High-throughput characterization of the influence of Streptococcus sanguinis genes on the interaction between Streptococcus sanguinis and Porphyromonas gingivalis.

Porphyromonas gingivalis is a keystone pathogen in periodontitis, and Streptococcus sanguinis is an abundant oral commensal bacterium associated with periodontal health. However, the interaction between P. gingivalis and S. sanguinis remains obscure. Here, we established a strategy for high-throughput measurement of the cell number of P. gingivalis in the coculture with S. sanguinis by detecting the concentration of hydrogen sulfate. The interaction between P. gingivalis and over 2000 S. sanguinis single-gene mutants was characterized using this strategy, and several interaction-associated genes in S. sanguinis were determined by detecting more P. gingivalis cells in the coculture with matched S. sanguinis mutants. Three S. sanguinis interaction-associated genes were predicted to be responsible for cysteine metabolism, and the supplementation of exogenous L-cysteine promoted the cell number of P. gingivalis in the coculture with S. sanguinis. Thus, exogenous L-cysteine and the compromised cysteine metabolism in S. sanguinis enhanced the growth of P. gingivalis in the existence of S. sanguinis. Additionally, the interaction between P. gingivalis and other Streptococcus spp. was examined, and S. pneumoniae was the only streptococci that had no inhibition on the cell number of P. gingivalis. In total, this study established a new strategy for high-throughput screening of the interaction between Streptococcus and P. gingivalis and discovered a set of genes in S. sanguinis that impacted the interaction. The influence of exogenous L-cysteine on the interaction between P. gingivalis and S. sanguinis in the oral cavity needs further investigation.

Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study.

AIM AND BACKGROUND: This study aimed to explore the potential synergistic interaction of virgin coconut oil (VCO) and virgin olive oil (VOO) mixture against Streptococcus sanguinis, Streptococcus mutans, and Lactobacillus casei in a single and mixture species through the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antiadherence, and antibiofilm activities. MATERIALS AND METHODS: The broth microdilution technique was used to individually determine the MIC of both oils and an oil mixture (in the ratio of 1:1) in a 96-well microtiter plate. As for the MBC, the subcultured method was used. The fractional inhibitory concentration index (ΣFIC) was determined to identify the interaction types between both oils. The oil mixture at its MIC was then tested on its antibiofilm and antiadherence effect. RESULTS: The MIC of the oil mixture against the tested microbiota was 50-100%. The oil mixture was bactericidal at 100% concentration for all the mentioned microbes except S. mutans. The ΣFIC value was 2 to 4, indicating that the VCO and VOO acted additively against the microbiota. Meanwhile, the oil mixture at MIC (50% for S. sanguinis and L. casei; 100% for S. mutans and mixture species) exhibited antiadherence and antibiofilm activity toward the microbiota in mixture species. CONCLUSION: The oil mixture possesses antibacterial, antibiofilm, and antiadherence properties toward the tested microbiota, mainly at 50-100% concentration of oil mixture. There was no synergistic interaction found between VCO and VOO. CLINICAL SIGNIFICANCE: Children and individuals with special care may benefit from using the oil mixture, primarily to regulate the biofilm formation and colonization of the bacteria. Furthermore, the oil mixture is natural and nontoxic compared to chemical-based oral healthcare products. How to cite this article: Ng YM, Sockalingam SNMP, Shafiei Z, et al. Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study. J Contemp Dent Pract 2024;25(3):260-266.

Functional Analysis of the Major Pilin Proteins of Type IV Pili in Streptococcus sanguinis CGMH010.

The pil gene cluster for Type IV pilus (Tfp) biosynthesis is commonly present and highly conserved in Streptococcus sanguinis. Nevertheless, Tfp-mediated twitching motility is less common among strains, and the factors determining twitching activity are not fully understood. Here, we analyzed the functions of three major pilin proteins (PilA1, PilA2, and PilA3) in the assembly and activity of Tfp in motile S. sanguinis CGMH010. Using various recombinant pilA deletion strains, we found that Tfp composed of different PilA proteins varied morphologically and functionally. Among the three PilA proteins, PilA1 was most critical in the assembly of twitching-active Tfp, and recombinant strains expressing motility generated more structured biofilms under constant shearing forces compared to the non-motile recombinant strains. Although PilA1 and PilA3 shared 94% identity, PilA3 could not compensate for the loss of PilA1, suggesting that the nature of PilA proteins plays an essential role in twitching activity. The single deletion of individual pilA genes had little effect on the invasion of host endothelia by S. sanguinis CGMH010. In contrast, the deletion of all three pilA genes or pilT, encoding the retraction ATPase, abolished Tfp-mediated invasion. Tfp- and PilT-dependent invasion were also detected in the non-motile S. sanguinis SK36, and thus, the retraction of Tfp, but not active twitching, was found to be essential for invasion.

Papillary fibroelastoma complicated by Streptococcus sanguinis bacteremia: a rare case of cardiac tumor with embolic events.

Fibroelastoma is a rare cardiac tumor that can cause embolization, stroke, myocardial infarction, heart failure, and cardiac arrest. Here, we report the case of a 45-year-old male who presented with right-sided weakness and fever. He was diagnosed with acute right frontal infarction and was found to have Streptococcus sanguinis bacteremia. Upon confirmation of a positive blood culture after 24 hours, treatment for endocarditis was initiated. Transesophageal echocardiography revealed findings highly suggestive of a papillary fibroelastoma (PFE). PFE ought to be regarded as a potential differential diagnosis in individuals who exhibit symptoms of fever, thromboembolism, and persistent bacteremia. Non-invasive imaging such as echocardiography is of great value in the diagnosis of PFE, while surgical resection remains the best treatment modality to overcome current and future associated complications.

Bicuspid Aortic Valve Endocarditis Caused by Streptococcus sanguinis: A Case Report.

Antibiotic prophylaxis prior to dental work in bicuspid aortic valve (BAV) patients is currently a matter of debate. The American Dental Association does not require those with native BAV to receive antibiotic prophylaxis prior to dental work as BAV is considered an "intermediate" risk for infective endocarditis (IE). We present the case of a 63-year-old male, with a medical history of BAV, who acquired Streptococcus sanguinis IE after a routine dental cleaning four months prior to initial onset of symptoms. He exhibited new-onset and severe aortic regurgitation at presentation, requiring urgent aortic valve replacement to restore valve function. BAV patients are at high risk of IE, emphasizing the need for prophylactic antibiotics in dental cleaning as well as invasive dental procedures in those with BAV.

Dental composite biodeterioration in the presence of oral Streptococci and extracellular metabolic products.

OBJECTIVE: Secondary caries is a primary cause of early restoration failure. While primary dental caries has been extensively researched, our knowledge about the impact of secondary caries on dental restorations is relatively limited. In this study, we examined how different clinically relevant microbially-influenced environments impact the degradation of nano-filled (FIL) and micro-hybrid (AEL) dental composites. METHODS: Material strength of two commercial dental composites was measured following incubation in aqueous media containing: i) cariogenic (Streptococcus mutans) and non-cariogenic bacteria (Streptococcus sanguinis) grown on sucrose or glucose, ii) abiotic mixtures of artificial saliva and sucrose and glucose fermentation products (volatile fatty acids and ethanol) in proportions known to be produced by these microorganisms, and iii) abiotic mixtures of artificial saliva and esterase, a common oral extracellular enzyme. RESULTS: Nano-filled FIL composite strength decreased in all three types of incubations, while micro-hybrid AEL composite strength only decreased significantly in biotic incubations. The strength of both composites was statistically significantly decreased in all biotic incubations containing both cariogenic and non-cariogenic bacteria beyond that induced by either abiotic mixtures of fermentation products or esterase alone. Finally, there were no statistically significant differences in composite strength decrease among the tested biotic conditions. CONCLUSIONS: The results show that conditions created during the growth of both cariogenic and non-cariogenic oral Streptococci substantially reduce commercial composite strength, and this effect warrants further study to identify the mechanism(s). CLINICAL SIGNIFICANCE: Dental biofilms of oral Streptococci bacteria significantly affect the mechanical strength of dental restorations.

Infective Endocarditis Caused by Streptococcus sanguinis Resulting in Stroke, Ruptured Infected Pseudoaneurysm of Superior Mesenteric Artery, and Rapidly Progressive Glomerulonephritis.

A 71-year-old-man was admitted to our hospital with a cerebral embolism and diagnosed with infective endocarditis (IE) caused by Streptococcus sanguinis. Mitral valve replacement was performed. About one month later, he experienced sudden abdominal pain and shock due to a ruptured infected mesenteric artery pseudoaneurysm. Forty-four days after abdominal surgery, he presented with rapidly progressive glomerulonephritis with anti-glomerular basement membrane antibodies. He was treated with plasma exchange and prednisolone, and his renal function gradually improved. Since postoperative complications often occur within a few years after surgery for IE, careful follow-up is important, even after antimicrobial therapy and valve surgery.

Noncanonical Streptococcus sanguinis ComCDE circuitry integrates environmental cues in transformation outcome decision.

Natural competence is the principal driver of streptococcal evolution. While acquisition of new traits could facilitate rapid fitness improvement for bacteria, entry into the competent state is a highly orchestrated event, involving an interplay between various pathways. We present a new type of competence-predation coordination mechanism in Streptococcus sanguinis. Unlike other streptococci that mediate competence through the ComABCDE regulon, several key components are missing in the S. sanguinis ComCDE circuitry. We assembled two synthetic biology devices linking competence-stimulating peptide (CSP) cleavage and export with a quantifiable readout to unravel the unique features of the S. sanguinis circuitry. Our results revealed the ComC precursor cleavage pattern and the two host ABC transporters implicated in the export of the S. sanguinis CSP. Moreover, we discovered a ComCDE-dependent bacteriocin locus. Overall, this study presents a mechanism for commensal streptococci to maximize transformation outcome in a fluid environment through extensive circuitry rewiring.

Amyloid Fibrils Produced by Streptococcus sanguinis Contribute to Biofilm Formation and Immune Evasion.

Bacterial surface proteins assembled into amyloids contribute to biofilm formation and host immune evasion. Streptococcus sanguinis, a pioneer colonizer of teeth commonly involved in cardiovascular infections, expresses about thirty-three proteins anchored to the cell wall by sortase A. Here, we characterized the production of amyloid in S. sanguinis strains differing in biofilm and immune evasion phenotypes and investigated the role of sortase A in amyloidogenesis. Amyloid was identified in biofilms formed by nine strains, using Congo red (CR) staining and cross-polarized light microscopy. Additionally, EGCG, an amyloid inhibitor, impaired biofilm maturation in a strain-specific fashion. The amounts of amyloid-like components quantified in culture fluids of nine strains using thioflavin T and fluorimetry negatively correlated with bacterial binding to complement-activating proteins (SAP, C1q), C3b deposition and rates of opsonophagocytosis in PMNs, implying amyloid production in immune evasion. The deletion of the sortase A gene (srtA) in strain SK36 compromised amyloid production and sucrose-independent biofilm maturation. The srtA mutant further showed increased susceptibility to C3b deposition and altered interactions with PMNs as well as reduced persistence in human blood. These findings highlight the contribution of amyloids to biofilm formation and host immune evasion in S. sanguinis strains, further indicating the participation of sortase A substrates in amyloidogenesis.

The Distribution of Eight Antimicrobial Resistance Genes in Streptococcus oralis, Streptococcus sanguinis, and Streptococcus gordonii Strains Isolated from Dental Plaque as Oral Commensals.

It has been proposed that oral commensal bacteria are potential reservoirs of a wide variety of antimicrobial resistance genes (ARGs) and could be the source of pathogenic bacteria; however, there is scarce information regarding this. In this study, three common streptococci of the mitis group (S. oralis, S. sanguinis, and S. gordonii) isolated from dental plaque (DP) were screened to identify if they were frequent reservoirs of specific ARGs (blaTEM, cfxA, tetM, tetW, tetQ, ermA, ermB, and ermC). DP samples were collected from 80 adults; one part of the sample was cultured, and from the other part DNA was obtained for first screening of the three streptococci species and the ARGs of interest. Selected samples were plated and colonies were selected for molecular identification. Thirty identified species were screened for the presence of the ARGs. From those selected, all of the S. sanguinis and S. oralis carried at least three, while only 30% of S. gordonii strains carried three or more. The most prevalent were tetM in 73%, and blaTEM and tetW both in 66.6%. On the other hand, ermA and cfxA were not present. Oral streptococci from the mitis group could be considered frequent reservoirs of specifically tetM, blaTEM, and tetW. In contrast, these three species appear not to be reservoirs of ermA and cfxA.

In Vitro Comparative Evaluation of the Efficacy of Antimicrobial Photodynamic Therapy, Chlorhexidine, Sodium Fluoride, and Hydrogen Peroxide for Acrylic Resin Disinfection.

Introduction: Plaque accumulation on the surface of removable orthodontic appliances could lead to dental caries, periodontitis, and fungal infections. This study evaluated the effectiveness of antimicrobial photodynamic therapy (aPDT), chlorhexidine (CHX), sodium fluoride (NaF), and hydrogen peroxide (H2O2) for the disinfection of acrylic resin. Methods: In this in vitro experimental study, 100 acrylic resin specimens were randomly divided into five groups (n=20 each): Enterococcus faecalis, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguinis, and Lactobacillus acidophilus. Each group was immersed separately in 5 mL of microbial suspension. They were then incubated until biofilm formation on their surface. Of each microorganism, one biofilm sample in phosphate-buffered saline was considered as negative control, and other biofilm samples (n=80) were subjected to aPDT with curcumin, 0.12% CHX (positive control), 1% H2O2, and 0.2% NaF. Finally, the number of colonies was counted. Data were analyzed by the Kruskal-Wallis and Mann-Whitney tests, two-way ANOVA, and Bonferroni adjustment at a significance level of 0.05. Results: The interaction effect of the treatment modality and type of microorganism was significant on the microbial count (effect size: 0.91, P<0.05). Maximum bacterial proliferation was noted in the following combinations: NaF/E. faecalis, H2O2/E. faecalis, and H2O2/S. salivarius. Microorganisms had no or insignificant growth and proliferation in the aPDT and CHX groups. Conclusion: The results supported the optimal antimicrobial efficacy of PDT which was comparable to that of CHX. aPDT showed superior antimicrobial efficacy to NaF and H2O2 for the disinfection of acrylic resin.

PepO and CppA modulate Streptococcus sanguinis susceptibility to complement immunity and virulence.

Streptococcus sanguinis is a ubiquitous commensal species of the oral cavity commonly involved as an opportunistic pathogen in cardiovascular infections. In this study, we investigated the functions of endopeptidase O (PepO) and a C3-degrading protease (CppA) in the systemic virulence of S. sanguinis. Isogenic mutants of pepO and cppA obtained in strain SK36 showed increased susceptibility to C3b deposition and to opsonophagocytosis by human polymorphonuclear neutrophils (PMN). These mutants differ, however, in their profiles of binding to serum amyloid P component (SAP) and C1q, whereas both showed reduced interaction with C4b-binding protein (C4BP) and/or factor H (FH) regulators as compared to SK36. The two mutants showed defects in ex vivo persistence in human blood, serum-mediated invasion of HCAEC endothelial cells, and virulence in a Galleria mellonella infection model. The transcriptional activities of pepO and cppA, assessed by RT-qPCR in nine wild-type strains, further indicated strain-specific profiles of pepO/cppA expression. Moreover, non-conserved amino acid substitutions were detected among the strains, mostly in CppA. Phylogenetic comparisons with homologues of streptococcal species of the oral and oropharyngeal sites suggested that S. sanguinis PepO and CppA have independent ancestralities. Thus, this study showed that PepO and CppA are complement evasion proteins expressed by S. sanguinis in a strain-specific manner, which are required for multiple functions associated with cardiovascular virulence.

Anticariogenic Activity of Celastrol and Its Enhancement of Streptococcal Antagonism in Multispecies Biofilm.

Dental caries is a chronic disease resulting from dysbiosis in the oral microbiome. Antagonism of commensal Streptococcus sanguinis and Streptococcus gordonii against cariogenic Streptococcus mutans is pivotal to keep the microecological balance. However, concerns are growing on antimicrobial agents in anticaries therapy, for broad spectrum antimicrobials may have a profound impact on the oral microbial community, especially on commensals. Here, we report celastrol, extracted from Traditional Chinese Medicine's Tripterygium wilfordii (TW) plant, as a promising anticaries candidate. Our results revealed that celastrol showed antibacterial and antibiofilm activity against cariogenic bacteria S. mutans while exhibiting low cytotoxicity. By using a multispecies biofilm formed by S. mutans UA159, S. sanguinis SK36, and S. gordonii DL1, we observed that even at relatively low concentrations, celastrol reduced S. mutans proportion and thereby inhibited lactic acid production as well as water-insoluble glucan formation. We found that celastrol thwarted S. mutans outgrowth through the activation of pyruvate oxidase (SpxB) and H2O2-dependent antagonism between commensal oral streptococci and S. mutans. Our data reveal new anticaries properties of celastrol that enhance oral streptococcal antagonism, which thwarts S. mutans outgrowth, indicating its potential to maintain oral microbial balance for prospective anticaries therapy.

An Unexpected Outcome of Streptococcus sanguinis Endocarditis Associated With Orthodontic Bracing in a Young Healthy Patient.

We present a case of Streptococcus sanguinis endocarditis in a 26-year-old female following orthodontic bracing. The rarity and debilitating consequences of endocarditis caused by Streptococcus sanguinis are elaborated. The patient exhibited severe regurgitation with the eccentric posteriorly directed flow, leading to significant cardiac strain, further accentuated by systolic flow reversal in the right superior pulmonary vein. Surgical intervention, including mitral valve replacement, was crucial in addressing the underlying infection, restoring valve function, and preventing further complications. However, a second mitral valve replacement was performed due to recurrent bioprosthesis endocarditis. This case underscores the unique challenges of Streptococcus sanguinis endocarditis, emphasizing the need for a multidisciplinary approach and individualized decision-making to optimize patient care.

In Situ Raman Analysis of Biofilm Exopolysaccharides Formed in Streptococcus mutans and Streptococcus sanguinis Commensal Cultures.

This study probed in vitro the mechanisms of competition/coexistence between Streptococcus sanguinis (known for being correlated with health in the oral cavity) and Streptococcus mutans (responsible for aciduric oral environment and formation of caries) by means of quantitative Raman spectroscopy and imaging. In situ Raman assessments of live bacterial culture/coculture focusing on biofilm exopolysaccharides supported the hypothesis that both species engaged in antagonistic interactions. Experiments of simultaneous colonization always resulted in coexistence, but they also revealed fundamental alterations of the biofilm with respect to their water-insoluble glucan structure. Raman spectra (collected at fixed time but different bacterial ratios) showed clear changes in chemical bonds in glucans, which pointed to an action by Streptococcus sanguinis to discontinue the impermeability of the biofilm constructed by Streptococcus mutans. The concurrent effects of glycosidic bond cleavage in water-insoluble α - 1,3-glucan and oxidation at various sites in glucans' molecular chains supported the hypothesis that secretion of oxygen radicals was the main "chemical weapon" used by Streptococcus sanguinis in coculture.

Identification and Correlation of Streptococcus mutans and Streptococcus sanguinis in Caries-active and Caries-free Children: A PCR Study.

Aim and objectives: Dental caries is currently considered an ecological imbalance within the oral biofilm leading to the dissolution of the tooth's hard tissues. It has been traditionally thought that two species belonging to the Streptococci group, Streptococcus mutans (SM) and Streptococcus sanguinis (SS), are the etiologically responsible for the onset of dental decay. Materials and methods: The present in vivo study was conducted on 40 children with caries-active (CA) and caries-free (CF). They were allocated into two groups, group I (CA) = 20 and group II (CF) = 20. The whole saliva was collected into the vials with buffer solution and was stored in cold storage. Polymerase chain reaction (PCR) was done to identify and correlate SM and SS in CA and CF children. Results: Comparison of mean SM level between CA and CF groups showed a statistically significant result at p = 0.001. Spearman's correlation between caries score and SM showed a strong correlation of 0.77 between caries score and SM, which was statistically significant at p = 0.001. Similarly, SS and caries scores showed a weak correlation of 0.22. Simple linear regression analysis to SM and caries score showed a significant increase of 4.74 units for 1 score increase in caries score, which is statistically significant. Conclusion: The presence of SM levels in children with caries is significant, whereas, in CF children, SS levels are present in increased levels. A strong correlation was seen between caries scores and SM. The simple linear regression analysis predicts a statistically significant increase by 4.74 units per increase of 1 score of caries at p < 0.001. As caries increase, SM count increases, but SS count decreases; as SS count increases, there is a reduction in SM counts. How to cite this article: Thimmegowda U, Belagatta V, Chikkanarasaiah N, et al. Identification and Correlation of Streptococcus mutans and Streptococcus sanguinis in Caries-active and Caries-free Children: A PCR Study. Int J Clin Pediatr Dent 2023;16(1):9-15.

Oral Microbiota Alteration and Roles in Epstein-Barr Virus Reactivation in Nasopharyngeal Carcinoma.

Microbiota has recently emerged as a critical factor associated with multiple malignancies. Nasopharyngeal carcinoma (NPC) is highly associated with Epstein-Barr virus (EBV); the oncovirus resides and is transmitted in the oral cavity. However, the alternation of oral microbiota in NPC patients and its potential link to EBV reactivation and host cell response under the simultaneous existence of EBV and specific bacteria is largely unknown. Here, oral microbiota profiles of 303 NPC patients and controls with detailed clinical information, including serum EBV anti-virus capsid antigen (VCA) IgA level, were conducted. A distinct microbial community with lower diversity and imbalanced composition in NPC patients was observed. Notably, among enriched bacteria in patients, Streptococcus sanguinis was associated with anti-VCA IgA, an indicator of NPC risk and EBV reactivation. By measuring the concentration of its metabolite, hydrogen peroxide (H2O2), in the saliva of clinical patients, we found the detection rate of H2O2 was 2-fold increased compared to healthy controls. Further coculture assay of EBV-positive Akata cells with bacteria in vitro showed that S. sanguinis induced EBV lytic activation by its metabolite, H2O2. Host and EBV whole genome-wide transcriptome sequencing and EBV methylation assays showed that H2O2 triggered the host cell signaling pathways, notably tumor necrosis factor alpha (TNF-α) via NF-κB, and induced the demethylation of the global EBV genome and the expression of EBV lytic-associated genes, which could result in an increase of virus particle release and potential favorable events toward tumorigenesis. In brief, our study identified a characterized oral microbial profile in NPC patients and established a robust link between specific oral microbial alteration and switch of latency to lytic EBV infection status in the oral cavity, which provides novel insights into EBV's productive cycle and might help to further clarify the etiology of NPC. IMPORTANCE EBV is classified as the group I human carcinogen and is associated with multiple cancers, including NPC. The interplays between the microbiota and oncovirus in cancer development remain largely unknown. In this study, we investigate the interactions between resident microbes and EBV coexistence in the oral cavity of NPC patients. We identify a distinct oral microbial feature for NPC patients. Among NPC-enriched bacteria, we illustrated that a specific species, S. sanguinis, associated with elevated anti-IgA VCA in patients, induced EBV lytic activation by its by-product, H2O2, and activated the TNF-α/NF-κB pathway of EBV-positive B cells in vitro, together with increased detection rate of H2O2 in patients' oral cavities, which strengthened the evidence of bacteria-virus-host interaction in physiological circumstances. The effects of imbalanced microbiota on the EBV latent-to-lytic switch in the oral cavity might create the likelihood of EBV infection in epithelial cells at the nasopharynx and help malignant transition and cancer development.

Streptococcus mutans membrane vesicles inhibit the biofilm formation of Streptococcus gordonii and Streptococcus sanguinis.

Streptococcus mutans, whose main virulence factor is glucosyltransferase (Gtf), has a substantial impact on the development of dental caries. S. mutans membrane vesicles (MVs), which are rich in Gtfs, have been shown to affect biofilm formation of other microorganisms. Streptococcus gordonii and Streptococcus sanguinis are initial colonizers of tooth surfaces, which provide attachment sites for subsequent microorganisms and are crucial in the development of oral biofilms. S. mutans and S. gordonii, as well as S. mutans and S. sanguinis, have a complex competitive and cooperative relationship, but it is unclear whether S. mutans MVs play a role in these interspecific interactions. Therefore, we co-cultured S. mutans MVs, having or lacking Gtfs, with S. gordonii and S. sanguinis. Our results showed that S. mutans MVs inhibited biofilm formation of S. gordonii and S. sanguinis but did not affect their planktonic growth; contrastingly, S. mutans ΔgtfBC mutant MVs had little effect on both their growth and biofilm formation. Additionally, there were fewer and more dispersed bacteria in the biofilms of the S. mutans MV-treated group than that in the control group. Furthermore, the expression levels of the biofilm-related virulence factors GtfG, GtfP, and SpxB in S. gordonii and S. sanguinis were significantly downregulated in response to S. mutans MVs. In conclusion, the results of our study showed that S. mutans MVs inhibited biofilm formation of S. gordonii and S. sanguinis, revealing an important role for MVs in interspecific interactions.

The In Vitro Effect of Laser Irradiation (Er:YAG and CO2) and Chemical Reagents (Hydrogen Peroxide, Sodium Hypochlorite, Chlorhexidine, or Sodium Fluoride) Alone or in Combination on Reducing Root Caries Bacteria.

(1) Lasers have been used for the treatment of dentinal hypersensitivity and bacterial reductions in periodontology. The purpose of this in vitro study was to evaluate the effect of Carbon Dioxide (CO2) and Erbium-doped Yttrium Aluminum Garnet (Er:YAG) lasers with chlorhexidine (CHX), hydrogen peroxide (H2O2), sodium hypochlorite (NaOCl), or sodium fluoride (NaF) on the viability of oral bacteria associated with root caries. (2) Streptococcus mutans, Streptococcus sanguinis, and Enterococcus faecalis were grown in Brain Heart Infusion (BHI) broth, diluted to an OD660 of 0.5, and treated with antiseptics with or without simultaneous irradiation with the Er:YAG and CO2 lasers for 30 s repeated three times. The treatment groups consisted of 1: no treatment, 2: 0.5% H2O2 alone, 3: 0.5% NaOCl alone, 4: 0.12% CHX alone, 5: 2% NaF alone, 6: laser alone, 7: laser with 0.5% H2O2, 8: laser with 0.5% NaOCl, 9: laser with 0.12% CHX, and 10: laser with 2% NaF for both lasers. The microbial viability was determined through plating and viable colonies were counted, converted into CFU/mL, and transformed into log form. The statistical analysis was performed using a two-tailed paired t-test. (3) The use of CO2 and Er:YAG lasers alone failed to show statistically significant antibacterial activity against any of the bacteria. The only effective monotreatment was CHX for S. mutans. The combined treatment of 0.5% NaOCl with Er:YAG produced the greatest reduction in overall viability. (4) The combination of the Er:YAG laser with 0.5% NaOCl resulted in the largest reduction in bacterial survival when compared to monotherapies with antimicrobial solutions or lasers.

Efectos del xilitol en el crecimiento bacteriano frente a Streptococcus sanguinis: Estudio in vitro

Streptococcus sanguinis forma parte del biofilm bucal, tiene función decisoria en el desarrollo de las enfermedades bucales prevalentes y a nivel sistémico actúa como patógeno oportunista. Objetivo: Evaluar in vitro los efectos del xilitol en el crecimiento bacteriano frente a Streptococcus sanguinis (ATCC 10556). Métodos: la muestra del estudio fue distribuida en 6 grupos: 4 grupos experimentales (xilitol 1M; 0,75M; 0,50M y 0,25M), un control negativo (agua destilada) y un control positivo (clorhexidina); el análisis estadístico se hizo mediante el software estadístico Infostat y se empleó las pruebas t-Student, ANOVA y Tukey para contrastar la hipótesis. Resultados: diferentes concentraciones de xilitol (0,25M; 0,50M; 0,75M y 1M) causaron un halo de inhibición entre 9,89 - 12,89 mm (24 horas) y 10,85 - 13,45 mm (48 horas). Conclusiones: diferentes concentraciones de xilitol inhiben el crecimiento bacteriano del Streptococcus sanguinis, este efecto inhibitorio aumenta a mayor concentración y tiempo de exposición.

Streptococcus sanguinis faz parte do biofilme oral, tem papel decisivo no desenvolvimento de doenças bucais prevalentes e atua como patógeno oportunista em nível sistêmico. Objetivo: Avaliar in vitro os efeitos do xilitol no crescimento bacteriano contra Streptococcus sanguinis (ATCC 10556). Métodos: A amostra do estudo foi distribuída em 6 grupos: 4 grupos experimentais (1M; 0,75M; 0,50M e 0,25M xilitol), um controle negativo (água destilada) e um controle positivo (clorexidina); a análise estatística foi feita com o software estatístico Infostat e os testes t-Student, ANOVA e Tukey para testar a hipótese. Resultados: diferentes concentrações de xilitol (0,25M; 0,50M; 075M e 1M) causou um halo de inibição entre 9,89 - 12,89 mm (24 horas) e 10,85 - 13,45 mm (48 horas). Conclusões: diferentes concentrações de xilitol inibem o crescimento bacteriano de Streptococcus sanguinis, este efeito inibitório aumenta com maior concentração e tempo de exposição.

Streptococcus sanguinis forms part of the oral biofilm, has a decisive role in the development of prevalent oral diseases and acts as an opportunistic pathogen at the systemic level. Aims: To evaluate in vitro the effects of xylitol on bacterial growth against Streptococcus sanguinis (ATCC 10556). Methods: The study sample was distributed into 6 groups: 4 experimental groups (1M; 0,75M; 0,50M and 0,25M xylitol), a negative control (distilled water) and a positive control (chlorhexidine). The statistical analysis was done using the statistical software Infostat and the tests used t-Student, ANOVA and Tukey to test the hypothesis. Results: different concentrations of xylitol (0,25M; 0,50M; 0,75M and 1M) caused an inhibition halo between 9,89 - 12,89 mm (24 hours) and 10,85 - 13,45 mm (48 hours). Conclusions: different concentrations of xylitol inhibit the bacterial growth of Streptococcus sanguinis, this inhibitory effect increases with higher concentration and exposure time.