G.C. Agar Base 1106 Condalab

GC Agar Base can contain various additives to be used for the isolation and cultivation of pathogenic microorganisms such as Neisseria gonorrhoeae, Haemophilus influenzae and N. meningitidis. GC Agar Base is employed with the addition of haemoglobin and supplements for the preparation of Chocolate Agar and Thayer-Martin Medium. The Chocolate Agar can be supplemented with the following supplements:

- VCN Supplement (Cat. CL-6013) - Turns the medium into Thayer-Martin Medium

- VCAT Supplement (Cat. CL-6014) - For the selective isolation of Neisseria

- VCNT Supplement (Cat. CL-6026) - Also used for the isolation of Neisseria

- LCAT Supplement (Cat. CL-6012) - For the isolation of pathogenic Neisseria

The addition of haemoglobin in Chocolate Agar provides hemin (X factor), required by Haemophilus species and promotes the growth of Neisseria species. A chemical enrichment composed of cofactors, vitamins, and nicotinamide adenine dinucleotide (NAD) is also required for the growth of Haemophilus and Neisseria spp. If required, antimicrobial supplements are added as inhibitors for an improved selectivity of the medium. In the base medium, peptone mixture provides nitrogen, vitamins, minerals, and amino acids essential for growth. Corn starch absorbs any toxic metabolites produced. Dipotassium and monopotassium phosphates act as buffer systems. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological Agar is the solidifying agent.

Thayer and Martin improved the selectivity of the GC agar by incorporating antibiotics such as colistin, vancomycin or nystatin, to grow fastidious microorganisms that require different growth factors. Thayer-Martin Medium is recommended for the primary isolation of N. gonorrhoeae and N. meningitidis from specimens with mixed flora taken from throat, vagina, rectum, and urethra samples. It is designed to reduce the overgrowth of gonococci and meningococci by contaminants, to suppress saprophytic Neisseria species growth and to encourage pathogenic Neisseria growth. On Thayer-Martin Medium the typical colonies of N. gonorrhoeae are white-grey, opaque, sometimes shiny, finely granular in appearance, variable in size (1-2 mm), round with entire or lobate edges and mucoid after 48 hours of incubation.