Molecular analysis of age‐related changes of Streptococcus anginosus group and Streptococcus mitis in saliva

The purpose of this study was to survey the prevalence of streptococcal species, especially Streptococcus anginosus (which has been reported to be associated with cancer in the upper digestive tract), Streptococcus constellatus, and Streptococcus intermedius in the saliva of different age groups. A sequence analysis of 16S rDNA was performed and DNA quantified using real‐time polymerase chain reaction. The S. anginosus level increased with age, whereas the levels of S. constellatus and S. intermedius did not change. Streptococcus mitis was the predominant species in the saliva of all the age groups but, unlike the S. anginosus, the proportion of S. mitis in the salivary bacteria decreased with age. The increase in S. anginosus with age should be carefully monitored because of its association with diseases, including cancer.     

Natural history of Candida species and yeasts in the oral cavities of infants

A longitudinal study was made of the presence of Candida species and yeasts in infants from the day of birth until 1-yr-old, diagnosed by the culture of oral swab samples. The isolation rate of Candida rose from 5.7 per cent neonatally to 14.2 per cent on discharge from hospital at 7 days. The prevalence increased sharply when the infants returned home, reaching 82 per cent at 4 weeks of age, but then slowly declined to 50 per cent at 1 yr. At 4 weeks, yeasts were isolated from an additional 14 per cent of infants. The predominant species was C. albicans with relatively few isolates of C. tropicalis, C. parapsilosis and C. pseudotropicalis. Estimates of neonatal serum antibody to C. albicans showed no correlation with initial or subsequent oral colonization by this organism.