Developed by French dermatologist Raymond J.A. Sabouraud in the late 1800’s primarily for the recovery of dermatophytes. Traditionally this media (despite being a selective media) did not contain antibiotics and relied on a low pH (5.6) for the inhibition of bacterial growth, however antibiotics are commonly used with SDA in current clinical use.
- Sabouraud’s agar is sufficient for the recovery of dermatophytes from cutaneous samples and yeasts from vaginal cultures.
- Not recommended as a primary isolation medium because it is insufficiently rich to recover certain fastidious pathogenic species, particularly most of the dimorphic fungi.
- Sabouraud’s dextrose agar (2%) is most useful as a medium for the subculture of fungi recovered on enriched medium to enhance typical sporulation and provide the more characteristic colony morphology.
This media is commercially available from a number of companies.
See comparison to inhibitory mould agar (IMA)
Sabouraud agar can be purchased from a variety of commercial sources or for laboratories needing large number of plates is often made “in-house”.
Sabouraud agar Recipe/Protocol
Per liter of medium:
Peptone, 10 g
Glucose, 40 g
Agar, 15 g
1. Combine all ingredients in ~900 ml of deioinized water.
2. Adjust to pH 5.6 with hydrochloric acid and adjust final volume to 1 liter.
3. Autoclave 20 minutes at 121°C, 15 lb/in2.
4. Cool to ~45 to 50°C and pour into petri dishes/tubes for slants.
Chloramphenicol is added at the users preference. If desired add 0.05g to the above recipe.
Emmons modification of Sabouraud agar
The neutral pH of the Emmons modification seems to enhance the growth of some pathogenic fungi, such as dermatophytes.
Per liter of medium:
Neo-peptone, 10 g
Glucose, 20 g
Agar, 20 g
1. Follow steps 1 through 4, above, except adjust the pH to the range of 6.8 to 7.0 with hydrochloric acid before autoclaving, cooling, and pouring.
Either Sabouraud agar or its Emmons version can be made more selective by adding antibiotics. Commonly used are gentamicin, which inhibits gram-negative bacteria, and/or chloramphenicol, which inhibits a wide range of gram-positives and gram-negatives, and cycloheximide, which inhibits primarily saprophytic fungi but not dermatophytes or yeasts (3). Chloramphenicol and gentamicin are used at 50 mg/liter (dissolved in 10 ml of 95% ethanol before adding to molten media) and cycloheximide at 0.5 g/liter (dissolved in 2 ml of acetone first) (2). Antibiotics should only be added after media has been autoclaved and then cooled to ~45 to 50°C. Keep all plates at 4°C until they are used, regardless of whether they contain antibiotics.