Morphological aspects of gastrointestinal tract invasion by Candida albicans in the infant mouse.

The infant mouse has proved to be a useful model for examination of various aspects of gastrointestinal and systemic candidosis. Oral-intragastric inoculation of 5-6-day-old mice with yeast of a virulent strain of Candida albicans (CA30) resulted in systemic spread within 30 min after challenge. Histological examinations of the gastrointestinal (GI) tract have shown that the highest frequency of invasion of the mucosa by yeast cells occurred in the region of the jejunum 1-3 h after inoculation. Results of ultrastructural examinations of sites where the fungus invaded the bowel wall suggested that C. albicans yeast cells are capable of progressive extracellular digestion of the intestinal mucus barrier and microvillus layer, followed by intracellular invasion of columnar epithelial cells. Minimal disruption of cytoplasmic contents of the host epithelial cells appears to result from invasion and transmigration of the pathogen. The infant mouse model is suggested to be well suited for localization of extracellular products of C. albicans yeast in vivo which may play pivotal roles in the invasion of host tissue during GI candidosis.