Hospitals Share Patients and Antibiotic-Resistant Bacteria

Steven Fox

August 01, 2013

Even a moderate increase in vancomycin-resistant enterococci (VRE) in a single hospital can significantly increase rates in other hospitals in the same region, according to a new study published in the August issue of the American Journal of Infection Control.

To assess the effect of VRE rates on hospitals in a shared region, Bruce Y. Lee, MD, from the Public Health Computational and Operations Research and the Graduate School of Public Health, University of Pittsburgh, Pennsylvania, and colleagues devised a simulation model.

They note that being aware of dynamic relationships among hospitals within the same region could have important implications for developing policies and making decisions regarding infection control.

"Without considering such relationships," they write, "decision makers may misattribute changes in a hospital's VRE burden to actions within that hospital, potentially leading to the allocation or removal of resources for control measures that may or may not appear to be effective."

To find out more about how resistant organisms are spread from one institution to another, Dr. Lee and coworkers first obtained 2006 to 2007 data on admissions and transfers from 29 adult acute care hospitals in Orange County, California. Those data included details on length of stay, where and when patients were admitted or discharged, and other encrypted patient information that helped the researchers track patient movement between hospitals.

The investigators then developed an agent-based model encompassing all the hospitals. The model simulated changes in colonization and prevalence of VRE in each of the hospitals, and it also determined how quickly problems in one hospital could affect the others.

They found that a sustained 10% increase in the prevalence of VRE colonization in any single hospital was associated with an average relative increase of 2.8% in the others. Although 2.8% was the average, increases of as much as 61.9% were seen in some hospitals.

In addition, the researchers stress that those effects did not always show up immediately, sometimes taking more than 10 years to become fully manifest. Not surprisingly, colonizations in bigger hospitals tended to have the greatest effect, region-wide.

The investigators say their model also identified what they called "free riders," or hospitals that experience decreases in incidence of VRE as a result of measures enacted in other hospitals.

They conclude, "[L]owering barriers to cooperation and collaboration among hospitals (eg, developing regional control programs, coordinating VRE control campaigns, and performing regional research studies) could favorably influence regional VRE prevalence."

This study was supported by the National Institute of General Medical Sciences Models of Infectious Disease Agent Study, the National Institutes of Health, and the Pennsylvania Department of Health. The authors have disclosed no relevant financial relationships.

Am J Infect Control. 2013;41:668-673. Full text


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.