Mammalian epithelial cell line kit for detection of Clostridium difficile toxin

The performance characteristics of a mammalian epithelial (MEP) cell line kit (Cytotoxi Test; Advanced Clinical Diagnostics, Toledo, Ohio) for the detection of Clostridium difficile toxin was compared with that of conventional tissue culture assays with human embryonic lung (HEL) cells in shell vials and human foreskin fibroblasts (HFFs) in test tubes. One hundred forty-nine stool samples were tested. The MEP cells were at least as sensitive as the HEL cells for use in C. difficile toxin detection. Results for the MEP cells were also obtained considerably more rapidly than those for HEL cells when the cells were examined at 4 and 24 h and then every 24 h for up to 5 days. Approximately one-third of all positive MEP cells were detected at 4 h and 95% were detected by 48 h. In comparison, in the HEL shell vial monolayers, only 6% of the positive cells were detectable at 4 h and 76% were detectable at 48 h. The times for C. difficile toxin-induced cytotoxicity in HFF cells were similar to those in HEL cells. Shell vials carrying HEL cell monolayers (ViroMed Laboratories Inc., Minnetonka, Minn.) are a sensitive and reliable commercial source for the detection of C. difficile toxin, although they cannot detect C. difficile as rapidly as the Cytotoxi test with the MEP cell monolayers.