MRSA admission screening may not reduce staph infection rates

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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, M.D., M.S., 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 9-month period, then switched to the other group for another 9 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 (midpoint) 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.

Source: Journal of the American Medical Association, USA

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