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Just Wait Til You Get Home

Even well scrubbed public restrooms host a plethora of microbes, report researchers led by San Diego State University's Scott Kelley in Applied and Environmental Microbiology.

He and his colleagues collected samples from four bathrooms — two men's rooms and two ladies' rooms — at SDSU. First, they cleaned the bathrooms with a bleach solution and then collected swabs of the toilet seats, floors, and soap dispensers hourly, daily, and weekly. They then performed metagenomic sequencing on these samples to determine what was lurking among the bathroom microbes.

Within a few hours of cleaning, the bathrooms had been re-colonized by bacteria, the researchers found. In their 602 samples, the researchers identified some 77,990 distinct operational taxonomic units, many of which could be traced to phyla that commonly inhabit the human gut, though skin-associated microbes were also present, especially Staphylococcus. Some viruses like enterophage, human papilloma, and herpes viruses were also uncovered.

Despite being cleaned with soap and water throughout the study period, the bathroom microbiomes stayed fairly constant, the researchers note.

"All human environments contain pathogens — your bedroom, the phone you're talking on, even the bugs inside of you could turn pathogenic at any time," co-author Jack Gilbert from Argonne National Laboratory tells NPR's Shots blog. "But we desperately need them in our lives."

Still, he tells Shots that good hygiene is important. "Don't lick the bathroom floor," he adds.