Despite common belief, bathrooms are not as unhealthy as one might think.
Microbial succession in a sterilized restroom begins with bacteria from the gut and the vagina, and is followed shortly by microbes from the skin, according to a recent study.
Researchers found that restrooms are dominated by a stable community structure of skin and outdoor associated bacteria, with few pathogenic bacteria making them similar to other built environments such as your home.
For the study, researchers characterized structure, function, and abundance of the microbial community, on floors, toilet seats, and soap dispensers, following decontamination of each surface. They then analyzed the surfaces hourly at first, and then daily, for up to eight weeks.
"We hypothesized that while enteric bacteria would be dispersed rapidly due to toilet flushing, they would not survive long, as most are not good competitors in cold, dry, oxygen-rich environments," Jack A. Gilbert, corresponding author of the study, said in a statement. "As such, we expected the skin microbes to take over -- which is exactly what we found."
They found that the communities associated with each surface became more similar in species and abundance within five hours following initial sterilization, and the resulting late-successional surface community structure remained stable for the remainder of the 8 weeks' sampling.
Toilet seat samples, alone, clustered according to restroom gender, with Lactobacillus and Anaerococcus--vaginal flora--dominating ladies' room toilet seats, while the gut-associated Roseburia and Blautia, were more copious on toilet seats in men's rooms.
Ultimately, skin and outdoor-associated taxa comprised 68 to 98 percent of cultured communities, with fecal taxa representing just 0-15 percent of these. And out-door-associated taxa predominated in restrooms prior to sterilization, as well as in long-term post-sterilization communities, suggesting that over the long term, human-associated bacteria need to be dispersed in restrooms in order to be maintained there.
The findings suggest that the restroom is no more healthy or unhealthy than a home.
"A key criterion of healthy or unhealthy might be the presence or relative abundance of pathogens," Gilbert said. "While we found cassettes associated with methicillin-resistant Staphylococcus aureus (MRSA) the predominant Staph organisms didn't harbor those genes, so MRSA may be there but it is very rare."
Restrooms, he says, are not necessarily unhealthy, but classifying them as healthy would not necessarily be accurate.
The findings are detailed in the journal Applied and Environmental Microbiology.
