Two-stage algorithm for Clostridium difficile: glutamate-dehydrogenase-positive toxin-negative enzyme immunoassay results may require further testing.

This study investigated 102 episodes in which a glutamate dehydrogenase-positive enzyme immunoassay (EIA)-toxin-negative result was obtained with a C. difficile testing protocol. Of these 102 stool samples, 46% were culture positive with a toxigenic strain and nine were followed by an EIA-toxin-positive result within 2-32 days. The data accord with our policy of keeping these patients in side-rooms until asymptomatic and of encouraging treatment of those with otherwise unexplained persistent diarrhoea. Adding a third testing modality [toxigenic culture or polymerase chain reaction (PCR)] appears desirable but there may be significant differences in sensitivity between different toxigenic culture or PCR methods.