MRSA: resistant Staphylococcus bacteria. Coloured transmission electron micrograph (TEM) of a deadly cluster of MRSA Staphylococcus aureus bacteria. Strains of MRSA (Methicillin-resistant Staphylo- coccus aureus) bacteria are resistant to most antibiotic drug agents; some yield to vancomycin. It is a Gram-positive spherical (coccus) bacteria. Here, some bacteria are seen dividing. MRSA is common in hospitals, infecting wounds of patients. S.aureus may cause boils, usually by entering the skin through a hair follicle or a cut. They are also responsible for internal abscesses and most types of acute suppurative infection. Magnification: x24,000 at 6x4.5cm size.