Evaluation of cycloserine-cefoxitin-fructose agar and cycloserine-cefoxitinfructose broth for recovery of Clostridium difficile from environmental

either 500 or 250,ug of cycloserine per ml were compared for efficacy in the isolation of Clostridium difficile from hospital ward environmental sites. A RODAC imprint technique was used to inoculate prereduced CCFA. Moistened swabs were used to inoculate prereduced CCFB from environmental sites immediately adjacent to the RODAC sample sites. CCFA (6 % positive) was significantly more sensitive than CCFB (3 % positive; P < 0.005), regardless of the cycloserine concentration. When the CCFA cycloserine concentration was decreased from 500 to 250,ug/ml, the overall rate of positive cultures rose from 4 to 17%. Medium containing 500,ig of cycloserine per ml may be too inhibitory to isolate many moderately sensitive strains of C. difficile from environmental sites. Regardless of the cycloserine concentration, the CCFA RODAC imprint technique is superior to the CCFB method. The etiologic link between Clostridium difficile and pseudo-membranous colitis has been well documented (1). Study of the epidemiology of C. difficile has identified both asympto-matic C. difficile culture-positive patients and contaminated environments as potential sources of diarrheal outbreaks (8). The environment surrounding both symptomatic and asymp