Association between periodontal disease and malignant soft tissue sarcomas.

OBJECTIVE: Malignant soft tissue sarcoma (MSTS) is a rare disease, but is seen in patients undergoing orthopedic surgery. Although the association of periodontal disease with various cancers occurring in the oral cavity, gastrointestinal tract, lungs, and prostate, has been reported, the association between periodontal disease and MSTS remains unclear. This study investigated the association between periodontal disease and MSTS in patients undergoing orthopedic surgery. SUBJECTS AND METHODS: One hundred fifteen patients who underwent orthopedic surgery between 2017 and 2021 were retrospectively enrolled (mean age = 66.8 ± 10.7 years). The patient background was adjusted by the propensity score (PS). Subsequently, the association of periodontal disease with MSTS was analyzed using PS inverse probability of treatment weighting (IPTW). Periodontal status was determined by evaluating the periodontal inflamed surface area, which was calculated by measuring the periodontal probing pocket depth and detecting bleeding on probing. RESULTS: Multivariate logistic regression analysis after adjustment by the PS showed that severe periodontitis was significantly associated with MSTS (odds ratio 2.81, p = 0.04). Furthermore, IPTW showed that severe periodontitis was significantly associated with MSTS (odds ratio 3.21, p = 0.01). CONCLUSION: The results indicate an association between periodontal inflammation and MSTS.

Association of remaining tooth number with postoperative respiratory complications in heart valve surgery patients.

OBJECTIVES: This study examined the association between the number of remaining teeth and the incidence of postoperative respiratory complications in patients undergoing heart valve surgery. METHODS: We retrospectively enrolled 157 patients who underwent heart valve surgery between April 2010 and March 2019. Data on patient characteristics including systemic and oral conditions were extracted and postoperative respiratory complications were set as outcomes. Patients were divided into two groups according to the number of remaining teeth (≥20, <20). After adjusting for confounding factors with propensity scoring, logistic regression analysis was performed to examine the association of remaining teeth number with the incidence of postoperative respiratory complications. In addition, subgroup analysis was performed by stratifying the data into quintiles based on the propensity score. RESULTS: Univariate analysis showed significant differences between the two groups in factors, including age, past cardiac surgery experience, New York Heart Association functional classification class IV, denture use, tooth extraction before surgery, occlusal support, and periodontitis. Logistic regression analysis showed that patients with <20 remaining teeth had a significantly higher incidence of postoperative respiratory complications than those with ≥20 remaining teeth, with an odds ratio of 29.800 (p = 0.004). Subgroup analysis showed that the odds ratio for the patients with <20 remaining teeth was 9.000 (p = 0.038). CONCLUSIONS: The results suggest that heart valve surgery patients shall get attention on oral disease prevention by dental care practitioners to maintain a sufficient number of teeth for the prevention of postoperative respiratory complications.

Surface-expressed phosphoglycerate mutase of Candida albicans binds to salivary DMBT1.

Candida albicans colonizes oral tissues and causes infectious diseases. Colonization of C. albicans on the oral mucosa and tooth enamel surfaces is established via the interaction between C. albicans adhesins and salivary proteins, forming a film on the oral tissues. Deleted in malignant brain tumors 1 (DMBT1), also known as salivary agglutinin or gp-340, belongs to the scavenger receptor cysteine-rich (SRCR) superfamily. In the oral cavity, immobilized DMBT1 on oral tissues causes microbial adherence. Recently, we demonstrated that C. albicans binds to DMBT1 and isolated a 25-kDa C. albicans adhesin involved in the interaction with the binding domain of DMBT1, namely, SRCRP2. In the present study, we searched for additional DMBT1-binding adhesins in C. albicans. The component isolated here had a molecular mass of 29 kDa and was found to be phosphoglycerate mutase (Gpm1). Isolated Gpm1 inhibited C. albicans binding to SRCRP2 and directly bound to SRCRP2 in a dose-dependent manner. Gpm1 localization on the C. albicans cell wall surface was confirmed by immunostaining. These results suggest that surface-expressed Gpm1 functions as an adhesin for the establishment of C. albicans cells on the oral mucosa and tooth enamel by binding to DMBT1.

Effect of perioperative oral management on postoperative bloodstream infection in heart valve surgery patients.

OBJECTIVE: There is a well-known relationship between oral hygiene and infective endocarditis. Epidemiological evidence regarding perioperative oral management (POM) for cancer surgery has been accumulated, but this evidence is not sufficient for cardiac surgery. Therefore, our purpose was to investigate whether POM can prevent postoperative complications in patients undergoing heart valve surgery. SUBJECTS AND METHODS: Using single-arm medical information, we retrospectively enrolled 301 patients who underwent heart valve surgery between April 2010 and March 2019. The patient background was adjusted by the propensity score (PS). We then analyzed the impact of POM on postoperative bloodstream infection (PBSI), postoperative pneumonia, and mortality using PS inverse probability of treatment weighting (IPTW). RESULTS: IPTW revealed that the POM group had a lower incidence of PBSI than the control group, with an odds ratio of 0.316 (p = 0.003). The mortality in the POM group was significantly lower than that in the control group (p = 0.023). Fourteen patients died in the present study and 6 of them were infection-related. CONCLUSIONS: POM was significantly associated with decreased incidence of PBSI and mortality. The results suggest that POM is beneficial for the prevention of PBSI and mortality in patients undergoing heart valve surgery.

Comparison of methods for the handling of metallic dental restorations before head and neck radiotherapy.

PURPOSE: During head and neck radiotherapy, backscatter from metallic dental restorations (MDRs) causes oral mucositis. Currently, two MDR handling methods are used: the replacement of MDRs with provisional restorations (MDR removal) and fabrication of dental spacers before radiotherapy. We compared the effects of these two methods on the incidence of oral mucositis during head and neck radiotherapy. METHODS: We enrolled 76 patients with MDRs who underwent radiotherapy for head and neck cancer between April 2016 and March 2020. We set grade 2 oral mucositis as an outcome. After adjustment of all covariates using the propensity score (PS), we analyzed the data using a Cox proportional hazards model. In addition, subgroup analysis was performed by stratifying the data into quintiles based on the PS. RESULTS: For the incidence of grade 2 oral mucositis due to head and neck radiotherapy, the hazard ratio for the MDR removal group relative to the dental spacer group was 0.344 (95% confidence interval, 0.121-0.980; P = 0.046). Subgroup analysis showed that the hazard ratio for the MDR removal group was 0.339 (95% confidence interval, 0.122-0.943; P = 0.038). CONCLUSION: The results suggest that MDR replacement is superior to dental spacer fabrication in reducing the incidence of oral mucositis during head and neck radiotherapy, although MDR removal carries several associated risks.

A novel mannose-containing sialoprotein adhesin involved in the binding of Candida albicans cells to DMBT1.

Candida albicans colonizes the oral cavity and causes oral candidiasis and early childhood caries synergistically with cariogenic Streptococcus mutans. Colonization of oral tissues with C. albicans is an essential step in the initiation of these infectious diseases. Deleted in malignant brain tumors 1 (DMBT1), also known as salivary agglutinin or gp-340, belongs to the scavenger receptor cysteine-rich (SRCR) superfamily and has important functions in innate immunity. In the oral cavity, DMBT1 causes microbial adherence to tooth enamel and oral mucosa surfaces, but the adherence of C. albicans to DMBT1 has not been examined. In this study, we investigated the binding of C. albicans to DMBT1 and isolated the fungal components responsible for the binding. Candida albicans specifically bound to DMBT1 and strongly bound to the peptide domain SRCRP2. Binding to SRCRP2 was inhibited by N-acetylneuraminic acid and mannose and by lectins recognizing these sugars. The isolated component had a molecular mass of 25 kDa, contained sialic acid and mannose residues, and inhibited C. albicans binding to SRCRP2. The localization of the 25-kDa protein on the surface of C. albicans cell walls was confirmed by immunostaining and a cell ELISA using an antiserum to the protein, and Western blotting revealed the presence of the 25-kDa protein in the cell wall fraction of C. albicans. These results suggest that the isolated adhesin is localized on the surface of C. albicans cell walls and that sialic acid and mannose residues in the adhesin play a significant role in the binding reaction.

Perioperative Oral Management Prevents Complications of Heart Valve Surgery.

OBJECTIVES: The effect of perioperative oral management on the prevention of postoperative complications remains unclear in cardiac surgery. Exploratory factor analysis was performed to examine whether a lack of perioperative oral management was associated with postoperative complications of heart valve surgery. MATERIALS AND METHODS: We retrospectively enrolled 365 patients who underwent heart valve surgery between April 2010 and March 2019. We extracted data on patient characteristics and set postoperative pneumonia and postoperative bloodstream infection as outcomes. A logistic regression analyses were performed to examine the effect of factors on the incidence of postoperative complications. RESULTS: Significant risk factors for postoperative pneumonia included dialysis, long operative time, and long-term intubation. Similarly, risk factors for postoperative bloodstream infection were long-term intubation and lack of perioperative oral management. Subsequently, we identified the risk factors for long-term intubation, which were common to both complications, and found they were emergency status, combined valvular disease, long operative time, and lack of perioperative oral management. CONCLUSIONS: We demonstrated that a lack of perioperative oral management could be a risk factor for postoperative bloodstream infection and long-term intubation in heart valve surgery. The results suggest that perioperative oral management is effective in preventing postoperative complications of heart valve surgery.

Pathogenic mechanisms of cariogenic Propionibacterium acidifaciens.

OBJECTIVE: Dental caries is one of the most common infectious diseases in humans. Older adults retain more teeth than did earlier generations and thus are at high risk of root caries. The root surface is covered by cementum, which facilitates the spread of caries lesions into dentinal tissues. Propionibacterium acidifaciens has been detected in dentinal caries lesions; however, the pathogenetic mechanisms are not known. The purpose of this study was to investigate the pathogenic mechanisms of cariogenic P. acidifaciens. METHODS: Saliva-induced aggregation of P. acidifaciens cells and adherence of the organism to saliva-coated hydroxyapatite were examined. Coaggregation of P. acidifaciens with other bacterial cells and binding of the organism to collagen were examined. Effect of Streptococcus mutans on the biofilm formation by P. acidifaciens was also examined. In addition, the effects of acids on the growth of P. acidifaciens were evaluated. RESULTS: P. acidifaciens exhibited strong binding to collagen but weak or moderate interaction with salivary proteins. P. acidifaciens showed weak coaggregation with streptococcal strains and Fusobacerium nucleatum. Biofilm formation by P. acidifaciens was inhibited by S. mutans. Moreover, P. acidifaciens tolerated to self-produced acids up to threshold concentrations. CONCLUSIONS: The results suggest that P. acidifaciens can bind to and survive inside dentinal tissue, and its acid production at low pH condition is involved in the development of dentinal caries.

DMBT1 involvement in the human aortic endothelial cell response to Streptococcus mutans.

Streptococcus mutans is a causative organism of dental caries and has been reported to be associated with the development of cardiovascular disease (CVD). Previous studies have demonstrated that S. mutans invades human aortic endothelial cells (HAECs) and HAECs invaded by S. mutans produce higher levels of CVD-related cytokines than non-invaded HAECs. DMBT1 (deleted in malignant brain tumors 1), also known as salivary agglutinin or gp-340, belongs to the scavenger receptor cysteine-rich superfamily. DMBT1 is expressed in epithelial and non-epithelial tissues and has multiple functions. The interaction between S. mutans and DMBT1 has been demonstrated in cariogenesis, but DMBT1 involvement in CVD has not been examined. In this study, we investigated DMBT1 expression in HAECs stimulated with S. mutans and examined the role of DMBT1 in the interaction between S. mutans and HAECs. All of the tested S. mutans strains induced higher production levels of DMBT1 in HAECs than those in unstimulated HAECs. More S. mutans cells adhered to DMBT1 knock down HAECs than to DMBT1-producing HAECs. Invasion of DMBT1 knock down HAECs by S. mutans was stronger than that of DMBT1-producing HAECs, and externally added DMBT1 reduced bacterial invasion. Cytokine production by DMBT1 knock down HAECs by S. mutans stimulation was higher than that by DMBT1-producing HAECs. These phenomena seemed to be due to the effect of released DMBT1, namely, the inhibition of bacterial adherence to HAECs by DMBT1. These results suggest that DMBT1 plays a protective role against the S. mutans-induced CVD process in HAECs.

Cross-cultural adaptation and psychometric properties of the Indonesia version of the self-efficacy oral health questionnaire for adolescents.

BACKGROUND: Self-efficacy can be interpreted as a self-belief that one has successfully committed to a specific situation or maintained a specific behaviour. AIM: We aimed to test the reliability and validity of a cross-cultural adaptation of the self-efficacy oral health (SEOH) questionnaire in the Indonesian language among adolescents and to understand the diverse perspectives of oral health self-efficacy related to gender. DESIGN: A cross-cultural adaptation of the SEOH self-administered questionnaire was completed followed by a dental caries examination. Sample size estimation suggested 341 adolescents aged 12-13 years. Eleven junior high schools were clustered and randomly selected from six districts across Jakarta, Indonesia. RESULTS: The SEOH was reliable with interclass correlation and Cronbach's alpha values of 0.86 and 0.86, respectively. Significant results for the construct and discriminant validity analyses were observed. There was no significant difference in terms of the total score between males and females, but there was a significant difference in terms of the psychology control domain. CONCLUSIONS: Our study results provide evidence supporting the reliability and validity of the Indonesian version of the SEOH questionnaire for adolescents across Indonesia.

Proper oral hygiene protocols decreased inflammation of gingivitis in a patient during chemotherapy with bevacizumab: a case report.

The case is a woman who had a diagnosis of ovarian cancer and endometrial cancer. After surgical therapy, platinum-based adjuvant treatment was performed, followed by additional bevacizumab administration. Because considerable gingivitis appeared, a proper approach for oral hygiene was performed. As a result, the symptom was reduced considerably.

Effect of perioperative oral care on prevention of postoperative pneumonia associated with esophageal cancer surgery: A multicenter case-control study with propensity score matching analysis.

The aim of this study was to investigate the effectiveness of oral care in prevention of postoperative pneumonia associated with esophageal cancer surgery.Postoperative pneumonia is a severe adverse event associated with esophageal cancer surgery. It is thought to be caused by aspiration of oropharyngeal fluid containing pathogens. However, the relationship between oral health status and postoperative pneumonia has not been well investigated.This study included 539 patients with esophageal cancer undergoing surgery at 1 of 7 university hospitals. While 306 patients received perioperative oral care, 233 did not. Various clinical factors as well as occurrence of postoperative pneumonia were retrospectively evaluated. Propensity-score matching was performed to minimize selection biases associated with comparison of retrospective data between the oral care and control groups. Factors related to postoperative pneumonia were analyzed by logistic regression analysis.Of the original 539 patients, 103 (19.1%) experienced postoperative pneumonia. The results of multivariate analysis of the 420 propensity score-matched patients revealed longer operation time, postoperative dysphagia, and lack of oral care intervention to be significantly correlated with postoperative pneumonia.The present findings demonstrate that perioperative oral care can reduce the risk of postoperative pneumonia in patients undergoing esophageal cancer surgery.

Impact of a 7-Day Field Training on Oral Health Condition in Japan Ground Self-Defense Force Personnel.

INTRODUCTION: In the Japan Ground Self-Defense Force (JGSDF), personnel periodically perform intensive training that mimics the conditions seen in battle and during natural disasters. Military training involves intensive, stressful conditions, and changes in immune responses have been found in personnel following training. Good oral condition is important for military personnel to fulfill their duties; however, they have difficulty performing daily oral care under training conditions. In this study, we investigated the impact of a 7-day field training on the oral health status of JGSDF personnel by comparing their oral condition before and just after training. MATERIALS AND METHODS: The participants were 59 male and 3 female JGSDF personnel undergoing a 7-day field training. All personnel provided informed written consent to participate, and this study was approved by the ethics committee of the Kagoshima University Graduate School of Medical and Dental Sciences. Oral health behaviors before and during the training period were surveyed using a self-administered questionnaire. Dental caries was assessed before training in terms of decayed, missing and filled teeth (DMFT), and periodontal condition was examined before and immediately after training using the community periodontal index (CPI). The presence of eight species of bacteria in dental plaque, including commensal streptococci that are early colonizers on the tooth surface, cariogenic bacteria, and periodontopathic bacteria, was determined using real-time polymerase chain reaction. We also assessed antibacterial factors and a stress marker in saliva samples. Sample collection was performed before and just after training. In addition to difference analysis between groups, logistic regression analysis was performed to examine the association between each health behavior and periodontal deterioration. RESULTS: The frequency of toothbrushing decreased, and snacking increased during the training period. Thirty-five personnel (56.5%) showed an increase in individual CPI code, and 57 personnel (91.9%) showed deterioration in the CPI code in 1 or more sextants after training (Figure 1). Toothbrushing frequency was significantly associated with CPI deterioration; the odds ratio in subjects who did not brush their teeth was 7.51 compared to those who brushed at least once during the training period. Severe periodontal deterioration was observed in the high-DMFT group (Figure 2), and toothbrushing frequency during the training period decreased more in this group compared to the low-DMFT group. The percentages of Streptococcus sanguinis and Streptococcus gordonii increased significantly after the training period suggesting dental plaque maturation, and an increase in S. sanguinis was associated with toothbrushing frequency. The lactoferrin concentration in saliva increased significantly after training. CONCLUSIONS: We demonstrated periodontal deterioration in JGSDF personnel after a 7-day training. Behavioral changes, especially discontinuation of regular toothbrushing, fostered dental plaque maturation, resulting in inflammatory changes in participants' periodontal condition. The results indicate the importance of performing toothbrushing at least once over a 7-day training period for prevention of periodontal deterioration. The regimen could be applicable to evacuees from disasters because they are under conditions of stress that may limit oral hygiene activity.

Recombinant Sox Enzymes from Paracoccus pantotrophus Degrade Hydrogen Sulfide, a Major Component of Oral Malodor.

Hydrogen sulfide (H2S) is emitted from industrial activities, and several chemotrophs possessing Sox enzymes are used for its removal. Oral malodor is a common issue in the dental field and major malodorous components are volatile sulfur compounds (VSCs), including H2S and methyl mercaptan. Paracoccus pantotrophus is an aerobic, neutrophilic facultatively autotrophic bacterium that possesses sulfur-oxidizing (Sox) enzymes in order to use sulfur compounds as an energy source. In the present study, we cloned the Sox enzymes of P. pantotrophus GB17 and evaluated their VSC-degrading activities for the prevention of oral malodor. Six genes, soxX, soxY, soxZ, soxA, soxB, and soxCD, were amplified from P. pantotrophus GB17. Each fragment was cloned into a vector for the expression of 6×His-tagged fusion proteins in Escherichia coli. Recombinant Sox (rSox) proteins were purified from whole-cell extracts of E. coli using nickel affinity chromatography. The enzyme mixture was investigated for the degradation of VSCs using gas chromatography. Each of the rSox enzymes was purified to apparent homogeneity, as confirmed by SDS-PAGE. The rSox enzyme mixture degraded H2S in dose- and time-dependent manners. All rSox enzymes were necessary for degrading H2S. The H2S-degrading activities of rSox enzymes were stable at 25-80°C, and the optimum pH was 7.0. The amount of H2S produced by periodontopathic bacteria or oral bacteria collected from human subjects decreased after an incubation with rSox enzymes. These results suggest that the combination of rSox enzymes from P. pantotrophus GB17 is useful for the prevention of oral malodor.

Preventive Effect on Post-Operative Pneumonia of Oral Health Care among Patients Who Undergo Esophageal Resection: A Multi-Center Retrospective Study.

BACKGROUND: Post-operative pneumonia is a frequent and possibly fatal complication of esophagectomy and is likely caused by aspiration of oropharyngeal fluid that contains pathogenic micro-organisms. We conducted a multi-center retrospective study to investigate the preventive effect of oral health care on post-operative pneumonia among patients with esophageal cancer who underwent esophagectomy. METHODS: A total of 280 patients underwent esophagectomy at three university hospitals. These patients were divided retrospectively into those who received pre-operative oral care from dentists and dental hygienists (oral care group; n = 173) and those who did not receive such care (control group; n = 107). We evaluated the correlations between the occurrence of post-operative pneumonia and 18 predictive variables (patient factors, tumor factors, treatment factors, and pre-operative oral care) using the χ(2) test and logistic regression analysis. The differences of mean hospital days and mortality rate in both groups were analyzed by the Student t-test. RESULTS: Age, post-operative dysphagia, and absence of pre-operative oral care were correlated significantly with post-operative pneumonia in the univariable analysis. Multivariable analysis revealed that diabetes mellitus, post-operative dysphagia, and the absence of pre-operative oral care were independent risk factors for post-operative pneumonia. The mean hospital stay and mortality rate did not differ between the oral care and control groups. CONCLUSION: Pre-operative oral care may be an effective and easy method to prevent post-operative pneumonia in patients who are undergoing esophagectomy.

Purification of a novel fibronectin binding protein from 'Granulicatella para-adiacens'.

The interaction of microorganisms with fibronectin plays an important role in infective endocarditis. Characterization of fibronectin binding is not sufficient for nutritionally variant streptococci (NVS), which is an important pathogen associated with this disease. In this study, we identified and purified the novel fibronectin binding protein (FBP) by sonication and column chromatography from a ' Granulicatella para-adiacens' strain isolated from the oral cavity of a healthy donor. The purified molecule was located at the top of the gel in SDS-PAGE analysis, and heat treatment in the presence of sodium dodecyl sulfate resulted in its dissociation into smaller molecules. An anti-purified protein antibody was reacted with the topmost component of the sonic extract only from two ' G. para-adiacens' strains in Western blot analyses. Immunofluorescence staining indicated that the protein of interest was located on the cell surface of ' G. para-adiacens', but not on other NVS species. Bacterial adherence to fibronectin was inhibited by the purified FBP preparation. Optimum conditions for fibronectin binding of purified FBP were shown to be an NaCl concentration higher than 150 mM and a pH of c. 7.0. These results provide additional information for the elucidation of fibronectin binding by NVS.

Staphylococcus aureus SasA is responsible for binding to the salivary agglutinin gp340, derived from human saliva.

Staphylococcus aureus is a major human pathogen that can colonize the nasal cavity, skin, intestine, and oral cavity as a commensal bacterium. gp340, also known as DMBT1 (deleted in malignant brain tumors 1), is associated with epithelial differentiation and innate immunity. In the oral cavity, gp340 induces salivary aggregation with several oral bacteria and promotes bacterial adhesion to tissues such as the teeth and mucosa. S. aureus is often isolated from the oral cavity, but the mechanism underlying its persistence in the oral cavity remains unclear. In this study, we investigated the interaction between S. aureus and gp340 and found that S. aureus interacts with saliva- and gp340-coated resin. We then identified the S. aureus factor(s) responsible for binding to gp340. The cell surface protein SasA, which is rich in basic amino acids (BR domain) at the N terminus, was responsible for binding to gp340. Inactivation of the sasA gene resulted in a significant decrease in S. aureus binding to gp340-coated resin. Also, recombinant SasA protein (rSasA) showed binding affinity to gp340, which was inhibited by the addition of N-acetylneuraminic acid. Surface plasmon resonance analysis showed that rSasA significantly bound to the NeuAcα(2-3)Galß(1-4)GlcNAc structure. These results indicate that SasA is responsible for binding to gp340 via the N-acetylneuraminic acid moiety.

GlmS and NagB regulate amino sugar metabolism in opposing directions and affect Streptococcus mutans virulence.

Streptococcus mutans is a cariogenic pathogen that produces an extracellular polysaccharide (glucan) from dietary sugars, which allows it to establish a reproductive niche and secrete acids that degrade tooth enamel. While two enzymes (GlmS and NagB) are known to be key factors affecting the entrance of amino sugars into glycolysis and cell wall synthesis in several other bacteria, their roles in S. mutans remain unclear. Therefore, we investigated the roles of GlmS and NagB in S. mutans sugar metabolism and determined whether they have an effect on virulence. NagB expression increased in the presence of GlcNAc while GlmS expression decreased, suggesting that the regulation of these enzymes, which functionally oppose one another, is dependent on the concentration of environmental GlcNAc. A glmS-inactivated mutant could not grow in the absence of GlcNAc, while nagB-inactivated mutant growth was decreased in the presence of GlcNAc. Also, nagB inactivation was found to decrease the expression of virulence factors, including cell-surface protein antigen and glucosyltransferase, and to decrease biofilm formation and saliva-induced S. mutans aggregation, while glmS inactivation had the opposite effects on virulence factor expression and bacterial aggregation. Our results suggest that GlmS and NagB function in sugar metabolism in opposing directions, increasing and decreasing S. mutans virulence, respectively.

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.

Gene cloning and characterization of Streptococcus intermedius fimbriae involved in saliva-mediated aggregation.

Streptococcus intermedius, an oral commensal and a cause of systemic pyogenic disease, expresses fimbriae. To identify the gene(s) encoding these fimbriae, we used a serum raised against purified fimbriae to screen libaries of recombinant lambda phages. The cloned gene cluster encoding S. intermedius fimbriae, (saliva-mediated aggregation and adherence-associated fimbriae), contained 4 ORFs, i.e. a putative ribonulease (Saf1), a putative adhesin (Saf2), the main pilus subunit (Saf3) and a sortase C (SrtC). Escherichia coli strains harboring recombinant phages and plasmids carrying the saf3 gene produced a 55kDa protein recognized by the antifimbriae serum. Saf3 contains an N-terminal signal sequence and a C-terminal cell-wall-anchoring motif LPXTG. Among strains of the Streptococcus anginosus group, only serotype g and untypable strains were found to contain the saf3 gene, to possess the fimbrial antigen and to exhibit saliva-mediated aggregation. Knockout mutants made by insertion of an erythromycin resistance gene into saf3 did not produce fimbrial structures or fimbrial antigens and did not participate in saliva-mediated aggregation. The adherent activity of mutants toward plastic wells coated with salivary agglutinin was about 65% that of the parental strain, and the reaction depended on calcium. There was no significant difference in adherence to hydroxyapatite beads pretreated with salivary agglutinin between the parental and mutant strains. These results demonstrated that Saf3 is associated with aggregation, and suggested that other molecule(s) are associated with adherence of S. intermedius.