 134 patients; 42 (31%) had EO MRSA pneumonia and 92 (69%) had LO MRSA pneumonia. The patients in the LO group were more likely to have risk factors for multidrug-resistant pathogens (98% vs. 76%, p<0.001). The MRSA USA300 strain was found with equal frequency in the EO and LO groups. Likewise, both groups had similar frequencies of isolates exhibiting PVL and SCCmec type IV.
  
  
  CONCLUSIONS
  Our findings provide further evidence of the continued migration of community-associated MRSA into the healthcare setting in the USA. MRSA USA300 genotype has emerged as a significant cause of LO nosocomial pneumonia in intensive care units. Appropriate anti-MRSA antimicrobial therapy should be considered for both EO and LO hospital-acquired pneumonia and ventilator-associated pneumonia.
authors: Summa Health System, Akron City Hospital, 525 E. Market Street, Akron, OH 44304, USA. pasqualt@summahealth.org
authors: Timothy R
authors: TR
authors: Pasquale
authors: Bonnie
authors: B
authors: Jabrocki
authors: Sara-Jane
authors: SJ
authors: Salstrom
authors: Timothy L
authors: TL
authors: Wiemken
authors: Paula
authors: P
authors: Peyrani
authors: Nadia Z
authors: NZ
authors: Haque
authors: Ernesto G
authors: EG
authors: Scerpella
authors: Kimbal D
authors: KD
authors: Ford
authors: Marcus J
authors: MJ
authors: Zervos
authors: Julio A
authors: JA
authors: Ramirez
authors: Thomas M
authors: TM
authors: File
mesh_terms: D000328:Adult; D000368:Aged; D015373:Bacterial Typing Techniques; D021821:Communicable Diseases, Emerging; D015897:Comorbidity; D003428:Cross Infection / Q000453:epidemiology*; D005260:Female; D005838:Genotype; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics*; D008875:Middle Aged; D011023:Pneumonia, Staphylococcal / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology