A Comparison of Six Selective Media for the Enumeration and Isolation of Staphylococci1

Abstract

The efficacy of Baird-Parker agar, Baird-Parker agar with bacitracin (0.8 μg/ml), Baird-Parker agar supplemented with acriflavin (7 μg/ml), polymyxin (20 units/ml) and sulphonamides (55 μg/ml), KRANEP agar, mannitol salt agar, and Staphylococcus medium 110 agar for the isolation and enumeration of Staphylococcus species was investigated. Bovine blood agar was used as the control medium. Thirty-seven staphylococci strains representing 23 species and 19 non-Staphylococcus species were tested. None of the six selective media supported the growth of all 37 Staphylococcus strains. The number of Staphylococcus species that grew on a specific medium ranged from only the S. aureus strains on Baird-Parker agar supplemented with acriflavin, polymyxin, and sulphonamides, to all but S. warneri BG 647 on Staphylococcus medium 110 agar. Strains of Bacillus, Corynebacterium, and Micrococcus grew on all six selective media.