Clostridium difficile: isolation and characteristics.

Clostridium difficile can be grown readily in Reinforced Clostridial Medium (RCM) containing 0-1-0-4% of o-, m- or p-cresol, or phenol. We recommend 0-2% of phenol or p-cresol in RCM for the isolation of this organism. The characteristic "cornfield" growth in RCM in 25-ml Universal containers is described. Glucose, fructose, galactose, mannose, raffinose, aesculin and mannitol are fermented with production of acid and gas; maltose, sucrose, glycogen, soluble starch and sorbitol are fermented with production of acid only. Lactose and rice starch are not fermented by any strain, and DL-methionine is not attacked. Nitrate is reduced to nitrite. Hydrogen sulphide and indole are not produced. Gelatin is attacked by all strains, but in some cases prolonged incubation is required. Hyaluronidase is produced, but not deoxyribonuclease. A lethal toxin appears to be produced. Strains possess shared and strain-specific antigens.