Frequency, intensity, species, and strains of oral Candida vary as a function of host age.

While the age of the host has been suggested as a determining factor in yeast carriage, no studies in which the genetic relatedness of isolates has been assessed in combination with the frequency and intensity of carriage as a function of host age have been performed in a single geographical locale and over a short time window. Therefore, by using a simple plating protocol to determine the frequency and intensity of carriage, sugar assimilation patterns to determine species, and Southern blot hybridization with the DNA fingerprinting probe Ca3 combined with computer-assisted analysis to determine the genetic relatedness of strains of Candida albicans, yeast carriage was analyzed as a function of age. All test individuals lived in the Iowa City, Iowa, locale and, except for some of the 0.5- to 1.5-year-olds, were dentate. The results demonstrate that for this test population, the frequency, average intensity, predominant species, and genetic relatedness of C. albicans strains varied as a function of host age. In addition, comparison with oral commensal organisms from the Ann Arbor, Mich., locale confirms the geographical specificity of C. albicans strains and the existence of an Iowa City-enriched strain which is most prevalent in elderly individuals.