Background: Since the 1980s the Western Australian (WA) Department of Health has promoted a comprehensive MRSA management policy involving the early identification, containment, and eradication of MRSA infection and colonisation. Although this policy has prevented MRSA from becoming endemic in WA acute care hospitals, the prevalence of MRSA in the WA community, including residential care facilities, has substantially increased in the last ten years. Consequently health care workers (HCW) may become colonised with MRSA in the community and transmit MRSA into the state’s hospitals. The aim of this study was to determine the prevalence of MRSA carriage in HCW in a WA acute care hospital and to determine the associated risk factors.
Methods: From December 2007 to April 2008 a period prevalence study was conducted at Royal Perth Hospital, an 800 bed WA acute care tertiary hospital. All HCWs were invited to participate. Basic demographics and a single swab from the anterior nares were collected. Staff recently exposed to a MRSA outbreak were excluded from the study.
Results: Fifteen hundred and forty–two HCWs (24% of all staff employed at the hospital) were enrolled in the study. Overall, 3.4% (n=52) of HCWs were colonised with MRSA. Colonisation rates were higher amongst nurses [6.8%] and patient care assistants (PCA) [5.2%], compared to allied health professionals [1.7%] and doctors [0.7%]. HCW (particularly nurses and PCA) were more likely to be colonised with MRSA if they were employed via an agency or had an extended length of service, however the most significant associated risk factor for colonisation was seen in HCW working in wards with an “open” MRSA policy (p<0.001); Just over 15% of nurses who worked in these wards were found to be MRSA colonised.
Using molecular typing methods four major clones were characterised including ST1-MRSA-IV [WA MRSA-1) (n=21 HCW), ST78-MRSA-IV [WA MRSA-2] (n=14 HCW) ST22-MRSA-IV [EMRSA-15] (n=9 HCW) and ST5-MRSA-IV [WA MRSA-3] (n=7 HCW). These clones are frequently isolated in the WA community and residential care facilities.
Conclusion: MRSA colonisation of HCW occurs primarily in those caring for patients colonised or infected with MRSA, particularly those with close and regular direct patient contact (ie nurses and PCA). Consequently, interward transfer of these staff from high MRSA prevalence wards to other areas should be restricted without prior screening. Surveillance screening should be regularly performed on staff working on wards with an “open” MRSA policy.