Comparison of ChromID C. difficile agar and cycloserine-cefoxitin-fructose agar for the recovery of Clostridium difficile

SummaryAimThe rapidly changing epidemiology of Clostridium difficile infection highlights the need for improved and continuing surveillance involving stool culturing to enable molecular tracking. Culture of C. difficile can be difficult and time consuming. In this report ChromID C. difficile agar (CDIF) was compared to cycloserine-cefoxitin-fructose-egg- yolk agar which contained 0.1% sodium taurocholate (TCCFA) as a germinant.ResultsAll ribotypes of C. difficile tested (n= 90) grew well on CDIF within 24 h and most gave characteristic small irregular black colonies with a raised umbonate profile. Counts from standard suspensions of C. difficile at 24 h (P < 0.005) and 48 h (p = 0.01) were significantly higher on CDIF than on TCCFA. Similar results were achieved after alcohol shock. When temperature shock was used to differentiate vegetative cells and spores, the total number of culturable and vegetative cells on CDIF was significantly higher than on TCCFA (culturable cells, p = 0.003 at 24 h and p = 0.002 at 48 h; vegetative cells, p = 0.0003 at 24 h and p = 0.0002 at 48 h).ConclusionsThese data suggest that CDIF is a better medium for the recovery of vegetative C. difficile than TCCFA and equal to TCCFA for spore recovery.