Columbia Agar Base

Columbia Agar Base
Nutritive Base Medium for Clinical and General Microbiology

Catalog Number: AS-1179

Overview
Columbia Agar Base is a highly nutritious, general-purpose dehydrated medium designed for the isolation and cultivation of both non-fastidious and fastidious microorganisms from clinical and non-clinical specimens. First described by Ellner et al. (1966), it incorporates specialised peptones, yeast extract, and beef extract to supply essential nitrogen, carbon, vitamins, and trace elements.

Corn starch functions as an energy reserve and neutralises toxic metabolites released from specimens, supporting robust growth and typical colony morphology. When supplemented with 5–10% defibrinated sheep blood, the medium becomes Columbia Blood Agar, enabling demonstration of haemolytic reactions and supporting organisms requiring X-factor (hemin). The unsupplemented base is non-selective and supports luxuriant growth under aerobic or CO₂-enriched conditions at 35–37 °C.

Applications
• Primary isolation of Gram-positive cocci (streptococci, staphylococci, enterococci) from blood, urine, and wound specimens
• Cultivation of Gram-negative rods including Enterobacteriaceae and Pseudomonas spp.
• Preparation of blood agar or chocolate agar for fastidious pathogens such as Haemophilus influenzae and Neisseria spp.
• Cultivation of yeasts (e.g., Candida spp.) and coryneform bacteria in routine workflows
• Base for selective media such as Columbia CNA Agar when supplemented with antibiotics

Key Features & Benefits
• Enriched peptone–yeast–beef extract formulation supports rapid, luxuriant growth
• Corn starch neutralises inhibitory by-products, improving recovery from mixed samples
• Versatile base for blood or antibiotic supplementation
• Produces larger, well-defined colonies compared with simpler nutrient agars
• Compatible with aerobic and CO₂-enriched incubation for capnophilic organisms

Principle of the Medium
Columbia Agar Base provides a balanced, nutrient-rich environment that supports a wide range of bacteria and fungi. Refined meat digests and yeast extract supply amino acids, peptides, vitamins, and minerals, while corn starch absorbs toxic substances that may inhibit growth. Blood supplementation adds growth factors and enables haemolysis-based differentiation.

Typical Composition (per litre)
Pancreatic Digest of Casein – 12.0 g
Peptic Digest of Animal Tissue – 5.0 g
Yeast Extract – 3.0 g
Beef Extract – 3.0 g
Corn Starch – 1.0 g
Sodium Chloride – 5.0 g
Agar – 13.5 g

Optional supplement:
Defibrinated Sheep Blood – 50.0 mL (5%)

Final pH: 7.3 ± 0.2 at 25 °C

Preparation
Suspend 39.5 g of dehydrated medium in 950 mL purified or distilled water.
Heat with gentle agitation to boiling until completely dissolved; avoid overheating to prevent starch gelatinisation.
Sterilise by autoclaving at 121 °C (15 psi) for 15 minutes.
Cool to 45–50 °C in a water bath.
For blood agar, aseptically add 50 mL sterile defibrinated sheep blood and mix gently.
Dispense into sterile Petri dishes (20–25 mL per plate) or tubes.
Allow to solidify and dry briefly if required.

Prepared base appears light amber and clear to slightly opalescent; with blood it becomes opaque and reddish.

Incubation
Inoculate using standard aseptic technique.
Incubate at 35–37 °C aerobically or in CO₂-enriched atmosphere as required.
Typical growth is observed within 18–24 hours, depending on organism.

Storage & Stability
Dehydrated medium: Store at 10–30 °C in a tightly closed container, protected from moisture and light
Prepared plates: Store at 2–8 °C in sealed plastic bags and use within 4–8 weeks
Discard if dehydrated, contaminated, discoloured, or overgrown

Intended Use
For laboratory research and microbiological quality control use only.
Not for human or veterinary consumption.
Not for diagnostic use without appropriate validation.

Quality & Compliance
Manufactured under controlled conditions to ensure batch-to-batch consistency.
Suitable for clinical, food, and environmental microbiology laboratories.
Performance comparable to leading international Columbia agar formulations.

Customs & Trade Information
HS / AHECC Code: 3821.00.00
Prepared culture media for the development or maintenance of microorganisms