USF St. Petersburg campus Honors Program Theses (Undergraduate)

First Advisor

Thesis Director: David John, Ph.D. Professor, College of Arts and Sciences


University of South Florida St. Petersburg

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It was hypothesized that rinsing a toothbrush in mouthwash after each use would reduce the amount of microbes that would grow on the toothbrush. Group 1 rinsed their toothbrushes in just water, and Group 2 rinsed their toothbrush in mouthwash after each use. Toothbrushes were collected and eluates were spread onto mannitol salt agars, eosin-methylene blue agars, blood agars, Sabouraud agars, and TYCSB agars and allowed to grow. Colony counts for all trials were converted to mean percent positives and mean percent positives >10. The difference in percent positives and percent positives >10 were statistically significant for p>0.1 for the mannitol salt, eosin-methylene blue, blood, and TYCSB agars. Overall, Group 2 had less microbial growth than Group 1 which supports the hypothesis. There was an unexplained, drastic variance in colony counts for the Sabouraud agars for both groups and therefore the results were not statistically significant.


A thesis submitted in partial fulfillment of the requirements of the University Honors Program University of South Florida, St. Petersburg May 4, 2016

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