Production of acetoin, acid production from mannitol under anaerobiosis and b-galactosidase activity in addition to acriflavin susceptibility were evaluated to differentiate between coagulase-positive strains of Staphylococcus (CPS) isolated from bovine mastitis. The strains were classified in the genus Staphylococcus by means of sensitivity to furazolidone, resistance to bacitracin, aerobic acid from glycerol in the presence of 0.4mg m<IMG SRC="http:/img/fbpe/cr/v32n1/a14img01.gif">-1 of eritromicin, catalase, and coagulated rabbit plasma by the tube test. The acriflavin susceptibility was tested on Baird Parker and P agar plates containing 7mg m<IMG SRC="http:/img/fbpe/cr/v32n1/a14img01.gif">-1 of acriflavin. Five coagulase-negative S. hyicus strains identified by the API Staph system and S. aureus ATCC 29213 were used as test controls. Thirty-eight out of the 49 CPS were identified as S. aureus and 11 as S. hyicus, while S. intermedius was not found. The API Staph system was used to confirm the identification of the coagulase-positive strains of S. hyicus, seven S. aureus strains not producing acetoin and four negative for anaerobic fermentation of mannitol. All the strains identified as S. aureus were resistant to acriflavin whereas S. hyicus were sensitive. It was concluded that the sensitivity to acriflavin can be used in addition to the tests of coagulase and acetoin production to differentiate CPS isolated from bovine mastitis.
coagulase-positive staphylococci; bovine mastitis; acriflavin susceptibility
