Audree Kopp, a woman from Louisville, Kentucky, had to get emergency surgery because a glittery hair tie gave her a nasty infection, thus suggesting that glittery hair ties may have a dark underside previously unknown to the general public. Kopp first noticed that something was up when she got a red bump on her wrist where she would keep her hair tie. She showed the bump to a doctor, who gave her some antibiotics. It kept growing, though, so she went to the E.R.
It turns out that the hair tie was collecting bacteria, which got under her skin through her pores and hair follicles. She ended up with three types of infections. Had the doctors not operated on her, she could have contracted sepsis.
Here's the full news report, if you want to see the graphic, open-wound photos (delicious!).