Sabouraud Dextrose Broth UseSabouraud Dextrose Broth is general-purpose media used for the cultivation of yeasts, moulds andaciduric bacteria.SummarySabouraud Dextrose Broth is Carliers (12) modification of the formulation described by Sabouraud for the cultivation of fungi, particularly those associated with skin infections. It is used in qualitative procedures for cultivation of pathogenic and non-pathogenic fungi, particularly dermatophytes. Carlier showed that this medium gives reliable results with Microsporum audouini, M.canis, Trichophyton mentagrophytes, T.flavum, T.rubrum and Candida albicans. The fungi maintain their typical cultural appearance and thus may be readily identified according to the standard macroscopic characters described by Sabouraud. Sabouraud Dextrose Broth is recommended in the Bacteriological Analytical Manual for cosmetics testing. PrincipleMixture of peptic digest of animal tissue & pancreatic digest of casein provide nitrogenous compounds, carbon and other growth factors. Dextrose is the carbohydrate source. The low pH of approximately 5.6 is favorable for the growth of fungi, especially dermatophytes and is slightly inhibitory to contaminating bacteria. Various antibiotics can be added to this medium for bacterial inhibition as well as to make it selective for the isolation of pathogenic fungi from material containing large number of other fungi or bacteria. Formula*Ingredients in grams per liter per liter Mixture of peptic digest of animal tissue 10.0& pancreatic digest of casein (1:1) Dextrose 20.0Final pH (at 250C) 5.6 ± 0.2 * Formula adjusted to suit performance parameters

Directions1. Suspend 30 gms of the powder in 1000 ml distilled water and mix thoroughly.2. Boil with frequent agitation to dissolve the powder completely. Avoid overheating the agar as it could cause a softer medium.3. Sterilize by autoclaving at 1210C (15 lbs pressure) for 15 minutes.Quality ControlDehydrated AppearanceLight yellow coloured, homogeneous, free flowing powder.Prepared Appearance Light amber coloured, clear to slightly opalescent gel.Cultural ResponseCultural characteristics after 48-72 hours at 300C.Organisms (ATCC) Aspergillus niger (16404) luxuriant

Candida albicans (10231) luxuriantSaccharomyces cerevisiae (9763) luxuriantEscherichia coli (25922) luxuriant*Lactobacillus casei (9595) luxuriant*Key:* = inhibited on media with low pHProcedure1. Allow the agar surface to dry before inoculating.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.3. Streak for isolation with a sterile loop.4. Incubate plates in an inverted position.5. Once inoculated, the medium should be protected from light and incubated aerobically at 25-300C with increased humidity for four weeks or longer.For Quantitative test1. Prepare decimal dilutions of the sample in a sterile diluent to obtain 30-300 colony forming units per plate.2. Inoculate using the pour plate or streak plate technique.3. Incubate plates aerobically for 7 days at 25-300C.Note: After autoclaving, do not heat the medium longer than 3 hours at 45-500C. Sterile solidified medium can be remelted only once.Interpretation of Results1. Identification of fungi is done by observing colony morphology, characteristic microscopic structures, rate of growth, etc. Yeasts are identified by various biochemical tests. Pour plate and spread plate method2. Count the number of colonies and express as colony forming units (CFU) per gram or ml of sample, taking into account the applicable dilution factor.Precautions / Limitations1. Some of the pathogenic fungi may produce infective spores, which can be easily dispersed in the laboratory. Examine such organisms only within a protective cabinet.2. When used for selective isolation, antimicrobials like chloramphenicol and cycloheximide may inhibit some pathogenic fungi. However, the mycelial phase of Histoplama capsulatum, Paracoccidioides brasiliensis, Sporothrix schoenckii and Blastomyces dermatidis is not inhibited by these antibiotics when incubated at 25-300C.3. A non-selective and selective medium should be inoculated for isolation of fungi from potentially contaminated specimens.