Identification and caracterisation of Staphylococcus species isolated from cow milk associated or not with mastitis

One hundred and eight strains of staphylococci are isolated from 73 samples of milk quarters associated or not with mastitis from three farmers. Forty seven strains of them are isolated from milk quarter receved in the course of diagnoctic of mastitis at the School of Veterinary Medecine. The identification of the different strains, by the ID system 32 Staph, shows the predominance of the coagulase negative staphylococci (79.7 %) with regard to Staphylococcus aureus (S: aureus) (17.5 %). The main isolated coagulase negative staphylococci are S. chromogenes (19.5 %) and S. epidermidis (10.5 %). The factor of virulence of the coagulase negative staphylococci, exopolysaccharid, is essentially produced by the following species : S. epidermidis, S. xylosus and S. warneri. The genomic analysis of strains of S. wameri, S. epidermidis, and S. xylosus shows their unclonal origin. The sensibility's profil of all strains of staphylococci reveals the high resistance of S. aureus to penicillin G. Coagulase negative staphylococci are more sensitive to penicillin G. However, S. haemolyticus presents resistances to the oxacillin, the gentamicin and erythromycine. No resistance for rifampicin and vancomycin was observed both on strains of S. aureus and coagulase negative staphylococci.