What Is Sabouraud Dextrose Agar?

To identify the various fungi, yeasts and molds in patient or environmental samples, you need an appropriate growth medium. Sabouraud dextrose agar is a common choice in the battery of media used to grow fungi.

Purpose

It was originally formulated by French physician Raymond Sabouraud to grow the fungi that cause ringworm. The current formulation allows Sabouraud dextrose agar to recover a large group of saprophytic and pathogenic fungi from a variety of sources.

PH

A low pH of 5.6 is very favorable for growing fungi. At the same time, it is useful because it can inhibit some bacteria that may contaminate or interfere with the culture.

Containers

Sabouraud dextrose agar comes in both agar plates and screw-capped tubes. The agar plates are good for growth because of better aeration, however, they occasionally dry out. The screw-capped tubes require less space for storage and have a lower dehydration rate.

Selectivity

Sabouraud dextrose agar in its most basic form provides little inhibition to contaminating organisms. The agar can be made or purchased with the addition of antibiotics when being more selective is required.

Incubation of Media

The inoculated Sabouraud dextrose agar should be incubated at 25 to 30 degrees Celsius. They are examined on a weekly basis for up to six weeks before reporting as negative.

References

• Bailey and Scott's Diagnostic Microbiology; Betty Forbes, Ph.D.; 2002
• Doctor Fungus: Culture Media