Long-term oral candidosis in rats.

The aim of the study was to investigate the carriage of infection rate during continuous oral inoculation of Candida albicans in conventionalized SPF rats after initial tetracycline medication. During the 34-week experiment 50% of the animals harboured Candida albicans in the mouth, whereas only 25% of the animals demonstrated pseudomycelial penetration of the oral mucosa. More than ninety per cent of the candidal foci were found in areas covered by a less densely cornified epithelium and were mainly localized to the sulcular folds, the gingival margin and the cheek. Only the dorsal surface of the tongue showed foci with obvious signs of long-standing candidal infection. The lingual papillae were lost and replaced by a flat-surface parakeratotic epithelium showing irregular hyperplasia, acanthosis but no atypia. Reactive changes were found in the underlying lingual muscular layer.