Are we SINK-ing with Gram Negatives?

Reviewed by: Valeria Fabre, MD, Johns Hopkins University School of Medicine

Two articles this month highlight the impact of the environment on healthcare-associated infections (HAIs). 

Novosad and colleagues describe the epidemiology of central-line–associated bloodstream infections (CLABSIs) in adults and children in acute-care locations based on the Centers for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN) data from 2011–2017. The study shows that most CLABSIs were from adult patients (44% from adult intensive care units (ICUs) and 30% from adult wards). During this time frame, there has been a 30% increase in CLABSIs due to yeast in adult ICUs (Candida represented 27% of all adult ICU CLABSIs in 2017) and a 55% increase in CLABSIs due to Enterobactericeae in Oncology wards. For 2017, Enterobactericeae were the most common CLABSI pathogen for PICU, adult wards, pediatric wards and Oncology. The substantial proportion of CLABSIs caused by environmental gram-negative bacteria highlights the need for improved water quality and improved cleaning and disinfection of surfaces around sinks and sink bowls. Similarly, the increase in yeast CLABSIs is concerning as candidemia has been traditionally linked to gut translocation and the observed increase in Candida CLABSIs cannot be fully explained by the changes in CAUTI definition. 

While the environment has been linked to an increase in gram-negative HAIs, the role of sink contamination has not been fully elucidated. Studies have shown that sink drains closer to toilets within patient rooms have much higher load of bacterial pathogens including KPC. Ramos-Castaneda and colleagues evaluated the impact of two hydrogen peroxide-based products on sink drain bacterial load and determined the optimal frequency with which these products should be applied. Twenty-six sinks in single ICU rooms were randomly assigned to no disinfectant, product A (hydrogen peroxide, octanoic acid, and peroxyacetic acid; Virasept, Ecolab, St Paul, MN -this product comes ready to use-) or product B (hydrogen peroxide-based disinfectant; Peroxide Multi Surface Cleaner and Disinfectant, Ecolab -this product requires dilution-). A blinded investigator performed sink swabs on days 0, 1, 3, 5 and 7 after the intervention and quantification of gram-negative burden was determined by serial dilution in saline plated to MacConkey agar. With similar baseline bacterial loads among 3 groups, there was a significant reduction in colony-forming units (CFU) on days 1 and 3 with both products although product A had a larger reduction in sink drain bacterial burden. CFU counts returned to baseline on day 5 in all groups indicating that a frequency of 3-5 days would be ideal for optimal skin disinfection.


  1. Novosad SA, et al. (2020). Pathogens causing central-line–associated bloodstream infections in acute-care hospitals—United States, 2011–2017. Infection Control & Hospital Epidemiology, 
  2. Ramos-Castaneda JA, et al. (2020). How frequently should sink drains be disinfected?. Infection Control & Hospital Epidemiology,
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