Fungal Agar w/ low pH (Mycological Agar w/ low pH)

Intended Use:

For selective enumeration and cultivation of saprophytic fungi and aciduric bacteria.

Composition**

Final pH (at 25°C): 4.8±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 35 grams in 1000 ml purified / distilled water. Heat, to boiling, to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Mycological media are basal media to which antifungal agents may be added for checking their effect on fungi or bacteria to render them selective for isolation and cultivation of fungi. Fungal Agar with low pH is used for saprophytic fungi.

Earlier media for fungi generally relied on an acidic pH to make the media less suitable for the growth of many bacteria (1).

Fungal Agar w/ low pH is prepared according to the formulation suggested by Huppert and Walker (2).

Fungal Agar w/ low pH is a selective agar for culturing and enumerating fungi and aciduric bacteria from beverages, poultry (3) and clinical material (4).

Soya peptone in the medium provides nitrogen, vitamins and minerals necessary to support bacterial growth. Dextrose is a carbon source required for the growth of fungi.

Type of specimen

Clinical samples - Sputum, nail and skin scrapings, etc; Food samples - beverages, poultry.

Specimen Collection and Handling:

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (5,6).

For food samples, follow appropriate techniques for sample collection and processing as per guidelines (7).

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

Warning and Precautions :

In Vitro diagnostic Use. For professional use only. 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 clinical specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations :

1. Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
2. Further serological and biochemical testing on colonies of pure culture is required for complete identification.

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 Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium Light amber coloured, clear to slightly opalescent gel forms in Petri plates

Reaction

Reaction of 3.5% w/v aqueous solution at 25°C. pH : 4.8±0.2

pH 4.60-5.00

Cultural Response

Cultural characteristics observed after an incubation at 25 - 30°C for 48-72 hours (For Trichophyton species longer incubation may be required for upto 7days).

Key:(*) Corresponding WDCM numbers. (#) - Formerly known as Aspergillus niger

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 in order 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 clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques (5,6).

Reference

1. A. J. Clin. Path., 1951, 21: 684.
2. Huppert M., and Walker L. J., 1958, Am. J. Clin. Pathol., 29:291.
3. Wetzler, Musick, Johnson and Mackenzie, 1962, Am. J. Publ. Hlth., 52:460.
4. Van Riesen and Jensen, 1958, Am. J. Med. Technol., 24:123.
5. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
6. 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.
7. Salfinger Y., and Tortorello M.L., 2015, Compendium of Methods for the Microbiological Examination of Foods, 5th Ed., American Public Health Association, Washington, D.C.