Reinforced Clostridium Medium

Principles and uses
Reinforced Clostridial Medium is a semisolid medium. It is recommended for the cultivation and enumeration of anaerobes, particularly Clostridium and other microorganisms, in foods and clinical specimens.
It was formulated by Hirsch and Grinstead in 1954.Their work demonstrated that the medium outperformed other media in supporting the growth of Clostridium from small inoculum and produced higher viable cell counts.
Peptone and beef extract provide nitrogen, vitamins, minerals and amino acids essential for growth. yeast extract is the source of vitamins, particularly of the B-group. Dextrose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Starch in the medium acts as a growth factor, probably functioning like a colloid protector, and neutralizes toxic products that form during the development of the organisms. L Cysteine hydrochloride is the reducing agent and sodium acetate is the buffer.
Since the medium is a non-selective enrichment one, it allows the growth of various anaerobic microorganisms and facultative bacteria when incubated under anaerobic conditions.
The European Pharmacopoeia, USP, recommends the Reinforced Clostridial Medium in the Paragraph 2.6.13 “Microbiological examination of non-Sterile products: test for specified microorganisms” for the testing of Clostridia in products.

Preparation
Suspend 38 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize in autoclave at 121°C for 15 minutes. Cool to 45-50 ºC and, if desired, add 0,02 g/l of polymyxin B in a sterile filtered solution.