Under the Microscope with Bill Rutala: Microbial Burden on Environmental Surfaces

Author: Dr. William Rutala, PhD, MPH, CIC

Categories: Clinical Pathogens/Alerts & Surface Disinfection October 10, 2021
Hospital Room Patient

Microbial burden on environmental surfaces in patient rooms before daily cleaning-Analysis of multiple confounding variables, authored by Boyce JM, Havill NL, Guercia KA, and Moore BA1 addresses the factors that contribute to an assessment of the microbial burden on environmental surfaces as well as determines the microbial burden on high-touch surfaces before cleaning/disinfection.

The study found that the level of microbial contamination on surfaces varies considerably. About 70% of the surfaces had ≤ 60 aerobic colony counts (ACC)/Rodac (mean 55.6 ACC/Rodac) but some samples were ≥200 ACC/Rodac.  Mean ACCs differed significantly by type of surface, with the highest mean ACCs occurring on surfaces near patients and in bathrooms.  Overall, about 30% of surfaces had ≥ 2.5 CFU/cm2 and would be classified as “dirty” before daily cleaning/disinfection. Using this criterion, the “dirtiest” surfaces were toilet seats (58.6%), bedside rails (52.1%), and bathroom grab bars (43.6%). Mean total ACCs per room did not differ significantly between quaternary ammonium compound (per melt-blown polypropylene wipe) use and improved hydrogen peroxide (per ready-to-use wipe). The mean ACCs differed significantly by site, type of ward, isolation room status, and study period. Surfaces with high ACCs were not necessarily contaminated with pathogens because overall ACCs do not correlate well with the level of pathogens present.

The key takeaways from this study are the level of microbial contamination on surfaces before cleaning/disinfection is generally low (mean 55.6 ACC/Rodac but there is high variance), mean total ACCs per room did not differ significantly between quaternary ammonium compounds, and improved hydrogen peroxide, and microbial burden on environmental surfaces is affected by multiple factors.

Boyce JM, Havill NL, Guercia KA, Moore BA. Microbial burden on environmental surfaces in patient rooms before daily cleaning-Analysis of multiple confounding variables. Infect Control Hosp Epidemiol 2021 Aug 16;1-5. doi: 10.1017/ice.2021.349.

Author

Dr. William Rutala, PhD, MPH, CIC PhD, MPH, CIC
Dr. William Rutala PhD, MPH, CIC Professor for the Division of Infectious Diseases, and Director of Hospital Epidemiology

Profile

Dr. William (Bill) Rutala is a Professor for the Division of Infectious Diseases at the University of North Carolina’s School of Medicine, and serves as the Director of Hospital Epidemiology, Occupational Health and Safety Program at the University of North Carolina Health Care System.

He is also Director and co-founder of the Statewide Program for Infection Control and Epidemiology at the UNC School of Medicine and a retired Colonel with the U.S. Army Reserve. Dr. Rutala is certified in infection control. He is an advisor to the Centers for Disease Control and Prevention (a former member of the Healthcare Infection Control Practices Advisory Committee [HICPAC], 1999-2003), the Food and Drug Administration (a former member of the General Hospital and Personal Use Devices Panel), the U.S. Environmental Protection Agency (a member of the Scientific Advisory Panel on Antimicrobial Research Strategies for Disinfectants) and the Federal Trade Commission.

Dr. Rutala is a member of various committees on the local, state, national and international level as well as several professional societies including the American Society for Microbiology, Association for Professionals in Infection Control and Epidemiology and the Society of Healthcare Epidemiology of America. He serves on the editorial board of the Infection Control and Hospital Epidemiology. He has more than 500 publications (peer-review articles, books, book chapters, abstracts) in the fields of infectious diseases, infection control, disinfection, sterilization and medical waste to include several guidelines (e.g., CDC Guideline for Disinfection and Sterilization in Healthcare Facilities). Dr. Rutala has also been an invited lecturer at over 300 state, national and international conferences (in over 40 states and 25 countries) and has testified twice before the U.S. Congress.

Dr. Rutala earned his Bachelor of Science degree in science from Rutgers University, his master’s degree in microbiology from the University of Tennessee and both his master’s in public health and doctorate in microbiology from the University of North Carolina School of Public Health.

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