Abstract
The aim of the study was to investigate whether, and to what extent, mono-association of germ-free rats with Clostridium difficile influences intestinal cell kinetics and epithelial structure. Young male germ-free rats were mono-associated with either a toxin-producing (group I) or a non-toxin-producing (group II) strain of C. difficile, for 3, 7 and 21 days. The mitotic activity was blocked with vincristine, and specimens from eight parts of the intestine were taken for microscopic examination. Aliquots of intestinal content were analysed for the presence of C. difficile and its toxins. All animals remained healthy throughout the study. After 3 days of mono-association, the mitotic activity increased in all compartments in both groups of animals. After 7 days, a marked fall in mitotic activity was observed in all compartments except caecum in the animals in group I and after 21 days, the mitotic activity was again increased in the small intestine but still low in the distal parts of the colon. At days 7 and 21, only minor alterations were seen in the animals in group II. In general, the morphological alterations were less pronounced than alterations in mitotic activity. A disrupted epithelial border was seen in one animal only (day 7, group I). Toxin could be detected in contents from large intestine at 7 and 21 days in the animals in group I. We conclude that the establishment of a toxin-producing C. difficile in a gnotobiotic rat model gives a marked but transient inhibition of mitotic activity and we hypothesize that this inhibition may give an opportunity for other bacteria to contribute to disease.