Effect of age on the sensitivity of cell cultures to Clostridium difficile toxin

The effect of age on the sensitivity of four cell lines, human foreskin fibroblasts (HFS), CHO-K1, HEp-2, and WI-38 to detect Clostridium difficile toxin was tested. This study also addressed the sensitivity of these cell lines as expressed by early toxin detection. Twenty-eight positive and 13 negative patient specimens were tested. Cell cultures were inoculated at ages 3, 4, 5, 6, 7, 9 and 14 days and examined for cytopathic effects at 4, 24, and 48 hours post-inoculation. The sensitivity of three of the four cell cultures to C. difficile toxin decreased as the age of the cell cultures increased. However, the sensitivity of the HFS cell line was not influenced by the age of the culture or the time the assay was read in comparison to the other three cell lines. Five- to six-day-old HFS cell cultures detected 22/28 positive samples within 4 hr after inoculation and 28/28 positive samples by 24 hr post-inoculation.