Chocolate II Agar is an improved medium for use in qualitative procedures for the isolation and cultivation of fastidious microorganisms, especially Neisseria and Haemophilus species, from a variety of clinical specimens.
SUMMARY AND EXPLANATION
Carpenter and Morton described an improved medium for the isolation of the gonococcus in 24 hours. The efficiency of this medium, GC Agar supplemented with hemoglobin and yeast concentrate, was demonstrated in a study of twelve media then in use for the isolation of this organism. The medium was improved by replacing the yeast concentrate with BBL™ IsoVitaleX™ Enrichment, a chemically defined supplement developed specially to aid the growth of gonococci, although it has broad application for other microorganisms; e.g., Haemophilus. Through careful selection and pretesting of raw materials, Chocolate II prepared plated medium promotes improved growth of gonococci and Haemophilus species. With most strains of N. gonorrhoeae, visible growth on primary isolation is seen after incubation of 18-24 hours.
Chocolate II Agar contains an improved GC Agar base (GC II Agar Base), bovine hemoglobin and IsoVitaleX Enrichment.
GC II Agar Base contains nitrogenous nutrients in the form of casein and meat peptones, phosphate buffer to maintain pH and corn starch, which neutralizes toxic fatty acids that may be present in the agar. Hemoglobin provides X factor (hemin) for Haemophilus species. IsoVitaleX Enrichment is a defined supplement which provides V factor (nicotinamide adenine dinucleotide, NAD) for Haemophilus species and vitamins, amino acids, co-enzymes, dextrose, ferric ion and other factors which improve the growth of pathogenic Neisseria.