Strains Of Oral Streptococci Research Articles

Bacterial adhesion to the soft and hard tissues of the oral cavity

This paper reviews current knowledge of protein‐mediated attachment of oral bacteria to the soft and hard tissues of the oral cavity. In relation to soft tissue attachment, the central role of lectin‐carbohydrate interactions is discussed, together with the potential role of interbacterial coaggregation. The review also presents some current studies on the attachment of strains of Streptococcus oralis, Streptococcus sanguis and Streptococcus mutatis to hydroxyapatite (HA) coated with a range of low molecular weight salivary proteins. The salivary proteins were obtained from human whole saliva by chromatography on Sepharose 4B and further fractionated on DEAE‐Sephacel. Fractions were characterised for protein, carbohydrate and anionic determinants such as sulphate and phosphate. The hydrophobicity of the fractions was determined by their affinity for Octyl‐Sepharose. Selected proteins were attached to HA (20 mg) at a range of concentrations from 20 μg.ml‐1 to 200 μg.m‐1. (3H)‐thymidine labelled cells of S....

In‐vitro bacteriocin‐mediated antagonism by oral streptococci against human carrier strains of staphylococci

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. mitior produced more than one distinct bacteriocin-like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1-12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher (P less than 0.001, chi 2 test and P less than 0.05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus (P less than 0.001 and P less than 0.01) and of oral Staph. epidermidis over oral Staph. aureus (P less than 0.01 and P less than 0.05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p-typing), of sensitivity patterns of staphylococci to bacteriocins (s-typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological viewpoints are discussed.

Polymerase chain reaction amplification, cloning, sequence determination and homologies of streptococcal ATPase-encoding DNAs

The highly conserved portion of the catalytic subunit (β-subunit) of the membrane-bound, proton-translocating ATPase from three strains of oral streptococci has been amplified via the polymerase chain reaction. Hybridization studies demonstrated the existence of homology between Escherichia coli and Bacillus megaterium β-subumt probes at the streptococcal DNA level. Highly degenerate primers, based on the E. coli and B. megaterium amino acid (aa) sequences, were used to amplify the homologues in Streptococcus mutans, S. sanguis and S. sobrinus. The 600 bp fragment from S. sobrinus has been cloned and its nucleotide (nt) sequence determined. Comparison of its nt and deduced aa sequence to that of E. coli and B. megaterium reveals a high degree of homology at the aa level.

Secretory IgA adsorption and oral streptococcal adhesion to human enamel and artificial solid substrata with various surface free energies

In this paper, secretory IgA adsorption from a single component sIgA solution and from human whole saliva onto human enamel and artificial solid substrata with various surface free energies was studied as a function of time. ELISA indicated that screening or displacement of adsorbed sIgA by other salivary proteins occurred only on low surface free energy substrata, not on high surface free energy substrata such as enamel. In addition, the adhesion of three oral streptococcal strains (Streptococcus mitis BMS, S. sanguis 12, and S. mutans NS), also having widely different surface free energies, to sIgA-coated surfaces was studied. The adhesion of all three streptococcal strains was significantly reduced in the presence of a sIgA coating. However, ranking the adhesion data with respect to the various substrata revealed a similar order to that in the case of uncoated substrata, indicating that substratum properties were at least partly transferred by the adsorbed protein film to the interface with adhering micro-organisms. For S. sanguis 12 and S. mitis BMS, adhesion decreased proportionally with the amounts of sIgA detected by ELISA, but for S. mutans NS such relations with the amounts of sIgA detected on the protein-coated substrata were not found. Thus, for S. mutans NS a specific antibody effect seems to exist in addition to a non-specific protein effect like that observed for S. sanguis 12 and S. mitis BMS.

Ability to bind salivary alpha-amylase discriminates certain viridans group streptococcal species

A collection of 144 viridans group streptococcal strains recently characterized as part of a taxonomic study was examined for the ability to bind salivary alpha-amylase. This property was found in most strains of Streptococcus gordonii and Streptococcus mitis and in occasional strains of Streptococcus anginosus and Streptococcus salivarius. In contrast, all strains of Streptococcus sanguis, Streptococcus oralis, Streptococcus vestibularis, and Streptococcus mutans lacked alpha-amylase-binding capacity. A rapid and easy assay described in this paper may be an important supplementary test for identification of oral streptococci.

Arginine catabolism by strains of oral streptococci

Arginine catabolism via the arginine deiminase pathway was found in Streptococcus sanguis 903. Citrulline and ornithine were released from resting cells incubated with arginine, arginine-containing peptides, or saliva. Maximum arginine catabolism by resting cells of S. sanguis 903 was found in the pH range 7-8 and at 45-48 degrees C. Arginine deiminase activity was found in the cytoplasm and in the cell-wall extract of this strain, while ornithine carbamoyltransferase activity was found in the cytoplasm and in extracts of cell walls and cytoplasmic membranes. Streptococcus mutans GS-5 and Streptococcus sobrinus strains OMZ 176 and 6715 could release arginine from salivary peptides but were incapable of significant arginine catabolism.

Sialidase activity of the "Streptococcus milleri group" and other viridans group streptococci

Viridans group streptococci were examined for the production of sialidase (neuraminidase) activity, using the fluorescent substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid in a simple and rapid (15-min) assay. Sialidase was produced by all strains of Streptococcus oralis and S. intermedius and by a majority of S. mitis strains. S. mutans, S. sobrinus, S. gordonii, S. sanguis, S. vestibularis, S. salivarius, S. anginosus, S. constellatus, "S. parasanguis," and the "tufted fibril group" were uniformly negative. Sialidase production may be a useful characteristic to assist in the identification of viridans group streptococci.

Glucosyltransferase production by Streptococcus sanguis Challis and comparison with other oral streptococci

Glucosyltransferase (GTF) activity in batch cultures of Streptococcus sanguis strain Challis in defined medium was maximum at peak growth and declined rapidly on further incubation into stationary phase. Activity was present in spent culture medium and was associated with 2 polypeptides of approximate Mrs 170 kDa (90% of activity) and 155 kDa (about 10% of activity). Other S. sanguis strains produced similar antigenically-related polypeptides but with varying activities, and antibodies to the S. sanguis enzyme did not react with enzymes produced by other species of oral streptococci. Increasing the [Na+] reduced GTF production by S. sanguis strains Challis and NCTC 7865, and by Streptococcus sobrinus, but not by Streptococcus salivarius. Addition of Tween 80 to cultures caused a rapid inhibition of GTF synthesis by strain Challis, but not by strain NCTC 7865. Benzyl alcohol had a slower and less inhibitory effect on GTF production by strain Challis. Tween 80 generally inhibited to varying degrees GTF production by other oral streptococci through in S. sobrinus it was stimulated. The results suggest controls operating on GTF synthesis and secretion by different strains of oral streptococci appear to be diverse.

Utilization of mucin by oral Streptococcus species

The ability of oral Streptococcus strains to utilize oligosaccharide chains in mucin as a source of carbohydrate was studied in batch cultures. Pig gastric mucin, as a substitute of human salivary mucin, was added to chemically defined medium containing no other carbohydrates. Strains of S. mitior attained the highest cell density, while mutans streptococci: S. mutans, S. sobrinus, S. rattus, grew very little in the medium with mucin. S. mitis, S. sanguis, and S. milleri in decreasing order, showed intermediate growth. Mucin breakdown as measured by sugar analyses indicated that oligosaccharide chains were only partially degraded. Every strain produced one or more exoglycosidases potentially involved in hydrolysis of oligosaccharide. The enzyme activities occurred mainly associated with the cells, and very little activity was found in the culture fluids. The relationships between glycosidase activities and growth, or mucin degradation were not always clear.

The influence of collector and bacterial cell surface properties on the deposition of oral streptococci in a parallel plate flow cell

Abstraet-The deposition of two strains of oral streptococci on collector surfaces with different surface free energies has been studied in a parallel plate flow cell at various buffer concentrations. One of the strains, Streptococcus salivarius HB, was characterized by the presence of proteinaceous surface appendages with lengths between 72 and 178 nm; whereas S. salivarius HB-C12, a spontaneous mutant of S. salivarius HB, was devoid of all surface appendages. Large differences were observed between the deposition rates of the two strains which were not predicted by theoretical calculations based on the convective diffusion equation using a DLVO-type potential function. This difference was attributed to the influence of the surface appendages of S. salivarius HB, which were absent on the mutant strain S. salivarius HB-C12. Furthermore, an additional attractive interaction, not accounted for in the DLVO theory, was needed in order to match the experimental deposition rates on the low surface free energy co...

The influence of a salivary coating on the molecular surface composition of oral streptococci as determined by Fourier transform infrared spectroscopy

In order to determine the influence of saliva treatment on the molecular surface composition of oral streptococci, infrared transmission spectroscopy on freeze-dried cells mixed in KBr was used. All IR spectra show similar absorption bands for the saliva-coated and uncoated strains involved, with the most important absorption bands located at 2930cm −1 (CH), 1653 cm −1 (AmI), 1541 cm −1 (AmII) and two bands at 1236 cm −1 and 1082cm −1, which were assigned to phosphate and sugar groups. However, calculation of absorption band ratios normalized with respect to the CH band around 2930cm −1, showed major differences between the saliva-coated and uncoated strains. All strains demonstrated an increase in the AmI/CH and AmII/CH absorption band ratios after saliva treatment indicative for protein adsorption, except for Streptococcus mitis BA showing a small decrease in the AmI/CH absorption band ratio. Two positive relationships could furthermore be established both between the AmII/CH absorption band ratio with the N/C elemental surface concentration ratio of the strains, previously determined from X-ray Photoelectron Spectroscopy (XPS) as well as between AmI/CH with the fraction of carbon atoms at the surface involved in amide bonds, also determined by XPS. This study clearly demonstrates the possibility of IR spectroscopy to determine the molecular surface properties of freeze-dried micro-organisms, as illustrated here from a comparison between the molecular composition of untreated and saliva-treated oral streptococcal strains.

Determination of viridans streptococci surface lipoteichoic acid by enzyme linked immune sorbent assay

An enzyme linked immune sorbent assay (ELISA) was developed to measure bacterial surface lipoteichoic acid (LTA). Numerous strains of oral streptococci belonging to the 'viridans' group were examined on three separate occasions. The results show that, under these cultural conditions, oral streptococci do not normally express LTA on the cell surface. Occasionally strains produced amounts of LTA detectable using the ELISA but this was not a reproducible phenomenon.

Determination of viridans streptococci surface lipoteichoic acid by enzyme linked immune sorbent assay.

An enzyme linked immune sorbent assay (ELISA) was developed to measure bacterial surface lipoteichoic acid (LTA). Numerous strains of oral streptococci belonging to the 'viridans' group were examined on three separate occasions. The results show that, under these cultural conditions, oral streptococci do not normally express LTA on the cell surface. Occasionally strains produced amounts of LTA detectable using the ELISA but this was not a reproducible phenomenon.

The effects of pellicle formation on streptococcal adhesion to human enamel and artificial substrata with various surface free-energies.

The influence of a pellicle on streptococcal adhesion was studied. A "ripened" two-hour salivary pellicle and an "early" five-minute salivary pellicle were formed on human enamel and artificial solid substrata with varying surface free-energies. Three strains of oral streptococci, also with widely different surface free-energies, were used for adhesion studies. Pellicle formation and streptococcal adhesion took place at a constant shear rate of 21 s-1. Adhesion of S. mitis BMS to bare and pellicle-covered enamel was low and not significantly affected by the presence of a pellicle (0.7 x 10(6) and 0.6 x 10(6) cells.cm-2, resp.), whereas the numbers of S. sanguis 12 and S. mutans NS adhering to bare enamel (4.2 x 10(6) cells.cm-2 and 13.8 x 10(6) cells, cm-2, resp) were significantly reduced by the presence of a pellicle. This reduction was almost complete after only five minutes of salivary protein adsorption (1.9 x 10(-6) and 1.1 x 10(6) cells.cm-2 for S. sanguis and S. mutans, resp.) but further reduced for S. sanguis adhering to a ripened pellicle (0.7 x 10(6) cells.cm-2). The numbers of streptococci adhering at equilibrium to bare enamel could be fitted to a thermodynamically based model, which was previously described for bacterial adhesion to homogenous artificial substrata. Streptococcal adhesion to artificial substrata exposed to saliva was low, and the differences among uncoated materials were markedly reduced even after only five minutes' exposure to saliva.

On a relation between interfacial free energy-dependent and noninterfacial free energy-dependent adherence of oral streptococci to solid substrata

In several systems bacterial adhesion occurs despite a positive interfacial free energy of adhesion, ΔFadh; this implies that other interactions are involved. We hypothesize that the number of bacteria adhering at ΔFadh=0 represents their ability to adhere by other, i.e., non-ΔFadh-dependent interactions. Eight strains of oral streptococci were allowed to adhere to three solid substrata with different surface free energies in a flow cell system. Strain-specific linear relations were found between the numbers of bacteria adhering at saturation, nb,s, and ΔFadh. When for all strains the numbers of adhering bacteria at ΔFadh=0 were plotted versus the slopes, denoting the sensitivity to ΔFadh, a linear relationship (r=0.92) was observed. It is, therefore, concluded that one strain-specific factor influences both ΔFadh-dependent and non-ΔFadh-dependent adherence. The numerical value of this factor, together with a surface energetic analysis, predicts the number of streptococci that will adhere to a given nonbiological substratum.

Differential modulation of adherence of oral streptococci by human neutrophil myeloperoxidase.

In this study, the modulation of adherence of hydrogen peroxide (H2O2)-producing and non-H2O2-producing strains of oral streptococci by the host leukocyte enzyme myeloperoxidase (MPO) was examined. It was found that exposure to MPO decreased adherence of many strains of oral streptococci to saliva-coated hydroxyapatite beads in the presence of exogenous H2O2 and chloride. The MPO-H2O2-Cl-system increased the adherence of one strain. In the absence of exogenous H2O2, the MPO-H2O2-Cl-system decreased the adherence of H2O2-producing strains only. Glucose increased streptococcal H2O2 production and also increased the anti-adhesive activity of MPO in the absence of exogenous H2O2. We conclude that: (1) host leukocytes can modulate the adherence of oral streptococci via MPO; (2) endogenous production of H2O2 by the oral streptococci can provide sufficient substrate H2O2 to drive this system; and (3) MPO will exert differential modulatory effects on the adherence of oral streptococci, based in part upon the level of endogenous H2O2 production and in part upon the particular characteristics of the adhesins of the bacteria.

Penicillin tolerance among oral streptococci.

Penicillin tolerance was elicited in 18 of 46 strains of viridans streptococci isolated from the mouths of 19 of 20 healthy subjects and in 31 of 54 consecutive blood-culture isolates of streptococci. Enterococci and Streptococcus sanguis were the organisms most frequently tolerant but the property was also common among isolates of S. mutans, S. mitior and Lancefield Group G streptococci. Pneumococci and S. salivarius were rarely tolerant. When incubated with penicillin at 5 x MIC in batch or continuous cultures, both tolerant and sensitive strains of oral streptococci declined in number less rapidly than S. pyogenes. However, combinations of penicillin and gentamicin killed tolerant and sensitive oral streptococci.

Refinement of an adherence assay for the measurement of bacterial attachment to silica beads

An in vitro adherence assay [4] which utilised radiolabelled bacteria and silica beads was used to investigate firm and loose attachment of bacteria. A systematic evaluation of the effects of the assay conditions, including incubation vessel, bacteria to bead interaction, bead washing and bead weight, was carried out in an attempt to improve the reproducibility of adherence measurements. Four oral streptococcal strains ( S. mutans NCTC 10449, S. sanguis NCTC 7863 and 10904, S. salivarius NCTC 8618) were studied with saliva coated and uncoated silica beads. Using the improved system, total bacterial adherence to uncoated beads was high (45–60% of bacteria present). While saliva coating of beads reduced total and firm adherence of all strains, these reductions were less marked ( P > 0.005) for S. sanguis NCTC 10904.

Adhesion of Oral Streptococci from a Flowing Suspension to Uncoated and Albumin-coated Surfaces

A flow cell system was developed which allowed the study of bacterial adhesion to solid substrata at well-defined shear rates. In addition, the system enabled the solid surfaces to be coated with a proteinaceous film under exactly the same shear conditions. In this flow cell system, adhesion of three strains of oral streptococci from a phosphate-buffered solution onto three different substrata was studied as a function of time in the absence and presence of a bovine serum albumin (BSA) coating at a shear rate of 21 s-1. To obtain a wide range in surface free energies (gamma) representative strains (gamma b 38-117 mJ m-2) and solid substrata (gamma s 20-109 mJ m-2) were selected. The number of bacteria adhering was counted microscopically. In the absence of a BSA coating a linear relation was found between the number of bacteria adhering at saturation (nb,s) and the calculated interfacial free energy of adhesion (delta Fadh) for each of the three strains. In the presence of a BSA coating the number of bacteria adhering was greatly decreased in all cases. However, despite the presence of the BSA coating there was still a linear relation between the number of bacteria adhering at saturation and the interfacial free energy of adhesion, calculated on the basis of the surface free energy of the uncoated substrata. It can be concluded that the bare, uncoated substratum still influenced bacterial adhesion in spite of the marked influence of a BSA coating.

Aminopeptidase activity in strains of oral streptococci.

Ten strains of oral streptococci were analyzed for aminopeptidase activity by isoelectric focusing and crossed immunoelectrophoresis together with enzyme staining procedures. Substrate specificities were determined using 15 aminoacyl‐β‐naphthylamides. All 10 strains tested showed enzyme activity with the arginine and leucine substrates. None of the strains exhibited activity with the glycine, cystine, or proline substrates. Some strains had multiple enzyme bands with some of the substrates. All strains had aminopeptidase bands located in the pi range 4.1–4.3, except Streptococcus mutans IB and Streptococcus milleri NCTC 10708. The isoelectric profiles of these strains, having enzyme bands in the range 4.45–4.9, differed markedly from the others. These were also the only strains where no arginine aminopeptidase cross‐reactivity occurred with the Streptococcus mitis ATCC 903 antiserum.