Streptococcal Selective Agar C.O.B.A.

Selectively isolate Streptococcus species with Thermo Scientific™ Oxoid™ Streptococcal Selective Agar C.O.B.A. (Colistin sulphate Oxolinic acid Blood Agar) Thermo Scientific™ Oxoid™ Columbia Blood Agar forms the base for the medium to which antimicrobial agents and defibrinated horse blood are added to aid in the identification of hemolytic colonies.

The presence of selective agents colistin sulphate and oxolinic acid in the medium result in total inhibition of Gram-negative organisms and almost all non-streptococcal Gram-positive organisms, while having no inhibitory effects on Streptococcus species.

Use Streptococcal Selective Agar C.O.B.A. for selective isolation of streptococcal species with clearly defined hemolytic reactions.

• Facilitates uninhibited selective growth of streptococci species, comparable to that of non-selective media.
• Clearly defined hemolytic reactions with addition of defibrinated blood.
• Ready-to-use convenience of prepared media.

Streptococci are commonly isolated from the upper respiratory tract. They are also often isolated from burns and other sites where frequently there is an abundance of competing organisms. In order to isolate streptococci, especially when present in small numbers, it is necessary to inhibit the competing flora without any adverse effect by the selective agents upon the Streptococcus species. The selective agents colistin sulphate and oxolinic acid have been found to have no inhibitory effect on Streptococcus species although amongst Group D organisms Enterococcus faecalis colonies are somewhat smaller. The combination of these two selective agents results in total inhibition of Gram-negative organisms and almost all non-streptococcal Gram-positive organisms. A very few staphylococci and coryneform organisms may grow with reduced colony size. The hemolytic reactions on media containing blood are clearly defined, and the colonial size and growth recovery of streptococcal groups A, B, C, D and G and S. pneumoniae are comparable to that on a non-selective medium.

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Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.