Examining Health Care Worker Contact Networks Behind VRE Transmission

Vancomycin-resistant enterococci (VRE) can sicken approximately 20,000 Americans annually, and the US Centers for Disease Control and Prevention (CDC) has labeled the bacteria a “concerning threat.”

Understanding the dynamics of VRE transmission is essential to improving prevention efforts. A recent study explored how patient colonization and environmental contamination impact the spread of VRE. But more information is needed on the role of health care workers in mediated contact networks and the transmission of VRE.

To address this deficiency in information, a team of investigators from the CDC Prevention Epicenters Program and the CDC MIND-Healthcare Program conducted a retrospective analysis. The team’s findings were published in Open Forum Infectious Diseases.

The data shed light on how health care mediated contact networks are involved in the spread of VRE and may present an opportunity to learn more about the dynamics of transmission for multidrug-resistant pathogens.

For the analysis the investigators assessed clinical and demographic patient data and also examined contact with health care workers.

The investigators accessed this information electronic health records collected by 5 John Hopkins Health System hospitals in Maryland and the District of Columbia. Of the 9000+ patients included in the database there were 2952 hospitalizations from 2364 patients. These patients had 2 or more VRE surveillance swabs, detecting 112 incident nosocomial acquisitions.

The average length of hospital stay was 12 days, during which patients made a median of 24 and an average of 26 contacts with health care workers, of which 9, or 40%, occurred within <1 hour after another patient contact.

A connection between patients was defined as 2 patients making contact with the same health care worker within a 60-minute period. These connections were assessed directionally to give a better picture of how VRE flowed through contact networks.

“Connections were directed, meaning that an HCW [health care worker] contacting patient A and then patient B within 60 minutes would be counted as a connection for patient B but not patient A,” study authors wrote.

The highest median and average daily contact rates were among nurses, followed by technicians and therapists.

About 40% of the health care worker contacts took place within an hour of contact with another patient. The average number of patient connections per day was 11.2, with a median of 9.

Patients that acquired VRE had an average number of 3.1 daily connections to VRE positive patients, compared with an average number of 2.0 daily connections among those who did not acquire VRE.

The study successfully demonstrated that electronic health record data can be examined to quantify health care worker mediated patient transmission of VRE within the hospital. It also demonstrates the potential to better implement interventions to contain VRE spread.

The role of contact precautions to prevent the spread of multidrug-resistant organisms has been a subject of debate for several years now. The discontinuation of routine contact precautions for VRE did not affect health care associated infection rates, a 2019 study across 12 hospitals demonstrated.

The discussion on how to curb the spread of drug-resistant pathogens within health care systems will continue for the foreseeable future, but new information like that examined in the recent transmission network study will be critical to moving the conversation forward onto new ground.