A sustained reduction of endemic methicillin resistant Staphylococcus aureus (MRSA) in an intensive care unit (ICU) at a tertiary hospital in Australia over an 8-year period in the absence of intensive infection control measures

  • Michelle Ananda-Rajah, Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, A, Australia
  • Dr Kirsty Buising, Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, Australia, Australia
  • Dr Emma McBryde, Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, Australia, Australia
  • Caroline Marshall, Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, Australia, Australia

    • Objectives
    Intensive efforts to control nosocomial MRSA remain controversial. We report a decline in MRSA blood stream and other clinical isolates from our ICU in the absence of specific interventions against MRSA.

    Methods
    Retrospective time series analysis of Staphylococcus aureus (SA) isolates from Royal Melbourne Hospital ICU 2000-2007. Clinical isolates were electronically extracted from the microbiology database. Screening swabs and duplicate isolates collected within 7days from sterile and 30days from non-sterile sites respectively were excluded.

    Results
    The number of MRSA (& total SA) clinical isolates/1000 occupied ICU bed days within consecutive 6 month periods from 2000-2007 is reported in table 1. The number of MRSA (& total SA) blood culture isolates (unadjusted for occupancy) per year from 2000-2007 is also presented in table 1. Trauma, cardiothoracic & other surgical patients comprised 63%(mean) of ICU admissions/year. No MRSA specific infection control program involving active screening, targeted patient decolonisation or isolation was implemented in the ICU. General measures introduced included a antibiotic stewardship program using a computerized tool to guide antibiotic selection (Jan 2001) regular ICU ward rounds by the infectious diseases service (from April 2004), temporary screening and barrier nursing of Acinetobacter colonised patients to control an outbreak of non-multiresistant Acinetobacter in the ICU (Nov 2004-Dec 2005) and hospital wide hand hygiene education using an alcohol based solution (from May 2005).


    Conclusion
    Sustained control of endemic MRSA was achieved by general quality improvement measures and limited infection control interventions. Intensive and expensive MRSA control measures may not always be necessary.

    Table 1
    6 months MRSA clinical SA clinical Year Positive Positive
    ending isolates/1000 isolates/1000 BC:MRSA BC: SA
    ICU bed days ICU bed days

    June 2000 31 53 2000 28 39
    Dec 2000 35 62
    June 2001 26 48 2001 18 28
    Dec 2001 23 50
    June 2002 14 50 2002 15 26
    Dec 2002 25 54
    June 2003 24 56 2003 18 30
    Dec 2003 26 53
    June 2004 26 56 2004 12 27
    Dec 2004 28 58
    June 2005 17 40 2005 11 20
    Dec 2005 16 43
    June 2006 6 38 2006 3 16
    Dec 2006 14 48
    June 2007 11 45 2007 4 16
    Dec 2007 3 22