STAPHYLOCOCCAL STRAINS INVOLVED IN BOVINE MASTITIS ARE INHIBITED BY STAPHYLOCOCCUS-AUREUS ANTIMICROBIAL PEPTIDES

The inhibitory activity of five bacteriocin (Bac)-producer strains of Staphylococcus aureus was tested against bacteria pathogenic for cattl e. Sixty-five epidemiologically unrelated strains of Staph. aureus inv olved in bovine mastitis were used as indicators in an agar diffusion test. Bacteriocins produced by four strains could inhibit only a limit ed number of test organisms. However, all 65 indicator strains proved to be susceptible to the combined action of both bacteriocins encoded by pRJ9, a Bac plasmid found in strain A53. Therefore, the bacteriocin s produced by this strain may represent new antimicrobial peptides wit h potential applications in the prevention and treatment of bovine mas titis.