Staphylococcus epidermidis bacteria. Animated coloured scanning electron micrograph (SEM) of Staphylococcus epidermidis from the ear canal. Gram-positive bacteria dominate the bacterial flora of the ear canal and the species distribution is relatively similar to that in the skin. Staphylococcus epidermidis is part of human skin flora (commensal). Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are often at risk of developing an infection. These infections can be both nosocomial (originating in a hospital) or community acquired, but they pose a greater threat to hospital patients.