title: Norleucine-tyrosine broth for rapid identification of Clostridium difficile by gas-liquid chromatography.
abstract: A new medium, norleucine-tyrosine (NT) broth, was developed for rapid identification of Clostridium difficile on the basis of caproic acid and p-cresol production. The NT broth consists of 0.5% Trypticase (BBL Microbiology Systems, Cockeysville, Md.), 0.5% yeast extract (Difco Laboratories, Detroit), 0.2% L-norleucine and 0.2% L-tyrosine (wt/vol; final concentrations), and a mixture of salts. The procedure for demonstrating caproic acid and p-cresol production involves extracting NT broth cultures with ether or chloroform and analyzing the extracts with a gas-liquid chromatograph equipped with a thermal conductivity detector, as is customary for analysis of volatile fatty acids. A total of 120 strains of C. difficile from diverse geographic locations were tested by this procedure, and they all produced caproic acid and p-cresol in NT broth. No other Clostridium species or other microorganisms tested have been found to produce both products in NT broth.
mesh_terms: D002208:Caproates / Q000096:biosynthesis; D002849:Chromatography, Gas; D003013:Clostridium / Q000378:metabolism*; D003408:Cresols / Q000378:metabolism; D009646:Norleucine / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
chemical_list: D002208:Caproates; D003408:Cresols; C032538:4-cresol; D014443:Tyrosine; D009646:Norleucine