It’s true what they say: Your keyboard is crawling with bacteria. But if you’re a woman, you may have less to worry about.

Researchers who took swabs from office equipment in New York, San Francisco and Tucson found more than 500 types of bacteria, most of which normally live on our skin or in our nasal, oral and intestinal cavities.

Chairs and phones accumulated the most bacteria, followed by desktops, keyboards and computer mice. In a few cases, hardy microbes commonly found in hot springs and volcanic islands appeared in the mix, perhaps tracked into the office after someone’s vacation.

New York and San Francisco’s bacterial diversity was virtually identical, while Tucson’s microbes tended to be heavy on desert-soil bacteria in addition to the human-derived species. San Francisco offices were the least contaminated.

And while the offices of men and women had the same types of species, women’s offices had, on average, 10 to 20 percent fewer of them. Differences in hygiene may account for that, the research team reported in the online journal PLoS ONE.