Oxytetracycline is a tetracycline used for treatment of infections caused by a variety of Gram positive and Gram negative microorganisms including Mycoplasma pneumoniae, Pasteurella pestis, Escherichia coli, Haemophilus influenzae (respiratory infections), and Diplococcus pneumoniae. It has a role as an antibacterial drug, a protein synthesis inhibitor, an antimicrobial agent, an anti-inflammatory drug and a bacterial metabolite. It is a tautomer of an oxytetracycline zwitterion.