title: Severe community-onset pneumonia in healthy adults caused by methicillin-resistant Staphylococcus aureus carrying the Panton-Valentine leukocidin genes.
abstract: BACKGROUND
  Recent worldwide reports of community-onset skin abscesses, outbreaks of furunculosis, and severe pneumonia associated with methicillin-resistant Staphylococcus aureus (MRSA) carrying Panton-Valentine leukocidin (PVL) genes and the staphylococcal cassette chromosome mec (SCCmec) type IV indicate that MRSA infections are evolving into a community-related problem. The majority of cases reported to date involve skin and soft-tissue infections, with severe pneumonia representing a relatively rare phenomenon. During a 2-month period in the winter of 2003-2004, four healthy adults presented to 1 of 2 Baltimore hospitals with severe necrotizing MRSA pneumonia in the absence of typical risk factors for MRSA infection.
  
  
  METHODS
  Patients' MRSA isolates were characterized by strain typing with use of pulsed-field gel electrophoresis and SCCmec typing with use of a multiplex polymerase chain reaction (PCR) assay and detection of PVL genes by PCR.
  
  
  RESULTS
  All 4 patients' MRSA isolates carried the PVL genes and the SCCmec type IV element and belonged to the USA300 pulsed-field type. These 3 findings are among the typical characteristics of community-onset MRSA strains. In addition, 2 of our patients had concomitant influenza A diagnosed, which likely contributed to the severity of their presentation.
  
  
  CONCLUSIONS
  To our knowledge, these patients represent the first reported North American adults with severe community-onset MRSA pneumonia caused by strains carrying the PVL genes.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD, USA. jfranc13@jhmi.edu
authors.forename: John S
authors.initials: JS
authors.lastname: Francis
authors.forename: Meg C
authors.initials: MC
authors.lastname: Doherty
authors.forename: Uri
authors.initials: U
authors.lastname: Lopatin
authors.forename: Cecilia P
authors.initials: CP
authors.lastname: Johnston
authors.forename: Gita
authors.initials: G
authors.lastname: Sinha
authors.forename: Tracy
authors.initials: T
authors.lastname: Ross
authors.forename: Mian
authors.initials: M
authors.lastname: Cai
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Hansel
authors.forename: Trish
authors.initials: T
authors.lastname: Perl
authors.forename: John R
authors.initials: JR
authors.lastname: Ticehurst
authors.forename: Karen
authors.initials: K
authors.lastname: Carroll
authors.forename: David L
authors.initials: DL
authors.lastname: Thomas
authors.forename: Eric
authors.initials: E
authors.lastname: Nuermberger
authors.forename: John G
authors.initials: JG
authors.lastname: Bartlett
mesh_terms: D000328:Adult; D001427:Bacterial Toxins; D015373:Bacterial Typing Techniques; D017714:Community-Acquired Infections / Q000382:microbiology*; D005098:Exotoxins; D005260:Female; D006801:Humans; D007956:Leukocidins / Q000235:genetics*; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D008875:Middle Aged; D018579:Patient Selection; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D037521:Virulence Factors / Q000032:analysis
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D037521:Virulence Factors; D008712:Methicillin