Risk for VRE linked to previous environmental contamination

Experts urge increased attention to disinfection in health care settings.

Issue: March 2008

Patients may be at an increased risk for vancomycin-resistant enterococci in health care settings if they are treated in areas where contamination with vancomycin-resistant enterococci has previously occurred, according to the results of a new study, which were published in Clinical Infectious Diseases.

Prior room contamination is highly predictive of vancomycin-resistant enterococci (VRE) acquisition, according to the study’s researchers, who stressed that increased attention to environmental disinfection is warranted to help reduce the risk for VRE infection.

“Everyone on the health care team — from doctors, to nurses, to medical students, to technicians — needs to take personal responsibility for preventing infections,” Marci Drees, MD, from the Center for Outcomes Research at Christiana Care Health System in Newark, Del., and one of the study’s researchers, told Infectious Disease News. “I think for too long we’ve had the attitude that these infections ‘just happen’ and are bad luck, but we now know that many are preventable. Preventing infections comes down to the basics: universal handwashing, wearing gowns and gloves when appropriate and thorough environmental cleaning. It’s easy to cut a corner here and there when you’re busy taking care of patients, but that’s how these infections happen.”

Study in hospitals

Drees and her colleagues conducted a 14-month study in two hospital intensive care units (ICUs). They obtained and analyzed environmental cultures once per week and patient cultures twice per week.

To determine risk factors for vancomycin-resistant enterococci acquisition, the researchers examined Cox proportional hazards models using time-dependent covariates for colonization pressure and antibiotic exposure. The researchers defined VRE acquisition as a positive culture result more than 48 hours after admission.

There were 1,330 patients admitted to the ICUs at the hospitals during the study period. According to the researchers, 638 of these patients were at risk for VRE. Fifty of the patients acquired a VRE infection.

Three of the most significant factors associated with the risk for a VRE infection included sharing a room with a VRE-colonized patient, being treated in a room where a VRE-colonized patient had been treated within the past two weeks and being treated in a room with previous positive culture results. Other factors associated with VRE acquisition included increased colonization pressure, increased use of antibiotics and leukemia.

Further results indicated that even after adjusting for colonization pressure and antibiotic exposure, the three environmental exposure factors were predictors for VRE risk.

Drees said the results showed that health care providers need to be more thorough with infection control measures. “If handwashing before and after patient care were truly universal, these organisms would not be passed among patients,” Drees said. “Clearly, patients’ bodies and environments become contaminated with VRE, and various methods to reduce this contamination have been shown to be beneficial. Reducing unnecessary antibiotic use is also important, as this is what is driving much of the resistance.” – Jay Lewis

For more information:

Drees M, Snydman DR, Schmid CH, et al. Prior environmental contamination increases the risk of acquisition of vancomycin-resistant enterococci. Clin Infect Dis. 2008;46:678-685.