Piperacillin sodium. Molecular model of the drug Piperacillin sodium (C23.H26.N5.Na.O7.S). This is a broad-spectrum beta-lactam antibiotic of the ureidopenicillin class. It is used almost exclusively in combination with the beta lactamase inhibitor tazobactam for the treatment of serious, hospital-acquired infections. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue), oxygen (red), sulfur (yellow) and sodium (violet).