Chocolate Agar – CHOC
Product Description & Summary
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. Heated horse blood added to the media gives it a “chocolate” appearance. This media is prepared, dispensed, and packaged under oxygen-free conditions to prevent the formation of oxidized products prior to use.
Interpretation of Results & Limitations
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. Microorganisms that grow on CHOC and incubated in 5% – 10% CO2 are not obligate anaerobes and findings should correlate with the microorganisms identified in the aerobic culture and direct Gram stain.
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.
|Organism Tested||ATCC #||Results in 5% CO2||Results in anaerobic conditions||Time|
|Fusobacterium necrophorum||25286||No Growth||Growth||24 – 48 hrs.|
|Neisseria gonorrhoeae*||43069||Growth||Inhibited Growth||48 hrs.|
|Haemophilus influenzae*||10211||Growth||Growth||24 – 48 hrs.|
|Streptococcus pneumoniae||49619||Growth||Growth||24 – 48 hrs.|
|Staphylococcus aureus||25923||Growth||Growth||24 – 48 hrs.|
|Escherichia coli||25922||Growth||Growth||24 hrs.|
* Organisms specified by CLSI: M22-A3 for quality control performance testing of Chocolate Agar.
Product Storage & Shelf Life
Storage: Upon receipt, store at 2 – 8oC in original package until use. Avoid overheating or freezing. Do not use media if there are signs of deterioration (shrinking, cracking, or discoloration due to oxidation of media) or contamination. The expiration date applies to the product in its original packaging and stored as directed. Do not use product past the expiration date shown on the container.
Shelf Life: 6 months from date of manufacture.