In the present study, 188
coagulase-negative Staphylococcus (CNS) strains were isolated from
bovine mastitis cases from 56 different Brazilian dairy herds, located in the Southeast region of the country, and were tested for antimicrobial substance production. Twelve CNS strains (6.4%) exhibited antagonistic activity against a Corynebacterium fimi
indicator strain. Most antimicrobial substances were sensitive to
proteolytic enzymes suggesting that they might be
bacteriocins (Bac). Amongst the CNS producers, six were identified as S. epidermidis, two as S. simulans, two as S. saprophyticus, one as S. hominis and one as S. arlettae. Plasmid profile analysis of these strains revealed the presence of at least one plasmid. The Bac(+) strains presented either no or few antibiotic resistance phenotypes. Three strains were shown to produce a
bacteriocin either identical or similar to
aureocin A70, a
bacteriocin previously isolated from an S. aureus strain isolated from food. The remaining Bac(+) strains produce
antimicrobial peptides that seem to be distinct from the best characterised staphylococcal
bacteriocins described so far. Some of them were able to inhibit Listeria monocytogenes, an important food-borne pathogen, and several strains of Streptococcus agalactiae associated with
bovine mastitis, suggesting a potential use of these
bacteriocins either in the prevention or in the treatment of streptococcal
mastitis.