title: Prevalence of methicillin-resistant Staphylococcus aureus : effect of different criteria for elimination of duplicates.
abstract: BACKGROUND
  The purpose of this study is to compare the effect of different systems for eliminating duplicates in order to optimize the calculation of the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infection.
  
  
  METHODS
  We compare the Clinical and Laboratory Standards Institute (CLSI) criterion, time criteria and the criterion recommended by the European Antimicrobial Surveillance System (EARSS).
  
  
  RESULTS
  Multiple isolates of MRSA are frequently recovered from successive cultures from the same patient (the average isolation rate of MRSA is 2.72), which demonstrates the importance of eliminating duplicates. When CLSI criterion data are compared to those obtained using other criteria, a significant increase in the number of S. aureus isolates was found applying time criteria (up to 36%) or the EARSS criterion (13%). There is also an increase in the methicillin resistance rate (between 3.31 and 3.96%; p < 0.01).
  
  
  CONCLUSIONS
  We believe that the EARSS method, with the proper quality controls and latest software tools available, is the best for determining the true situation of MRSA.
authors.affiliation: S. Microbiología, Hospital General Universitario de Elche, Spain.
authors.forename: Ledicia
authors.initials: L
authors.lastname: Álvarez-Paredes
authors.forename: Natividad
authors.initials: N
authors.lastname: López-Riquelme
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Rodríguez
authors.forename: Miguel
authors.initials: M
authors.lastname: Santibañez
authors.forename: Sofía
authors.initials: S
authors.lastname: Belda
authors.forename: Antonio
authors.initials: A
authors.lastname: Galiana
authors.forename: Pilar
authors.initials: P
authors.lastname: López
authors.forename: Montserrat
authors.initials: M
authors.lastname: Ruiz-García
authors.forename: Gloria
authors.initials: G
authors.lastname: Royo
mesh_terms: D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D015995:Prevalence; D012137:Respiratory System / Q000382:microbiology; D012867:Skin / Q000382:microbiology; D018461:Soft Tissue Infections / Q000382:microbiology; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000302:isolation & purification