Ceftaroline fosamil molecule. Computer illustration showing the molecular structure of ceftaroline fosamil. Ceftaroline fosamil is a beta-Lactam antibiotic with activity against methicillin-resistant Staphylococcus aureus (MRSA). Atoms are represented as spheres: carbon (light blue), hydrogen (white), nitrogen (dark blue), oxygen (red), phosphorus (orange), sulphur (yellow) and bonds between the atoms by cylinders.