Use of sodium taurocholate to enhance spore recovery on a medium selective for Clostridium difficile

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Abstract
Isolation of C. difficile from fecal specimens [human] was facilitated by the development of a selective and differential medium, cefoxitin-cycloserine-fructose agar (CCFA). In the medium, 0.1% sodium taurocholate was used instead of the 2.5% egg yolk. The growth of 15 isolates of C. difficile was compared on the resulting medium with growth on conventional CCFA. The taurocholate-containing medium (TCCFA) quantitatively recovered vegetative forms of C. difficile in the same numbers as CCFA medium. Recovery of spores was a mean 1.7 log10 higher on TCCFA than on CCFA. Thirty-six of 60 patient stool specimens growing C. difficile gave a heavier growth on TCCFA than on CCFA; 9 failed to yield C. difficile on CCFA. TCCFA detected spores at 75 colony-forming units per ml from artificially inoculated fecal specimens when conventional stool culturing techniques were used. Fluorescence of C. difficile colonies was more intense on TCCFA than on CCFA. TCCFA was simpler to prepare and, overall, was more sensitive than CCFA.