COOKED MEAT MEDIUM (R.C. MEDIUM) (MEAT GRANULES)

Cooked Meat Medium contains beef heart, solids, which provide amino acids and other nutrients. It also contains glutathione, a reducing substance that permits the growth of obligate anaerobes. The sulfhydryl groups, which impart reducing effect, are more available in denatured protein and hence cooked meat is added in the medium. The addition of dextrose allows rapid and heavy growth of anaerobic bacteria in a short time and leads to more rapid identification of important anaerobes. Growth in Cooked Meat Medium is indicated by turbidity or bubble formation by some organisms. Blackening and disintegration of the meat particles indicate proteolysis. For best results, medium should be used on the day it is prepared, otherwise it should be boiled or steamed for a few minutes and allowed to cool without agitation and then inoculated. Inoculation should be made near the bottom of the tube in the meat particles for anaerobic cultures. Aerobes grow at the top whilst more anaerobic species grow deeper in the medium.

For the isolation of Clostridium from food, use a stomacher to prepare 10% suspension of the food in peptone water diluent. Make dilutions and plates, both suspensions and dilutions on Willis and Hobbs Medium Base, Tryptose Sulphite Cycloserine (T.C.S.) Agar Base. Place a metronidazole disc on the inoculum. Incubate anaerobically at 37°C overnight. To count the clostridia, pour the plates with the dilutions on Perfringens Agar Base (O.P.S.P.). Incubate duplicate plates aerobically and anaerobically to distinguish between clostridia and other organisms. Add some of the suspension to two tubes of Cooked Meat Medium. Heat one tube for 10 min at 80°C and incubate as above. Growth of clostridia is visualized as turbidity or gas bubbles. This medium can be further tested for presence of Clostridium.

For cultivation of aerobes and anaerobes especially pathogenic Clostridia and also for maintenance of stock cultures.