The reddish pink rash spreads quickly. jlcampbell104/FlickrYour skin usually deflects any bacteria it encounters, protecting you from all sorts of infections. However, when you get a bug bite or a rash, some of that bacteria can sneak in, potentially causing serious consequences. For example, you might develop cellulitis – it’s the most common infection that occurs when bacteria breach the skin barrier. An estimated 1 in 503 people, or 0.2%, of the population get this painful red rash each year.