Chocolate Agar is an alternative medium for the isolation of fastidious organisms from clinical specimens. In 1945, Johnston reported a medium which produced Neisseria gonorrhoeae colonies within 24 hours1 whose recovery time was further reduced by Carpenter and Morton formulation that is enriched with hemoglobin and yeast extract giving the Chocolate Agar formulation2.
Fastidious organisms such as Haemophilus and Neisseria require specially enriched culture media and conditions. The red blood cells from the blood in chocolate agar have been heated until they are lysed, giving the medium its 'chocolate' appearance. This provides the medium heat-labile X factor (heme/hemin) and the V factor (nicotinamide adenine dinucleotide, NAD) necessary for the growth of Haemophilus influenzae in addition to other nutrients. Further incorporation of pyridoxal into chocolate medium resulted in a medium that useful in the recovery of nutritionally deficient Streptococcus species.
Chocolate agar, however, does not reveal hemolysis data, so species differentiation among the members of Haemophilus must be performed in another manner.
|Product Name||Catalog #||Quantity|
|Chocolate Agar mono plate, 90 x 15 mm||CC9230P||10/pk|
The following organisms are routinely used for testing for this medium.
|Neisseria gonorrhoeae ATCC® 43069||Growth|
|Haemophilus influenzaATCC® 10211||Growth|
|Chocolate Agar with Pyridoxal:|
|Neisseria gonorrhoeaeATCC® 43069||Growth|
|Haemophilus influenza ATCC® 10211||Growth|
|Streptococcus mitis ATCC® 6249||Growth|
User Quality Control
Check for signs of contamination and deterioration. Users of commercially prepared media may be required to perform quality control testing with at least one known organism to demonstrate growth or a positive reaction; and at least one organism to demonstrate inhibition or a negative reaction (where applicable).
Ingredients g/L(Final pH 7.2 +/- 0.2 at 25°C)
|Chocolate Agar with Pyridoxal contains:|
2 total citations
- Johnston, et al. 1945. J. Ven. Dis. Inf.; 26:239.
- Carpenter, C.M. and H.E. Morton. 1947. Proc. N.Y. State Assoc. Public Health Labs; 27:58-60.