Staphylococcus epidermidis. Coloured Scanning Electron Micrograph (SEM) of colonies of the bacteria Staphylococcus epidermidis. It is a Gram- positive cocci (spherically-shaped) bacteria that has a tendency to form grape-like clusters, as seen here. Staphylococcus epidermidis is usually non-pathogenic and found all over the human skin, and on many mucous surfaces. It is associated with acne and other minor skin lesions. It colonizes plastic, resulting in bacteraemia around catheters and surgical implants (such as heart valves). Such infections often do not respond to antibiotic treatment, and implants may have to be removed. Magnification: x7,200 at 6x6cm size. x11,000 at 4x4"~SQUARE"