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Columbia Agar Base with 7% Horse Blood & 50mg/L Neomycin Based on Columbia Agar enriched with 7% Horse Blood this formulation has been modified to include Neomycin, which will inhibit most gram-positive and gram-negative aerobes, making it suitable for use as a selective medium for the isolation of many anaerobes. -
A very nutritious general-purpose medium based on Columbia Agar Base enriched with 7% Sheep Blood, suitable for the isolation of most organisms including most fastidious anaerobes of clinical significance. Many workers claim that β haemolysis is more readily apparent, particularly in group A streptococci, when Sheep Blood is used in place of Horse Blood. -
This is a selective medium for the isolation of Staphylococcus and Streptococcus spp. Based on Columbia Agar, it is enriched by the addition of Sheep Blood (7%) the medium is also made selective by the inclusion of Colistin and Naladixic Acid to suppress the growth of the majority of Gram negative bacteria. The addition of sheep blood the medium allows for good colonial appearance, pigment production and excellent haemolysis from beta-haemolytic streptococci. -
Columbia Blood Agar with 5% Defibrinated Horse Blood & Cap Selective Supplement This is a medium for the selective isolation of Staphylococcus spp. and Streptococcus spp. primarily from clinical specimens. Based on Columbia Agar Base enriched with 5% Horse Blood the medium is made selective by the inclusion of Colistin and Aztreonam to suppress the growth of the majority of Gram negative bacteria. -
Dermatophyte Test Medium with Chloramphenicol & Cyclohexamide (Actidione) This is a selective medium for the isolation of dermatophytes that includes a Phenol Red indicator to assist in the differentiation between dermatophytes and other pathogenic fungi. Although the low pH (5.5) of the medium inhibits most bacteria, Chloramphenicol is added to further reduce the risk when processing material that may be more heavily contaminated. Cyclohexamide (Actidione) is also added to suppress the growth of most yeasts and saprophytic fungi. Dermatophytes appear as fluffy white colonies and produce a red colour on the medium while other fungi cause the medium to become yellow due to acid production. Yeasts will also grow on this medium but are readily distinguished by their distinct white/creamy colonies and distinctive smell. NB: Prolonged incubation should be avoided as this may cause fungi other than dermatophytes to turn the medium red -
Desoxycholate Citrate Agar (DCA) (Hynes) One of several media designed for the differential selective isolation of Salmonella and Shigella spp from clinical and environmental samples. Lactose is added to the medium together with Neutral Red indicator to assist in the differentiation of Lactose and Non-Lactose fermenting organisms. The medium is made selective by the inclusion of Sodium Desoxycholate and Sodium Thiosulphate, which will inhibit most gram-positive organisms. The Sodium Thiosulphate is also broken down by the enzyme thiosulphate reductase to form Sodium Sulphite and Hydrogen Sulphide. The Hydrogen Sulphide, if present, will in turn react with the ferric ions to produce a black precipitate of Ferrous Sulphide and give rise to the classical black centre of most Salmonellae. It has been suggested that this medium may be more suitable for secondary post-enrichment isolation while the original formulation is more appropriate for the primary inoculation of samples. -
Dichloran Rose-Bengal Chloramphenicol (DRBC) Agar Dichloran Rose Bengal Chloramphenicol Agar is based on the formulation described by King et al. It is a selective medium for the isolation and enumeration of yeasts and mould that are of significance in food spoilage. The medium is a modification to Rose Bengal Chloramphenicol Agar and is recommended by the International Standard ISO 21527:2008 part 1. -
DNase Agar is used primarily in clinical laboratories to differentiate Staphylococcus aureus from other staphylococci based on deoxyribonuclease activity. Staphylococcus aureus produce DNase enzymes that hydrolyse DNA resulting in a colourless zone around the colonies, described as being DNase positive, whereas coagulase negative staphylococci do not produce clearing. This particular formulation can also be used for Streptococci and Serratia. NB: As with most tests of this type a positive result should not be taken in isolation and other appropriate tests, e.g. Coagulase Test, Latex Agglutination etc, should be carried out.
