Pediatric diabetic ketoacidosis presenting with Streptococcus intermedius brain abscess.

OBJECTIVES: Report a novel case of new-onset type 1 diabetes in a pediatric patient presenting with DKA and concurrent Streptococcus intermedius brain abscess. CASE PRESENTATION: The following case report is that of a previously healthy 12 year-old girl presenting with new-onset type 1 diabetes with mild diabetic ketoacidosis and subsequently found to have a brain abscess. Over the course of her hospital stay, she developed seizures and was found to have a 1.3 × 1.0 × 1.2 cm right frontal parasagittal mass culture-positive for S. intermedius. Neurologic symptoms were unmasked once insulin treatment was initiated and ketosis improved, supporting the relationship between therapeutic ketosis and the management of medication-refractory epilepsy. CONCLUSIONS: This case both supports the relationship between therapeutic ketosis and the management of medication-refractory epilepsy and highlights the need to carefully consider comorbid conditions in patients with DKA and new onset neurological symptoms.

Enhancement of aqueous solubility and antibiofilm activity of 4-allylpyrocatechol by polymeric micelles.

4-Allylpyrocatechol (APC), a major active compound of Piper betle, possesses strong antimicrobial activity. However, the water-insoluble property of APC limits its clinical and pharmaceutical use. To solve this problem, APC loaded polymeric micelles (PMAC) was fabricated using the thin-film hydration method. Nanoparticles of PMAC were characterized using a photon correlation spectrophotometer and transmission electron microscope (TEM). Antibiofilm activity of PMAC was investigated using crystal violet assay and confocal laser scanning microscopy (CLSM). Cytotoxic effects of PMAC on normal cells were investigated using MTT assay. The results demonstrate that a ratio of APC to the polymer plays an important role in the physicochemical characteristics of PMAC. The most suitable PMAC formulation having a small particle size (38.8 ± 1.4 nm), narrow size distribution (0.28 ± 0.10), a high negative zeta potential (- 16.43 ± 0.55 mV), and high entrapment efficiency (86.33 ± 14.27%) can be obtained from the ratio 1:4. The water solubility of this PMAC is significantly improved, approximately 1,000-fold higher than the unentrapped APC. TEM images demonstrate that PMAC is spherical in shape. The inhibitory effects of PMAC (1.5 mg APC/mL) against Streptococcus intermedius and Streptococcus mutans biofilms are significantly stronger than chlorhexidine (0.06 mg/mL). Images from CLSM demonstrate the destruction and thickness reduction of the pathogenic biofilms after contacting with PMAC. The MTT assay confirms that PMAC at this concentration is non-toxic to normal cells. These results obviously indicate that PMAC is a promising natural and harmless antimicrobial agent suitable for use in the oral cavity for inhibition of pathogenic bacterial biofilms.

The pyogenic potential of the different Streptococcus anginosus group bacterial species: retrospective cohort study.

Streptococcus anginosus Group (SAG) bacteria are common causes of pyogenic infections (PIs). We examined the association between SAG species and the presence of a PI through a retrospective, observational, cohort study, between the years 2009 and 2015. All adults with clinically significant SAG infections in one hospital in Israel were assessed for association between SAG species and the presence of a PI defined as an abscess, empyema, or deep/organ space surgical site infection. Risk factors for PI were assessed using multivariate backward stepwise logistic regression analysis. We identified 263 patients with significant SAG infections, 182 (69%) of which were caused by S. anginosus, 45 (17·1%) by S treptococcus constellatus and 36 (13·7%) by S treptococcus intermedius. The mean age of the patients was 56·8 ± 19·1 years. PIs were identified among 160 (60%) of the patients and were mostly non-bacteraemic (147/160, 91·8%), while most non-PI patients had bacteraemia (70/103, 68%). S. anginosus and S. constellatus were associated with a significantly lower incidence of PI than S. intermedius, OR 0·18 (95% CI 0·06-0·53) and 0·14 (0·04-0·48), respectively. Patients with PI were younger and, in general, had less co-morbidities. S. intermedius was associated with pyogenic non-bacteraemic infections, while S. anginosus and S. constellatus were associated with bacteraemia with no abscess or empyema formation. These data may indicate differences in virulence mechanisms of these SAG bacteria.

A broadly distributed toxin family mediates contact-dependent antagonism between gram-positive bacteria.

The Firmicutes are a phylum of bacteria that dominate numerous polymicrobial habitats of importance to human health and industry. Although these communities are often densely colonized, a broadly distributed contact-dependent mechanism of interbacterial antagonism utilized by Firmicutes has not been elucidated. Here we show that proteins belonging to the LXG polymorphic toxin family present in Streptococcus intermedius mediate cell contact- and Esx secretion pathway-dependent growth inhibition of diverse Firmicute species. The structure of one such toxin revealed a previously unobserved protein fold that we demonstrate directs the degradation of a uniquely bacterial molecule required for cell wall biosynthesis, lipid II. Consistent with our functional data linking LXG toxins to interbacterial interactions in S. intermedius, we show that LXG genes are prevalent in the human gut microbiome, a polymicrobial community dominated by Firmicutes. We speculate that interbacterial antagonism mediated by LXG toxins plays a critical role in shaping Firmicute-rich bacterial communities.

Effects of extracellular DNA and DNA-binding protein on the development of a Streptococcus intermedius biofilm.

AIMS: The aim of this study was to clarify the effects of homologous and heterologous extracellular DNAs (eDNAs) and histone-like DNA-binding protein (HLP) on Streptococcus intermedius biofilm development and rigidity. METHODS AND RESULTS: Formed biofilm mass was measured with 0·1% crystal violet staining method and observed with a scanning electron microscope. The localizations of eDNA and extracellular HLP (eHLP) in formed biofilm were detected by staining with 7-hydoxyl-9H-(1,3-dichloro-9,9-dimethylacridin-2-one) and anti-HLP antibody without fixation, respectively. DNase I treatment (200 U ml(-1)) markedly decreased biofilm formation and cell density in biofilms. Colocalization of eHLP and eDNA in biofilm was confirmed. The addition of eDNA (up to 1 µg ml(-1)) purified from Strep. intermedius, other Gram-positive bacteria, Gram-negative bacteria, or human KB cells into the Strep. intermedius culture increased the biofilm mass of all tested strains of Strep. intermedius, wild-type, HLP-downregulated strain and control strains. In contrast, the addition of eDNA (>1 µg ml(-1)) decreased the biofilm mass of all Strep. intermedius strains. CONCLUSIONS: These findings demonstrated that eDNA and eHLP play crucial roles in biofilm development and its rigidity. SIGNIFICANCE AND IMPACT OF THE STUDY: eDNA- and HLP-targeting strategies may be applicable to novel treatments for bacterial biofilm-related infectious diseases.

Real-time monitoring of the adherence of Streptococcus anginosus group bacteria to extracellular matrix decorin and biglycan proteoglycans in biofilm formation.

Members of the Streptococcus anginosus group (SAGs) are significant pathogens. However, their pathogenic mechanisms are incompletely understood. This study investigates the adherence of SAGs to the matrix proteoglycans decorin and biglycan of soft gingival and alveolar bone. Recombinant chondroitin 4-sulphate(C4S)-conjugated decorin and biglycan were synthesised using mammalian expression systems. C4S-conjugated decorin/biglycan and dermatan sulphate (DS) decorin/biglycan were isolated from ovine alveolar bone and gingival connective tissue, respectively. Using surface plasmon resonance, adherence of the SAGs S. anginosus, Streptococcus constellatus and Streptococcus intermedius to immobilised proteoglycan was assessed as a function of real-time biofilm formation. All isolates adhered to gingival proteoglycan, 59% percent of isolates adhered to alveolar proteoglycans, 70% to recombinant decorin and 76% to recombinant biglycan. Higher adherence was generally noted for S. constellatus and S. intermedius isolates. No differences in adherence were noted between commensal and pathogenic strains to decorin or biglycan. DS demonstrated greater adherence compared to C4S. Removal of the glycosaminoglycan chains with chondroitinase ABC resulted in no or minimal adherence for all isolates. These results suggest that SAGs bind to the extracellular matrix proteoglycans decorin and biglycan, with interaction mediated by the conjugated glycosaminoglycan chain.

Effect of saliva viscosity on the co-aggregation between oral streptococci and Actinomyces naeslundii.

BACKGROUND: The co-aggregation of oral bacteria leads to their clearance from the oral cavity. Poor oral hygiene and high saliva viscosity are common amongst the elderly; thus, they frequently suffer from pneumonia caused by the aspiration of oral microorganisms. OBJECTIVES: To examine the direct effect of saliva viscosity on the co-aggregation of oral streptococci with actinomyces. MATERIALS AND METHODS: Fifteen oral streptococcal and a single actinomyces strain were used. Co-aggregation was assessed by a visual assay in phosphate buffer and a spectrophotometric assay in the same buffer containing 0-60% glycerol or whole saliva. RESULTS: Nine oral streptococci co-aggregated with Actinomyces naeslundii ATCC12104 in the visual assay and were subsequently used for the spectrophotometric analysis. All tested strains displayed a decrease in co-aggregation with increasing amounts of glycerol in the buffer. The co-aggregation of Streptococcus oralis with A. naeslundii recovered to baseline level following the removal of glycerol. The per cent co-aggregation of S. oralis with A. naeslundii was significantly correlated with the viscosity in unstimulated and stimulated whole saliva samples (correlation coefficients: -0.52 and -0.48, respectively). CONCLUSION: This study suggests that saliva viscosity affects the co-aggregation of oral streptococci with actinomyces and that bacterial co-aggregation decreases with increasing saliva viscosity.

Invasion of human aortic endothelial cells by oral viridans group streptococci and induction of inflammatory cytokine production.

Oral viridans group streptococci are the major commensal bacteria of the supragingival oral biofilm and have been detected in human atheromatous plaque. Atherosclerosis involves an ongoing inflammatory response, reportedly involving chronic infection caused by multiple pathogens. The aim of this study was to examine the invasion of human aortic endothelial cells (HAECs) by oral viridans group streptococci and the subsequent cytokine production by viable invaded HAECs. The invasion of HAECs by bacteria was examined using antibiotic protection assays and was visualized by confocal scanning laser microscopy. The inhibitory effects of catalase and cytochalasin D on the invasion of HAECs were also examined. The production of cytokines by invaded or infected HAECs was determined using enzyme-linked immunosorbent assays, and a real-time polymerase chain reaction method was used to evaluate the expression of cytokine messenger RNA. The oral streptococci tested were capable of invading HAECs. The number of invasive bacteria increased with the length of the co-culture period. After a certain co-culture period, some organisms were cytotoxic to the HAECs. Catalase and cytochalasin D inhibited the invasion of HAECs by the organism. HAECs invaded by Streptococcus mutans Xc, Streptococcus gordonii DL1 (Challis), Streptococcus gordonii ATCC 10558 and Streptococcus salivarius ATCC 13419 produced more cytokine(s) (interleukin-6, interleukin-8, monocyte chemoattractant protein-1) than non-invaded HAECs. The HAECs invaded by S. mutans Xc produced the largest amounts of cytokines, and the messenger RNA expression of cytokines by invaded HAECs increased markedly compared with that by non-invaded HAECs. These results suggest that oral streptococci may participate in the pathogenesis of atherosclerosis.

Evaluation of genotypic and phenotypic methods for differentiation of the members of the Anginosus group streptococci.

The terminology and classification of the Anginosus group streptococci has been inconsistent. We tested the utility of 16S rRNA gene and tuf gene sequencing and conventional biochemical tests for the reliable differentiation of the Anginosus group streptococci. Biochemical testing included Rapid ID 32 Strep, API Strep, Fluo-Card Milleri, Wee-tabs, and Lancefield antigen typing. Altogether, 61 Anginosus group isolates from skin and soft tissue infections and four reference strains were included. Our results showed a good agreement between 16S rRNA gene and tuf gene sequencing. Using the full sequence was less discriminatory than using the first part of the 16S rRNA gene. The three species could not be separated with the API 20 Strep test. Streptococcus intermedius could be differentiated from the other two species by beta-galactosidase (ONPG) and beta-N-acetyl-glucosaminidase reactions. Rapid ID 32 Strep beta-glucosidase reaction was useful in separating S. anginosus strains from S. constellatus. In conclusion, both 16S rRNA gene and tuf gene sequencing can be used for the reliable identification of the Anginosus group streptococci. S. intermedius can be readily differentiated from the other two species by phenotypic tests; however, 16S rRNA gene or tuf gene sequencing may be needed for separating some strains of S. constellatus from S. anginosus.

Biofilm formation and autoinducer-2 signaling in Streptococcus intermedius: role of thermal and pH factors.

BACKGROUND/AIM: Bacteria sense their population density using autoinducer (AI) signaling systems. The AI-2 signal is thought to mediate communication among and within bacterial species. Streptococcus intermedius is a commensal organism frequently associated with periodontitis and purulent infections. We investigated the role of AI-2 signaling in S. intermedius biofilm formation under temperatures and pH levels relevant to human physiology. METHODS: Bioluminescence was used to monitor the change in AI-2 levels at various temperatures. Growth and biofilm formation in S. intermedius and its luxS mutant SI006 were measured at 35, 37, 39, and 41 degrees C and in pH ranging from 5.7 to 7.5. To confirm the role of AI-2 signals in biofilm formation, the AI-2 precursor (S)-4,5-dihydroxy-2,3-pentanedione (DPD) was used to complement SI006 biofilm formation. RESULTS: S. intermedius AI-2 signals were detected at all growth temperatures but reached the highest levels at 37 degrees C. SI006 displayed significantly less biofilm formation than S. intermedius wild-type (WT); however, the role of AI-2 on biofilm formation was confined to 37 degrees C. DPD supplementation significantly increased SI006 biofilm formation to the S. intermedius WT level. The role of AI-2 in S. intermedius biofilm formation was not influenced by pH. High temperatures and low pH enhanced biofilm formation in both S. intermedius and its luxS mutant. CONCLUSIONS: High temperature and acidic conditions may favor biofilm formation by S. intermedius. The role of AI-2 in biofilm formation by S. intermedius, however, varies with physiological temperature changes. These results may assist in understanding possible behavior relative to health and disease.

The essentiality and involvement of Streptococcus intermedius histone-like DNA-binding protein in bacterial viability and normal growth.

Streptococcus intermedius histone-like DNA-binding protein (Si-HLP) is a homodimeric protein and, conserved with Escherichia coli HU, a well-documented nucleoid-associated protein (NAP). In E. coli, HU plays important roles as both structural and regulatory factors, but it is not essential for E. coli viability. Streptococcal HLP has been found to bind host cells and induce cytokine production, but its physiological role remains poorly defined. In the present study, using gene insertion knockout and tetracycline-regulated antisense RNA expression techniques, we determined whether Si-HLP is essential for bacterial viability and normal growth in S. intermedius. The Si-HLP-downregulated S. intermedius strain showed alterations in its morphology and surface properties. Downregulation of Si-HLP led to an expanded nucleoid to fill the intracellular space. Transcription levels of several genes, including virulence-associated factors, were found to be activated or repressed in the antisense Si-hlp RNA-expressing strain by real-time PCR and reverse-transcription PCR. Collectively, these data suggest that Si-HLP serves as an essential NAP governing the nucleoid architecture and controlling the gene transcription profile in S. intermedius.

Role of hyaluronidase in Streptococcus intermedius biofilm.

Streptococcus intermedius is found in biofilms on teeth and as a commensal member of the gastrointestinal and urinary floras, but may also be associated with deep-seated purulent infections and infective endocarditis. S. intermedius produces hyaluronidase, an enzyme that breaks down hyaluronan (HA), a major component of the extracellular matrix of connective tissue. We investigated the involvement of hyaluronidase in S. intermedius biofilm formation and dispersal as well as adhesion to human cells. The hyaluronidase activity and expression of the hyl gene were higher in growth media supplemented with HA. Inactivation of the S. intermedius hyaluronidase resulted in a mutant that formed up to 31 % more biofilm in media supplemented with HA. Hyaluronidase added to the medium caused dispersal of S. intermedius biofilm. Adhesion to epithelial cells was similar in the wild-type and the hyaluronidase mutant. We concluded that hyaluronidase may be important for S. intermedius detachment from biofilms but not for adhesion to epithelial cells. The ability of S. intermedius to detach from the surface and to spread may be crucial in the pathogenicity of this micro-organism.

Synthetic bromated furanone inhibits autoinducer-2-mediated communication and biofilm formation in oral streptococci.

INTRODUCTION: Autoinducer-2 (AI-2) is a widespread communication-signal molecule that allows bacteria to sense and react to environmental factors. In some streptococci AI-2 is reported to be involved in virulence expression and biofilm formation. It has earlier been shown that the alga Delisea pulchra produces bromated furanones, which prevent bacterial colonization of the algae. METHODS AND RESULTS: We have previously published a novel and simple synthesis of (Z)-5-bromomethylene-2(5H)-furanone. In this study we showed that our synthesized furanone inhibited biofilm formation and bioluminescence induction by Streptococcus anginosus, Streptococcus intermedius, and Streptococcus mutans, as well as bioluminescence induction by Vibrio harveyi BB152. CONCLUSION: We suggest that the effect is linked to interference with the AI-2 signaling pathway because adding furanone to the medium had no effect on the ability of the AI-2-defective S. anginosus luxS and S. intermedius luxS mutants to form biofilms.

Estimation of salivary bacteria capable of inhibiting and stimulating Streptococcus mutans and its correlation to dental caries and untreated carious teeth.

Bacteriocins are bacteriocidal proteinaceous molecules produced by the Gram-positive bacteria not active against the produced strain. Many investigations have revealed that certain bacteria using antibacterial or the inhibitory substance inhibit some other bacteria. A study was conducted in a group of 60 children to ascertain whether any correlation exists between the proportion of salivary bacteria inhibiting and stimulating Streptococcus mutans and the oral health indices (DMFT, deft and Community Periodontal Index of Treatment Needs). A definite inverse correlation was observed between the percentage of salivary inhibiting S. mutans and untreated carious teeth (UCT).

Involvement of antigen I/II surface proteins in Streptococcus mutans and Streptococcus intermedius biofilm formation.

BACKGROUND/AIM: Dental diseases are caused by microorganisms organized in biofilms. Streptococcus mutans and Streptococcus intermedius are commensals of the human oral cavity. S. mutans is associated with caries, whereas S. intermedius is associated with purulent infections. Oral streptococci including S. mutants and S. intermedius express a family of surface proteins termed antigen I/II (Ag I/II). Ag I/II is implicated in adhesion; however, its role in biofilm formation has not yet been investigated. METHODS: By using isogenic Ag I/II-deficient mutants of S. mutans and S. intermedius we studied the influence of Ag I/II on in vitro biofilm formation. Biofilm was quantified in polystyrene microtiter plates and visualized by scanning electron microscopy. Ag I/II expression in planktonic and biofilm cells, as well as in the presence or absence of saliva was investigated by immunoblotting. RESULTS: In the presence of saliva, the Ag I/II-deficient mutants formed 65% less biofilm than the wild-types. In the absence of saliva, no difference was observed in S. mutans, whereas the S. intermedius Ag I/II mutant formed 41% less biofilm. Ag I/II expression was reduced in the presence of saliva. No differences in expression were observed between biofilm and planktonic cells. CONCLUSION: The results indicated that Ag I/II may be important during biofilm formation particularly in the presence of saliva. These findings may provide useful information regarding the importance of Ag I/II in biofilm formation and in the search of new strategies to control biofilm-mediated infections.

Intermedilysin is essential for the invasion of hepatoma HepG2 cells by Streptococcus intermedius.

Streptococcus intermedius causes endogenous infections leading to abscesses. This species produces intermedilysin (ILY), a human-specific cytolysin. Because of the significant correlation between higher ILY production levels by S. intermedius and deep-seated abscesses, we constructed ily knockout mutant UNS38 B3 and complementation strain UNS38 B3R1 in order to investigate the role of ILY in deep-seated infections. Strain UNS38 reduced the viability of human liver cell line HepG2 at infection but not of rat liver cell line BRL3A. Isogenic mutant strain UNS38 B3 was not cytotoxic in either cell line. Quantification of S. intermedius revealed that in infected HepG2 cells UNS38 but not UNS38 B3 increased intracellularly concomitantly with increasing cell damage. This difference between UNS38 and UNS38 B3 was not observed with UNS38 B3R1. Invasion and proliferation in BRL3A cells was not observed. Masking UNS38 or UNS38 B3R1 with ILY antibody drastically decreased adherence and invasion of HepG2. Moreover, coating strain UNS38 B3 with ILY partially restored adherence to HepG2 but without subsequent bacterial growth. At 1 day post-infection, many intact UNS38 were detected in the damaged phagosomes of HepG2 with bacterial proliferation observed in the cytoplasm of dead HepG2 after an additional 2 day incubation. These results indicate that surface-bound ILY on S. intermedius is an important factor for invasion of human cells by this bacterium and that secretion of ILY within host cells is essential for subsequent host cell death. These data strongly implicate ILY as an important factor in the pathogenesis of abscesses in vivo by this streptococcus.

Single species biofilm-forming ability of root canal isolates on gutta-percha points.

The participation of bacterial biofilms in the over-filled gutta-percha points associated with refractory periapical periodontitis has recently been reported. This study investigated the initial biofilm-forming ability of root canal isolates (Enterococcus faecalis, Streptococcus sanguis, Strep. intermedius, Strep. pyogenes, Staphylococcus aureus, Fusobacterium nucleatum, Propionibacterium acnes, Porphyromonas gingivalis and Prevotella intermedia) on gutta-percha points in vitro. Each bacterial strain was suspended in 100% cell culture medium or in culture medium containing 4.5, 45 or 90% (vol/vol) serum. The bacterial suspensions were then co-incubated anaerobically with gutta-percha points for 7 d. The gutta-percha points were processed for scanning electron microscopic observation and examined for biofilm presence and thickness. E. faecalis, Strep. sanguis, Strep. intermedius, Strep. pyogenes and Staph. aureus biofilms were generated on the surfaces of the specimens incubated in culture medium supplemented with 45 or 90% (vol/vol) serum. The E. faecalis and Strep. sanguis biofilms were significantly thicker than those of Strep. intermedius, Strep. pyogenes and Staph. aureus. No biofilms were detected on the specimens incubated with F. nucleatum, Prop. acnes, Porph. gingivalis and Prev. intermedia. These findings suggest that Gram-positive facultative anaerobes have the ability to colonize and form extracellular matrices on gutta-percha points, while serum plays a crucial role in biofilm formation.

Biofilm mode of growth of Streptococcus intermedius favored by a competence-stimulating signaling peptide.

Gram-positive and gram-negative bacteria use quorum sensing to coordinate population behavior. In several streptococci, quorum sensing mediated by competence-stimulating peptides (CSP) is associated with development of competence for transformation. We show here that a synthetic CSP favored the biofilm mode of growth of Streptococcus intermedius without affecting the rate of culture growth.

Human salivary aggregation in Streptococcus intermedius type g strains: relationship with IgA.

Bacterial aggregation is an important step in elimination from the human body to protect against infection. Streptococcus intermedius K1K aggregates in human saliva. In this study, the salivary agglutinin was identified. The aggregation level was very strong in sonic-treated saliva and 1-microm filtrate. Preincubation of human saliva with anti-human alpha chain serum or anti-human whole saliva serum completely inhibited aggregation, but preincubation with anti-human micro chain serum or anti-Fc fragment of human IgG serum had no effect. Agglutinin of human saliva that could aggregate the strain K1K was purified using DEAE-Sepharose CL-6B, Phenyl-Sepharose CL-4B and Sephacryl S200HR gel filtration. Purified salivary agglutinin was characterized with electrophoresis and immunological techniques, indicating that purified material was IgA. Bacterial aggregation was dependent on the presence of calcium. Saliva filtrate specimens from eight healthy men and eight women showed different aggregation activities. Three men and one woman had little activity. These data show that the present bacterial aggregation was an immunoreaction between IgA in saliva and the bacteria dependent on the levels of calcium. In addition, the IgA in human saliva related with possible calcium-dependent antigen(s) on the surface of strain K1K.

Purification of saliva agglutinin of Streptococcus intermedius and its association with bacterial aggregation and adherence.

Streptococcus intermedius strain 1208-1 cells were aggregated in the presence of saliva. The saliva agglutinin was purified by centrifugation, filtration, and gel filtration. SDS-PAGE analyses indicated that the purified agglutinin consisted of two high-molecular-mass proteins. Aggregation was dependent on calcium over pH 5.5, with 1 mM being the most effective concentration. Boiling inactivated purified agglutinin. S. intermedius strain 3 and Streptococcus mutans strain 1 were aggregated in the purified agglutinin. After adsorption with strain 1208-1 cells, the saliva sample did not exhibit any aggregation activity, and the agglutinin bands were no longer visible by SDS-PAGE. Adherence analyses demonstrated that the purified agglutinin immobilized on the surfaces of polystyrene wells, actinomyces cells, and apatite beads accounted for the binding of streptococcus cells. Agglutinin also effectively inhibited adherence to apatite beads coated with native saliva.