Glucose Uptake by Streptococcus mutans, Streptococcus mitis , and Actinomyces viscosus in the Presence of Human Saliva

Abstract

Glucose uptake was examined by using whole-cell suspensions of Streptococcus mutans (strains BHT, Ingbritt, and GS-5), Streptococcus mitis (strains 9811 and 72X41), and Actinomyces viscosus (strains T6 and WVU626) incubated for up to 90 min in 0 to 82% (vol/vol) human whole salivary supernatant. Glucose uptake by the S. mutans strains was completely inhibited at all saliva concentrations. Dithiothreitol (DTT), present during saliva incubation, prevented saliva inhibition. Glucose uptake was also restored when saliva-inhibited cells were subsequently exposed to DTT. The inclusion of catalase in the saliva incubation mixtures resulted in protection equal to that obtained with DTT. The S. mitis strains were also inhibited by saliva but to a far lesser extent that S. mutans. DTT and catalase also protected S. mitis from saliva inhibition. Both A. viscosus strains were completely refractory to saliva inhibition of glucose uptake. Based on (i) the sensitivity of the catalase-negative streptococci and the resistance of catalase-positive actinomyces to saliva inhibition and (ii) the equal and complete protection to saliva inhibition afforded by DTT and catalase, we conclude that the lactoperoxidase-SCN-H202 system in saliva was the only antibacterial system expressed under our experimental conditions. The relative resistance of S. mitis 9811 (compared with S. mutans BHT) to saliva inhibition was shown not to result from poor H202 production in either glucose-supplemented buffer or saliva solutions. S. mitis produced inhibitory quantities of H202 that equaled or exceeded S. mutans H202 accumulation. It is suggested that S. mitis might possess a greater ability to repair lactoperoxidase-mediated damage than does S. mutans. Every organism studied exhibited a saliva concentration-dependent, cell growth-independent stimulation of glucose uptake after 60 to 90 min of incubation. The A. viscosus and S. mitis strains showed saliva stimulation (or stabilization) of glucose uptake with unsupplemented saliva. In the case of S. mutans, saliva stimulation was only observed when DTT was present. The possible role of salivary lactoperoxidase as a modulator of the intraoral site specificities exhibited by S. mutans is discussed.

Relationships between levels of lysozyme, lactoferrin, salivary peroxidase, and secretory immunoglobulin A in stimulated parotid saliva

“…Clinical investigation could focus on relationships between cluster membership and oral disease or on differences in the prevalence of specific oral microbes among clusters. Initial in vitro investigation could focus on comparison of saliva from members of different clusters with respect to viability (15), metabolic activity (12), aggregation (15), and adherence to hydroxyapatite (L. M. Tellefson and G. R. Germaine, J. Dent. Res.…”

Relationship of the human salivary peroxidase system to oral health

“…Numerous species of oral bacteria are inhibited by the oxidation products of the salivary peroxidase system. Among these are clinically important species such as lactobacilli (23)(24)(25)(26), streptococci (10,(27)(28)(29)(30)(31)(32)(33), and actinomyces (30,33). Some catalase-positive bacteria are resistant to SPS inhibition (29).…”

“…The susceptibility of many species of oral bacteria to inhibition by the SPS is dependent, in part, on their own H2O2 production. Al-though both peroxldogetiic and non-peroxidogenic species are inhibited by the SPS, peroxide-producing bacteria are mote resistant to inhibition than are tion-peroxidogenic bacteria (31,33)'. This differential sensitivity may play an important part in the regulatory function of the salivary peroxidase system.…”

“…That the salivary peroxidase system does funetion iti vivo is indieated by the presenee of the produets of the system (FIOSCN/OSCN') in expectorated whole saliva (18,20,74), drooled whole saliva (11,20,33,74,75), submandibular saliva (74), and parotid saliva (11,74).…”

Combined inhibitory effect of fluoride and hypothiocyanite on the viability and glucose metabolism of Streptococcus mutans, se retype c

“…and SnF2, are more inhibitory than NaF or NH4F. Also salivary peroxidase systemproduced HOSCN/OSCN" is antimicrobial against a number of oral pathogens, such as mutans streptococci, lactobacilli, Actinomyces species and some periodontopathic bacteria (5,8,17,36). There are, however, only few data on the combination of these two components (12,35).…”