Estimation of methicillin-resistant Staphylococcus aureus transmission by considering colonization pressure at the time of hospital admission

J Hosp Infect. 2005 May;60(1):27-31. doi: 10.1016/j.jhin.2004.10.008.


Our objective was to evaluate the accuracy of a methicillin-resistant Staphylococcus aureus (MRSA) rate using the imported MRSA reservoir identified at the time of hospital admission. Two indicators were used: the number of imported MRSA patient-days/total number of patient-days [representing colonization pressure (CP) at the time of admission] and the incidence of hospital-acquired MRSA isolated from clinical samples expressed as density/100 patient-days for carriers identified at the time of admission [representing the incidence taking CP into account (ICP)]. The variations of these indicators were analysed and compared with two more common indicators: percentage of MRSA acquired in our hospital and the incidence of hospital-acquired MRSA isolated from clinical samples expressed as density/1000 patient-days within three four-month periods during 2002. Common indicators varied similarly, with marked decline during the third period; first-period CP was twice that of other periods (P<10(-6)) and the highest (>two-fold) ICP was seen in the summer (second) period (P<0.001) when the personnel/patient ratio was the lowest. Thus, comparison of different indicators within four-month periods underlines important differences between common and novel indicators. Despite several limitations, ICP should be helpful in the interpretation of MRSA surveillance data, particularly for estimating the extent of MRSA transmission.

Publication types

  • Validation Study

MeSH terms

  • Bias
  • Carrier State / epidemiology*
  • Carrier State / microbiology
  • Carrier State / prevention & control
  • Carrier State / transmission
  • Chi-Square Distribution
  • Cross Infection / epidemiology*
  • Cross Infection / microbiology
  • Cross Infection / prevention & control
  • Cross Infection / transmission
  • Data Interpretation, Statistical
  • France / epidemiology
  • Health Services Needs and Demand
  • Hospitals, Public
  • Hospitals, Teaching
  • Humans
  • Incidence
  • Infection Control / methods*
  • Infection Control / standards
  • Length of Stay / statistics & numerical data*
  • Mass Screening
  • Methicillin Resistance*
  • Patient Admission / statistics & numerical data
  • Quality Indicators, Health Care
  • Risk Adjustment
  • Risk Factors
  • Seasons
  • Staphylococcal Infections / epidemiology*
  • Staphylococcal Infections / microbiology
  • Staphylococcal Infections / prevention & control
  • Staphylococcal Infections / transmission
  • Staphylococcus aureus*