More is not always better

Pergam Lab, Vaccine and Infections Disease Division

    Since the early 1990s vancomycin antibiotic resistant enterococci  (VRE) have become a concern for hospitalized populations including hematopoietic cell transplant (HCT) recipients. HCT recipients are immunosuppressed as a result of their treatment and experience higher occurrences of bloodstream infections leading to increased morbidity and mortality. VRE is one of the leading causes of gastrointestinal (GI) tract colonization, leading to bacteremia in this population, occurring in 28-61% of HCT recipients. Risk factors for VRE in this population include hospitalization, catheter use, previous use of vancomycin and immunosuppression. The Centers for Disease Control and Prevention has set up guidelines to reduce spread and occurrences of VRE. An outline of steps can be found in Morbidity and Mortality Weekly Reports. Briefly, the CDC recommends surveillance of GI colonization, contact precautions for colonized patients, and environmental cleaning with disinfectants. Since the steps have been in place there is controversy over the best practices and each facility should assess their disease burden and preventative measures individually. In a study published in the Journal of Infection Dr. Pergam (Vaccine and Infectious Diseases Division) and colleagues study the effects of infection prevention at Seattle Cancer Care Alliance looking at VRE colonization, VRE bacteremia, and mortality over the last ten years.

Scanning Electron Micrograph of Vancomycin Resistant Enterococci. Photo Credit: Janice Haney Carr, CDC

            Over a ten-year period yielding 1,492 HCT recipients, 14% had VRE colonization pre-HCT and starting post-HCT 2.8% developed VRE bacteremia within 100 days. This value is considered low when compared to other published studies, suggesting that the institute has a good track record with VRE over the ten-years studied. Differences between institutes could be attributed to differences in antibiotic use, transplantation procedures, and infection control practices. In order to try and attribute risk to VRE specific protocols, the group looked at patients from the last decade, when practices to combat VRE acquisition and spread changed. Recipients can be separated into three categories, pre-chlorhexidine bathing, pre-UV cleaning of rooms, and post-intervention. This allowed the researchers to gauge VRE morbidity risk factors, specific for this institute and practices. There appeared to be no difference in outcome between implementation of prevention strategies over the duration. However, other risk factors were found.  Pre-HCT colonization appeared to be the biggest risk factor for post-HCT occurrence and mortality. Pre-transplant assessment of morality (PAM) score also was associated with risk; the higher the score the higher the VRE bacteremia chances are, especially in pre-HCT colonized patients.

            Results from this study were similar to others published suggesting that extra measures, which cost time and money, did not further reduce the already small VRE bacteremia occurrence. From this we can infer that discontinuing routine screens and contact isolation should not change occurrence rates. Dr. Pergam commented, “Isolation is the current recommendations at most cancer centers, but this data suggests perhaps this approach needs to be reconsidered. We hope instead to focus our efforts on antibiotic overuse as a major method for curbing this hospital-acquired infection.” This would allow for more resources, money and time to be spent on horizontal interventions and standard adherence to hand hygiene, environmental disinfection, and infection prevention programs rather than a pathogen specific program. The less unique protocols the easier it is for healthcare professionals to follow institutes overall best practices.

MacAllister TJ, Stohs E, Liu C, Bryan A, Whimbley E, Phipps A, Pergam SA. 2018. 10-year trends in vancomycin-resistant Enterococci among allogeneic hematopoietic cell transplant recipients. Journal of Infection. Epub ahead of print.

Funding provided by the National Cancer Institute.

Fred Hutch/UW Cancer Consortium faculty members Steven Pergam, Amanda Phipps, and Catherine Liu contributed to this research.