Influence of antibiotics or certain intestinal bacteria on orally administered Candida albicans in germ-free and conventional mice.

Candida albicans, administered by gastric intubation, persisted in the gastrointestinal tract of gnotobiotic mice for long periods but was eliminated within a relatively short period of time in pathogen-free mice. Oxytetracycline administered by mouth had no reproducible effect on the persistence of C. albicans in the gastrointestinal tract of either germ-free or pathogen-free mice. Prolonged administration of streptomycin extended the time that C. albicans could be recovered from feces of pathogen-free mice when compared to mice not receiving the antibiotic or those receiving a single large dose. There was a brief interval of time during which C. albicans could not be recovered from the feces of gnotobiotic mice contaminated with certain intestinal bacteria, but eventually all mice began to shed the fungus again. C. albicans administered by mouth was not pathogenic for germ-free or pathogen-free mice. It can be concluded from these findings that mice do not possess an innate resistance to C. albicans but that pathogen-free mice do possess some ecological mechanism which prevents establishment of the fungus in their gastrointestinal tract. The reason for the difference in colonization of C. albicans in germ-free or gnotobiotic mice and pathogen-free mice was not determined.