Novobiocin is a narrow-spectrum antibiotic that may be bacteriostatic or bactericidal at higher concentrations. It is active mostly against gram-positive bacteria but also against a few gram-negative bacteria. There is a synergistic effect with tetracyclines. Many species of bacteria can develop resistance to novobiocin. Adverse reactions are quite frequent after administration. Its main use is in combination with other agents for treatment of bovine mastitis.