Growth and virulence of Candida albicans after oral inoculation in the chick with a monoflora of either Escherichia coli or Streptococcus faecalis.

Balish, Edward (Syracuse University, Syracuse, N.Y.), and A. W. Phillips. Growth and virulence of Candida albicans after oral inoculation in the chick with a monoflora of either Escherichia coli or Streptococcus faecalis. J. Bacteriol. 91:1744-1749. 1966.-Bacterial protection against intestinal infection by Candida albicans was investigated in chicks with a monoflora of either Escherichia coli or Streptococcus faecalis. These animals were obtained by orally inoculating germ-free chicks (3 days old) with pure cultures of bacteria. Each bacterial species was established in large numbers in the gut of separate groups of animals within 24 hr of inoculation; these numbers were similar in chicks examined 34 days later, at which time all animals were killed. The numbers of bacteria from contents of the crop, small intestine, and ceca were similar in chicks with the E. coli monoflora. Comparable results were obtained in chicks with the S. faecalis monoflora, except for decreased numbers in the duodenum and jejunum. Some of the monoflora chicks (7 days old) were transferred into separate isolators, orally inoculated with C. albicans, and observed for 34 days. All chicks grew well and appeared healthy. However, examinations at autopsy revealed severe crop infections in chicks with a diflora containing S. faecalis. Preferential growth of hyphae (C. albicans) occurred in the lesions and throughout the gut. The numbers of S. faecalis in the gut were comparable to those found in unchallenged animals. Agglutinins against C. albicans were not detected in our test or control chicks. Chicks with a diflora containing E. coli and C. albicans had a few microscopic crop lesions containing small numbers of hyphae. C. albicans was well established in the gut of these animals, largely as the yeast form. The numbers of E. coli in the gut were similar to those in control chicks. Thus, it was concluded that E. coli provided protection against crop infection by C. albicans. In crop contents from unchallenged animals, chicks with S. faecalis monoflora were about pH 5, whereas birds with E. coli monoflora were about pH 7. The challenge did not greatly change the former value, and the latter was slightly decreased. In the crop of unchallenged birds, negative E(h) values were found in chicks with S. faecalis and positive E(h) values in those with E. coli. Challenge did not greatly change these values. These data on pH and E(h) were related to conditions for morphogenesis of C. albicans and virulence. No major difference in the concentrations of serum proteins was seen in chicks with E. coli or S. faecalis after challenge with C. albicans. Possible mechanisms of the protective effect of E. coli are discussed.