Contribution of the interaction of Streptococcus mutans serotype k strains with fibrinogen to the pathogenicity of infective endocarditis

Cell wall glycosyltransferase of Streptococcus mutans impacts its dissemination to murine organs

Streptococcus mutans, a cariogenic bacterium in humans, is associated with systemic disorders. Its cariogenic factors include glucosyltransferases (GTFs) and the glycosyltransferase rhamnose-glucose polysaccharide I (RgpI), which is involved in cell wall synthesis. However, the potential roles of these enzymes in systemic disorders remain unclear. We constructed a luciferase-tagged S. mutans UA159 mutant strain that lacked rgpI to explore the involvement of this enzyme in the systemic pathogenicity of S. mutans. We also employed the luciferase-tagged S. mutans UA159 variant, which exhibited reduced GTF production and therefore had a low glucan synthesis ability. We intravenously inoculated these luciferase-tagged mutants and parent strains into 12-week-old male BALB/c mice to evaluate their distribution to organs. Strong luminescence was noted in the spleen and kidneys, indicating that S. mutans was disseminated to these organs. Several organs collected from mice inoculated with the luciferase-tagged parent strain emitted a signal, and inflammatory cytokine production was detected in the blood. The luminescence intensity was lower in the kidneys of mice challenged with the mutant strain, which has a low glucan synthesis ability. Conversely, challenge with the rgpI deletion mutant strain resulted in the lowest number of luminescent organs, with a lower intensity and attenuated inflammation. Furthermore, all the mice inoculated with the rgpI deletion mutant strain survived, whereas not all the mice inoculated with the parent strain survived. Collectively, these results suggest that RgpI is involved in the systemic pathogenicity of S. mutans UA159.

Roles of Streptococcus mutans in human health: beyond dental caries

Streptococcus mutans (S. mutans) is the main pathogenic bacterium causing dental caries, and the modes in which its traits, such as acid production, acid tolerance, and adhesion that contribute to the dental caries process, has been clarified. However, a growing number of animal experiments and clinical revelations signify that these traits of S. mutans are not restricted to the detriment of dental tissues. These traits can assist S. mutans in evading the immune system within body fluids; they empower S. mutans to adhere not merely to the surface of teeth but also to other tissues such as vascular endothelium; they can additionally trigger inflammatory reactions and inflict damage on various organs, thereby leading to the occurrence of systemic diseases. These traits mostly originate from some correlative findings, lacking a comprehensive evaluation of the impact of S. mutans on systemic diseases. Therefore, this review mainly centers on the dissemination route of S. mutans: "Entering the blood circulation - Occurrence of tissue adhesion - Extensive possible proinflammatory mechanisms - Concentration in individual organs" and analyses the specific effects and possible mechanisms of S. mutans in systemic diseases such as cerebral hemorrhage, inflammatory bowel disease, tumors, and infective endocarditis that have been identified hitherto.

Contribution of collagen-binding protein Cnm of Streptococcus mutans to induced IgA nephropathy-like nephritis in rats

IgA nephropathy (IgAN), the most common primary glomerulonephritis, is considered an intractable disease with unknown pathogenic factors. In our previous study, Streptococcus mutans, the major causative bacteria of dental caries, which expresses Cnm, was related to the induction of IgAN-like nephritis. In the present study, the Cnm-positive S. mutans parental strain, a Cnm-defective isogenic mutant strain, its complementation strain, and recombinant Cnm (rCnm) protein were administered intravenously to Sprague Dawley rats, and the condition of their kidneys was evaluated focusing on the pathogenicity of Cnm. Rats treated with parental and complement bacterial strains and rCnm protein developed IgAN-like nephritis with mesangial proliferation and IgA and C3 mesangial deposition. Scanning immunoelectron microscopy revealed that rCnm was present in the electron-dense deposition area of the mesangial region in the rCnm protein group. These results demonstrated that the Cnm protein itself is an important factor in the induction of IgAN in rats.

Inhibitory Effect of Adsorption of Streptococcus mutans onto Scallop-Derived Hydroxyapatite

Hydroxyapatite adsorbs various substances, but little is known about the effects on oral bacteria of adsorption onto hydroxyapatite derived from scallop shells. In the present study, we analyzed the effects of adsorption of Streptococcus mutans onto scallop-derived hydroxyapatite. When scallop-derived hydroxyapatite was mixed with S. mutans, a high proportion of the bacterial cells adsorbed onto the hydroxyapatite in a time-dependent manner. An RNA sequencing analysis of S. mutans adsorbed onto hydroxyapatite showed that the upregulation of genes resulted in abnormalities in pathways involved in glycogen and histidine metabolism and biosynthesis compared with cells in the absence of hydroxyapatite. S. mutans adsorbed onto hydroxyapatite was not killed, but the growth of the bacteria was inhibited. Electron microscopy showed morphological changes in S. mutans cells adsorbed onto hydroxyapatite. Our results suggest that hydroxyapatite derived from scallop shells showed a high adsorption ability for S. mutans. This hydroxyapatite also caused changes in gene expression related to the metabolic and biosynthetic processes, including the glycogen and histidine of S. mutans, which may result in a morphological change in the surface layer and the inhibition of the growth of the bacteria.

The systemic oral health connection: Biofilms

Frequently, periodontal health and it's associated oral biofilm has not been addressed in those patients who have systemic health issues, especially those who are not responding to medical treatment via their physician. Oral biofilm may be present in the periodontal sulcus in the absence of clinical disease of periodontal disease (bleeding on probing, gingival inflammation) and periodontal reaction is dependent on the patient's immune response to the associated bacterial and their byproducts. Increasing evidence has been emerging the past decade connecting oral biofilm with systemic conditions, either initiating them or complicating those medical conditions. The patient's health needs to be thought of as a whole-body system with connections that may originate in the oral cavity and have distant affects throughout the body. To maximize total health, a coordination in healthcare needs to be a symbiosis between the physician and dentist to eliminate the oral biofilm and aid in prevention of systemic disease or minimize those effects to improve the patient's overall health and quality of life. Various areas of systemic health have been associated with the bacteria and their byproducts in the oral biofilm. Those include cardiovascular disease, chronic kidney disease, diabetes, pulmonary disease, prostate cancer, colon cancer, pancreatic cancer, pre-term pregnancy, erectile dysfunction Alzheimer's disease and Rheumatoid arthritis. This article will discuss oral biofilm, its affects systemically and review the medical conditions associated with the oral systemic connection with an extensive review of the literature.

Coagulation Disorders in Infective Endocarditis: Role of Pathogens, Biomarkers, Antithrombotic Therapy (Systematic Review)

The issue of antithrombotic therapy in patients with infective endocarditis has been studied for over 75 years. During that time studying of pathogenesis of the disease and its embolic complications, lead to the introduction of the concept of “immunothrombosis”. That mechanism allows infective agents (mostly bacteria) to be cloaked from the immune system and to multiply freely, leading to growth of vegetation, thus resulting in higher chance of fragmentation. Small-scale experimental and clinical studies on the correction of hemostatic disorders in infective endocarditis, that were performed in 20th century, didn’t show any significant results, that could affect clinical practice. However, reinterpretation of available data on coagulative system will allow to have elements of hemostasis as an application point in treating infective endocarditis. The article will discuss latest insights on the role of hemostasis system in pathophysisology of infective endocarditis, its effects on the development of the embolic complications, perspectives for diagnostics and treatment.

Anti-Adherence and Antimicrobial Activities of Silver Nanoparticles against Serotypes C and K of Streptococcus mutans on Orthodontic Appliances

Background and Objectives: Streptococcus mutans (S. mutans) is the main microorganism associated with the presence of dental caries and specific serotypes of this bacteria have been related to several systemic diseases limiting general health. In orthodontics, white spot lesions (WSL), represent a great challenge for clinicians due to the great fluctuation of their prevalence and incidence during conventional orthodontic treatments. Although silver nanoparticles (AgNP) have been demonstrated to have great antimicrobial properties in several microorganisms, including S. mutans bacteria, there is no available information about anti adherence and antimicrobial properties of AgNP exposed to two of the most relevant serotypes of S. mutans adhered on orthodontic materials used for conventional therapeutics. The objective of this study was to determine anti-adherence and antimicrobial levels of AgNP against serotypes c and k of S. mutans on conventional orthodontic appliances. Materials and Methods: An AgNP solution was prepared and characterized using dispersion light scattering (DLS) and transmission electron microscopy (TEM). Antimicrobial and anti-adherence activities of AgNP were determined using minimal inhibitory concentrations (MIC) and bacterial adherence testing against serotypes c and k of S. mutans clinically isolated and confirmed by PCR assay. Results: The prepared AgNP had spherical shapes with a good size distribution (29.3 ± 0.7 nm) with negative and well-defined electrical charges (−36.5 ± 5.7 mV). AgNP had good bacterial growth (55.7 ± 19.3 µg/mL for serotype c, and 111.4 ± 38.6 µg/mL for serotype k) and adherence inhibitions for all bacterial strains and orthodontic wires (p < 0.05). The serotype k showed statistically the highest microbial adherence (p < 0.05). The SS wires promoted more bacterial adhesion (149.0 ± 253.6 UFC/mL × 104) than CuNiTi (3.3 ± 6.0 UFC/mL × 104) and NiTi (101.1 ± 108.5 UFC/mL × 104) arches. SEM analysis suggests CuNiTi wires demonstrated better topographical conditions for bacterial adherence while AFM evaluation determined cell wall irregularities in bacterial cells exposed to AgNP. Conclusions: This study suggests the widespread use of AgNP as a potential anti-adherent and antimicrobial agent for the prevention of WSL during conventional orthodontic therapies and, collaterally, other systemic diseases.

Deciphering mechanisms and implications of bacterial translocation in human health and disease

Significant increases in potential microbial translocation, especially along the oral-gut axis, have been identified in many immune-related and inflammatory diseases, such as inflammatory bowel disease, colorectal cancer, rheumatoid arthritis, and liver cirrhosis, for which we currently have no cure or long-term treatment options. Recent advances in computational and experimental omics approaches now enable strain tracking, functional profiling, and strain isolation in unprecedented detail, which has the potential to elucidate the causes and consequences of microbial translocation. In this review, we discuss current evidence for the detection of bacterial translocation, examine different translocation axes with a primary focus on the oral-gut axis, and outline currently known translocation mechanisms and how they adversely affect the host in disease. Finally, we conclude with an overview of state-of-the-art computational and experimental tools for strain tracking and highlight the required next steps to elucidate the role of bacterial translocation in human health.

Evaluation of the collagen-binding properties and virulence of killed Streptococcus mutans in a silkworm model

Streptococcus mutans, a major pathogen of dental caries, is also known as a causative agent of cardiovascular disease. A 120 kDa collagen-binding protein (Cnm) of S. mutans is an important contributor to the pathogenicity of cardiovascular disease. Although dead bacteria have been detected in cardiovascular specimens by molecular biological methods, the pathogenicity of the bacteria remains unknown. Here, we analyzed the pathogenicity of killed S. mutans by focusing on collagen-binding ability and the effects on silkworms. In live S. mutans, Cnm-positive S. mutans had high collagen-binding activity, while Cnm-negative S. mutans had no such activity. After treatment with killed Cnm-positive S. mutans, amoxicillin-treated bacteria still had collagen-binding ability, while lysozyme-treated bacteria lost this ability. When live and amoxicillin-treated S. mutans strains were administered to silkworms, the survival rates of the silkworms were reduced; this reduction was more pronounced in Cnm-positive S. mutans infection than in Cnm-negative S. mutans infection. However, the administration of any of the lysozyme-treated bacteria did not reduce the survival rate of the silkworms. These results suggest that amoxicillin-killed Cnm-positive S. mutans strains maintain collagen-binding properties and pathogenicity in the silkworm model, and are possibly associated with pathogenicity in cardiovascular diseases.

VicRK and CovR polymorphisms in Streptococcus mutans strains associated with cardiovascular infections

Introduction. Streptococcus mutans, a common species of the oral microbiome, expresses virulence genes promoting cariogenic dental biofilms, persistence in the bloodstream and cardiovascular infections.Gap statement. Virulence gene expression is variable among S. mutans strains and controlled by the transcription regulatory systems VicRK and CovR.Aim. This study investigates polymorphisms in the vicRK and covR loci in S. mutans strains isolated from the oral cavity or from the bloodstream, which were shown to differ in expression of covR, vicRK and downstream genes.Methodology. The transcriptional activities of covR, vicR and vicK were compared by RT-qPCR between blood and oral strains after exposure to human serum. PCR-amplified promoter and/or coding regions of covR and vicRK of 18 strains (11 oral and 7 blood) were sequenced and compared to the reference strain UA159.Results. Serum exposure significantly reduced covR and vicR/K transcript levels in most strains (P<0.05), but reductions were higher in oral than in blood strains. Single-nucleotide polymorphisms (SNPs) were detected in covR regulatory and coding regions, but SNPs affecting the CovR effector domain were only present in two blood strains. Although vicR was highly conserved, vicK showed several SNPs, and SNPs affecting VicK regions important for autokinase activity were found in three blood strains.Conclusions. This study reveals transcriptional and structural diversity in covR and vicR/K, and identifies polymorphisms of functional relevance in blood strains, indicating that covR and vicRK might be important loci for S. mutans adaptation to host selective pressures associated with virulence diversity.

Bacterial adhesion to collagens: implications for biofilm formation and disease progression in the oral cavity

Collagen is the most abundant structural protein in the body and the main component of the extracellular matrix of most tissues, including dentine and periodontal tissues. Despite the well-characterized role of collagen and specifically type-I collagen, as a ligand for host cells, its role as a substrate for bacterial adhesion and biofilm formation is less explored. Therefore, the purpose of this review is to discuss recent findings regarding the adhesion of oral bacteria to collagen surfaces and its role in the progression and severity of oral and systemic diseases. Initial oral colonizers such as streptococci have evolved collagen-binding proteins (cbp) that are important for the colonization of dentine and periodontal tissues. Also, periodontal pathogens such as Porphyromonas gingivalis and Tannerella forsythia utilise cbps for tissue sensing and subsequent invasion. The implications of bacteria-collagen coupling in the context of collagen biomaterials and regenerative dentistry approaches are also addressed. Furthermore, the importance of interdisciplinary techniques such as atomic force microscopy for the nanocharacterization of bacteria-collagen interactions is also considered. Overall, understanding the process of oral bacterial adhesion onto collagen is important for developing future therapeutic approaches against oral and systemic diseases, by modulating the early stages of biofilm formation.

Streptococcus mutans in atherosclerotic plaque: Molecular and immunohistochemical evaluations

OBJECTIVES

To verify the presence of Streptococcus mutans (S. mutans) in atherosclerotic plaque (AP) using techniques with different sensitivities, correlating with histological changes in plaque and immunoexpression of inflammatory markers.

MATERIALS AND METHODS

Thirteen AP samples were subjected to real-time polymerase chain reaction (qRT-PCR), histopathological analyses, histochemical analysis by Giemsa staining (GS), and immunohistochemical analysis for S. mutans, IL-1β, and TNF-α (streptavidin-biotin-peroxidase method). Ten necropsy samples of healthy vessels were used as controls.

RESULTS

All AP samples showed histopathological characteristics of severe atherosclerosis and were positive for S. mutans (100.0%) in qRT-PCR and immunohistochemical analyses. GS showed that Streptococcus sp. colonized the lipid-rich core regions and fibrous tissue, while the control group was negative for Streptococcus sp. IL-1β and TNF-α were expressed in 100% and 92.3% of the AP tested, respectively. The control samples were positive for S. mutans in qRT-PCR analysis, but negative for S. mutans, IL-1β, and TNF-α in immunohistochemical analyses.

CONCLUSION

The detection of S. mutans in AP and the visualization of Streptococcus sp. suggested a possible association between S. mutans and atherosclerosis. The results obtained from the control samples suggested the presence of DNA fragments or innocuous bacteria that were not associated with tissue alteration. However, future studies are necessary to provide more information.

PepO is a target of the two-component systems VicRK and CovR required for systemic virulence of Streptococcus mutans

Streptococcus mutans, a cariogenic species, is often associated with cardiovascular infections. Systemic virulence of specific S. mutans serotypes has been associated with the expression of the collagen- and laminin-binding protein Cnm, which is transcriptionally regulated by VicRK and CovR. In this study, we characterized a VicRK- and CovR-regulated gene, pepO, coding for a conserved endopeptidase. Transcriptional and protein analyses revealed that pepO is highly expressed in S. mutans strains resistant to complement immunity (blood isolates) compared to oral isolates. Gel mobility assay, transcriptional, and Western blot analyses revealed that pepO is repressed by VicR and induced by CovR. Deletion of pepO in the Cnm+ strain OMZ175 (OMZpepO) or in the Cnm- UA159 (UApepO) led to an increased susceptibility to C3b deposition, and to low binding to complement proteins C1q and C4BP. Additionally, pepO mutants showed diminished ex vivo survival in human blood and impaired capacity to kill G. mellonella larvae. Inactivation of cnm in OMZ175 (OMZcnm) resulted in increased resistance to C3b deposition and unaltered blood survival, although both pepO and cnm mutants displayed attenuated virulence in G. mellonella. Unlike OMZcnm, OMZpepO could invade HCAEC endothelial cells. Supporting these phenotypes, recombinant proteins rPepO and rCnmA showed specific profiles of binding to C1q, C4BP, and to other plasma (plasminogen, fibronectin) and extracellular matrix proteins (type I collagen, laminin). Therefore this study identifies a novel VicRK/CovR-target required for immune evasion and host persistence, pepO, expanding the roles of VicRK and CovR in regulating S. mutans virulence.

Potential involvement of Streptococcus mutans possessing collagen binding protein Cnm in infective endocarditis

Streptococcus mutans, a significant contributor to dental caries, is occasionally isolated from the blood of patients with infective endocarditis. We previously showed that S. mutans strains expressing collagen-binding protein (Cnm) are present in the oral cavity of approximately 10-20% of humans and that they can effectively invade human umbilical vein endothelial cells (HUVECs). Here, we investigated the potential molecular mechanisms of HUVEC invasion by Cnm-positive S. mutans. The ability of Cnm-positive S. mutans to invade HUVECs was significantly increased by the presence of serum, purified type IV collagen, and fibrinogen (p < 0.001). Microarray analyses of HUVECs infected by Cnm-positive or -negative S. mutans strains identified several transcripts that were differentially upregulated during invasion, including those encoding the small G protein regulatory proteins ARHGEF38 and ARHGAP9. Upregulation of these proteins occurred during invasion only in the presence of serum. Knockdown of ARHGEF38 strongly reduced HUVEC invasion by Cnm-positive S. mutans. In a rat model of infective endocarditis, cardiac endothelial cell damage was more prominent following infection with a Cnm-positive strain compared with a Cnm-negative strain. These results suggest that the type IV collagen-Cnm-ARHGEF38 pathway may play a crucial role in the pathogenesis of infective endocarditis.

Intravenous administration of Streptococcus mutans induces IgA nephropathy-like lesions

Background

IgA nephropathy (IgAN) is one of the most frequently occurring types of chronic glomerulonephritis. Previous analyses have revealed that a major pathogen of dental caries, Streptococcus mutans [which expresses collagen-binding protein (Cnm) on its surface], is involved in the pathogenesis of IgAN.

Methods

Cnm-positive S. mutans isolated from a patient with IgAN was intravenously administered to specific pathogen-free Sprague–Dawley rats to evaluate their kidney conditions.

Results

The urinary protein level of the S. mutans group reached a plateau at 30 days, with increased numbers of mesangial cells and an increased mesangial matrix. The numbers of rats with IgA-positive and/or C3-positive glomeruli were significantly greater in the S. mutans group than in the control group at 45 days (P < 0.05). Electron microscopy analyses revealed electron-dense depositions in the mesangial area among rats in the S. mutans group. There were significantly more CD68-positive cells (macrophages) in the glomeruli of the S. mutans group than in the glomeruli of the control group during the late phase (P < 0.05), similar to the findings in patients with IgAN.

Conclusion

Our results suggested that intravenous administration of Cnm-positive S. mutans caused transient induction of IgAN-like lesions in rats.

Contribution of Severe Dental Caries Induced by Streptococcus mutans to the Pathogenicity of Infective Endocarditis

Streptococcus mutans, a major pathogen of dental caries, is regarded as a causative agent of infective endocarditis (IE), which mainly occurs in patients with underlying heart disease. However, it remains unknown whether severe dental caries that extend to pulp space represent a possible route of infection. In the present study, we evaluated the virulence of S. mutans for IE development using rats with concurrent severe dental caries and heart valve injury. Dental caries was induced in rats through the combination of a caries-inducing diet and the administration of S. mutans into the oral cavity. Then, the heart valves of a subset of rats were injured using a sterile catheter and wire under general anesthesia. The rats were euthanized at various times with various stages of dental caries. The number of teeth affected by dental caries with pulp exposure was increased in the rats in a time-dependent manner. S. mutans was recovered from injured heart tissue, which was mainly observed in rats with higher number of S. mutans bacteria in mandibular bone and a larger number of teeth in which caries extended to pulp. Dental caries was more severe in rats with heart injury than in rats without heart injury. Sequencing analysis targeting 16S rRNA revealed that specific oral bacteria appeared only in rats with heart injury, which may be related to the development of dental caries. Our findings suggest that dental caries caused by the combination of S. mutans infection and sucrose intake may contribute to S. mutans colonization in injured heart tissue.

Calcific Aortic Valve Disease-Natural History and Future Therapeutic Strategies

Calcific aortic valve disease (CAVD) is the most frequent heart valve disorder. It is characterized by an active remodeling process accompanied with valve mineralization, that results in a progressive aortic valve narrowing, significant restriction of the valvular area, and impairment of blood flow.The pathophysiology of CAVD is a multifaceted process, involving genetic factors, chronic inflammation, lipid deposition, and valve mineralization. Mineralization is strictly related to the inflammatory process in which both, innate, and adaptive immunity are involved. The underlying pathophysiological pathways that go from inflammation to calcification and, finally lead to severe stenosis, remain, however, incompletely understood. Histopathological studies are limited to patients with severe CAVD and no samples are available for longitudinal studies of disease progression. Therefore, alternative routes should be explored to investigate the pathogenesis and progression of CAVD.Recently, increasing evidence suggests that epigenetic markers such as non-coding RNAs are implicated in the landscape of phenotypical changes occurring in CAVD. Furthermore, the microbiome, an essential player in several diseases, including the cardiovascular ones, has recently been linked to the inflammation process occurring in CAVD. In the present review, we analyze and discuss the CAVD pathophysiology and future therapeutic strategies, focusing on the real and putative role of inflammation, calcification, and microbiome.

Beta-Hemolytic Streptococcal Infective Endocarditis: Characteristics and Outcomes From a Large, Multinational Cohort

Background

Beta-hemolytic streptococci (BHS) are an uncommon cause of infective endocarditis (IE). The aim of this study was to describe the clinical features and outcomes of patients with BHS IE in a large multinational cohort and compare them with patients with viridans streptococcal IE.

Methods

The International Collaboration on Endocarditis Prospective Cohort Study (ICE-PCS) is a large multinational database that recruited patients with IE prospectively using a standardized data set. Sixty-four sites in 28 countries reported patients prospectively using a standard case report form developed by ICE collaborators.

Results

Among 1336 definite cases of streptococcal IE, 823 were caused by VGS and 147 by BHS. Patients with BHS IE had a lower prevalence of native valve (P < .005) and congenital heart disease predisposition (P = .002), but higher prevalence of implantable cardiac device predisposition (P < .005). Clinically, they were more likely to present acutely (P < .005) and with fever (P = .024). BHS IE was more likely to be complicated by stroke and other systemic emboli (P < .005). The overall in-hospital mortality of BHS IE was significantly higher than that of VGS IE (P = .001). In univariate analysis, variables associated with in-hospital mortality for BHS IE were age (odds ratio [OR], 1.044; P = .004), prosthetic valve IE (OR, 3.029; P = .022), congestive heart failure (OR, 2.513; P = .034), and stroke (OR, 3.198; P = .009).

Conclusions

BHS IE is characterized by an acute presentation and higher rate of stroke, systemic emboli, and in-hospital mortality than VGS IE. Implantable cardiac devices as a predisposing factor were more often found in BHS IE compared with VGS IE.

Inhibitory effect of a mouth rinse formulated with chlorhexidine gluconate, ethanol, and green tea extract against major oral bacterial species

Mouth rinses are a useful supplementary tool for the prevention of oral infectious diseases. Although the antimicrobial effects of mouth rinses have been investigated, there are few studies focusing on the comparison of the effects among various oral bacterial species. In the present study, the inhibitory effect of a commercial mouth rinse, "ConCoolF," and each of its major components, chlorhexidine gluconate, ethanol, and green tea extract, on multiple species of oral bacteria were investigated. Inhibition of bacterial growth was observed in all cariogenic streptococcal species with different genera, serotypes, and strains isolated from different countries when either the complete mouth rinse or chlorhexidine gluconate were used. However, no growth inhibition was observed when the bacteria were exposed to ethanol or green tea extract. Interestingly, growth inhibition was greatly reduced in non-cariogenic streptococci compared with cariogenic streptococci. In addition, both the mouth rinse and chlorhexidine gluconate inhibited the biofilms formed by both Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis), among which the inhibitory effect against S. mutans was higher than that against P. gingivalis. These results suggest that a mouth rinse containing chlorhexidine gluconate, ethanol, and green tea extract, or chlorhexidine gluconate alone, exhibits antimicrobial activity against several oral bacteria species, having greater activity against pathogenic bacteria.

Streptococcus mutans isolated from a 4-year-old girl diagnosed with infective endocarditis

Objectives

Infective endocarditis (IE) has an extremely high fatality rate. In this study, we isolated a strain of Streptococcus mutans, which we called HM, from the blood drawn from a 4-year-old girl diagnosed with IE. We aimed to fully type the HM strain and investigate its biological properties, including its virulence with respect to IE.

Material and methods

A 16S rRNA phylogenetic tree and glucosyltransferase gene sequences were used to type HM. Serotyping was performed using the Ouchterlony method. Morphological observations were made using phase contrast and electron microscopy. Fibrinogen adhesion and biofilm formation were investigated to examine the tissue colonization properties of HM, whereas its bodily origin was determined from its fingerprinting pattern.

Results

The isolated strain was S. mutans serotype e. However, its morphology was observed to be short chains, unlike that of the NCTC 10449 reference strain. Fibrinogen adhesion and biofilm formation were more apparent than in NCTC 10449. The fingerprinting pattern showed that HM came from the patient's saliva.

Conclusions

HM differs from NCTC 10449 in its higher fibrinogen affinity. HM was also found to be derived from the oral cavity. These results highlight the importance of good oral hygiene for the prevention of IE in children.

Association between Alzheimer's Disease and Oral and Gut Microbiota: Are Pore Forming Proteins the Missing Link?

Alzheimer's disease (AD) is a neurodegenerative condition affecting millions of people worldwide. It is associated with cerebral amyloid-β (Aβ) plaque deposition in the brain, synaptic disconnection, and subsequent progressive neuronal death. Although considerable progress has been made to elucidate the pathogenesis of AD, the specific causes of the disease remain highly unknown. Recent research has suggested a potential association between certain infectious diseases and dementia, either directly due to bacterial brain invasion and toxin production, or indirectly by modulating the immune response. Therefore, in the present review we focus on the emerging issues of bacterial infection and AD, including the existence of antimicrobial peptides having pore-forming properties that act in a similar way to pores formed by Aβ in a variety of cell membranes. Special focus is placed on oral bacteria and biofilms, and on the potential mechanisms associating bacterial infection and toxin production in AD. The role of bacterial outer membrane vesicles on the transport and delivery of toxins as well as porins to the brain is also discussed. Aβ has shown to possess antimicrobial activity against several bacteria, and therefore could be upregulated as a response to bacteria and bacterial toxins in the brain. Although further research is needed, we believe that the control of biofilm-mediated diseases could be an important potential prevention mechanism for AD development.

Streptococcus mutans serotypes and collagen-binding proteins Cnm/Cbm in children with caries analysed by PCR

Streptococcus mutans, a primary bacterium associated with dental caries, has four known clinical serotypes (c, e, fand k). Certain serotypes, the presence of multiple serotypes and strains with collagen-binding proteins (CBP, Cnm and Cbm) have been linked with systemic disease. Evaluation of S mutans serotype distribution and caries association is needed in the United States. The purpose of this study was to evaluate the prevalence of S mutans serotypes from two cohorts of African-American children in rural Alabama using three sample types (saliva, plaque and individual S mutans isolates) by PCR detection for association with caries. Detection of CBP was also performed by PCR. In total, 129 children were evaluated and overall prevalence of serotypes were: serotype c(98%), e(26%), f(7%) and k(52%). Serotype c was statistically associated with higher caries scores in older children (P < 0.001) and serotype k was statistically more likely in females (P = 0.004). Fourteen per cent of children had CBP. Thirteen S mutans isolates from five children tested positive for both CBP. This study is the first to report on the prevalence of S mutans serotypes in a US population using the PCR-based approach. The frequency of serotype k in this study is the highest reported in any population, illustrating the need for further study to determine the prevalence of this clinically relevant serotype in the US. This is the first study to report S mutans isolates with both Cnm and Cbm in the same strain, and further analysis is needed to determine the clinical significance of these strains.

Mouthwash containing Croton doctoris essential oil: in vitro study using a validated model of caries induction

Aim: To validate an in vitro caries model and to evaluate an experimental mouthwash containing Croton doctoris essential oil.  Materials & methods: To validate the experimental model, we used McBain medium and polymicrobial biofilms. The EOM (essential oil mouthwash) was tested using the validated model. Microbial composition (colony-forming unit/ml), acidogenicity, enamel demineralization (percentage of surface enamel hardness loss), cytotoxicity and essential oil composition were evaluated. Results: The model was validated with 0.5% sucrose, duration of 4 days and treatments twice per day. There were statistically significant differences between the EOM, the negative control and chlorhexidine mouthwash in colony-forming unit/ml and percentage of surface enamel hardness loss. Cytotoxicity was similar to that of chlorhexidine mouthwash.  A total of 66.11% of the essential oil consists of sesquiterpenes. Conclusion: The experimental mouthwash showed antimicrobial activity against polymicrobial biofilms and reduced enamel demineralization.

Dental Decay and Oral Findings in Children and Adolescents Affected by Different Types of Cerebral Palsy: A Comparative Study

OBJECTIVE

To compare dental caries and oral findings in patients affected by different types of Cerebral Palsy (CP).

STUDY DESIGN

This cross-sectional study involved 120 children and adolescents with a diagnosis of CP. WHO diagnostic criteria were used to determine DMFT (caries diagnosis), the pocket depth and attachment level (periodontitis diagnosis). Additionally, the study evaluated dental erosion, traumatic dental injuries, treatment needs index (TNI), oral habits, malocclusions, gingival overgrowth, and dental fluorosis.

RESULTS

The most frequent CP type was spastic (62.5%), followed by mixed (18.3%), ataxic (10%), and athetoid (9.1). Patients affected by mixed CP showed a higher prevalence in decayed, DMFT index and TNI compared with the other types of CP (p<0.05). The frequency of malocclusion in the clinical evaluation was 87.5% and in plaster models was 49.2%.

CONCLUSIONS

Dental caries was an important issue in mixed and athetoid CP groups. Oral habits and malocclusions were the most significant oral health problems in individuals with CP.

Contribution of Streptococcus mutans Strains with Collagen-Binding Proteins in the Presence of Serum to the Pathogenesis of Infective Endocarditis

Streptococcus mutans, a major pathogen of dental caries, is considered one of the causative agents of infective endocarditis (IE). Recently, bacterial DNA encoding 120-kDa cell surface collagen-binding proteins (CBPs) has frequently been detected from S. mutans-positive IE patients. In addition, some of the CBP-positive S. mutans strains lacked a 190-kDa protein antigen (PA), whose absence strengthened the adhesion to and invasion of endothelial cells. The interaction between pathogenic bacteria and serum or plasma is considered an important virulence factor in developing systemic diseases; thus, we decided to analyze the pathogenesis of IE induced by S. mutans strains with different patterns of CBP and PA expression by focusing on the interaction with serum or plasma. CBP-positive (CBP⁺)/PA-negative (PA^-) strains showed prominent aggregation in the presence of human serum or plasma, which was significantly greater than that with CBP⁺/PA-positive (PA⁺) and CBP-negative (CBP^-)/PA+ strains. Aggregation of CBP⁺/PA^- strains was also observed in the presence of a high concentration of type IV collagen, a major extracellular matrix protein in serum. In addition, aggregation of CBP⁺/PA^- strains was drastically reduced when serum complement was inactivated. Furthermore, an ex vivo adherence model and an in vivo rat model of IE showed that extirpated heart valves infected with CBP⁺/PA^- strains displayed prominent bacterial mass formation, which was not observed following infection with CBP⁺/PA⁺ and CBP^-/PA⁺ strains. These results suggest that CBP⁺/PA^-S. mutans strains utilize serum to contribute to their pathogenicity in IE.

Streptococcus Mutans Adhesin Biotypes that Match and Predict Individual Caries Development

Dental caries, which affects billions of people, is a chronic infectious disease that involves Streptococcus mutans, which is nevertheless a poor predictor of individual caries development. We therefore investigated if adhesin types of S.mutans with sucrose-independent adhesion to host DMBT1 (i.e. SpaP A, B or C) and collagen (i.e. Cnm, Cbm) match and predict individual differences in caries development. The adhesin types were measured in whole saliva by qPCR in 452 12-year-old Swedish children and related to caries at baseline and prospectively at a 5-year follow-up. Strains isolated from the children were explored for genetic and phenotypic properties. The presence of SpaP B and Cnm subtypes coincided with increased 5-year caries increment, and their binding to DMBT1 and saliva correlated with individual caries scores. The SpaP B subtypes are enriched in amino acid substitutions that coincided with caries and binding and specify biotypes of S. mutans with increased acid tolerance. The findings reveal adhesin subtypes of S. mutans that match and predict individual differences in caries development and provide a rationale for individualized oral care.

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Adhesin subtypes of Streptococcus mutans match and predict individual caries development.

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Adhesin binding to salivary DMBT1 correlates with individual caries scores.

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The adhesin types coincide with distinct biotypes of S. mutans.

Dental caries, which affects billions of people, involves the bacterium Streptococcus mutans, which is nevertheless a poor predictor of caries development. The present findings provide the first evidence that S. mutans adhesin subtypes match and predict individual 5-year caries development in Swedish children. The binding strength of the adhesin subtypes correlates with individual caries scores, and the adhesin subtypes specify biotypes of S. mutans that also differ in acid tolerance. The present findings provide a rationale for individualized oral care and improved systemic health because chronic caries infection and carrying high-virulence strains pose a systemic disease risk.

Methods of Biotyping of Streptococcus mutans Species with the Routine Test as a Prognostic Value in Early Childhood Caries

Purpose

In order to investigate the suitability of Streptococcus mutans species biotyping by measuring the activity of selected enzymes from a commercial test, criteria were established for biotyping clinical strains from children with dental caries. In addition, the relationships between the selected biotypes, sensitivity to commonly used antibiotics, and early childhood caries were determined.

Methods

A total of 142 S. mutans isolates from dental plaque of children with caries were divided into different biotypes. Patients were divided into two groups: noncavitated (1-2 in ICDAS) and cavitated (5-6 in ICDAS) lesions. Biotyping criteria were determined based on both the arbitrary method and the clusterization method. The susceptibility of the strains to amoxicillin, cefazolin, erythromycin, and teicoplanin was studied by diluting a solid medium.

Results

Biotype I was the most common. Mean MIC values showed that the strains belonging to biotypes II and IV were the most sensitive to amoxicillin. For predetermined biotypes, observed differences were dependent on the severity of dental caries.

Conclusions

The proposed method of S. mutans strains biotyping is relatively quick and simple to use, provided the application of suitable biotyping criteria, and may contribute to the effective prevention of dental caries induced by S. mutans.

Clinical and molecular characteristics of infective β-hemolytic streptococcal endocarditis

Streptococcus pyogenes (S. pyogenes) and Streptococcus dysgalactiae subspecies equisimilis (SDSE) cause considerable morbidity and mortality, and show similarities in disease manifestations and pathogenic mechanisms. Their involvement in infective endocarditis, however, has not been well described. Invasive S. pyogenes and SDSE infections in Health Region Bergen, Norway, in the period 1999-2013 were reviewed, and sixteen cases of endocarditis were identified. The median duration of symptoms was 2.5days, the frequency of embolic events 50%, 38% received valve replacement and the 30-day mortality was 25%. In S. pyogenes, a significant correlation was observed between the repertoire of fibronectin-binding genes, phenotypic binding ability to fibronectin and disease manifestations. Conversely, no associations between phenotypic and genotypic characteristics were detected in SDSE. S. pyogenes and SDSE endocarditis is characterized by rapid and severe clinical manifestations. The pathogenesis is multifactorial, but our results infer a potential role of fibronectin binding in the development of S. pyogenes endocarditis.

Novel method for the depletion of cariogenic bacteria using dextranomer microspheres

Streptococcus mutans is recognized as one of the key contributors to the dysbiotic state that results in dental caries. Existing treatment strategies reduce the incidence of tooth decay, but they also eliminate both the cariogenic and beneficial microbes. Here we introduce a novel treatment alternative using Sephadex, cross-linked dextranomer microspheres (DMs), typically used for gel filtration chromatography. In addition DM beads can be used for affinity purification of glucosyltransferases (GTFs) from S. mutans. In this study we take advantage of the native pathogenic mechanisms used by S. mutans to adhere, form a biofilm and induce dental caries through the expression of surface-associated GTFs. We demonstrate that planktonic and biofilm-grown (adhered to hydroxyapatite-coated pegs to mimic the tooth surface) S. mutans, specifically and competitively attach to DMs. Further investigation demonstrated that DMs are a specific affinity resin for S. mutans and other cariogenic/pathogenic oral streptococci, whereas other commensal and probiotic strains failed to readily adhere to DMs. Using antimicrobial cargo loaded into the DM lumen, we demonstrate that when in co-culture with non-binding to even modestly binding commensal species, S. mutans was selectively killed. This proof of concept study introduces a novel means to safely and effectively reduce the pool of S. mutans and other pathogenic streptococci in the oral cavity with limited disturbance of the necessary commensal (healthy) microbiota when compared with current oral healthcare products.

Contributions of Streptococcus mutans Cnm and PA antigens to aggravation of non-alcoholic steatohepatitis in mice

Streptococcus mutans, a major pathogen of dental caries, can cause infective endocarditis after invading the bloodstream. Recently, intravenous administration of specific S. mutans strains was shown to aggravate non-alcoholic steatohepatitis (NASH) in a mouse model fed a high-fat diet. Here, we investigated the mechanism of this aggravation in a NASH mouse model by focusing on the S. mutans cell surface collagen-binding protein (Cnm) and the 190-kDa protein antigen (PA). Mice that were intravenously administered a S. mutans strain with a defect in Cnm (TW871CND) or PA (TW871PD) did not show clinical or histopathological signs of NASH aggravation, in contrast to those administered the parent strain TW871. The immunochemical analyses demonstrated higher levels of interferon-γ and metallothionein expression in the TW871 group than in the TW871CND and TW871PD groups. Analysis of bacterial affinity to cultured hepatic cells in the presence of unsaturated fatty acids revealed that the incorporation rate of TW871 was significantly higher than those of TW871CND and TW871PD. Together, our results suggest that Cnm and PA are important cell surface proteins for the NASH aggravation caused by S. mutans adhesion and affinity for hepatic cells.

Antibody-Based Therapy for Enterococcal Catheter-Associated Urinary Tract Infections

Gram-positive bacteria in the genus Enterococcus are a frequent cause of catheter-associated urinary tract infection (CAUTI), a disease whose treatment is increasingly challenged by multiantibiotic-resistant strains. We have recently shown that E. faecalis uses the Ebp pilus, a heteropolymeric surface fiber, to bind the host protein fibrinogen as a critical step in CAUTI pathogenesis. Fibrinogen is deposited on catheters due to catheter-induced inflammation and is recognized by the N-terminal domain of EbpA (EbpA^NTD), the Ebp pilus's adhesin. In a murine model, vaccination with EbpA^NTD confers significant protection against CAUTI. Here, we explored the mechanism of protection using passive transfer of immune sera to show that antisera blocking EbpA^NTD-fibrinogen interactions not only is prophylactic but also can act therapeutically to reduce bacterial titers of an existing infection. Analysis of 55 clinical CAUTI, bloodstream, and gastrointestinal isolates, including E. faecalis, E. faecium, and vancomycin-resistant enterococci (VRE), revealed a diversity of levels of EbpA expression and fibrinogen-binding efficiency in vitro Strikingly, analysis of 10 strains representative of fibrinogen-binding diversity demonstrated that, irrespective of EbpA levels, EbpA^NTD antibodies were universally protective. The results indicate that, despite diversity in levels of fibrinogen binding, strategies that target the disruption of EbpA^NTD-fibrinogen interactions have considerable promise for treatment of CAUTI.

IMPORTANCE

Urinary catheterization is a routine medical procedure, and it has been estimated that 30 million Foley catheters are used annually in the United States. Importantly, placement of a urinary catheter renders the patient susceptible to developing a catheter-associated urinary tract infection, accounting for 1 million cases per year. Additionally, these infections can lead to serious complications, including bloodstream infection and death. Enterococcus strains are a common cause of these infections, and management of enterococcal infections has been more difficult in recent years due to the development of antibiotic resistance and the ability of strains to disseminate, resulting in a major threat in hospital settings. In this study, we developed an antibiotic-sparing treatment that is effective against diverse enterococcal isolates, including vancomycin-resistant enterococci, during catheter-associated urinary tract infections.

CovR Regulates Streptococcus mutans Susceptibility To Complement Immunity and Survival in Blood

Streptococcus mutans, a major pathogen of dental caries, may promote systemic infections after accessing the bloodstream from oral niches. In this study, we investigate pathways of complement immunity against S. mutans and show that the orphan regulator CovR (CovR_Sm) modulates susceptibility to complement opsonization and survival in blood. S. mutans blood isolates showed reduced susceptibility to C3b deposition compared to oral isolates. Reduced expression of covR_Sm in blood strains was associated with increased transcription of CovR_Sm-repressed genes required for S. mutans interactions with glucans (gbpC, gbpB, and epsC), sucrose-derived exopolysaccharides (EPS). Consistently, blood strains showed an increased capacity to bind glucan in vitro Deletion of covR_Sm in strain UA159 (UAcov) impaired C3b deposition and binding to serum IgG and C-reactive protein (CRP) as well as phagocytosis through C3b/iC3b receptors and killing by neutrophils. Opposite effects were observed in mutants of gbpC, epsC, or gtfBCD (required for glucan synthesis). C3b deposition on UA159 was abolished in C1q-depleted serum, implying that the classical pathway is essential for complement activation on S. mutans Growth in sucrose-containing medium impaired the binding of C3b and IgG to UA159, UAcov, and blood isolates but had absent or reduced effects on C3b deposition in gtfBCD, gbpC, and epsC mutants. UAcov further showed increased ex vivo survival in human blood in an EPS-dependent way. Consistently, reduced survival was observed for the gbpC and epsC mutants. Finally, UAcov showed an increased ability to cause bacteremia in a rat model. These results reveal that CovR_Sm modulates systemic virulence by regulating functions affecting S. mutans susceptibility to complement opsonization.

Antimicrobial Properties of Biofunctionalized Silver Nanoparticles on Clinical Isolates of Streptococcus mutans and Its Serotypes

(1) Background: Streptococcus mutans (S. mutans) is the principal pathogen involved in the formation of dental caries. Other systemic diseases have also been associated with specific S. mutans serotypes (c, e, f, and k). Silver nanoparticles (SNP) have been demonstrated to have good antibacterial effects against S. mutans; therefore, limited studies have evaluated the antimicrobial activity of biofunctionalized SNP on S. mutans serotypes. The purpose of this work was to prepare and characterize coated SNP using two different organic components and to evaluate the antimicrobial activity of SNP in clinical isolates of S. mutans strains and serotypes; (2) Methods: SNP with bovine serum albumin (BSA) or chitosan (CS) coatings were prepared and the physical, chemical and microbiological properties of SNP were evaluated; (3) Results: Both types of coated SNP showed antimicrobial activity against S. mutans bacteria and serotypes. Better inhibition was associated with smaller particles and BSA coatings; however, no significant differences were found between the different serotypes, indicating a similar sensitivity to the coated SNP; (4) Conclusion: This study concludes that BSA and CS coated SNP had good antimicrobial activity against S. mutans strains and the four serotypes, and this study suggest the widespread use of SNP as an antimicrobial agent for the inhibition of S. mutans bacteria.

Contribution of the Collagen-Binding Proteins of Streptococcus mutans to Bacterial Colonization of Inflamed Dental Pulp

Streptococcus mutans is a major pathogen of dental caries. Collagen-binding proteins (CBPs) (approximately 120 kDa), termed Cnm and Cbm, are regarded as important cell surface antigens related to the adherence of S. mutans to collagenous tissue. Furthermore, CBP-positive S. mutans strains are associated with various systemic diseases involving bacteremia, such as infective endocarditis. Endodontic infection is considered to be an important cause of bacteremia, but little is known regarding the presence of S. mutans in dental pulp tissue. In the present study, the distribution and virulence of S. mutans in dental pulp tissues were investigated by focusing on CBPs. Adhesion and invasion properties of various S. mutans strains were analyzed using human dental pulp fibroblasts (HDPFs). CBP-positive strains had a significantly higher rate of adhesion to HDPFs compared with CBP-defective isogenic mutant strains (P<0.001). In addition, CBP-positive strains induced HDPF proliferation, which is a possible mechanism related to development of hyperplastic pulpitis. The distribution of S. mutans strains isolated from infected root canal specimens was then analyzed by PCR. We found that approximately 50% of the root canal specimens were positive for S. mutans. Approximately 20% of these strains were Cnm-positive, while no Cbm-positive strains were isolated. The Cnm-positive strains isolated from the specimens showed adhesion to HDPFs. Our results suggest that CBP-positive S. mutans strains exhibit high colonization in dental pulp. This could be a possible virulence factor for various systemic diseases.

Collagen-binding proteins of Streptococcus mutans and related streptococci

The ability of Streptococcus mutans to interact with collagen through the expression of collagen-binding proteins (CBPs) bestows this oral pathogen with an alternative to the sucrose-dependent mechanism of colonization classically attributed to caries development. Based on the abundance and distribution of collagen throughout the human body, stringent adherence to this molecule grants S. mutans with the opportunity to establish infection at different host sites. Surface proteins, such as SpaP, WapA, Cnm and Cbm, have been shown to bind collagen in vitro, and it has been suggested that these molecules play a role in colonization of oral and extra-oral tissues. However, robust collagen binding is not achieved by all strains of S. mutans, particularly those that lack Cnm or Cbm. These observations merit careful dissection of the contribution from these different CBPs towards tissue colonization and virulence. In this review, we will discuss the current understanding of mechanisms used by S. mutans and related streptococci to colonize collagenous tissues, and the possible contribution of CBPs to infections in different sites of the host.

Frequency of dental caries in active and inactive systemic lupus erythematous patients: salivary and bacterial factors

OBJECTIVE

The objective of this study was to determine dental caries frequency and to analyze salivary and bacterial factors associated with active and inactive systemic lupus erythematous (SLE) patients. Also, a proposal to identify dental caries by a surface, teeth, and the patient was developed.

MATERIAL AND METHODS

A cross-sectional, blinded study that included 60 SLE patients divided into two groups of 30 subjects each, according to the Activity Index for Diagnosis of Systemic Lupus Erythematous (SLEDAI). The decayed, missing, and filled teeth (DMFT) index and Integrative Dental Caries Index (IDCI) were used for analyzing dental caries. The saliva variables recorded were: flow, pH, and buffer capacity. The DNA copies of Streptococcus mutans and Streptococcus sobrinus were estimated by real-time PCR.

RESULTS

The caries frequency was 85% for SLE subjects (73.3% for inactive systemic lupus erythematous (ISLE) and 100% for active systemic lupus erythematous (ASLE)); DMFT for the SLE group was 12.6 ± 5.7 and the IDCI was (9.8 ± 5.9). The ASLE group showed a salivary flow of 0.65 compared with 0.97 ml/1 min from the ISLE group; all variables mentioned above showed a statistical difference (p < 0.05). The salivary pH was 4.6 (6.06 for ISLE and 3.9 for ASLE). The DNA copies of S. mutans and S. sobrinus were high; all variables mentioned above show a significant statistical difference (p < 0.05) between groups.

CONCLUSION

SLE patients had high DMFT and IDCI scores that were associated with a decrease in salivary flow, pH, and buffer capacity. There were high counts of S. sobrinus and S. mutans species, and IDCI is a useful tool to provide more detail about dental caries in epidemiological studies.

Molecular Analysis of Oral Bacteria in Heart Valve of Patients With Cardiovascular Disease by Real-Time Polymerase Chain Reaction

Structural deficiencies and functional abnormalities of heart valves represent an important cause of cardiovascular morbidity and mortality, and a number of diseases, such as aortic stenosis, have been recently associated with infectious agents. This study aimed to analyze oral bacteria in dental plaque, saliva, and cardiac valves of patients with cardiovascular disease. Samples of supragingival plaque, subgingival plaque, saliva, and cardiac valve tissue were collected from 42 patients with heart valve disease. Molecular analysis of Streptococcus mutans, Prevotella intermedia, Porphyromonas gingivalis, and Treponema denticola was performed through real-time PCR. The micro-organism most frequently detected in heart valve samples was the S. mutans (89.3%), followed by P. intermedia (19.1%), P. gingivalis (4.2%), and T. denticola (2.1%). The mean decayed, missing, filled teeth (DMFT) was 26.4 ± 6.9 (mean ± SD), and according to the highest score of periodontal disease observed for each patient, periodontal pockets > 4 mm and dental calculus were detected in 43.4% and 34.7% of patients, respectively. In conclusion, oral bacteria, especially S. mutans, were found in the cardiac valve samples of patients with a high rate of caries and gingivitis/periodontitis.

The collagen binding protein Cnm contributes to oral colonization and cariogenicity of Streptococcus mutans OMZ175

Streptococcus mutans is the etiological agent of dental caries and one of the many bacterial species implicated in infective endocarditis. The expression of the collagen-binding protein Cnm by S. mutans has been associated with extraoral infections, but its relevance for dental caries has only been theorized to date. Due to the collagenous composition of dentinal and root tissues, we hypothesized that Cnm may facilitate the colonization of these surfaces, thereby enhancing the pathogenic potential of S. mutans in advancing carious lesions. As shown for extraoral endothelial cell lines, Cnm mediates the invasion of oral keratinocytes and fibroblasts by S. mutans. In this study, we show that in the Cnm(+) native strain, OMZ175, Cnm mediates stringent adhesion to dentinal and root tissues as well as collagen-coated surfaces and promotes both cariogenicity and carriage in vivo. In vitro, ex vivo, and in vivo experiments revealed that while Cnm is not universally required for S. mutans cariogenicity, it contributes to (i) the invasion of the oral epithelium, (ii) enhanced binding on collagenous surfaces, (iii) implantation of oral biofilms, and (IV) the severity of caries due to a native Cnm(+) isolate. Taken together, our findings reveal that Cnm is a colonization factor that contributes to the pathogenicity of certain S. mutans strains in their native habitat, the oral cavity.