POTATO FLAKE MEDIA

Cat. no. W59 Potato Flake Agar, 15x100mm Plate, 26ml 10 plates/bag
Cat. no. X32 Potato Flake Agar, 50ml HardyFlask™, 12ml Slant 20 flasks/box
Cat. no. W159 Potato Flake Selective Agar, 15x100mm Plate, 26ml 10 plates/bag
Cat. no. X59 Potato Flake Selective Agar, 50ml HardyFlask™, 12ml Slant 20 flasks/box

INTENDED USE

Hardy Diagnostics Potato Flake Media is used in the cultivation, isolation, and induction of sporulation of fungi from clinical specimens.

SUMMARY

As a result of therapeutic technology advances and the continuing AIDS epidemic, rates of fungal infections have increased significantly in recent years. Proper diagnosis and treatment of fungal disease is dependent upon the accurate identification of these emerging pathogens. (1) Although yeasts can be identified in clinical microbiology laboratories by biochemical tests, molds require microscopic evaluation of morphological structures for their proper identification. Identification of fungi in clinical laboratories is further complicated by the failure to observe characteristic morphological structures on standard mycological media. Hardy Diagnostics Potato Flake Media is specifically designed to enhance the production of characteristic morphological features in molds. (7)

Potato Flake Agar, based on the formula recommended by M.G. Rinaldi, is designed to contain the proper formulation of carbon, protein and nutrient sources recommended for the identification of mold fungi encountered in the clinical mycology laboratory. (6) Glucose is added to the medium to provide a carbon and energy source. The media also contains potato flakes which promote conidiation by molds. The pH is adjusted to approximately 5.6 in order to enhance the growth of fungi and to slightly inhibit bacterial growth commonly found as contaminants. (1-4,6) In addition, selective agents are added to increase the inhibitory properties of Potato Flake Selective Agar to inhibit growth of gram-positive and gram-negative bacteria.

FORMULA

Ingredients per liter of deionized water:*

Potato Flakes 20.0gm
Glucose 10.0gm
Agar 15.0gm

In addition to the above ingredients,
Potato Flake Selective Agar contains 11.0mg of selective agents per liter.

Final pH 5.6 +/- 0.3 at 25ºC.

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

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-8ºC. (except Cat. no. X32 and L64 should be stored at 2-30ºC) 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.

PRECAUTIONS

PROCEDURE

Specimen Collection: Consult listed references for information on specimen collection. (1-4) Infectious material should be submitted directly to the laboratory without delay and protected from excessive heat and cold. If there is to be a delay in processing, the specimen should be inoculated onto an appropriate transport media and refrigerated until inoculation.

Method of Use:

1. Allow media to warm to room temperature, and the agar surface to dry before inoculating. A non-selective medium should be inoculated along with the selective medium for isolation of fungi from potentially contaminated specimens. Consult listed references for appropriate incubation temperature. (1-4)

2. Inoculate and streak the specimen as soon as possible after collection. If the specimen to be cultured is on a swab, roll the swab over a small area of the agar surface. Streak for isolation with a sterile loop. If the specimen is collected on a loop or needle, inoculate the plate with fungi in two or three distinct places by pressing the inoculum onto the agar surface.

3. Incubate plates in an inverted position. Once inoculated, media should be protected from light and incubated aerobically at 25-35ºC. with increased humidity for four weeks or longer. Our MycoSeal™ product (Cat. no. SS9225) may be used to seal the plates to keep moisture from evaporating from the Potato Flake plated media, while still allowing atmospheric circulation.

4. Examine plates for typical colonial and hyphal morphology and color. Cultures should be held from 4 to 6 weeks before being reported as negative.

INTERPRETATION OF RESULTS

Identification of fungi is performed by observing various aspects of colony morphology, characteristic microscopic structures, rate of growth, media which supports the organisms growth, and source of the specimen. Consult the listed references for information regarding the identification and further testing of fungi and yeast cultures. (1-4,7,8)

LIMITATIONS

A non-selective and selective medium should be inoculated for isolation of fungi from potentially contaminated specimens. (1)

Potato Flake Selective Agar is not recommended for Nocardia spp. that are sensitive to quinolones. Other media, such as Sabouraud Dextrose, would be recommended to select for these organisms.

MATERIALS REQUIRED BUT NOT PROVIDED

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

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Potato Flake Agar:
Candida albicans
ATCC ® 10231
A 24-48hr 15-30°C Aerobic Growth
Trichophyton mentagrophytes
ATCC ® 9533
G up to 7 days 15-30°C Aerobic Growth
Aspergillus brasiliensis
formerly A. niger
ATCC ® 16404

G up to 7 days 15-30°C Aerobic Growth
Potato Flake Selective Agar:
Candida albicans
ATCC ® 10231
A 24-48hr 15-30°C Aerobic Growth
Aspergillus brasiliensis
formerly A. niger
ATCC ® 16404

G up to 7 days 15-30°C Aerobic Growth
Trichophyton mentagrophytes
ATCC ® 9533
G up to 7 days 15-30°C Aerobic Growth
Staphylococcus aureus
ATCC ® 25923
B 18-24hr 35°C Aerobic Partial to complete inhibition
Escherichia coli
ATCC ® 25922
B 18-24hr 35°C Aerobic Partial to complete inhibition

User Quality Control

PHYSICAL APPEARANCE

Potato Flake Media should appear slightly opaque, may have a slight precipitate, and white in color.

A. niger growing on Potato Flake Agar

Aspergillus brasiliensis formerly A. niger (ATCC ® 16404) colonies growing on Potato Flake Agar (Cat no. W59). Incubated aerobically for 72 hours at 30ºC.

T. mentagrophytes growing on Potato Flake Agar

Trichophyton mentagrophytes (ATCC ® 19533) colonies growing on Potato Flake Agar (Cat no. W59). Incubated aerobically for 72 hours at 30ºC.



Potato Flake Agar

Uninoculated plate of Potato Flake Agar (Cat. no. W59)



REFERENCES

1. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

2. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

3. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology, J.B. Lippincott Company, Philadelphia, PA.

4. Ajello, et al. 1963. CDC Laboratory Manual for Medical Mycology, PHS Publication No. 994. U.S. Gov't Printing Office, Washington, D.C.

5. Thom, C. and M.B. Church. 1926. The Aspergilli. Williams & Wilkins Co., Baltimore, MD.

6. Rinaldi, M.G. 1982. Use Of Potato Flakes In Clinical Mycology. J. Clin. Microbiol.; 15:1159-1160.

7. Larone, D.H. Medically Important Fungi: A Guide to Identification, American Society for Microbiology. Washington, D.C.

8. St. Germain, Guy, et al. 1996. Identifying Filamentous Fungi. Star Publishing Company, Belmont, CA.


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

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