Thanksgiving usually means a trip on the New Jersey Turnpike for me and my family, and it’s practically a tradition to stop at one of that highway’s big rest areas to use the bathroom. So I was interested to read a study published Wednesday afternoon in the online journal PLoS ONE that says such public bathrooms teem are teeming with bacteria, most of it deposited on surfaces via human hands, feces and urine.

(Before I continue, let’s keep in mind that bacteria are everywhere, all the time, and that most bacteria aren’t pathogens, i.e. the kinds that can make us sick.)

The study’s authors wanted to figure out which locales within public bathrooms carry the greatest bacterial loads and which kinds of bacteria were most common in those places. They did not look into the relationship between the presence of bacteria and the incidence of illness.

The researchers took swab samples of bacteria from the floors, toilet surfaces (including flush handles), faucets, door handles and other sites in 12 bathrooms (6 men’s rooms, 6 women’s rooms) at the University of Colorado, Boulder. Using “high put-through” devices that identify strains of bacteria without having to culture them (and wait for results), they found that the floors had the greatest variety of bacteria, much of it from soil that people likely dragged in on their shoes. Soil-based bacteria was also common on flush handles; the authors surmise that was because people often flush with their foot instead of their hand to avoid contaminating themselves with germs.

Women’s rooms were more populated with certain bacteria associated with female genitals, which the authors figure was spread to toilet surfaces via urine. Much of the fecal bacteria they found on toilet surfaces and the floor surrounding toilets may have been transported to those places when the toilets were flushed and some of the bowl contents aerosolized.

All in all, most of the bacteria found throughout the bathrooms were those typically found on human skin. That finding’s important, the authors note, because those bacteria can include pathogens such as Staphylococcus aureus, which can easily be spread when hands come into contact with contaminated surfaces.

The take-home message? Wash your hands after you use the bathroom, folks.