Do you ever wonder how clean our bathrooms are, or question what kinds of bacterial communities are lurking in the public bathrooms you use? Well lucky for you and I, a team of scientists wondered the same exact thing. Published in Applied and Environmental Microbiology, the scientists sampled the microbial communities of four public restrooms at San Diego State University to better understand how they shifted over time.

At the beginning of the study, the restrooms were sterilized using a bleach solution. Just one-hour post sterilization, the bathrooms were already filled with microbes again and as you can imagine, a significant portion of the microbes were of fecal origin. They found that despite varying frequency of use and sampling bathrooms of both sexes, the four bathrooms all eventually had microbial communities that were very similar to one another.

The scientists found one specific bacterium, Staphylococcus, was prevalent in all the restrooms. One kind of staph can be very pathogenic, specifically when it is resistant to antibiotics (MRSA), however Staphylococcus does often live harmless in our bodies. They did not find any Staphylococcus that was resistant to antibiotics in any of the restrooms. The restrooms were cleaned regularly using soap and water over the course of this study, yet the microbial communities remained largely stable.

You may read this and be grossed out about bacteria being prevalent in public restrooms even after regular cleaning, but they are most likely harmless, or even beneficial. Perhaps bleaching a bathroom may be like taking antibiotics - it leaves open the possibility for harmful bacteria to colonize, like what Clostridium difficile does in the gut.