Comparative pathogenicity of streptococci of human origin in hamster caries

Abstract

A NUMBER of streptococci isolated from different host species, while possessing different antigenic and biochemical properties, appear to be related by their ability to induce experimental dental caries in animals. ORLAND (1955) induced experimental caries in germ-free rats with a strain of enterococcus; FITZGERALD, JORDAN and STANLEY (1960) also induced caries in germ-free rats, but with a different streptococcal strain (FA-1) of rat origin; and FITZGERALD and KEYES (1960) reported the development of experimental caries in hamsters with a streptococcal strain (HS-1) of hamster origin. The results of the work in experimental caries in animals suggested that dental caries in rodents was a specific bacterial disease in which certain strains of streptococci were of aetiologic significance. ZINNER et al. (1965a) reported the isolation of streptococcal strains from human carious lesions that were morphologically and antigenically similar to either the hamster (HS-1) or the rat (FA-1) strains. The human hamster-like strain, AHT, induced experimental caries in hamsters and the rat-like strain, BHT, induced caries in gnotobiotic rats (ZINNER et al. 1965b), both animal species requiring a special cariogenic diet (KEYES, 1959). In preliminary studies of human carious lesions it appeared that AHT-type strains were associated with severe, active, and rapidly progressive lesions while the BHTtype strains were associated with slowly progressive lesions (ZINNER ef al. 1965b). The present study compares the cariogenic activity of both strains in hamsters. Nineteen-day old hamsters, albino and golden, weighing 30 g, were maintained on a cariogenic diet (KEYES, 1959) and orally infected with AHT or BHT strains by established techniques (FITZGERALD et al. 1960). The albino hamsters were supplied originally by the National Institute of Dental Research and maintained at the National Children’s Cardiac Hospital for the past 5 years. The golden hamsters were purchased locally and the colony has been maintained since 1959.