Natural History of Streptococcus sanguinis in the Oral Cavity of Infants: Evidence for a Discrete Window of Infectivity

Abstract

The heterogeneous group of oral bacteria within the sanguinis (sanguis) streptococci comprise members of the indigenous biota of the human oral cavity. While the association of Streptococcus sanguinis with bacterial endocarditis is well described in the literature, S. sanguinis is thought to play a benign, if not a beneficial, role in the oral cavity. Little is known, however, about the natural history of S. sanguinis and its specific relationship with other oral bacteria. As part of a longitudinal study concerning the transmission and acquisition of oral bacteria within mother-infant pairs, we examined the initial acquisition of S. sanguinis and described its colonization relative to tooth emergence and its proportions in plaque and saliva as a function of other biological events, including subsequent colonization with mutans streptococci. A second cohort of infants was recruited to define the taxonomic affiliation of S. sanguinis. We found that the colonization of the S. sanguinis occurs during a discrete "window of infectivity" at a median age of 9 months in the infants. Its colonization is tooth dependent and correlated to the time of tooth emergence; its proportions in saliva increase as new teeth emerge. In addition, early colonization of S. sanguinis and its elevated levels in the oral cavity were correlated to a significant delay in the colonization of mutans streptococci. Underpinning this apparent antagonism between S. sanguinis and mutans streptococci is the observation that after mutans streptococci colonize the infant, the levels of S. sanguinis decrease. Children who do not harbor detectable levels of mutans streptococci have significantly higher levels of S. sanguinis in their saliva than do children colonized with mutans streptococci. Collectively, these findings suggest that the colonization of S. sanguinis may influence the subsequent colonization of mutans streptococci, and this in turn may suggest several ecological approaches toward controlling dental caries.The heterogeneous group of oral streptococci comprising the sanguinis streptococci are members of the human indigenous biota. (The previously recognized species of the genus Streptococcus named "sanguis" has recently been changed to "sanguinis" so as to conform to the rules of Latin grammar [32]). S. sanguinis is recognized not only for its historical association with life-threatening bacterial endocarditis, but also because of its putative antagonistic role in dental caries (20) and periodontal diseases (27). In terms of the former, S. sanguinis may compete with the mutans streptococci for colonization sites on tooth surfaces, since both groups of bacteria require the presence of teeth for colonization (6, 7) and may exhibit direct biochemical antagonism in situ (33). Because the cariogenic potential of S. sanguinis is deemed low compared to that of the mutans streptococci, several investigators have suggested that the S. mutans/S. sanguinis ratio may serve as an indicator for caries risk, i.e., the smaller the ratio, the lesser the ris...

Periodontitis is associated with a loss of colonization by Streptococcus sanguinis

“…Early colonization with S. sanguinis is significantly correlated with a delay in colonization by S. mutans. After S. mutans colonization, the levels of S. sanguinis decrease (Caufield et al, 2000;Kreth et al, 2005).…”

“…Early colonization with S. sanguinis is significantly correlated with a delay in colonization by S. mutans. After S. mutans colonization, the levels of S. sanguinis decrease (Caufield et al, 2000;Kreth et al, 2005).Several other studies have focused on the in vitro relationship between S. sanguinis and some of the periodontal pathogens. Hillman et al (1985) showed that, in samples from oral sites where S. sanguinis was detected, Tannerella forsythia was present in 1 % of the cases, and in samples where S. sanguinis was not detected, Tannerella forsythia was present in 10 % of the oral sites.…”

Adhesion of Streptococcus mutans to Different Types of Brackets

“…S sanguis seems to have an antagonistic relationship with S mutans as far as adhesion and colonization are concerned. 18 In the presence of S sanguis, the binding sites of S mutans on the salivary pellicle formed on the bracket are reduced. Our results would thus seem to be consistent with the theory that S sanguis acts as an antagonistic bacterium.…”

Precision-guided antimicrobial peptide as a targeted modulator of human microbial ecology

“…The antagonism between S. mutans and streptococci of the mitis group, particularly S. sanguins and S. gordonii, at the ecological level has been well-documented (26). Epidemiological studies revealed that high levels of S. mutans are always concurrent with low levels of S. sanguinis (27), whereas high levels of S. sanguinis in the oral cavity correlate with delayed S. mutans colonization (28). Recent work by Kreth et al (29) showed sophisticated interspecies interactions between these two species that might play an essential role in balancing competition and coexistence within the oral community.…”