Piperacillin and tazobactam injection (brand name Zosyn) is used to treat a wide range of moderate to severe bacterial infections. It is a combination medication containing a penicillin antibiotic (piperacillin) and a beta-lactamase inhibitor (tazobactam). The tazobactam prevents certain bacteria from destroying the piperacillin, thereby extending its effectiveness. Common uses include treating infections of the: Lungs: Including both hospital-acquired and community-acquired pneumonia. Abdomen: Such as appendicitis, peritonitis, and other complex intra-abdominal infections. Skin and soft tissues: Including cellulitis, cutaneous abscesses, and diabetic foot infections. Female reproductive organs: Such as pelvic inflammatory disease and postpartum endometritis. Urinary tract: Including both uncomplicated and complicated urinary tract infections.