Clostridium Perfringens Agar Base (m-CP) is a medium used for the rapid isolation and presumptive identification of Clostridium perfringens from water samples. m-CP Agar was first used for the rapid quantisation of Clostridium perfringens from various water samples (seawater, drinking water and sewage) for human consumption and from environmental water samples. It is recommended in European Council Directive 98/83/EC for testing the quality of water intended for human consumption by the membrane filtration technique.

The medium was shown to give better recovery of Clostridium perfringens from water and sewage samples. It can be used for monitoring all types of waters. C. perfringens is present in large numbers in water and sewage and its spores are resistant to wastewater treatment practices, extremes in temperature, and environmental stress. The medium has been recommended for the examination of chlorinated waters and untreated water containing industrial wastes lethal to non-spore forming bacteria, sewage sludge, and situations in which the detection of remote as well as recent pollution is desirable.

Tryptose provides nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group essential for bacterial growth. Sucrose is a complex carbohydrate energy source. L-Cysteine hydrochloride is the reducing agent and Bromocresol purple is the pH indicator. Bacteriological Agar is the solidifying agent.