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University of Kentucky – Virus and Disinfectant Testing

John Summersett, University of Kentucky
April 20, 2020

Since attending the first APPA Town Hall, I have found them to be most interesting and informative. In the past when I helped teach microbiology to dental students I would use an example of E. coli to show how disinfectants work. I took a population of 1,000,000 cells and showed how even using a disinfectant that had a kill rate of 99.99 percent the number of organisms which remained. E. coli has a reproduction rate of 37 minutes. Using the duplication concept the original population would return within 4 hours.  This would show how when cleaning it is so important to 1) read the directions and not the length of time the surface must remain wet, and 2) follow these directions and be sure the surface is wet for the required time.

We also used an experiment to show how just shaking hands could spread a disease. In this experiment we coated a candy bar with an organism. A student would just hold the bar for a few seconds. He then would shake hands with someone else. This shaking hands would progress down the line. Each individual’s hand would be swabbed and cultured. We found this process would go about 10 students until no more of the original organism remained. This showed how disease can spread. Just imagine if the individual would touch the face and allow this to get into their system.

I found last week the comment about the use of dry hydrogen peroxide to be very interesting. I did some checking and found this method does have an EPA registration number.  Another experiment I have been involved in was the use of UV lights within an air handling system. In this experiment we did some testing for mold and found over a 95 percent reduction in the viable mold population in the air stream. Our experiment confirmed what others had done in the past.