Non-stock item: AS — pack minimum order, allow weeks for delivery. AS — 25 pack minimum order, allow weeks for delivery. CHOC agar is an enriched non-selective media supplemented with cofactor V nicotinamide adenine dinucleotide; NAD and cofactor X hemin , and facilitates the growth of fastidious anaerobes.
CHOC agar is recommended for aerotolerance testing of obligate anaerobes. This media is prepared, dispensed, and packaged under oxygen-free conditions to prevent the formation of oxidized products prior to use.
If used properly, this media should support good growth of most pathogens found in clinical infections including Haemophilus influenzae , Neisseria gonorrhoeae, and other fastidious aerobes and anaerobes in the correct environment.
CHOC agar will not provide complete information for identification of bacterial isolates. Additional test procedures and media are required for complete identification. It is important to note that some anaerobic microorganisms can be aerotolerant, such as certain species of Clostridium, Actinomyces, Propionibacterium, Bifidobacterium, and Lactobacillus.
These aerotolerant microorganisms typically grow well in anaerobic conditions but poorly in carbon dioxide or air. Consult reference materials for additional information. The following organisms are routinely used for quality assurance performance testing at Anaerobe Systems. Peptone provides the organism with nitrogen, amino acids, and other elements essential for growth, sodium chloride maintains the osmotic balance, agar acts as a solidifying agent.
In commercial preparation, casein and animal tissue digest provides the organism with nitrogen, amino acids, and other elements. Since Neisseria species are highly sensitive to toxic substances such as fatty acids; cornstarch is added to neutralize possible toxic metabolites. Potassium phosphate helps to maintain a uniform pH during growth.
Hemoglobin solution provides X factor hemin required by Haemophilus species, and isovitox enrichment provides V-factor nicotinamide dinucleotide , and other complex compounds that enhance the growth of Neisseria species. The composition of chocolate agar is the same as blood agar. The only difference is blood agar is heated in a water bath to prepare chocolate agar.
Commercially available chocolate agar medium, however, has a different composition and requires no addition of blood. Chocolate agar slants appear brown to brownish-red color. Result interpretation: Almost all organisms grow on chocolate agar giving grey colonies of various sizes. However, since it is used specifically to isolate fastidious pathogens such as Neisseria and Haemophilus , there colony morphology are described below. Any growth should be regarded as positive, and the whole lot should be discarded.
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