title: Methicillin-resistant Staphylococcus aureus: site of acquisition and strain variation in high-risk nursing home residents with indwelling devices.
abstract: OBJECTIVE
  Characterize the clinical and molecular epidemiology of new methicillin-resistant Staphylococcus aureus (MRSA) acquisitions at nasal and extranasal sites among high-risk nursing home (NH) residents.
  
  
  METHODS
  Multicenter prospective observational study.
  
  
  METHODS
  Six NHs in southeast Michigan.
  
  
  METHODS
  A total of 120 NH residents with an indwelling device (feeding tube and/or urinary catheter).
  
  
  METHODS
  Active surveillance cultures from the nares, oropharynx, groin, perianal area, wounds (if present), and device insertion site(s) were collected upon enrollment, at day 14, and monthly thereafter. Pulsed-field gel electrophoresis and polymerase chain reaction for SCCmec, agr, and Panton-Valentine leukocidin were performed.
  
  
  RESULTS
  Of 120 participants observed for 16,290 device-days, 50 acquired MRSA (78% transiently, 22% persistently). New MRSA acquisitions were common in extranasal sites, particularly at device insertion, groin, and perianal areas (27%, 23%, and 17.6% of all acquisitions, respectively). Screening extranasal sites greatly increases the detection of MRSA colonization (100% of persistent carriers and 97.4% of transient carriers detected with nares, groin, perianal, and device site sampling vs 54.5% and 25.6%, respectively, for nares samples alone). Colonization at suprapubic urinary catheter sites generally persisted. Healthcare-associated MRSA (USA100 and USA100 variants) were the dominant strains (79.3% of all new acquisition isolates). Strain diversity was more common in transient carriers, including acquisition of USA500 and USA300 strains.
  
  
  CONCLUSIONS
  Indwelling device insertion sites as well as the groin and perianal area are important sites of new MRSA acquisitions in NH residents and play a role in the persistency of MRSA carriage. Clonal types differ among persistent and transient colonizers.
authors.affiliation: University of Michigan School of Public Health, Ann Arbor, Michigan.
authors.forename: Kristen E
authors.initials: KE
authors.lastname: Gibson
authors.forename: Sara E
authors.initials: SE
authors.lastname: McNamara
authors.forename: Marco
authors.initials: M
authors.lastname: Cassone
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Perri
authors.forename: Marcus
authors.initials: M
authors.lastname: Zervos
authors.forename: Lona
authors.initials: L
authors.lastname: Mody
mesh_terms: D000368:Aged; D001427:Bacterial Toxins / Q000032:analysis; D015373:Bacterial Typing Techniques / Q000379:methods / Q000706:statistics & numerical data; D002408:Catheters, Indwelling / Q000382:microbiology*; D003428:Cross Infection / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D016521:Electrophoresis, Gel, Pulsed-Field; D005098:Exotoxins / Q000032:analysis; D005260:Female; D006119:Groin / Q000382:microbiology*; D006707:Homes for the Aged / Q000706:statistics & numerical data*; D006801:Humans; D007956:Leukocidins / Q000032:analysis; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000302:isolation & purification / Q000502:physiology; D008824:Michigan / Q000453:epidemiology; D009296:Nasal Cavity / Q000382:microbiology*; D009735:Nursing Homes / Q000706:statistics & numerical data*; D011446:Prospective Studies; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin