title: A retrospective cohort study into acquisition of MRSA and associated risk factors after implementation of universal screening in Scottish hospitals.
abstract: OBJECTIVE
  To estimate the proportion of patients who acquire methicillin-resistant Staphylococcus aureus (MRSA) while in hospital and to identify risk factors associated with acquisition of MRSA.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Adult patients discharged from 36 general specialty wards of 2 Scottish hospitals that had implemented universal screening for MRSA on admission.
  
  
  METHODS
  Patients were screened for MRSA on discharge from hospital by using multisite body swabs that were tested by culture. Discharge screening results were linked to admission screening results. Genotyping was undertaken to identify newly acquired MRSA in MRSA-positive patients on admission.
  
  
  RESULTS
  Of the 5,155 patients screened for MRSA on discharge, 2.9% (95% confidence interval [CI], 2.43-3.34) were found to be positive. In the subcohort screened on both admission and discharge (n = 2,724), 1.3% of all patients acquired MRSA while in hospital (incidence rate, 2.1/1,000 hospital bed-days in this cohort [95% CI, 1.5-2.9]), while 1.3% remained MRSA positive throughout hospital stay. Three risk factors for acquisition of MRSA were identified: age above 64 years, self-reported renal failure, and self-reported presence of open wounds. On a population level, the prevalence of MRSA colonization did not differ between admission and discharge.
  
  
  CONCLUSIONS
  Cross-transmission of MRSA takes place in Scottish hospitals that have implemented universal screening for MRSA. This study reinforces the importance of infection prevention and control measures to prevent MRSA cross-transmission in hospitals; universal screening for MRSA on admission will in itself not be sufficient to reduce the number of MRSA colonizations and subsequent MRSA infections.
authors.affiliation: Health Protection Scotland, Glasgow, UK. evhvanvelzen@gmail.com
authors.forename: E V H
authors.initials: EV
authors.lastname: van Velzen
authors.forename: J S
authors.initials: JS
authors.lastname: Reilly
authors.forename: K
authors.initials: K
authors.lastname: Kavanagh
authors.forename: A
authors.initials: A
authors.lastname: Leanord
authors.forename: G F S
authors.initials: GF
authors.lastname: Edwards
authors.forename: E K
authors.initials: EK
authors.lastname: Girvan
authors.forename: I M
authors.initials: IM
authors.lastname: Gould
authors.forename: F M
authors.initials: FM
authors.lastname: Mackenzie
authors.forename: R
authors.initials: R
authors.lastname: Masterton
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003428:Cross Infection / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008403:Mass Screening; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D010351:Patient Discharge / Q000706:statistics & numerical data; D051437:Renal Insufficiency / Q000150:complications; D012189:Retrospective Studies; D012606:Scotland / Q000453:epidemiology; D057566:Self Report; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission*; D014947:Wounds and Injuries / Q000150:complications