Hydrolytic enzyme production by Clostridium difficile and its relationship to toxin production and virulence in the hamster model.

Thirty isolates of Clostridium difficile expressing different degrees of toxigenicity and virulence in an animal model were assayed for the production of chondroitin-4-sulphatase, hyaluronidase, heparinase, collagenase and protease. All strains demonstrated some hydrolytic enzyme activity. There was no direct correlation between toxigenic status, or virulence, and hydrolytic enzyme production. However, all five strains known to be highly virulent in the hamster model had hyaluronidase, chondroitin-4-sulphatase and collagenase activity whereas only three of five toxigenic but poorly virulent strains had these activities, the collagenase activity being weak in all three cases. The only two proteolytic strains are also highly virulent. The potential tissue damaging properties of these hydrolytic enzymes may help to explain the differences in virulence of C. difficile strains seen in the Syrian hamster model of antibiotic-associated colitis, and may contribute to the spectrum of disease seen in man. It is also possible that chondroitin-4-sulphatase, hyaluronidase and collagenase activity may release essential nutrients, promoting establishment of C. difficile in the gut.