This medium is prepared by replacing Peptone special with HiVeg special peptone which is free from BSE/TSE risks. G.C. HiVeg Agar Base with added blood or haemoglobin and other supplements is recommended for selective isolation and cultivation of fastidious organisms like Gonococci and Haemophilus species. This medium can also be employed as a basal medium in the preparation of Chocolate HiVeg Agar (MV103) and Thayer Martin HiVeg Medium Base (MV413). Originally, animal based Chocolate Agar was developed by Johnston for the growth of fastidious Neisseria gonorrhoeae within 24 hours (1). Addition of haemoglobin to this medium had improved the growth, as studied by Carpenter and Morton (2). Incubation is to be done at 37°C in an atmosphere of 5-10% carbon dioxide and 70% humidity. It is recommended that all presumptive Neisseriae should also be confirmed by carbohydrate fermentation tests and other serological tests.
G.C. HiVeg Agar Base contains HiVeg special peptone which supplies nutrients to the organisms. The presence of starch ensures that the toxic metabolites produced by Neisseria are neutralized and the phosphates prevent changes in the pH due to amine production that can affect the survival of the organisms. X-factor needed for Haemophilus species is provided by haemoglobin. The other supplement provides V factor i.e. NAD (Nicotinamide adenine dinucleotide) for Haemophilus species and amino acids, coenzymes, ferric ions etc. improves the growth of pathogenic Neisseria.
Directions:Suspend 7.2 grams in 100 ml distilled water to make a double strength base. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 50°C and aseptically add separately prepared Haemoglobin (FD022) (100 ml sterile 2% solution) and GC Supplement (FD021). Mix well and pour into sterile petri plates. To increase the selectivity of medium antibiotic supplements may be added as VCN Supplement (FD023), VCNT Supplement (FD024), Linco T Supplement (FD026), Vanclo T Supplement (FD028). To enhance the nutritional properties of medium, Vitamino Growth Supplement (FD025) or Yeast Autolysate Supplement (FD027) may be added.