The antimicrobial triclosan is a common ingredient in hand soap. But it's also found in shampoos, deodorants, toothpaste, even lip gloss. So it's not too surprising that triclosan also shows up in blood, urine, breast milk and mucus. But here's the weird thing—those triclosan residues may actually boost bacterial growth in our bodies. So says a study in the journal mBio. [Adnan K. Syed et al, Triclosan Promotes Staphylococcus aureus Nasal Colonization]

Researchers swabbed inside the noses of 90 adults. 37 of the 90 tested positive for triclosan—and those who did were twice as likely to have the bug Staphylococcus aureus living in their noses. Rats, too, were more susceptible to staph if fed triclosan.
 
Seems counterintuitive, but when bacteria are exposed to sublethal levels of antibiotics, they get stressed, and “they attach to surfaces and hunker down, in things we call biofilms." That's study author Blaise Boles, of the University of Michigan.

He says that stash of staph could put your health at risk. "Individuals that have Staph. aureus in their nose before they undergo surgery are about seven times more likely to get a Staph. aureus surgical site infection." Which is when you'll really need those antibiotics.

—Christopher Intagliata

[The above text is a transcript of this podcast.]