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Selectively isolate and differentiate Clostridium spp. from clinical specimens using McClung-Toabe Agar.
Selectively isolate and differentiate Clostridium spp. using Thermo Scientific™ Remel™ McClung-Toabe Agar. In 1947, McClung and Toabe developed this differential plating medium to detect lecithinase and lipase production by Clostridium spp1. This agar was further modified by Dowell and Hawkins by adding neomycin to selectively isolate and differentiate certain obligately anaerobic bacteria such as Clostridium perfringens2.
Use McClung-Toabe Agar for selectively isolate and differentiate Clostridium spp.
Clostridium spp. produce the enzymes lecithinase and lipase. Egg yolk suspension (50%) present in the medium serves as the substrate to detect lecithinase and lipase activity3. Lecithinase degrades lecithin and produces an insoluble, opaque precipitate in the medium surrounding growth4. Lipase breaks down free fats in the egg yolk forming in an iridescent sheen on the colony surface.
This medium contains gelatin peptone that supplies amino acids and other nitrogenous compounds necessary for the growth of anaerobic bacteria. Dextrose serves as an energy source. Egg yolk serves as a substrate for detection of lecithinase and lipase activity3 and also reduces the toxic effect of organic peroxides which may accumulate in the medium. Neomycin acts as the selective agent which inhibits many gram-positive and gram-negative organisms. Agar is the solidifying agent.