Prevalence of MRSA in the environment in an Irish hospital

  • Orla Sherlock, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin., Ireland
  • Ms Eilish Creamer, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin., Ireland
  • Dr Deirdre Fitzgerald-Hughes, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin.
  • Dr Derek Sullivan, Dublin Dental School and Hospital, Trinity College Dublin., Ireland
  • Ms Mary O'Donnell, Dublin Dental School and Hospital, Trinity College Dublin., Ireland
  • Dr Angela Rossney, National MRSA Reference Laboratory, St James’s Hospital, Dublin, Ireland
  • Dr Robert Cunney, Health Protection Surveillance Centre, Dublin, Ireland
  • Prof Hilary Humphreys, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9.
  • Peter Kinnevey, Microbiology Research Unit, Dublin Dental School & Hospital, University of Dublin, Ireland
  • Anna Shore, Microbiology Research Unit, Dublin Dental School & Hospital, Ireland
  • Prof David Coleman, Microbiology Research Unit, Dublin Dental School & Hospital, Trinity College, University of Dublin, Ireland

    • Objective: MRSA is endemic in many Irish hospitals. A four-year translational research grant was awarded to an Irish consortium to study the prevention and control of healthcare-associated MRSA in Beaumont Hospital, Dublin. An element of this translational study is to determine the level of MRSA in the environment of the hospital. Results from the first nine months of a twelve month observational phase are described here.

    Methods: Environmental samples from two medical and two surgical wards in a 700-bed acute hospital were collected at three time points over two 6-week testing periods in each ward. Swabs were collected from a variety of high contact surfaces (surface swabbed was 10cm2 cultured by salt enrichment using tryptic soy broth with 6.5% NaCl and subcultured onto MRSA-Select chromogenic agar. Air samples were collected by either air pump filtering or "settle" plates onto MRSA-Select agar for MRSA isolation, Columbia blood agar for bacterial total viable counts (TVC) and Sabouraud dextrose agar for fungal TVC's.

    Results: A total of 962 specimens were screened for MRSA, 8.2% were positive. MRSA was recovered from 8.9% of bed mattresses (34/378), 7.6% of bed frames (13/170), 4.0% of pillows (8/199), 3.3% of lockers (2/60), 6.1% of other high contact surfaces and 20% of air samples (18/90). TVC's from 88 surface specimens yielded an average of 516 cfu/10cm2 while air TVC's yielded 78cfu/m3 and fungal air counts were on average 25 cfu/m3of air.

    Conclusions: Prevalence of environment contamination with MRSA in Beaumont hospital varied from 3.3% to 8.9% of surfaces tested but higher prevalence rates were detected in air samples (20%). Importantly, MRSA-positive specimens were mainly associated with the immediate environs of MRSA-positive patients. This data confirms the need for continued improvement of environmental hygiene in Irish hospitals. The next phase of the study will assess new decontamination technologies to enhance environmental hygiene.