A normal microbiome is essential for healthy individuals and develops from contacts with other humans and the environment. However, as humans in industrialized areas spend more time in the built environment, we encounter a reduced diversity of microbes. Public restrooms represent an area with multiple common surfaces where individuals can be exposed to microbes from external sources. Males and females are known to have distinct microbiomes, so gender specific bathrooms could provide a smaller diversity than is represented across all individuals. Recent changes in social attitudes have led to an increase in gender-neutral public bathrooms, but it is not yet clear if the microbial community in gender-neutral bathrooms will have a unique community composition or an additive mixture of male and female communities. Our research questions were: 1) does gender (or gender-neutral) assignment cause differences in bacterial amounts on surfaces and 2) do different bathroom surfaces differ in bacterial amounts? College campuses are ideal to test these questions since they have consistent and high usage and identical cleaning regimes. We tested six different public bathroom surface types for CFUs by swabbing surfaces for several time points after cleaning and sterilization across male, female, and neutral bathrooms.
Results/Conclusions
We tested bacterial CFUs 0, 3, 6, 9 minutes and 1 and 24 hours after sterilization and found CFUs within 3 minutes with no difference from pre-cleaned control at 1 hour. Afterwards, all surfaces were swabbed at least 1 hour after last being cleaned. Across all surfaces, women’s rooms had significantly more CFUs than men’s rooms. But CFU counts were significantly highest on surfaces in gender-neutral bathrooms. This increase suggests that there is an additive effect on the abundance of bacteria when used by multiple genders. Different surfaces all had significantly different abundances of CFUs and there was a significant interaction between bathroom gender and type of surface measured. Bathroom gender assignment led to different CFU counts on door, stall, and toilet handles, as well as toilet seats but not on sink or soap dispenser handles. On the surfaces that differed between genders, gender-neutral > women > male with the exception of stall handles where gender-neutral > male > female. Surfaces in all bathrooms had CFUs of Staphylococcus aureus and epidermidis, though there were no significant differences. These results suggest bathroom gender assignment could alter the diversity and abundance of bacteria we encounter on a day to day basis.