Establishment and distribution of Actinomyces viscosus and Actinomyces naeslundii in the human oral cavity

Abstract

The intraoral establishment and proportional distribution of suspected periodontal pathogens Actinomyces viscosus and Actinomyces naeslundii were studied using a recently developed differential plating medium, CNAC 20. Saliva and dental plaque samples were collected from 108 subjects ranging in age from infants to young adults; tongue and buccal mucosa samples were collected from only the adult subjects. Catalase negative A. naeslundii was isolated from 40% of the predentate infants' ad almost all other subjects' saliva samples. It predominated among CNAC 20 isolates in the saliva of subjects of all age groups, in the plaques of young children, and in the adult tongue samples. In contrast, catalase positive A. viscosus was not isolated from predentate infant samples, and its frequency of isolation increased slowly with age (>50% detection by age 7). A. viscosus was isolated in highest relative proportions from dental plaque and buccal mucosa samples. The two closely related species A. viscosus and A. naeslundii apparently differ in respect to factors determining the host age at which they colonize and their relative intraoral distribution in humans.