Detection of the ADP-ribosyltransferase toxin gene (cdtA) and its activityin Clostridium difficile isolates from Equidae

Clostridium difficile is an antibiotic-associated emerging pathogen of huma ns and animals. Thus far three toxins of C. difficile have been described: an enterotoxin (ToxA), a cytotoxin (ToxB) and an ADP-ribosyltransferase (CD T). In the present work we describe the first isolation of CDT producing C. difficile from Equidae with gastro-intestinal disease. Out of 17 C, diffic ile strains isolated from Equidae, 11 were positive for the genes tcdA and tcdB encoding ToxA and ToxB. In addition four of these 11 isolates were pos itive for the cdrA gene encoding the catalytic subunit of the ADP-ribosyltr ansferase CDT. Interestingly none of the isolates derived from canines (41 isolates) and felines (4 isolates) harboured the cdtA gene. In C. difficile field isolates which contained the cdtA gene, ADP-ribosyltransferase activ ity could also be detected in culture supernatants indicating expression an d secretion of CDT. All strains were associated with intestinal disorders. but no association was found for the occurrence of toxins with a specific c linical diagnosis. (C) 2000 Federation of European Microbiological Societie s. Published by Elsevier Science B.V. All rights reserved.