Sabouraud Dextrose Agar w/ Soya Lecithin and Polysorbate 80

Sabouraud Dextrose Agar with Soya Lecithin and polysorbate 80 is used for the cultivation of yeasts, moulds and aciduric bacteria.

Composition**

Final pH ( at 25°C): 5.6±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 70.7 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well and dispense as desired.

Principle And Interpretation

Sabouraud Dextrose Agar with Soya Lecithin and Polysorbate 80 is the modification of formulation described by Sabouraud for determining efficiency of sterilization of container etc. with respect to yeast moulds and aciduric bacteria.

Mycological peptone provides nitrogenous compounds. Dextrose provides an energy source. The low pH favours fungal growth and inhibits contaminating bacteria from clinical specimens (2).

Some pathogenic fungi may produce infective spores which are easily dispersed in air, so examination should be carried out in safety cabinet.

Lecithin and polysorbate 80 are neutralizers reported to inactivate residual disinfectants from where the sample is collected (3). Lecithin neutralizes quartenery ammonium compounds and polysorbate 80 neutralizes phenolic disinfectants, hexachlorophene formalin, and with lecithin neutralizes ethanol (4). Collection of samples from areas before and after the treatment with disinfectant evaluates cleaning procedures in environmental sanitation. The presence and number of fungi is determined by the appearance of colonies on the agar surface.

Quality Control

Appearance Cream to yellow coloured 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 7.07% w/v aqueous solution at 25°C. pH : 5.6±0.2

pH 5.40-5.80

Cultural Response Cultural characteristics observed after an incubation at 30°C for 48-72 hours.

Cultural Response

Key : * - Formerly known as Aspergillus niger

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.

Reference

1. Sabouraud K., 1892, Ann. Dermatol. Syphilol, 3:1061.
2. Murray PR, Baren EJ, Jorgensen JH, Pfaller MA, Yolken RH (editors) 2003, Manual of clinical Microbiology, 8th ed., ASM, Washington, D.C.
3. Brummer; 1976 appl Environ. Microbiol 32:80.
4. Favero (Clairm); 1967, Biological Contamination Control Committee, a state of the ant report., Am Assoc. for contamination control.