title: Staphylococcus aureus bacteremia at 5 US academic medical centers, 2008-2011: significant geographic variation in community-onset infections.
abstract: BACKGROUND
  The incidence of community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) bacteremia rose from the late 1990s through the 2000s. However, hospital-onset (HO) MRSA rates have recently declined in the United States and Europe.
  
  
  METHODS
  Data were abstracted from infection prevention databases between 1 January 2008 and 31 December 2011 at 5 US academic medical centers to determine the number of single-patient blood cultures positive for MRSA and methicillin-susceptible S. aureus (MSSA) per calendar year, stratified into CO and HO infections.
  
  
  RESULTS
  Across the 5 centers, 4171 episodes of bacteremia were identified. Center A (Los Angeles, California) experienced a significant decline in CO-MRSA bacteremia rates (from a peak in 2009 of 0.42 to 0.18 per 1000 patient-days in 2011 [P = .005]), whereas CO-MSSA rates remained stable. Centers B (San Francisco, California), D (Chicago, Illinois), and E (Raleigh-Durham, North Carolina) experienced a stable incidence of CO-MRSA and CO-MSSA bacteremia. In contrast, at center C (New York, New York), the incidence of CO-MRSA increased >3-fold (from 0.11 to 0.34 cases per 1000 patient-days [P < .001]). At most of the sites, HO-MRSA decreased and HO-MSSA rates were stable. USA300 accounted for 52% (104/202) of genotyped MRSA isolates overall, but this varied by center, ranging from 35% to 80%.
  
  
  CONCLUSIONS
  CO-MRSA rates and the contribution of USA300 MRSA varied dramatically across diverse geographical areas in the United States. Enhanced infection control efforts are unlikely to account for such variation in CO infection rates. Bioecological and clinical explanations for geographical differences in CO-MRSA bacteremia rates merit further study.
authors.affiliation: Department of Medicine and Health Studies Department of Pediatrics, University of Chicago, Illinois.
authors.forename: Michael Z
authors.initials: MZ
authors.lastname: David
authors.affiliation: Department of Pediatrics, University of Chicago, Illinois.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Daum
authors.affiliation: Department of David Geffen School of Medicine, University of California, Los Angeles (UCLA) Division of Infectious Diseases, Harbor-UCLA Medical Center and the Los Angeles Biomedical Research Institute, Torrance, California.
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Bayer
authors.affiliation: Department of Medicine, University of California, San Francisco.
authors.forename: Henry F
authors.initials: HF
authors.lastname: Chambers
authors.affiliation: Department of Medicine, Duke University Medical Center, Raleigh-Durham, North Carolina.
authors.forename: Vance G
authors.initials: VG
authors.lastname: Fowler
authors.affiliation: Department of David Geffen School of Medicine, University of California, Los Angeles (UCLA) Division of Infectious Diseases, Harbor-UCLA Medical Center and the Los Angeles Biomedical Research Institute, Torrance, California.
authors.forename: Loren G
authors.initials: LG
authors.lastname: Miller
authors.affiliation: Montefiore Medical Center/Albert Einstein College of Medicine, New York.
authors.forename: Belinda
authors.initials: B
authors.lastname: Ostrowsky
authors.affiliation: Department of Pediatrics, University of Chicago, Illinois.
authors.forename: Alison
authors.initials: A
authors.lastname: Baesa
authors.affiliation: Department of Pediatrics, University of Chicago, Illinois.
authors.forename: Susan
authors.initials: S
authors.lastname: Boyle-Vavra
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center and the Los Angeles Biomedical Research Institute, Torrance, California.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Eells
authors.affiliation: Infection Control Program, University of Chicago Medicine, Illinois.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Garcia-Houchins
authors.affiliation: Montefiore Medical Center/Albert Einstein College of Medicine, New York.
authors.forename: Philip
authors.initials: P
authors.lastname: Gialanella
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center and the Los Angeles Biomedical Research Institute, Torrance, California.
authors.forename: Raul
authors.initials: R
authors.lastname: Macias-Gil
authors.affiliation: Department of Medicine, Duke University Medical Center, Raleigh-Durham, North Carolina.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Rude
authors.affiliation: Department of Medicine, Duke University Medical Center, Raleigh-Durham, North Carolina.
authors.forename: Felicia
authors.initials: F
authors.lastname: Ruffin
authors.affiliation: Department of Pediatrics, University of Chicago, Illinois.
authors.forename: Julia J
authors.initials: JJ
authors.lastname: Sieth
authors.affiliation: Department of Medicine, University of California, San Francisco.
authors.forename: Joann
authors.initials: J
authors.lastname: Volinski
authors.affiliation: Department of David Geffen School of Medicine, University of California, Los Angeles (UCLA) Division of General Internal Medicine, Harbor-UCLA Medical Center and the Los Angeles Biomedical Research Institute, Torrance, California.
authors.forename: Brad
authors.initials: B
authors.lastname: Spellberg
mesh_terms: D000046:Academic Medical Centers; D000293:Adolescent; D000328:Adult; D016470:Bacteremia; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection; D016208:Databases, Factual; D005798:Genes, Bacterial; D005838:Genotype; D049674:History, 21st Century; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D058885:Multilocus Sequence Typing; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000266:history / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: MRSA; Staphylococcus aureus; bacteremia; epidemiology; genotyping