MRSA Screening at Hospital Does Not Appear to Reduce Infection Rate

New findings do not support the recommendation for universal screening on hospital admission for methicillin-resistant Staphylococcus aureus (MRSA) to reduce the rate of hospital-acquired infections in surgical patients, according to a study in the March 12 issue of JAMA.

Individuals who carry antimicrobial-resistant disease-producing agents such as MRSA places patients at high risk of infection. Early identification of patients with MRSA and subsequent prevention of patient-to-patient spread through infection control measures are believed to be important interventions to control MRSA.

Experts and policy makers, nationally and internationally, recommend universal admission screening as a means to control MRSA. However, no controlled trial has tested the hypothesis that rapid MRSA screening may improve patient outcome by decreasing MRSA cross-transmission and increasing the adequacy of pre-operative prophylaxis [disease prevention], the authors write.

Stephan Harbarth, MD, MS, and colleagues with the University of Geneva Hospitals and Medical School, Geneva, Switzerland, conducted a study to evaluate the effect of a early MRSA detection strategy on MRSA infections acquired in a hospital (nosocomial ) among 21,754 surgical patients at a Swiss teaching hospital. There were two MRSA control strategies: rapid screening on admission plus standard infection control measures vs. standard infection control alone.

Twelve surgical wards including different surgical specialties were enrolled according to a pre-specified protocol, assigned to either the control (n = 10,910) or intervention (n = 10,844) group for a nine-month period, then switched to the other group for another nine months. During the screening intervention periods, patients admitted to the intervention wards for more than 24 hours were screened before or on admission by a molecular technique for rapid, early detection of MRSA. Overall, 10,193 (94 percent) of the intervention group patients were screened with the rapid test during the intervention periods. Median time from admission screening to notification of test results was 22.5 hours.

Admission screening during the intervention periods identified a total of 515 MRSA-positive patients among the screened patients (5.1 percent). The majority of patients (n = 337 [65 percent]) had not been previously identified as MRSA carriers and would have been missed without systematic screening on admission. The authors estimate that to detect 1 previously unidentified MRSA carrier on admission, 30 patients would have to be screened.

A total of 93 patients (1.11 per 1,000 patient-days) developed nosocomial MRSA infection in the intervention periods compared with 76 patients (0.91 per 1,000 patient-days) in the control periods. The rate of MRSA surgical site infection and nosocomial MRSA acquisition did not change significantly. Fifty-three of 93 infected patients (57 percent) in the intervention wards were MRSA-free on admission and developed MRSA infection during hospitalization.

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 MRSA infections in a large surgical department. To increase effectiveness, MRSA screening could be targeted to surgical patients who undergo elective procedures with a high risk of MRSA infection. In such cases, earlier identification would allow sufficient time for optimal preoperative handling, including preoperative decontamination and adjustment of surgical prophylaxis. Finally, we suggest that surgical services and infection control teams should carefully assess their local MRSA epidemiology and patient profiles before introducing a universal screening policy, the authors conclude.

In an accompanying editorial, Preventing MRSA Infections: Finding It is Not Enough, Daniel J. Diekema, MD, of the University of Iowa Carver College of Medicine and Iowa City Veterans Affairs Medical Center, Iowa City, and Michael Climo, MD, of the Virginia Commonwealth University Medical Center and Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Va., write that more research is required regarding controlling MRSA infections. While awaiting more and better data, what should clinicians do to control MRSA in hospitals? The first part of a tiered approach should include careful assessment of MRSA within the local healthcare environment. Hospitals should first adhere to established infection control principles and pursue patient safety initiatives known to reduce morbidity and mortality from all healthcare-associated infectious pathogens. Despite the attention rightly focused on MRSA, this pathogen causes only 8 percent of hospital-acquired infections in the United States, according to the most recent data from the National Healthcare Safety Network.

They continue, Interventions that will address those 8 percent plus the other 92 percent of hospital infections include intensive and multifaceted hand hygiene programs; bundled interventions to reduce central venous catheterrelated bloodstream infections, ventilator-associated pneumonia, and surgical site infections; and source control in the form of chlorhexidine [an antiseptic] bathing of intensive care unit patients. These interventions are simple and cost-effective and have the benefit of reducing all infections, including those due to MRSA. If healthcare-associated infections can be reduced to near zero with bundled interventions, MRSA infection rates should fall concordantly.

Reference: JAMA. 2008;299[10]:1149-1157.

Source: American Medical Association