Bacteria in the Restroom - Pondering Succession and Stability

Did you ever wonder about the bacteria on the surfaces in the restroom?  Well, you probably figured there were bacteria there (and thus you use your foot to flush the commode), but hopefully you pondered deeper thoughts rather than postulating bacterial succession on the floor as well as the seat in which you sit.

Well some did ponder such questions, completed a study and published those results (Ecological Succession and Viability of Human-Associated Microbiota on Restroom Surfaces).  They showed that the ecological succession of bacterial populations does occur and that in general, a stable community does occur after 8 hours, and is made up of skin and environmental organisms rather than gut microorganisms.

"The prevalence of skin-associated, rather than feces-associated taxa, in the late-successional community suggests that organisms are selected for their ability to persist in a dry, aerobic environment, which is a very different environment from the gut. Human-associated microbiota, including Staphylococcus strains, can remain viable on BE surfaces for many hours after their dispersal [cleaning] agents are removed. This suggests that common BE surfaces may be significant fomites for viable human pathogens."

There is a transition from gut microbes to skin and outdoor microbes. 

".....showed that the early successional community is dominated by taxa associated with feces that are likely aerosolized by toilet flushing and are largely displaced by skin- and outdoor-associated taxa within 8 h (Fig. 2B and 4). The stable communities present on toilet seats and soap dispensers were comprised of 45% feces- and 45% skin-associated taxa"

Is there a difference between the men's room and the woman's room?

"Only toilet seat samples clustered based on the sex of the population using the restroom (ANOSIM R 0.199, P 0.001; Fig. 5A), with Lactobacillus and Anaerococcus dominating toilet seats in the restrooms for females (31–33), and the gut-associated Roseburia and Blautia being more abundant on toilet seats in the restrooms for males (ANOVA, false discovery rate [FDR]-corrected P 0.05; Fig. 5B). High-use and low-use restrooms had significantly different toilet seat and soap dispenser microbial communities (ANOSIM R 0.142 and P 0.001 and ANOSIMR 0.091 and P 0.001, respectively; Fig. 5C), but floor-associated communities were not significantly different."

 So even though the restroom is clean, and the poopy bacteria may be gone, it is still important to wash your hands.