Measures to Prevent and Control Vancomycin-Resistant Enterococci: Do They Really Matter?

To the Editor—The study by Lemieux et al ¹ from Ontario, Canada, and other recent studies in this journal highlight the continuing importance of vancomycin-resistant enterococci (VRE) but also the varying approaches depending on circumstances. ^{2 , 3} Complete cessation of control measures for VRE in 4 large academic hospitals in Ontario had no significant impact on VRE bloodstream infection (BSI) rates, or carriage rates. ¹ A single-center study from Buffalo, New York, in a hematology-oncology unit found no increased incidence of VRE BSI after discontinuation of contact precautions although all patients were admitted to a single room. ² However, a systematic review of the incidence of VRE infection in the United States found that VRE continues to be an important cause of healthcare-associated infection and that, in Atlanta and Detroit, there have been increases in recent years associated with mortality, longer length of stay, and higher healthcare costs. ³

The literature does confirm the success of interventions, either in single-center studies or in other studies, even if many of these studies are less than ideal. A bundle that included active surveillance and better environmental hygiene in Singapore resulted in a significant decrease in cases of VRE infection and colonization; the authors felt that VRE screening and isolation were an in important component of that bundle. ⁴ While there is considerable variation regarding which patients should be screened for VRE and how, in some centers screening itself often seems to have a beneficial effect. ⁵ This benefit may arise from increased awareness leading to better compliance with standard precautions.

Many horizontal infection prevention and control measures applied to all patients can have a beneficial impact on the VRE load. For example, chlorhexidine bathing in a stem-cell transplantation unit over a 9-year period reduced rates of VRE colonization and infection, but the potential for increased resistance to chlorhexidine was suggested. ⁶ In addition, the results of this before-and-after study may have been influenced by other factors. The inconsistency of research studies on VRE prevention and control have been well illustrated in a recent systematic review of measures carried out by de Angelis et al. ⁷ Of 549 initial studies, only 9 met the eligibility criteria for scientific rigor, and in most cases these studies described multiple interventions. ⁷

Measures to prevent VRE need to be tailored to specific patient groups, the local epidemiology, the clinical setting, and other measures being undertaken to prevent infection. For example, in a well-designed interrupted time-series study and cluster-randomized trial involving 13 intensive care units in the Netherlands, improved hand hygiene and chlorhexidine body washing were the only significant factors in reducing the acquisition of antimicrobial-resistant bacteria, including VRE. ⁸ This study also evaluated the impact of rapid detection using molecular methods, but it did not have a significant impact in a critical care setting. Like methicillin-resistant Staphylococcus aureus and Clostridium difficile, VRE can persist for prolonged periods in significant numbers in the environment. In a 30-month, prospective, intervention study on 6 high-risk units, the additional use of hydrogen peroxide to decontamination regimens significantly reduced the chances of acquiring a multidrug-resistant organism (MDRO), but much of the explanation for the overall effect on MDROs arose from the beneficial impact on VRE acquisition. ⁹ Even where hydrogen peroxide is not used or is not feasible, improved environmental decontamination is important in preventing VRE and other healthcare-associated infections. This, together with enhanced hand hygiene remain essential as efforts to decolonize patients are only partially successful and probably only for limited periods of time, given the normal habitat of VRE and the complex microbiome in the gastrointestinal tract. ¹⁰

In recent years, greater emphasis has been placed on measures to prevent Clostridium difficile infection and infections due to carbapenamase-producing bacteria, but a significant healthcare burden is associated with VRE, with the added concern of resistance to agents used in treatment, such as linezolid and daptomycin. Some centers would be wise to continue with active screening to monitor trends and to target additional measures, even if many of the measures to prevent and control VRE are similar to those for other nosocomial pathogens, including improved hand-hygiene, better environmental decontamination, and antibiotic stewardship. Consequently, we should be reluctant to discontinue even selective screening and contact precautions until larger studies in more diverse clinical settings are carried out.