Collaborative MRSA Control Efforts Would Pay Off

A computer simulation suggests that coordinating MRSA prevention efforts in hospitals throughout a region would decrease MRSA prevalence more effectively than implementing prevention measures in a single hospital.

Coordinated surveillance and isolation of methicillin-resistant Staphylococcus aureus (MRSA) infections by all hospitals in a region can help achieve better MRSA control than solo efforts, according to the results of a study published in the October 2012 edition of Health Affairs.

Hospitals in a county or region often share patients, but infection control measures are generally not coordinated among hospitals unless the locations are associated legally or financially, the researchers noted. As a result, their study used a computational model developed by the National Institutes of Health Models of Infectious Disease Agent Study MRSA Working Group to determine the impact of testing patients for MRSA colonization at admission and requiring staff members who interact with MRSA-positive patients to follow contact isolation procedures.

The researchers focused on 29 acute care hospitals in Orange County, California. The model simulated a daily average of 3740 virtual patients in the hospitals and surrounding community. MRSA rates used in the simulation were based on actual hospital records, and the virtual patients in the simulation were assigned to intensive care units or general hospital wards for periods that corresponded to actual patients’ length-of-stay. After release, some of the virtual patients returned to the community, while others were admitted to another hospital. Other virtual patients were readmitted to the same or a different hospital at a later date, according to probabilities derived from the hospitals’ records.

The researchers tested the simulated preventive measures in several different ways, including implementing them in a single county hospital, in high-volume hospitals (those with 10,000 or more admissions per year), high-capacity hospitals, and in all hospitals in Orange County. In the high-capacity hospital simulation, the researchers modeled implementing the measures in the 3 largest (307 beds on average), 5 largest (281 beds average), and 10 largest (232 beds average) facilities.

According to the simulation results, a lone hospital implementing MRSA surveillance and isolation procedures with a 75% compliance rate would see an 11.27% decrease in median relative MRSA prevalence (range: 6.73% to 19.08%) and would avoid a median of 37 MRSA cases per year. Under this scenario, hospitals that did not implement MRSA prevention procedures would experience some benefit as well, seeing a median reduction in MRSA prevalence of 0.27% and a median decrease of 1 MRSA case per year.

However, according to the simulation in which all hospitals in the county implemented the intervention simultaneously, again assuming a 75% rate of compliance with isolation procedures, facilities would benefit even more than they would by implementing the procedures alone. In this scenario, acute-care hospitals would see an additional median decrease of 3.85% in MRSA prevalence, and long-term acute care facilities would see an additional median decrease of 12.13% in MRSA prevalence.

The simulation found, unsurprisingly, that MRSA prevalence falls as the rate of compliance with isolation procedures increases. (Increasing isolation compliance from 25% to 50% roughly doubles the effect, and increasing compliance from 50% to 75% roughly doubles the effect again.) This finding underscores the importance of increasing surveillance and compliance with isolation procedures in hospitals, the researchers noted.

“Our study shows that coordination of MRSA prevention practices in infection control, even among small groups of hospitals, can benefit all hospitals in a county, even those that do not implement the intervention,” the researchers wrote. “The effects of persuading other hospitals in the same county to implement control mechanisms can help hospitals achieve better infection control than they could on their own. The more hospitals that work together, the greater the benefits accrued.”