A new study by researchers in Switzerland found that screening patients on admission to hospital to find out if they carry methicillin-resistant Staphylococcus aureus (MRSA) did not significantly reduce hospital acquired infection rates in surgical patients. The findings do not support the idea that MRSA screening of all patients on admission is worthwhile.

The study is the work of Dr Stephan Harbarth and colleagues based at the University of Geneva Hospitals and Medical School, Geneva, and published in the March 12 issue of the Journal of the American Medical Association (JAMA).

The researchers said in their background information that policy makers and experts have called repeatedly for MRSA screening of all patients admitted to hospital as an essential way to reduce hospital acquired MRSA because it is thought that patients who carry the bacteria put others at high risk of infection.

However, until now, there has been no controlled trial to test the idea that rapid screening for MRSA reduces cross-infection and increases the chances of pre-operative disease prevention.

Harbarth and colleagues evaluated the effect of an early MRSA screening programme on 21,754 surgical patients at a Swiss teaching hospital. The study followed a controlled method in that it compared the effect of rapid MRSA screening plus standard infection control against standard infection control on its own.

The patients were in 12 different surgical wards, each for a particular type of surgery. Each ward was designated either a control group or an intervention group for 9 months, and then they swapped over for another 9 months, so each ward had 9 months of control period and 9 months of intervention period, but not necessarily in that order.

The results showed that:

  • Overall, 94 per cent of the patients (10,193 of 10,844) admitted to wards in intervention periods were rapid tested for MRSA using a molecular method.
  • For this group, the median time from admission to having the test results back was 22.5 hours.
  • 515 of MRSA screened patients tested positive (5.1 per cent).
  • Most of these (65 per cent, or 337), had not been identified as carriers of MRSA before and would not have been spotted without the admission test.
  • Thus, to find 1 MRSA carrier who had not been identified before, 30 patients would have to be screened, based on these figures.
  • 93 patients (equivalent to 1.11 per 1,000 patient days) were infected with hospital acquired MRSA in wards during intervention periods.
  • This compared with 76 patients (0.91 per 1,000 patient days) in the wards during control periods.
  • 53 of the 93 infected patients (57 per cent) did not have MRSA on admission and acquired it while in hospital.
  • The rate of hospital acquired MRSA infection and MRSA surgical site infection did not change significantly between the intervention periods and the control periods.

The authors concluded that:

“Overall, our real-life trial did not show an added benefit for widespread rapid screening on admission compared with standard MRSA control alone in preventing nosocomial [hospital acquired] MRSA infections in a large surgical department.”

They suggested that effectiveness could be increased if MRSA screening were:

“Targeted to surgical patients who undergo elective procedures with a high risk of MRSA infection.”

In such cases,” they added, “earlier identification would allow sufficient time for optimal preoperative handling, including preoperative decontamination and adjustment of surgical prophylaxis [disease prevention]”.

The authors recommended that medical teams responsible for surgical services and infection control:

“Carefully assess their local MRSA epidemiology and patient profiles before introducing a universal screening policy.”

“Universal Screening for Methicillin-Resistant Staphylococcus aureus at Hospital Admission and Nosocomial Infection in Surgical Patients.”
Stephan Harbarth; Carolina Fankhauser; Jacques Schrenzel; Jan Christenson; Pascal Gervaz; Catherine Bandiera-Clerc; Gesuele Renzi; Nathalie Vernaz; Hugo Sax; Didier Pittet.
JAMA Vol. 299 No. 10, March 12, 2008

Click here for Abstract.

Sources: JAMA press release and abstract.

Written by: Catharine Paddock, PhD