Columbia agar, USP

Cat. no. G250 Columbia Agar, USP, 15x 100mm Plate, 18ml 10 plates/bag


Hardy Diagnostics Columbia Agar, USP is recommended for use as a general purpose medium for the isolation and cultivation of nonfastidious and fastidious microorganisms and for the growth promotion of Clostridium spp. as recommended by the U.S. Pharmacopeia.


Columbia Agar, USP is recommended by the U.S. Pharmacopeia for use in growth promotion testing of Clostridia.(2) Clostridium species have variable physiological capacities that govern their tolerance of oxygen and may range from strictly anaerobic to aerotolerant metabolisms.

Columbia Agar without enrichment can be used as a general purpose medium. This nutritionally rich medium was developed by Ellner et al. from Columbia University.(1) The formula calls for a combination of peptones from pancreatic digest of casein, peptic digest of animal tissue and beef extract, which support growth. Additional metabolic energy is derived from corn starch and yeast extract. Yeast extract also serves as a source of B-complex vitamins. Sodium chloride is added to maintain osmotic balance. Agar is the solidifying agent.


Ingredients per liter of deionized water:*

Pancreatic Digest of Casein 10.0gm
Meat Peptic Digest 5.0gm
Heart Pancreatic Digest 3.0gm
Yeast Extract 5.0gm
Maize Starch 1.0gm
Sodium Chloride 5.0gm
Agar 13.5gm

Final pH 7.3 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.



Method of Use: Allow the plates to warm to room temperature and the agar surface to dry before inoculating. The U.S. Pharmacopeia recommnends subculturing from Reinforced Clostridial Medium, USP (Cat. no. U172).(2) Heavily inoculate and streak the specimen for isolation with a sterile loop as soon as possible after collection. Incubate plates aerobically or anaerobically at 30-35ºC. for 48 hours to 5 days, depending on growth requirements. Examine colonial morphology.


Examine Columbia Agar, USP for growth. The presence of Clostridia is indicated by the occurrence of anaerobic growth. Further examination of colonies may be expected to show gram-positive rods (with or without endospores) that yield a negative catalase reaction.(2) Consult listed references for interpretation criteria and further biochemical testing of growth.(1, 2)



Standard microbiological supplies and equipment such as loops, swabs, applicator sticks, other culture media, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Staphylococcus aureus
ATCC® 25923**
A 24-48 hrs 35°C Aerobic Growth
Streptococcus pyogenes
ATCC® 19615**
A 24-48 hrs 35°C Aerobic Growth
Escherichia coli
ATCC® 25922**
A 24-48 hrs 35°C Aerobic Growth
Clostridium sporogenes
ATCC® 19404**
J 48 hrs 30-35°C Anaerobic Growth

**Tested in accordance with USP <62>.(2)



Columbia Agar, USP should appear hazy, and light amber in color.


1. Ellner, P. D., C. J. Stoessel, E. Drakeford, and F. Vasi. 1966. A new culture medium for medical bacteriology. Am. J. Clin. Pathol. 45:502-504.

2. The Official Compendia of Standards. USP General Chapter <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms. USP-NF. United States Pharmacopeial Convention Inc., Rockville, MD.

ATCC is a registered trademark of the American Type Culture Collection.