Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Key Considerations for Microbial Viability Measurements

Published

Author(s)

Joy Dunkers, Sandra M. Da Silva, Stephanie Servetas, James J. Filliben, Guilherme L. Pinheiro, Nancy Lin

Abstract

Making reliable measurements of antimicrobial killing efficacy requires careful consideration of the sources of biological variability, measurement bias and error throughout the entire workflow. For ultraviolet-C (UV-C) disinfection, killing efficacy is most commonly measured using plate counting where the log10 reduction in colony forming units (CFUs) is calculated using the inoculum CFU count before and after UV-C exposure. Although CFU counting is not a rapid diagnostic, it is fit-for-purpose for testing UV-C sources and establishing room disinfection protocols. Best practices for minimizing biological and technical error in plate counting have been established. Careful consideration of sources of variability during all experimental stages can help minimize error propagated to the final log10 reduction value. Instrument calibration, sample preparation, counting and viability measurements performed at NIST provide insights that could further improve confidence in killing efficacy results.
Proceedings Title
Conference Proceedings for Workshop on Ultraviolet Disinfection Technologies & Healthcare
Associated Infections: Defining Standards and Metrology Needs
Conference Dates
January 14-15, 2020
Conference Location
Gaithersburg, MD, US
Conference Title
Workshop on Ultraviolet Disinfection Technologies & Healthcare Associated Infections: Defining
Standards and Metrology Needs

Citation

Dunkers, J. , Da Silva, S. , Servetas, S. , Filliben, J. , Pinheiro, G. and Lin, N. (2020), Key Considerations for Microbial Viability Measurements, Conference Proceedings for Workshop on Ultraviolet Disinfection Technologies & Healthcare Associated Infections: Defining Standards and Metrology Needs, Gaithersburg, MD, US, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=929444 (Accessed September 23, 2022)
Created January 14, 2020, Updated October 14, 2021