Sabouraud Dextrose Broth

Description

Sabouraud USP Broth is formulated according to the US Pharmacopoeia, US NF and the 21 CFR guidelines. In the latest editions of these methods, Tryptone Soy Broth may be used for sterility checking in pharmaceutical products for injection. This formulation is similar to Antibiotic Medium No. 13 by Grove and Randall and the 21 CFR guideline.

This medium is not selective, but the low pH inhibits the growth of non-acidophilic microorganisms. Special measures must be taken while reconstituting and heating the medium due to this strong acid reaction and the high content of glucose. It is important to preheat the autoclave and thereby reach the sterilization temperature as soon as possible, otherwise the glucose becomes caramelized, turning the medium dark and reducing its effectiveness.

Technique

Collect, dilute and prepare samples and volumes as required according to specifications, directives, official standard regulations and/or expected results. Dispense liquid medium in appropriate containers if the original container is of large volume.

Inoculate aseptically the tubes with the prepared sample or its dilution.

Incubate the tubes tightly closed aerobically at 20-25 °C for up to 5 days.

(Incubation times, temperature and sample volumes may vary depending on the sample, on the specifications, etc.)

Read turbidity (growth indicator) and use any confirmatory, secondary medium to get isolated colonies.

Presumptive isolation/recovery of yeast and moulds must be confirmed by further microbiological and biochemical tests.

Each laboratory must evaluate the results according to their specifications.

Calculate total microbial count per mL of sample by multiplying the average number of colonies per plate by the inverse dilution factor if a diluted sample was streaked. Report results as colony forming units (CFU) per mL or g along with incubation time and temperature.

Physical/chemical control

Microbiological control

Prepare tubes - inoculate: practical range 10-100 CFU (productivity) according to harmonized Eur. Pharmacopoeia.

Aerobiosis. Incubation at 20-25 °C. Reading at 2-3 days up to 5 days.

Sterility control

Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.

Check at 7 days after incubation in same conditions.

• AJELLO, L. (1957) Cultural Methods for Human Pathogenic Fungi J. Chron. Dis. 5:545-551.
• DOWNES, F.P. & K. ITO (2001) Compendium of methods for the microbiological examination of foods. APHA. Washington. DC. USA.
• EUROPEAN PHARMACOPOEIA 8.0 (2014) 8th ed. § 2.6.13. Microbiological examination of non-sterile products: Test for specified microorganisms. Harmonised Method. EDQM. Council of Europe. Strasbourg.
• ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
• MARSHALL, R.T. (1992) Standard methods for the examination of dairy products. 16th ed. APHA. Washington. DC. USA.
• SABOURAUD, R. (1910) Les Teignes. Masson. Paris.
• USP 33 - NF 28 (2011) <62> Microbiological examination of non-sterile products: Test for specified microorganisms. Harmonised Method. USP Corp. Inc. Rockville. MD. USA.
• USP 33 - NF 28 (2011) <81> Antibiotics - Microbial Assays. USP Corp. Inc. Rockville. MD. USA.