Universal screening for mrsa at hospital admission may not reduce infection rates

Universal screening for mrsa at hospital admission may not reduce infection rates

According to a study published in JAMA, universal screening at hospital admission for methicillin-resistant Staphylococcus aureus (MRSA) does not seem to reduce the rate of hospital-acquired infections in surgical patients.

MRSA is an antimicrobial-resistant disease-producing agent that can infect surgical patients. It is thought that in order to control MRSA, doctors and hospitals must identify patients with MRSA as early as possible. They also must use infection control measures to prevent patients from spreading the infection to other patients. The researchers write: "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 study, conducted by Stephan Harbarth, M.D., M.S. (University of Geneva Hospitals and Medical School, Geneva, Switzerland) and colleagues, aimed to determine the effect of an early detection strategy for MRSA on MRSA infections acquired in a hospital. These hospital-acquired infections like MRSA are termed "nosocomial", and include infections that are secondary to the patient's original condition; urinary tract infections and pneumonia are common nosocomial infections. Harbath and colleagues studied 21,754 surgical patients at a Swiss teaching hospital, and used two MRSA control strategies: 1) rapid screening on admission plus standard infection control measures and 2) standard infection control alone.

The researchers chose twelve surgical wards with various surgical specialties to enroll in the study that met requirements of a pre-determined protocol. Each ward was assigned to either the control (10,910 patients) or intervention (10,844 patients) group for a 9-month period. The groups then switched for a subsequent 9-month period. Upon or before admission to a surgical ward in the intervention group for more than 24 hours, a molecular technique for rapid, early detection of MRSA was applied to patients. About 94% (10,193 patients) of the intervention group received the rapid test during the intervention periods. There was a median time of 22.5 hours from admission screening to notification of test results.

A total of 515 (5.1%) of the screened patients were diagnosed as MRSA-positive during the intervention periods. Sixty-five percent of these (337 patients) had not been previously identified as MRSA carriers. Without systematic screening upon admission, they would have been missed. According to estimates made by the authors, 30 patients would have to be checked in order to detect 1 previously unidentified MRSA carrier at admission.

In the intervention periods, 93 patients (1.11 per 1,000 patient-days) developed nosocomial MRSA infection, whereas 76 patients (0.91 per 1,000 patient-days) developed infections it in the control periods. The authors did not find a significant change in the rate of MRSA surgical site infections and nosocomial MRSA acquisitions. Of the 93 infected patients in the intervention wards, 53 (57 percent) did not have MRSA upon admission but developed MRSA 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," conclude the authors.

An editorial in the same issue of the journal, by Daniel J. Diekema, M.D. (University of Iowa Carver College of Medicine and Iowa City Veterans Affairs Medical Center, Iowa City) and Michael Climo, M.D. (Virginia Commonwealth University Medical Center and Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Va.), suggests that more research is needed in order to control 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 health care environment. Hospitals should first adhere to established infection control principles and pursue patient safety initiatives known to reduce morbidity and mortality from all health care-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," write Diekema and Climo.

They conclude: "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 catheter-related 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 health care-associated infections can be reduced to near zero with bundled interventions, MRSA infection rates should fall concordantly."

JAMA. . 299(10):1149-1157.

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