Gram Negative Staph
Staphylococcus infections (or "staph infections" for short) are caused by Staphylococcus bacteria. This group of bacteria has gained a lot of interest in the past several years because of methicillin-resistant Staphylococcus aureus (MRSA for short), a strain of staph that is more difficult to treat because it is impervious to the effects of certain antibiotics.
Staph bacteria are commonly found on the skin, in the nose, and within the mucous membranes of healthy people (some people believe that staph bacteria are gram-negative, but they are actually gram-positive bacteria). Most of the time, the bacteria do not cause infections. When they do, they most commonly affect the skin. These skin infections may appear as pimples, pustules, boils, or spider bites. The affected skin is often red, swollen, painful, and can have pus or other drainage.
(To learn more about these gram-positive bacteria, click Staph Infection Causes. This article takes a closer look at the many different types of staph bacteria, including MRSA.)