title: Evaluation of a chromogenic culture medium for isolation of Clostridium difficile within 24 hours.
abstract: Rapid and effective methods for the isolation of Clostridium difficile from stool samples are desirable to obtain isolates for typing or to facilitate accurate diagnosis of C. difficile-associated diarrhea. We report on the evaluation of a prototype chromogenic medium (ID C. difficile prototype [IDCd]) for isolation of C. difficile. The chromogenic medium was compared using (i) 368 untreated stool samples that were also inoculated onto CLO medium, (ii) 339 stool samples that were subjected to alcohol shock and also inoculated onto five distinct selective agars, and (iii) standardized suspensions of 10 C. difficile ribotypes (untreated and alcohol treated) that were also inoculated onto five distinct selective agars. Two hundred thirty-six isolates of C. difficile were recovered from 368 untreated stool samples, and all but 1 of these strains (99.6%) were recovered on IDCd within 24 h, whereas 74.6% of isolates were recovered on CLO medium after 48 h. Of 339 alcohol-treated stool samples cultured onto IDCd and five other selective agars, C. difficile was recovered from 218 samples using a combination of all media. The use of IDCd allowed recovery of 96.3% of isolates within 24 h, whereas 51 to 83% of isolates were recovered within 24 h using the five other media. Finally, when they were challenged with pure cultures, all 10 ribotypes of C. difficile generated higher colony counts on IDCd irrespective of alcohol pretreatment or duration of incubation. We conclude that IDCd is an effective medium for isolation of C. difficile from stool samples within 24 h.
authors.affiliation: Department of Microbiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom. john.perry@nuth.nhs.uk
authors.forename: John D
authors.initials: JD
authors.lastname: Perry
authors.forename: Kerry
authors.initials: K
authors.lastname: Asir
authors.forename: Diane
authors.initials: D
authors.lastname: Halimi
authors.forename: Sylvain
authors.initials: S
authors.lastname: Orenga
authors.forename: Joanne
authors.initials: J
authors.lastname: Dale
authors.forename: Michelle
authors.initials: M
authors.lastname: Payne
authors.forename: Ruth
authors.initials: R
authors.lastname: Carlton
authors.forename: Jim
authors.initials: J
authors.lastname: Evans
authors.forename: F Kate
authors.initials: FK
authors.lastname: Gould
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D002863:Chromogenic Compounds / Q000378:metabolism; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003470:Culture Media / Q000737:chemistry*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D013997:Time Factors
chemical_list: D002863:Chromogenic Compounds; D003470:Culture Media