AC Agar

Intended Use

Recommended for cultivation of a wide variety of microorganisms particularly for sterility testing.

Composition**

Final pH ( at 25°C): 7.2±0.2

**Formula adjusted, standardized to suit performance parameters

# Equivalent to Beef extract

Directions

Suspend 35.2 grams in 1000 ml of purified / distilled water. Heat to boiling to dissolve the medium completely. Distribute in tubes or bottles to give the desired depth and sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. If the medium is not used on same day, it is advisable to drive off dissolved gases by boiling or steaming in the autoclave and cool without agitation.

Principle And Interpretation

AC Medium support an early and luxuriant growth of aerobic, anaerobic and microaerophilic microorganisms. Many pathogenic and saprophytic aerobes can also be isolated and cultivated using AC Medium (5). This medium can also be used for sterility testing of solutions and biological products not containing mercurial preservatives. AC Agar does not exhibit the toxicity shown by some media containing sodium thioglycollate for some organisms as reported by Christensen (1) and Malin and Finn (6). Earlier studies performed have reported the usefulness of using this medium for the cultivation of a wide variety of organisms (7,8). Kolb and Schneither (4) used AC Agar to test the viability of Bacillus anthracis after exposure to methyl bromide to test the efficiency of methyl bromide as a germicidal and sporicidal agent.

Proteose peptone, HM peptone B, yeast extract and malt extract serve as the carbon and nitrogen sources in addition to being a source of vitamins and cofactors. Dextrose serves as the fermentable carbohydrate source of energy. Ascorbic acid in the media helps to improve the clarity of the medium.

Type of specimen

Pharmaceutical samples- Environmental monitoring

After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/ face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations

1. This medium is general purpose medium and may not support the growth of fastidious organisms.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.

Quality Control

Appearance: Cream to yellow homogeneous free flowing powder

Gelling: Semisolid, comparable with 0.1 % Agar gel.

Colour and Clarity of prepared medium: Medium amber coloured clear to slightly opalescent solution

Reaction: Reaction of 3.52% w/v aqueous solution at 25°C. pH : 7.2±0.2

pH: 7.00-7.40

Cultural Response: Cultural characteristics observed after an incubation at 35-37°C for 18-24 hours (Clostridium species incubated anaerobically).

Key : *- Corresponding WDCM numbers

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 20-30°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle inorder to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition Seal the container tightly after use.

Product performance is best if used within stated expiry period.

Disposal

User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (2,3).

References

1. Christensen, 1944, Paper read at New York Meeting, American Public Health Association.
2. Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
3. Jorgensen, J.H., Pfaller, M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1.
4. Kolb and Schneiter, 1950, J. Bacteriol., 59:401.
5. MacFaddin J. F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. I. Williams & Wilkins, Baltimore, Md.
6. Malin and Finn, 1951, J. Bacteriol., 62:349.
7. Reed and Orr, 1943, J. Bacteriol., 45:309.
8. Schneiter, Dunn and Caminita, 1945, Public Health Rep., 60:789.