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Sabouraud Dextrose Agar

Name: Sabouraud Dextrose Agar
SKU: SDA-M
Availability: InStock

Sabouraud Dextrose Agar

$25.00 – $45.00

250 mL, 500 mL
Number of sizes: 2
Type: Agar Gel

Prepared Media – Ready to Dissolve

No sub-products available for this product.

SKU: SDA-M Category: Ready To Dissolve

Description

Intended Use and Principle of Procedure

Sabouraud Dextrose Agar conforms with the specifications of The United States Pharmacopeia (USP).

Sabouraud Dextrose Agar is used in qualitative procedures for the cultivation of pathogenic and nonpathogenic fungi, particularly dermatophytes. The medium is rendered more selective for fungi
by the addition of antimicrobics. Sabouraud Dextrose Broth and Sabouraud Maltose Agar and Broth are also used for culturing yeasts, molds, and aciduric microorganisms.

Fluid Sabouraud Medium is used for cultivating yeasts, molds, and aciduric microorganisms and detecting yeasts and molds in normally sterile materials.

Sabouraud dextrose media are peptone media supplemented with dextrose to support the growth of fungi. Media are also provided with maltose substituted for the dextrose. Peptones are sources of nitrogenous growth factors. Carbohydrates provide an energy source for the growth of microorganisms. Gentamicin is an aminoglycoside antibiotic that inhibits the growth of gram-negative bacteria. Chloramphenicol is inhibitory to a wide range of gram-negative and gram-positive bacteria, and cycloheximide is an antifungal agent that is primarily active against saprophytic fungi and does not inhibit yeasts or dermatophytes.

Lecithin neutralizes quaternary ammonium compounds, and polysorbate 80 neutralizes substituted phenolic disinfectants.

For the Sterile Pack products, the entire double-bagged product is subjected to a sterilizing dose of gamma radiation. Thus, the contents inside the outer bag are sterile. This allows the inner bag to be aseptically removed and brought into an environment- a mentally controlled area without introducing contaminants. A third sterile bag is included as a transport device. Since the agar medium has been sterilized after packaging, the presence of microbial growth after sampling and incubation can be relied upon to represent the presence of environmental contami- nants and not pre-existing microorganisms in the medium that may have been introduced during manufacture. The RODAC plates have a marked grid to facilitate counting organisms. The Sterile Pack Finger Dab Isolator plates are triple-bagged and are intended for sampling gloved hands.

Summary and Explanation

Sabouraud Dextrose Agar is a general-purpose medium that Sabouraud devised for the cultivation of dermatophytes.1 The low pH of approximately 5.6 is favorable for the growth of fungi, especially dermatophytes, and slightly inhibitory to contaminating bacteria in clinical specimens.2-4 This medium is recommended in the USP for use in performing total combined mold and yeast counts (Microbial Limit Tests).

The addition of antimicrobics is a modification designed to increase bacterial inhibition.

RODAC (Replicate Organism Detection and Counting) environmental sampling plates are specially constructed so that an agar medium can be over-filled, producing a meniscus or dome-shaped surface that can be pressed onto a surface for sampling its microbial burden. These plates are used in a variety of programs to establish and monitor cleaning techniques and schedules.6-10 After touching the surface to be sampled with the medium, the environmental sampling dish is covered and incubated at an appropriate temperature. The presence and number of microorganisms are determined by the appearance of colonies on the surface of the agar medium.11 Collection of samples from the same area before and after cleaning and treatment with a disinfectant permits the evaluation of the efficacy of sanitary procedures.

Sabouraud Maltose Agar is a modification of Sabouraud Dextrose Agar with maltose substituted for the dextrose. It is a selective medium due to the acid pH. Davidson et al. reported that Sabouraud Maltose Agar was a satisfactory medium in their studies of infections caused by Microsporum audouini, M. lanosum, and Trichophyton gypseum. Davidson and Dowding also used this medium to isolate T. gypseum from a case of tinea barbae.

Sabouraud Maltose Broth is a modification of Sabouraud Dextrose Broth in which maltose is substituted for dextrose. It is selective due to its acid pH and is used for the detection of fungi.

Fluid Sabouraud Medium is employed in sterility test procedures to determine the presence of molds, yeasts, and aciduric microorganisms. The acid reaction of the final medium is inhibitive to a large number of bacteria and makes the medium particularly well-suited for cultivating fungi and acidophilic microorganisms.

Formulae

Enzymatic Digest of Casein	10.0g
Dextrose	40.0g
Agar	15.0g

Procedure

For the isolation of fungi from potentially contaminated specimens, a selective medium should be inoculated along with the nonselective medium. Incubate the containers at 25-30°C with increased humidity. All cultures should be examined at least weekly for fungal growth and should be held for 4-6 weeks before being reported as negative.

Liquefy the medium in pour tubes by heating it in boiling water. Cool to 45-50°C and pour into sterile Petri dishes. Allow to solidify for a minimum of 30 minutes.

Prepared tubed slants are primarily intended for use with pure cultures for maintenance or other purposes. With prepared
plates and Mycoflask bottles, streak the specimen as soon as possible after it is received in the laboratory, using a sterile inoculating loop to obtain isolated colonies. Consult appropriate references for information about the processing and inoculation of specimens.

For the Sterile Pack media, sample selected surfaces by firmly pressing the agar medium against the test area. Hold the plate with your thumb and second finger, and use your index finger to press the plate bottom firmly against the surface. Pressure should be the same for every sample. Do not move the plate laterally, as this spreads contaminants over the agar surface, making the resolution of colonies difficult. Slightly curved surfaces may be sampled with a rolling motion.

Areas (walls, floors, etc.) to be assayed may be divided into sections or grids, and samples taken from specific points within the grid.

Incubate exposed plates at 35-37°C for 48 hours and 25°C for 7 days or as required.

Directions for Preparation from Dehydrated Product

1. Suspend/dissolve the powder in 1 L of purified water:

Difco Sabouraud Dextrose Agar – 65 g;

Mix thoroughly.

2. Heat the agar media with frequent agitation and boil for 1 minute to completely dissolve the powder. Avoid overheating, which could cause a softer medium.

3. Autoclave at 121°C for 15 minutes.

4. Test samples of the finished product for performance using stable, typical control cultures.

Identification Specification and Cultural Response

Dehydrated Appearance:	Fine, homogeneous, free of extraneous material, may contain a large number of minute to small tan specks.
Prepared Appearance: Solution:	Pale to medium, yellow to tan, clear to slightly hazy. 6.5% solution, soluble in purified water upon boiling. Solution is pale to medium, yellow to tan, and clear to slightly hazy.
pH:	5.6 ± 0.2
Cultural Response:	Prepare the medium per label directions. Inoculate with fresh cultures and incubate at 25 ± 2°C for 7 days.
Reaction	6.5%
Solution	25°C

Microorganism	ATCC	Recovery
Aspergillus niger	16404	Good
Aureobasidium pullulans	9348	Good
Blastomyces dermatitidis	56218	Good
Candida albicans	60193	Good
Cryptococcus neoformans	32045	Good
Microsporum audouinii	9079	Good
Nocardia asteroides	19247	Good
Penicillium roquefortii	9295	Good
Trichophyton mentagrophytes	9533	Good

Limitations Of The Procedure

Some fungi may be inhibited by the acidic pH of the medium and by the antimicrobics in the selective media.

Expected Results

After sufficient incubation, the containers should show isolated colonies in streaked areas and confluent growth in areas of heavy inoculation. Transfer of growth from slants to plated media may be required to obtain pure cultures of fungi.

Examine containers for fungal colonies exhibiting typical color and morphology.20 Biochemical tests and serological procedures should be performed to confirm findings.

In the RODAC procedure, colonies are counted (fewer than 200 colonies for accurate counts) and expressed as either the number of colonies per RODAC plate or the number of colonies per cm.2,21,22 Criteria for cleanliness of equipment and environment (surfaces) can be developed by using a database derived from repeated routine sampling of specific sites.

Subculture colonies of interest so that positive identification can be made by means of biochemical testing and/or microscopic examination of organism smears.

References

1. Ajello, Georg, Kaplan, and Kaufman. 1963. CDC laboratory manual for medical mycology. PHS Publication No. 994, U.S. Government Printing Office, Washington, D.C.

2. Reisner, Woods, Thompson, Larone, Garcia and Shimizu. 1999. In Murray, Baron, Pfaller, Tenover and Yolken (ed.). Manual of clinical microbiology, 7th ed. American Society for Microbiology, Washington, D.C.

3. Kwon-Chung and Bennett. 1992. Medical mycology. Lea & Febiger, Philadelphia, Pa.

4. United States Pharmacopeial Convention, Inc. 2001. The United States pharmacopeia 25/The national formulary 20 – 2002. United States Pharmacopeial Convention, Inc., Rockville, Md.

5. Hall & Hartnett. 1964. Public Health Rep. 79: 1021.

6. Vesley and Michaelson. 1964. Health Lab. Sci. 1:107.

7. Pryor and McDuff. 1969. Exec. Housekeeper, March.

8. Dell. 1979. Pharm. Technol. 3: 47.

9. Cannon, Beckelheimer and Maxcy. 1985. In Richardson (ed.), Standard methods for the examina- tion of dairy products, 15th ed. American Public Health Association, Washington, D.C.

10. McGowan. 1985. In Lennette, Balows, Hausler and Shadomy (ed.), Manual of clinical microbiol- ogy, 4th ed. American Society for Microbiology, Washington, D.C.

11. Davidson, Dowding, and Buller. 1932. Can. J. Res. 6:1.

12. Davidson and Dowding. 1932. Arch. Dermatol. Syphilol. 26:660.

13. Lorian (ed.). 1996. Antibiotics in laboratory medicine, 4th ed. Williams & Wilkins, Baltimore, Md.

14. Favero, Gabis and Vesley. 1984. In Speck (ed.), Compendium of methods for the microbiological examination of foods, 2nd ed. American Public Health Association, Washington, D.C.

15. Quisno, Gibby, and Foter. 1946. Am. J. Pharm. 118: 320.

16. Erlandson and Lawrence. 1953. Science 118: 274

17. Brummer. 1976. Appl. Environ. Microbiol. 32: 80.

18. Association for the Advancement of Medical Instrumentation. 1984. Process control guidelines for gamma radiation sterilization of medical devices. Association for the Advancement of Medical Instrumentation, Arlington, Va.

19. Larone. 1995. Medically important fungi: a guide to identification, 3rd ed. American Society for Microbiology, Washington, D.C.

20. Vanderzant and Splittstoesser (ed.). 1992. Compendium of methods for the microbiological examination of foods, 3rd ed. American Public Health Association, Washington, D.C.

21. Marshall (ed.) 1993. Standard methods for the examination of dairy products, 16th ed. American Public Health Association, Washington, D.C.

22. ICMSF. 1988. Microorganisms in foods 4. Intern. Comm. on Microbiology Spec. for Foods. Blackwall Scient. Publs., Palo Alto, Calif.

Additional information

Size	250mL, 500mL

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Sabouraud Dextrose Agar

Sabouraud Dextrose Agar

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