The Effects of Isopropyl and Cetylpyridinium Chloride on the Resistance of Bacteria Populations

This experiment tests bacteria resistances to the active ingredients of two popular mouthwashes.  The method of testing was simple.  Bacteria were swabbed out of a human mouth, cultivated in a Petri dish, and coffee filters that were dipped into the treatments of Isopropyl and Cetylpyridinium Chloride were added and tested against it.  It is hypothesized that the bacteria would build up resilience to the active ingredients of Listerine and Crest Pro-Health, Isopropyl and Cetylpyridinium Chloride.  A 2 sample t-test was performed to test this hypothesis.  The average distances of each generation of treatments were added together and compared against each other.  There was no significant difference in the values of CPC and Isopropyl, meaning that CPC and Isopropyl did not have different effects on the bacteria; although, Isopropyl had a larger affect.  The bacteria grew a resistance to both active ingredients; however, that resistance was only temporary, and was more subtle in CPC than Isopropyl.  The original hypothesis was therefore accepted due to the development of a resistance.

Research Done By:

Cassie Dusute
Fitzgerald High School

Kyle Greger
Warren Woods Tower High School