Patient sharing among hospitals in one county or region combined with a failure to share infection control information can lead to an increase in cases of vancomycin-resistant enterococci (VRE) at all hospitals in that county when one facility experiences a moderate increase in cases.

A sustained increase of 10 percent of VRE cases in one hospital can lead to a nearly 3 percent increase in VRE at every hospital in that county, according to a recent study published by the Association for Professionals in Infection Control and Epidemiology (APIC).

Enterococci are the second most common organisms recovered from catheter-associated infections, and skin and soft tissue infections in the United States, according to the study. Estimates of cases in U.S. hospitals range from 20,931 to 85,586 infections involving the so-called superbug.

"Our study demonstrates how extensive patient sharing among different hospitals in a single region substantially influences VRE burden in those hospitals," says Bruce Y. Lee, M.D., lead author and associate professor of international health, director of operations research, International Vaccine Access Center, and director of public health and infectious diseases computational and operations research at the Johns Hopkins Bloomberg School of Public Health, Baltimore.

Lee led a team of researchers from the Bloomberg School of Public Health, Pittsburgh Supercomputing Center at the University of Pittsburgh, and the University of California–Irvine, who created the Regional Healthcare Ecosystem Analyst.

The system tracked the movement of VRE-colonized patients who were carrying the organism, but not necessarily infected, over a one-year period in Orange County, Calif., and assessed how increases or decreases in one hospital's VRE cases affected other hospitals in the county.

"Over the course of a year, a given hospital will end up sending patients either directly or indirectly to almost 90 percent of the other hospitals. So that's the main mechanism for how VRE spreads," Lee says. There are about 30 hospitals in Orange County.

Many hospitals commonly do not test for VRE or track which or how many patients carry VRE or have VRE infections, Lee says. "Even those that do track the number of cases often do not share this information with other hospitals. Therefore, hospitals are unaware of which hospitals may have problems with VRE."

If a hospital were to inform another health care facility that a transferred patient has VRE, the receiving hospital could take measures to control the spread, he says.

"If patients are identified as having VRE through testing, they can be placed under contact isolation or precautions taken, which means anyone encountering them should put on a gown and gloves. They also can be placed in a private or semiprivate room to reduce contact with other patients," Lee says.

Other potential measures to stop the spread include enhanced environmental cleaning of bed sheets, furniture and floors or placing patients with VRE in the same room. Decolonization of patients – trying to remove the pathogen through antiseptics or antibiotics — also has been tried to control the pathogen, Lee adds.