"Staph," or staphylococcus, is a type of bacteria that naturally exist in the environment, including on people's skin. If the bacteria enter under the skin through a cut or scrape, the staph bacteria may cause skin infections that look like pimples or boils. Infections caused by staph may be red, swollen, painful, or have pus or other drainage. Most staph infections are minor and can be treated without antibiotics. Some staph infections resist treatment to a class of antibiotics and are known as Methicillin-Resistant Staphylococcus aureus or MRSA. This makes these infections harder to treat because it is resistant to the antibiotic most commonly used. There are however, a couple of other antibiotics to which the bacteria are susceptible and can be used to treat the infection.