Oral Streptococci Research Articles

Hyaluronic acid-based gels for oral application: Comparison of in vitro effects on gingival cells and bacteria

PurposeThis study aimed to evaluate the cytotoxic effects of different topical hyaluronic acid-based gels on human gingival fibroblasts and oral bacteria. MethodsFour different hyaluronate gels - Bexident® Aftas (BA), GUM® AftaClear (AfC), Gengigel®(G), Aloclair® Plus (AlC) and a chlorhexidine gel - Bexident®Gums(BG) were selected. Human gingival fibroblasts (HGF) were seeded in 48-well plates with different gel/culture medium concentrations (v/v%) and cell viability was evaluated at 1 and 3 days of culture. Cell morphology was assessed, and alterations graded according to ISO 10993–5:2009(E). Streptococcus oralis CECT 907T colony was, seed on 48-well plate or spread onto the blood agar plates and exposed to the different gel's concentration. The optical density (OD) was assessed, and the diameter of the inhibition zone was measured (mm). ResultsBA and G elicited reduced HGF cytotoxicity, followed by AfC. AlC and BG were cytotoxic at concentrations up to 3% for all exposure times. PCM images of HGF showed moderate-to-severe alterations for AlC and BG and slight to mild changes, for BA, AfC and G. The highest antibacterial activity against S.oralis was observed on AlC and AfC, and no antibacterial activity was observed for BA and G. Inhibitory effect in sessile colonies was only observed in AlC and BG. ConclusionsAlC demonstrated superior antibacterial activities against S.oralis but a higher cytotoxic potential in HGF. BA and G presented the lowest cytotoxicity with little to no antibacterial effect. AfC demonstrated bacteriostatic effects and low cytotoxicity on HGF.

Streptococcus taonis sp. nov., a novel bacterial species isolated from a blood culture of a patient.

One Gram stain-positive, catalase-negative, α-hemolytic, chain-forming or paired cocci, designated ST22-14T, was isolated from a blood culture of a child with suspected infection. The results of 16S rRNA gene sequences analyses showed that the most closely related species to strain ST22-14T were "Streptococcus vulneris" DM3B3T (99.2%), Streptococcus mitis NCTC 12261T (99.0%), "Streptococcus gwangjuense" ChDC B345T, (99.0%), Streptococcus oralis subsp. dentisani 7747T (99.0%), Streptococcus downii CECT 9732T (99.0%), and Streptococcus infantis ATCC 700779T (98.9%). The genome of strain ST22-14T consists of 2,053,261bp with a G + C content of 39.4%. Average nucleotide identity values between strain ST22-14T and Streptococcus mitis NCTC 12261T or other five species were from 82.2 to 88.0%. In silico DNA-DNA hybridization of ST22-14T showed an estimated DNA reassociation value of 34.6% with the closest species. The main cellular fatty acids of strain ST22-14T were 16:0, 18:0, 14:0, 18:1ω7c and 18:1ω6c. Based on these results, strain ST22-14T should be classified as a novel species of genus Streptococcus, for which the name Streptococcus taonis sp. nov. is proposed (type strain ST22-14T = NBRC 116002T = BCRC 81402T).

The Impact of Candida albicans in the Development, Kinetics, Structure, and Cell Viability of Biofilms on Implant Surfaces-An In Vitro Study with a Validated Multispecies Biofilm Model.

This study aimed to evaluate the impact of Candida albicans on subgingival biofilm formation on dental implant surfaces. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to compare biofilm structure and microbial biomass in the presence and absence of the fungus after periods of 24, 48, and 72 h. Quantitative polymerase chain reaction (qPCR) was used to quantify the number of viable and total micro-organisms for each of the biofilm-forming strains. A general linear model was applied to compare CLSM and qPCR results between the control and test conditions. The biofilm developed with C. albicans at 72 h had a higher bacterial biomass and a significantly higher cell viability (p < 0.05). After both 48 and 72 h of incubation, in the presence of C. albicans, there was a significant increase in counts of Fusobacterium nucleatum and Porphyromonas gingivalis and in the cell viability of Streptococcus oralis, Aggregatibacter actinomycetemcomitans, F. nucleatum, and P. gingivalis. Using a dynamic in vitro multispecies biofilm model, C. albicans exacerbated the development of the biofilm grown on dental implant surfaces, significantly increasing the number and cell viability of periodontal bacteria.

Patient-derived pathogenic microbe deposition enhances exposure risk in pediatric clinics

Healthcare-associated infections (HAIs) pose significant risks to pediatric patients in outpatient settings. To prevent HAIs, understanding the sources and transmission routes of pathogenic microorganisms is crucial. This study aimed to identify the sources of opportunistic bacterial pathogens (OBPs) in pediatric outpatient settings and determine their transmission routes. Furthermore, assessing the public health risks associated with the core OBPs is important. We collected 310 samples from various sites in pediatric outpatient areas and quantified the bacteria using qPCR and CFU counting. We also performed 16S rRNA gene and single-bacterial whole-genome sequencing to profile the transmission routes and antibiotic resistance characteristics of OBPs. We observed significant variations in microbial diversity and composition among sampling sites in pediatric outpatient settings, with active communication of the microbiota between linked areas. We found that the primary source of OBPs in multi-person contact areas was the hand surface, particularly in pediatric patients. Five core OBPs, Staphylococcus epidermidis, Acinetobacter baumannii, Pseudomonas aeruginosa, Streptococcus mitis, and Streptococcus oralis, were mainly derived from pediatric patients and spread into the environment. These OBPs accumulated at multi-person contact sites, resulting in high microbial diversity in these areas. Transmission tests confirmed the challenging spread of these pathogens, with S. epidermidis transferring from the patient's hand to the environment, leading to an increased abundance and emergence of related strains. More importantly, S. epidermidis isolated from pediatric patients carried more antibiotic-resistance genes. In addition, two strains of multidrug-resistant A. baumannii were isolated from both a child and a parent, confirming the transmission of the five core OBPs centered around pediatric patients and multi-person contact areas. Our results demonstrate that pediatric patients serve as a significant source of OBPs in pediatric outpatient settings. OBPs carried by pediatric patients pose a high public health risk. To effectively control HAIs, increasing hand hygiene measures in pediatric patients and enhancing the frequency of disinfection in multi-person contact areas remains crucial. By targeting these preventive measures, the spread of OBPs can be reduced, thereby mitigating the risk of HAIs in pediatric outpatient settings.

Genetic characterization of glyoxalase pathway in oral streptococci and its contribution to interbacterial competition

ABSTRACT Objectives To analyze contributions to microbial ecology of Reactive Electrophile Species (RES), including methylglyoxal, generated during glycolysis. Methods Genetic analyses were performed on the glyoxalase pathway in Streptococcus mutans (SM) and Streptococcus sanguinis (SS), followed by phenotypic assays and transcription analysis. Results Deleting glyoxalase I (lguL) reduced RES tolerance to a far greater extent in SM than in SS, decreasing the competitiveness of SM against SS. Although SM displays a greater RES tolerance than SS, lguL-null mutants of either species showed similar tolerance; a finding consistent with the ability of methylglyoxal to induce the expression of lguL in SM, but not in SS. A novel paralogue of lguL (named gloA2) was identified in most streptococci. SM mutant ∆gloA2SM showed little change in methylglyoxal tolerance yet a significant growth defect and increased autolysis on fructose, a phenotype reversed by the addition of glutathione, or by the deletion of a fructose: phosphotransferase system (PTS) that generates fructose-1-phosphate (F-1-P). Conclusions Fructose contributes to RES generation in a PTS-specific manner, and GloA2 may be required to degrade certain RES derived from F-1-P. This study reveals the critical roles of RES in fitness and interbacterial competition and the effects of PTS in modulating RES metabolism.

Antimicrobial efficacy of antiplaque agents of common toothpastes against Porphyromonas gingivalis and Streptococcus oralis: An in vitro study

Background: This study was designed to evaluate the antimicrobial activity of common gum protection and antiplaque toothpastes against Porphyromonas gingivalis ( P. gingivalis ) and Streptococcus oralis ( S. oralis ) as important periodontal pathogens. Materials and Methods: This experimental study investigated the antimicrobial activity of 15 commonly used toothpastes from different companies on the two common types of periopathogens, S. oralis and P. gingivalis . The antimicrobial activity of toothpaste was evaluated at three concentrations of 100%, 50%, and 25% and analyzed by agar well diffusion plate method and zone of inhibition. The obtained data were compared and statistically analyzed by SPSS software using one-way ANOVA and the least significant difference post hoc tests (α = 0.05). Results: One-way ANOVA showed that the mean diameter of the two-bacterial zone of inhibition was significantly different at 100%, 50%, and 25% concentrations of toothpastes ( P &lt; 0.001). In general, the mean diameter of the zone of inhibition was greater at 100% concentration than the other two concentrations in all toothpastes. The highest zone of inhibition of the S. oralis was in the toothpastes containing tin. Further, the highest zone of inhibition of P. gingivalis was found in the triclosan-containing toothpastes. Conclusion: Toothpastes containing triclosan had the most antimicrobial activity against P. gingivalis . Moreover, toothpastes containing tin compounds had the most antimicrobial effect against S. oralis .

Ancient Genomes From Bronze Age Remains Reveal Deep Diversity and Recent Adaptive Episodes for Human Oral Pathobionts.

Ancient microbial genomes can illuminate pathobiont evolution across millenia, with teeth providing a rich substrate. However, the characterization of prehistoric oral pathobiont diversity is limited. In Europe, only preagricultural genomes have been subject to phylogenetic analysis, with none compared to more recent archaeological periods. Here, we report well-preserved microbiomes from two 4,000-year-old teeth from an Irish limestone cave. These contained bacteria implicated in periodontitis, as well as Streptococcus mutans, the major cause of caries and rare in the ancient genomic record. Despite deriving from the same individual, these teeth produced divergent Tannerella forsythia genomes, indicating higher levels of strain diversity in prehistoric populations. We find evidence of microbiome dysbiosis, with a disproportionate quantity of S. mutans sequences relative to other oral streptococci. This high abundance allowed for metagenomic assembly, resulting in its first reported ancient genome. Phylogenetic analysis indicates major postmedieval population expansions for both species, highlighting the inordinate impact of recent dietary changes. In T. forsythia, this expansion is associated with the replacement of older lineages, possibly reflecting a genome-wide selective sweep. Accordingly, we see dramatic changes in T. forsythia's virulence repertoire across this period. S. mutans shows a contrasting pattern, with deeply divergent lineages persisting in modern populations. This may be due to its highly recombining nature, allowing for maintenance of diversity through selective episodes. Nonetheless, an explosion in recent coalescences and significantly shorter branch lengths separating bacteriocin-carrying strains indicate major changes in S. mutans demography and function coinciding with sugar popularization during the industrial period.

Oral streptococci: modulators of health and disease.

Streptococci are primary colonizers of the oral cavity where they are ubiquitously present and an integral part of the commensal oral biofilm microflora. The role oral streptococci play in the interaction with the host is ambivalent. On the one hand, they function as gatekeepers of homeostasis and are a prerequisite for the maintenance of oral health - they shape the oral microbiota, modulate the immune system to enable bacterial survival, and antagonize pathogenic species. On the other hand, also recognized pathogens, such as oral Streptococcus mutans and Streptococcus sobrinus, which trigger the onset of dental caries belong to the genus Streptococcus. In the context of periodontitis, oral streptococci as excellent initial biofilm formers have an accessory function, enabling late biofilm colonizers to inhabit gingival pockets and cause disease. The pathogenic potential of oral streptococci fully unfolds when their dissemination into the bloodstream occurs; streptococcal infection can cause extra-oral diseases, such as infective endocarditis and hemorrhagic stroke. In this review, the taxonomic diversity of oral streptococci, their role and prevalence in the oral cavity and their contribution to oral health and disease will be discussed, focusing on the virulence factors these species employ for interactions at the host interface.

Exploring the In Vitro Antibacterial Potential of Specific Probiotic Strains against Oral Pathogens.

The microbiota in the oral cavity has a strict connection to its host. Its imbalance may determine oral diseases and can also have an impact on the systemic health. Probiotic strains may help in the restoration of a balanced condition. For this purpose, we screened the antibacterial and antiadhesive activities of many viable probiotic strains (Lactobacillus acidophilus PBS066, Lactobacillus crispatus LCR030, Lactobacillus gasseri LG050, Lactiplantibacillus plantarum PBS067, Limosilactobacillus reuteri PBS072, Lacticaseibacillus rhamnosus LRH020, Bifidobacterium animalis subsp. lactis BL050, Lacticaseibacillus paracasei LPC 1101, L. paracasei LPC 1082, and L. paracasei LPC 1114) against two main oral pathogens, Streptococcus mutans and Aggregatibacter actinomycetemcomitans, involved in dental caries and periodontal disease development and progression. Considering both the agar overlay preventive and treatment models, seven probiotics determined greater inhibition zones against the tested pathogens. This behavior was further analyzed by the plate count method and scanning electron microscope imaging. L. plantarum PBS067, L. rhamnosus LRH020, L. paracasei LPC 1101, L. paracasei LPC 1082, and L. paracasei LPC 1114 prevent the growth and adhesion of oral pathogens in a strain-specific manner (p < 0.0001). These probiotics might be considered as an alternative effective adjuvant to improve oral and systemic well-being for future personalized treatments.

Human PRH1, PRH2 susceptibility and resistance and Streptococcus mutans virulence phenotypes specify different microbial profiles in caries

Lifestyle- and sucrose-dependent polymicrobial ecological shifts are a primary cause of caries in populations with high caries prevalence. In populations with low prevalence, PRH1, PRH2 susceptibility and resistance phenotypes may interact with the Streptococcus mutans adhesin cariogenicity phenotype to affect caries progression, but studies are lacking on how these factors affect the microbial profile of caries. We analysed how the residency and infection profiles of S.mutans adhesin (SpaP A/B/C and Cnm/Cbm) phenotypes and commensal streptococci and lactobacilli influenced caries progression in a prospective case-referent sample of 452 Swedish adolescents with high (P4a), moderate (P6), and low (P1) caries PRH1, PRH2 phenotypes. Isolates of S.mutans from participants were analysed for adhesin expression and glycosylation and invitro and in situ mechanisms related to caries activity. Among adolescents with the resistant (P1) phenotype, infection with S.mutans high-virulence phenotypes was required for caries progression. In contrast, with highly (P4a) or moderately (P6) susceptible phenotypes, caries developed from a broader polymicrobial flora that included moderately cariogenic oral commensal streptococci and lactobacilli and S.mutans phenotypes. High virulence involved unstable residency and fluctuating SpaP ABC, B-1, or Cnm expression/glycosylation phenotypes, whereas low/moderate virulence involved SpaP A phenotypes with stable residency. Adhesin phenotypes did not display changes in individual host residency but were paired within individuals and geographic regions. These results suggest that receptor PRH1, PRH2 susceptibility and resistance and S.mutans adhesin virulence phenotypes specify different microbial profiles in caries. Swedish Research Council and funding bodies listed in the acknowledgement section.

3Y-TZP/Ta Biocermet as a Dental Material: An Analysis of the In Vitro Adherence of Streptococcus Oralis Biofilm and an In Vivo Pilot Study in Dogs.

The surface adhesion of bacterial cells and the in vivo biocompatibility of a new ceramic-metal composite made of zirconium dioxide and tantalum were evaluated. Within the framework of an in vitro study using the crystal violet staining and colony counting methods, a relatively similar adhesion of Streptococcus oralis to the 3Y-TZP/Ta biocermet (roughness Ra = 0.12 ± 0.04 µm) and Ti-Al6-V4 titanium alloy (Ra = 0.04 ± 0.01 µm) was found. In addition, in an in vivo preliminary study focused on the histological analysis of a series of rods implanted in the jaws of beagle dogs for a six-month period, the absence of any fibrous tissue or inflammatory reaction at the interface between the implanted 3Y-TZP/Ta biocermets and the new bone was found. Thus, it can be concluded that the developed ceramic-metal biocomposite may be a promising new material for use in dentistry.

Human saliva modifies growth, biofilm architecture, and competitive behaviors of oral streptococci.

Dental caries (tooth decay) is the most prevalent disease for both children and adults nationwide. Caries are initiated from demineralization of the enamel due to organic acid production through the metabolic activity of oral bacteria growing in biofilm communities attached to the tooth's surface. Mutans group streptococci are closely associated with caries development and initiation of the cariogenic cycle, which decreases the amount of acid-sensitive, health-associated commensal bacteria while selecting for aciduric and acidogenic species that then further drives the disease process. Defining the exchanges that occur between mutans group streptococci and oral commensals in a condition that closely mimics their natural environment is of critical need toward identifying factors that can influence odontopathogen establishment, persistence, and outgrowth. The goal of our research is to develop strategies, potentially through manipulation of microbial interactions characterized here, that prevent the emergence of mutans group streptococci while keeping the protective flora intact.

Identifying the oral microbiome of adolescents with and without dental fluorosis based on full-length 16S rRNA gene sequencing.

Dental fluorosis, resulting from long-term environmental exposure to fluoride, is prevalent among diverse populations worldwide. Severe fluorosis not only compromises the aesthetic appeal of teeth but also impairs their functionality. This study aims to investigate the oral microbiome in dental fluorosis and the health individuals of adolescents living in the endemic fluorosis area of Guizhou, China through full-length 16S rDNA sequencing. Fourty-six individuals meet the sampling criteria, and we divided these samples into the following groups: a healthy group (H = 23) and a dental fluorosis group (F = 23), and two subgroups of Miao ethnicity: a healthy Miao group (Hm = 13) and a dental fluorosis Miao group (Fm = 15). A total of 660,389 high-quality sequences were obtained, and 12,007 Amplicon Sequence Variants (ASVs) were identified, revealing significant variations in oral microbiome between Fm and Hm groups. The composition of oral microbiota was similar between the H and F groups. At the genus level, Pseudopropionibacterium and at the species level, Streptococcus oralis_subsp.dentisani_clade_058 were less abundant in group F than in group H (P < 0.05). Further analysis revealed that the abundance of Capnocytophaga gingivalis and Kingella denitrificans was significantly lower in Fm fluorosis patients than in the Hm group (P < 0.05). Based on the LEfSe analysis, the potential core biomarkers in the oral of Fm fluorosis patients were identified at different taxonomic levels, ranging from phylum to species. These include Gammaproteobacteria, Prevotella sp_HMT_304, Gemella sanguinis, and Gracilibacteria_(GN02). Network analysis revealed that the microbiota in the fluorosis group exhibited more complex interactions with each other than the healthy group. Notably, within the Hm group, the potential biomarkers Capnocytophaga gingivalis and Kingella denitrificans exhibited a positive correlation. Finally, we employed PICRUSt2 analysis to explore the abundance clustering of the top 30 functional units in each sample, and we found that the metabolic pathway compositions of the four groups were similar. In summary, our findings suggest that the microbial composition of plaque in Hm patients with dental fluorosis is significantly altered, and we identified the potential marker microorganisms that contribute to these changes.

Evaluation of Plant Essential Oils as Natural Alternatives for Alcohol-based Mouthwashes: Spotlight—Lemongrass and Citronella Java

Abstract Objective The purpose of our study was to evaluate plant-derived essential oils (EOs) as natural alternatives to commercial alcohol-based mouthwashes in the prevention of dental caries since several recent studies have linked high incidence of oral cancer among users with a history of prolonged use of alcohol-based mouthwashes. Materials and Methods Lemongrass, Citronella Java, Gingergrass, and Caraway seed EOs were tested against commonly occurring multidrug-resistant (MDR) oral bacteria namely Micrococcus luteus, Enterococcus faecalis, Streptococcus oralis, and Streptococcus salivarius. Agar well diffusion method was used to determine the antibacterial effectiveness of these EOs. Samples of Citronella Java and Lemongrass EO were also analyzed by gas chromatography (GC). Results Lemongrass and Citronella Java exhibited the highest antibacterial activity against all four bacterial strains. Inhibition zones of Lemongrass were 12, 21.3, 28.3, and 32 mm in diameter against E. faecalis, M. luteus, S. oralis, and S. salivarius, respectively. In comparison, inhibition zones of Citronella Java were 11.5, 17, 20.7, and 20.2 mm in diameter against E. faecalis, M. luteus, S. oralis, and S. salivarius, respectively. A significant finding in our study was that antibacterial activity of Lemongrass was much higher than that of tetracycline, a broad-spectrum antibiotic, against S. oralis and S. salivarius, while the inhibitory effects of Citronella Java against these two oral streptococci were comparable to tetracycline. The major components of Citronella Java identified by GC were citronellal, citronellol, and geraniol, whereas Lemongrass was primarily composed of cis and trans forms of citral. Conclusion Our results suggest that Lemongrass and Citronella Java could be promising natural alternatives to alcohol-based mouthwashes against MDR oral bacteria in the prevention of dental caries.

Oral streptococci S. anginosus and S. mitis induce distinct morphological, inflammatory, and metabolic signatures in macrophages.

Oral streptococci, key players in oral biofilm formation, are implicated in oral dysbiosis and various clinical conditions, including dental caries, gingivitis, periodontal disease, and oral cancer. Specifically, Streptococcus anginosus is associated with esophageal, gastric, and pharyngeal cancers, while Streptococcus mitis is linked to oral cancer. However, no study has investigated the mechanistic links between these Streptococcus species and cancer-related inflammatory responses. As an initial step, we probed the innate immune response triggered by S. anginosus and S. mitis in RAW264.7 macrophages. These bacteria exerted time- and dose-dependent effects on macrophage morphology without affecting cell viability. Compared with untreated macrophages, macrophages infected with S. anginosus exhibited a robust proinflammatory response characterized by significantly increased levels of inflammatory cytokines and mediators, including TNF, IL-6, IL-1β, NOS2, and COX2, accompanied by enhanced NF-κB activation. In contrast, S. mitis-infected macrophages failed to elicit a robust inflammatory response. Seahorse Xfe96 analysis revealed an increased extracellular acidification rate in macrophages infected with S. anginosus compared with S. mitis. At the 24-h time point, the presence of S. anginosus led to reduced extracellular itaconate, while S. mitis triggered increased itaconate levels, highlighting distinct metabolic profiles in macrophages during infection in contrast to aconitate decarboxylase expression observed at the 6-h time point. This initial investigation highlights how S. anginosus and S. mitis, two Gram-positive bacteria from the same genus, can prompt distinct immune responses and metabolic shifts in macrophages during infection.IMPORTANCEThe surge in head and neck cancer cases among individuals devoid of typical risk factors such as Human Papilloma Virus (HPV) infection and tobacco and alcohol use sparks an argumentative discussion around the emerging role of oral microbiota as a novel risk factor in oral squamous cell carcinoma (OSCC). While substantial research has dissected the gut microbiome's influence on physiology, the oral microbiome, notably oral streptococci, has been underappreciated during mucosal immunopathogenesis. Streptococcus anginosus, a viridans streptococci group, has been linked to abscess formation and an elevated presence in esophageal cancer and OSCC. The current study aims to probe the innate immune response to S. anginosus compared with the early colonizer Streptococcus mitis as an important first step toward understanding the impact of distinct oral Streptococcus species on the host immune response, which is an understudied determinant of OSCC development and progression.

The Antimicrobial Potential of the Hop (Humulus lupulus L.) Extract against Staphylococcus aureus and Oral Streptococci.

Plant extracts are in the focus of the pharmaceutical industry as potential antimicrobials for oral care due to their high antimicrobial activity coupled with low production costs and safety for eukaryotic cells. Here, we show that the extract from Hop (Humulus lupulus L.) exhibits antimicrobial activity against Staphylococcus aureus and Streptococci in both planktonic and biofilm-embedded forms. An extract was prepared by acetone extraction from hop infructescences, followed by purification and solubilization of the remaining fraction in ethanol. The effect of the extract on S. aureus (MSSA and MRSA) was comparable with the reference antibiotics (amikacin, ciprofloxacin, and ceftriaxone) and did not depend on the bacterial resistance to methicillin. The extract also demonstrated synergy with amikacin on six S. aureus clinical isolates, on four of six isolates with ciprofloxacin, and on three of six isolates with ceftriaxone. On various Streptococci, while demonstrating lower antimicrobial activity, an extract exhibited a considerable synergistic effect in combination with two of three of these antibiotics, decreasing their MIC up to 512-fold. Moreover, the extract was able to penetrate S. aureus and S. mutans biofilms, leading to almost complete bacterial death within them. The thin-layer chromatography and LC-MS of the extract revealed the presence of prenylated flavonoids (2',4',6',4-tetrahydroxy-3'-geranylchalcone) and acylphloroglucides (cohumulone, colupulone, humulone, and lupulone), apparently responsible for the observed antimicrobial activity and ability to increase the efficiency of antibiotics. Taken together, these data suggest an extract from H. lupulus as a promising antimicrobial agent for use both as a solely antiseptic and to potentiate conventional antimicrobials.

Molecular identification of Streptococcus mutans and Streptococcus sobrinus from un-stimulated saliva and their association with dental caries and orthodontic appliances

Background: Oral streptococci, particularly Streptococcus mutans (S. mutans), have been associated with several diseases affecting multiple anatomical sites. Streptococcus mutans and Streptococcus sobrinus (S. sobrinus), which belong to the Mutans streptococci group, are examples of Gram-positive bacteria that demonstrate facultative anaerobic growth characteristics. These bacteria are frequently seen as members of the native oral microbiota and are largely recognized as the primary causative agents of dental caries. Objective: To molecularly identify S. mutans and S. sobrinus using PCR and investigate their relationship with the caries status and orthodontia appliances. Method: The cross-sectional study, which was conducted in Baghdad from February 2021 to November 2022, involved 359 un-stimulated saliva samples from 340 participants were collected and processed immediately by culturing anaerobically (37°C/72 h) on Mitis Salivarius Bacitracin Agar (MSB-Agar). Morphological characteristics of the colonies, Gram stain were achieved for the bacterial growth. DNA extracted from cultured bacteria. S. mutans and S. sobrinus were identified molecularly by amplifying gtfB and gtfI, respectively, from DNA samples using conventional PCR. Results: From 279/ 336 (83.04%) bacterial DNA samples, 118/279 (42.29%) were positive for S. mutans gtfB and/or S. sobrinus gtfI; S. mutans 84/118 (71.2%), S. sobrinus 6/118 (5.1%) and mixed S. mutans/S. sobrinus 28/118 (23.7%). The results of association between molecular identification of S. mutans with dental caries and missing teeth features of individuals were statically not significant (0.068 and 0.323 &gt; 0.05, respectively), while was significant with filling teeth and orthodontic appliance (0.020, 0.027 &lt; 0.05, respectively). The relationship between molecular identification of S. sobrinus and dental caries, missing, filling teeth and orthodontic were statistically not significant (0.069, 0.975, 0.845 and 0.458 &gt; 0.05), respectively. The relationship between molecular identification of mixed S. mutans/S. sobrinus with dental caries was statically significant (0.042 &lt; 0.05). Conclusion: S. mutans was more prevalence; identification and discrimination for S. mutans/S. sobrinus (depending on gtfB and gtfI) by PCR was more efficacy. Mixed S. mutans/S. sobrinus in a reasonable percentage were related with the hard dental caries status. Identification by colony morphology alone was not achievable in this study. Mitis Salivarius agar with Bacitracin (MSB) is extremely selective for S. mutans and S. sobrinus but cannot distinguish them morphologically.

Characterization of MdpS: an in-depth analysis of a MUC5B-degrading protease from Streptococcus oralis.

Oral biofilms, comprising hundreds of bacteria and other microorganisms on oral mucosal and dental surfaces, play a central role in oral health and disease dynamics. Streptococcus oralis, a key constituent of these biofilms, contributes significantly to the formation of which, serving as an early colonizer and microcolony scaffold. The interaction between S. oralis and the orally predominant mucin, MUC5B, is pivotal in biofilm development, yet the mechanism underlying MUC5B degradation remains poorly understood. This study introduces MdpS (Mucin Degrading Protease from Streptococcus oralis), a protease that extensively hydrolyses MUC5B and offers an insight into its evolutionary conservation, physicochemical properties, and substrate- and amino acid specificity. MdpS exhibits high sequence conservation within the species and also explicitly among early biofilm colonizing streptococci. It is a calcium or magnesium dependent serine protease with strict physicochemical preferences, including narrow pH and temperature tolerance, and high sensitivity to increasing concentrations of sodium chloride and reducing agents. Furthermore, MdpS primarily hydrolyzes proteins with O-glycans, but also shows activity toward immunoglobulins IgA1/2 and IgM, suggesting potential immunomodulatory effects. Significantly, MdpS extensively degrades MUC5B in the N- and C-terminal domains, emphasizing its role in mucin degradation, with implications for carbon and nitrogen sequestration for S. oralis or oral biofilm cross-feeding. Moreover, depending on substrate glycosylation, the amino acids serine, threonine or cysteine triggers the enzymatic action. Understanding the interplay between S. oralis and MUC5B, facilitated by MdpS, has significant implications for the management of a healthy eubiotic oral microenvironment, offering potential targets for interventions aimed at modulating oral biofilm composition and succession. Additionally, since MdpS does not rely on O-glycan removal prior to extensive peptide backbone hydrolysis, the MdpS data challenges the current model of MUC5B degradation. These findings emphasize the necessity for further research in this field.

Engineered probiotic overcomes pathogen defences using signal interference and antibiotic production to treat infection in mice

Probiotic supplements are suggested to promote human health by preventing pathogen colonization. However, the mechanistic bases for their efficacy in vivo are largely uncharacterized. Here using metabolomics and bacterial genetics, we show that the human oral probiotic Streptococcus salivarius K12 (SAL) produces salivabactin, an antibiotic that effectively inhibits pathogenic Streptococcus pyogenes (GAS) in vitro and in mice. However, prophylactic dosing with SAL enhanced GAS colonization in mice and ex vivo in human saliva. We showed that, on co-colonization, GAS responds to a SAL intercellular peptide signal that controls SAL salivabactin production. GAS produces a secreted protease, SpeB, that targets SAL-derived salivaricins and enhances GAS survival. Using this knowledge, we re-engineered probiotic SAL to prevent signal eavesdropping by GAS and potentiate SAL antimicrobials. This engineered probiotic demonstrated superior efficacy in preventing GAS colonization in vivo. Our findings show that knowledge of interspecies interactions can identify antibiotic- and probiotic-based strategies to combat infection.

Is Oral Streptococcus mutans with Collagen-Binding Protein a Risk Factor for Intracranial Aneurysm Rupture or Formation?

Introduction: Streptococcus mutans (SM) with the collagen-binding protein Cnm is a unique member of the oral resident flora because it causes hemorrhagic vascular disorders. In the multicenter study, we examined the relationship between Cnm-positive SM (CP-SM) and intracranial aneurysm (IA) rupture, which remains unknown. Methods: Between May 2013 and June 2018, we collected whole saliva samples from 431 patients with ruptured IAs (RIAs) and 470 patients with unruptured IAs (UIAs). Data were collected on age, sex, smoking and drinking habits, family history of subarachnoid hemorrhage, aneurysm size, number of teeth, and comorbidities of lifestyle disease. Results: There was no difference in the positivity rate of patients with CP-SM between the patients with RIAs (17.2%) and those with UIAs (19.4%). In subanalysis, the rate of positivity for CP-SM was significantly higher in all IAs <5 mm than in those ≥10 mm in diameter (p = 0.0304). In the entire cohort, the rate of positivity for CP-SM was lower in larger aneurysms than in smaller aneurysms (p = 0.0393). Conclusions: CP-SM was not involved in the rupture of UIAs. In the subanalysis, the possibility of its involvement in the formation of vulnerable aneurysms remained.