title: Health care-associated invasive MRSA infections, 2005-2008.
abstract: BACKGROUND
  Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen of public health importance; MRSA prevention programs that may affect MRSA transmission and infection are increasingly common in health care settings. Whether there have been changes in MRSA infection incidence as these programs become established is unknown; however, recent data have shown that rates of MRSA bloodstream infections (BSIs) in intensive care units are decreasing.
  
  
  OBJECTIVE
  To describe changes in rates of invasive health care-associated MRSA infections from 2005 through 2008 among residents of 9 US metropolitan areas.
  
  
  METHODS
  Active, population-based surveillance for invasive MRSA in 9 metropolitan areas covering a population of approximately 15 million persons. All reports of laboratory-identified episodes of invasive (from a normally sterile body site) MRSA infections from 2005 through 2008 were evaluated and classified based on the setting of the positive culture and the presence or absence of health care exposures. Health care-associated infections (ie, hospital-onset and health care-associated community-onset), which made up 82% of the total infections, were included in this analysis.
  
  
  METHODS
  Change in incidence of invasive health care-associated MRSA infections and health care-associated MRSA BSIs using population of the catchment area as the denominator.
  
  
  RESULTS
  From 2005 through 2008, there were 21,503 episodes of invasive MRSA infection; 17,508 were health care associated. Of these, 15,458 were MRSA BSIs. The incidence rate of hospital-onset invasive MRSA infections was 1.02 per 10,000 population in 2005 and decreased 9.4% per year (95% confidence interval [CI], 14.7% to 3.8%; P = .005), and the incidence of health care-associated community-onset infections was 2.20 per 10,000 population in 2005 and decreased 5.7% per year (95% CI, 9.7% to 1.6%; P = .01). The decrease was most prominent for the subset of infections with BSIs (hospital-onset: -11.2%; 95% CI -15.9% to -6.3%; health care-associated community-onset: -6.6%; 95% CI -9.5% to -3.7%).
  
  
  CONCLUSIONS
  Over the 4-year period from 2005 through 2008 in 9 diverse metropolitan areas, rates of invasive health care-associated MRSA infections decreased among patients with health care-associated infections that began in the community and also decreased among those with hospital-onset invasive disease.
authors.affiliation: Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. AKallen@cdc.gov
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Kallen
authors.forename: Yi
authors.initials: Y
authors.lastname: Mu
authors.forename: Sandra
authors.initials: S
authors.lastname: Bulens
authors.forename: Arthur
authors.initials: A
authors.lastname: Reingold
authors.forename: Susan
authors.initials: S
authors.lastname: Petit
authors.forename: Ken
authors.initials: K
authors.lastname: Gershman
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ray
authors.forename: Lee H
authors.initials: LH
authors.lastname: Harrison
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.forename: Ghinwa
authors.initials: G
authors.lastname: Dumyati
authors.forename: John M
authors.initials: JM
authors.lastname: Townes
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Priti R
authors.initials: PR
authors.lastname: Patel
authors.forename: Scott K
authors.initials: SK
authors.lastname: Fridkin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000517:prevention & control; D003428:Cross Infection / Q000453:epidemiology* / Q000517:prevention & control*; D005260:Female; D006268:Health Facilities / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D017053:Infection Control; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008875:Middle Aged; D011159:Population Surveillance; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000517:prevention & control*; D014481:United States / Q000453:epidemiology; D055815:Young Adult