A method for treating or preventing mastitis in mammals is disclosed. The method contemplates the intramammary injection or dipping the teat with micrococcin antibiotics, preferably micrococcin P1 or P2, which do not interfere with the production of cheese and yoghurt using milk from treated animals. Hydrophobic antibiotics such as micrococcin P1 or P2 can be administered prior to infection to effectively suppress the rate, severity, and duration of subsequent bacterial infection, or can be administered subsequent to infection to effectively treat mastitis.