Oral Pathogenic Bacteria Research Articles

Periodontitis is an inflammatory disease of oxidative stress: We should treat it that way.

Periodontitis is a highly prevalent disease. As it progresses, it causes serious morbidity in the form of periodontal abscesses and tooth loss and, in the latter stages, pain. It is also now known that periodontitis is strongly associated with several nonoral diseases. Thus, patients with periodontitis are at greater risk for the development and/or exacerbation of diabetes, chronic obstructive pulmonary disease, and cardiovascular diseases, among other conditions. Although it is without question that specific groups of oral bacteria which populate dental plaque play a causative role in the development of periodontitis, it is now thought that once this disease has been triggered, other factors play an equal, and possibly more important, role in its progression, particularly in severe cases or in cases that prove difficult to treat. In this regard, we allude to the host response, specifically the notion that the host, once infected with oral periodontal pathogenic bacteria, will mount a defense response mediated largely through the innate immune system. The most abundant cell type of the innate immune system - polymorphonuclear neutrophils - can, when protecting the host from microbial invasion, mount a response that includes upregulation of proinflammatory cytokines, matrix metalloproteinases, and reactive oxygen species, all of which then contribute to the tissue damage and loss of teeth commonly associated with periodontitis. Of the mechanisms referred to here, we suggest that upregulation of reactive oxygen species might play one of the most important roles in the establishment and progression of periodontitis (as well as in other diseases of inflammation) through the development of oxidative stress. In this overview, we discuss both innate and epigenetic factors (eg, diabetes, smoking) that lead to the development of oxidative stress. This oxidative stress then provides an environment conducive to the destructive processes observed in periodontitis. Therefore, we shall describe some of the fundamental characteristics of oxidative stress and its effects on the periodontium, discuss the diseases and other factors that cause oxidative stress, and, finally, review potentially novel therapeutic approaches for the management (and possibly even the reversal) of periodontitis, which rely on the use of therapies, such as resveratrol and other antioxidants, that provide increased antioxidant activity in the host.

Antimicrobial Effect of Natural Berry Juices on Common Oral Pathogenic Bacteria.

(1) Background: Antimicrobial agents such as chlorhexidine (CHX) are commonly used in oral plaque control. However, sometimes those agents lack antimicrobial efficiency or cause undesired side effects. To identify alternative anti-infective agents, the present study investigated the antibacterial activity of all-fruit juices derived from blackcurrant, redcurrant, cranberry and raspberry on common oral pathogenic gram-positive and gram-negative bacteria (Streptococcus mutans, Streptococcus gordonii, Streptococcus sobrinus, Actinomyces naeslundii, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Enterococcus faecalis). (2) Methods: Antibacterial efficiency was evaluated by agar diffusion assay and in direct contact with bacteria in planktonic culture. Furthermore, cytotoxicity on human gingival fibroblasts was determined. (3) Results: Blackcurrant juice was most efficient at suppressing bacteria; followed by the activity of redcurrant and cranberry juice. Raspberry juice only suppressed P. gingivalis significantly. Only high-concentrated blackcurrant juice showed minimal cytotoxic effects which were significantly less compared to the action of CHX. (4) Conclusion: Extracts from natural berry juices might be used for safe and efficient suppression of oral pathogenic bacterial species.

Role of Probiotics in Oral Health Maintenance Among Patients Undergoing Fixed Orthodontic Therapy: a Systematic Review of Randomized Controlled Clinical Trials.

The aim was to assess the role of probiotics in oral health maintenance among patients undergoing fixed orthodontic therapy (OT). An unrestricted search of indexed databases was performed until April 2020 using the following Mesh-terms: (1) probiotic and (2) orthodontic. Randomized controlled clinical trials (RCTs) evaluating the influence of probiotic therapy (PT) towards oral health maintenance/improvement in patients undergoing fixed OT were included. Data screening, selection, and extraction were performed; and the risk of bias was assessed using the Cochrane Collaboration's tool. All evaluations were performed by 2 independent researchers; and disagreements were resolved via discussion. Nine RCTs were included. Eight studies reported that PT improves oral health in patients undergoing fixed OT. Seven studies showed that PT reduces the counts of oral pathogenic bacteria in the oral biofilm and/or saliva. One study reported that PT reduces halitosis in patients undergoing fixed OT. One study found that PT reduces the scores of plaque index (PI) and gingival index (GI); and one study reported that PT has no significant influence on PI and GI in patients undergoing fixed OT. One study reported that PT does not prevent the formation of white spot lesions during fixed OT. Three and 6 studies had a moderate and low risk of bias, respectively. A power analysis was performed in 4 studies. In conclusion, probiotics exhibit antimicrobial activity against oral pathogenic bacteria; however, due to the limitations of the studies assessed, further well-designed RCTs are needed.

New Pyrimidinone-Fused 1,4-Naphthoquinone Derivatives Inhibit the Growth of Drug Resistant Oral Bacteria.

Background: Dental caries is considered to be a preventable disease, and various antimicrobial agents have been developed for the prevention of dental disease. However, many bacteria show resistance to existing agents. Methods/Principal Findings: In this study, four known 1,4-naphthoquinones and newly synthesized 10 pyrimidinone-fused 1,4-naphthoquinones, i.e. KHQ 701, 702, 711, 712, 713, 714, 715, 716, 717 and 718, were evaluated for antimicrobial activity against Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis, Actinomyces viscosus and Fusobacterium nucleatum. Pyrimidinone-fused 1,4-naphthoquinones were synthesized in good yields through a series of chemical reactions from a commercially available 1,4-dihydroxynaphthoic acid. MIC values of KHQ 711, 712, 713, 714, 715, 716, 717 and 718 were 6.25–50 μg/mL against E. faecalis (CCARM 5511), 6.25–25 μg/mL against E. faecium (KACC11954) and S. aureus (CCARM 3506), 1.56–25 μg/mL against S. epidermidis (KACC 13234), 3.125–100 μg/mL against S. mutans (KACC16833), 1.56–100 μg/mL against S. sobrinus (KCTC5809) and P. gingivalis (KCTC 5352), 3.125–50 μg/mL against A. viscosus (KCTC 9146) and 3.125–12.5 μg/mL against F. nucleatum (KCTC 2640) with a broth microdilution assay. A disk diffusion assay with KHQ derivatives also exhibited strong susceptibility with inhibition zones of 0.96 to 1.2 cm in size against P. gingivalis. Among the 10 compounds evaluated, KHQ 711, 712, 713, 715, 716 and 717 demonstrated strong antimicrobial activities against the 9 types of pathogenic oral bacteria. A pyrimidin-4-one moiety comprising a phenyl group at the C2 position and a benzyl group at the N3 position appears to be essential for physiological activity. Conclusion/Significance: Pyrimidinone-fused 1,4-naphthoquinones synthesized from simple starting compounds and four known 1,4-naphthoquinones were synthesized and showed strong antibacterial activity to the 9 common oral bacteria. These results suggest that these derivatives should be prospective for the treatment of dental diseases caused by oral bacteria, including drug-resistant strains.

Biofilm Eradication Activity of Herb and Spice Extracts Alone and in Combination Against Oral and Food-Borne Pathogenic Bacteria.

The purpose of this study was to select herbs and spices with potent biofilm eradication activities. Further, the combined effects of herb and spice extracts against pathogenic biofilms were evaluated. The biofilm eradication activities of ethanol extracts of 104 herbs and spices were measured by combining a colorimetric microbial viability assay with a biofilm formation technique. Ethanol extract of clove had potent biofilm eradication activities against Escherichia coli, Porphyromonas gingivalis, and Streptococcus mutans. Ethanol extracts of eucalyptus and rosemary had potent biofilm eradication activities against P. gingivalis, Staphylococcus aureus and S. mutans. The combination of extracts of clove with eucalyptus or rosemary showed synergistic or additive effects, or both, on biofilm eradication activities. The main biofilm inhibitors in the ethanol extracts of clove, eucalyptus and rosemary were eugenol, macrocarpals and carnosic acid, respectively. The combinations of extracts of clove with eucalyptus or rosemary had potent biofilm eradication activities against oral and food-borne pathogenic bacteria. The findings of the present study reveal that specific combinations of herb and spice extracts may prevent and control biofilm-related oral diseases, food spoilage, and food poisoning.

Effect of oral plaque control on postoperative pneumonia following lung cancer surgery.

BackgroundThere have been few studies on the relationship between oral status and postoperative pneumonia (POP) in patients with lung cancer, and whether improving their oral condition assists with a lower incidence of POP before lung cancer surgery remains controversial. This retrospective study was conducted by a stomatologist to assess the effect of controlling oral pathogenic bacteria of patients with lung cancer to prevent POP.MethodsA total of 235 patients with lung cancer who underwent lobectomy by open thoracotomy between July 2015 and December 2018 were selected and given the choice of being in the experimental or control group. A total of 122 participants in the experimental group received professional oral plaque control, and 113 participants in the control group did not receive plaque control. All clinical data of participants in both groups were retrospectively studied to determine the incidence of POP at the thirtieth day of discharge from hospital.ResultsEight in the experimental group and six in the control group were excluded from the study. It was found that four of 114 patients suffered from POP in the experimental group (incidence = 3.51%). A total of 17 of 107 patients in the control group had pulmonary infection (incidence = 15.89%). Odds ratio was 0.19. The incidence of POP in the experimental group was significantly lower than that of the control group (P < 0.05).ConclusionsProfessional oral plaque control is associated with a lower incidence of POP following lung cancer surgery and is therefore a favorable factor for preventing POP, and should be carried out before the surgical treatment of lung cancer.Key pointsProfessional oral plaque control was associated with a lower incidence of POP following lung cancer surgery, and it is recommended this should be carried out before the surgical treatment of lung cancer.

Osmunda japonica Extract Suppresses Pro-Inflammatory Cytokines by Downregulating NF-κB Activation in Periodontal Ligament Fibroblasts Infected with Oral Pathogenic Bacteria.

Periodontal diseases are caused by bacterial infection and may progress to chronic dental disease; severe inflammation may result in bone loss. Therefore, it is necessary to prevent bacterial infection or control inflammation. Periodontal ligament fibroblasts (PDLFs) are responsible for the maintenance of tissue integrity and immune and inflammatory events in periodontal diseases. The formation of bacterial complexes by Fusobacterium nucleatum and Porphyromonas gingivalis is crucial in the pathogenesis of periodontal disease. F. nucleatum is a facultative anaerobic species, considered to be a key mediator of dental plaque maturation and aggregation of other oral bacteria. P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting virulence factors. In this study, we investigated whether Osmunda japonica extract exerted anti-inflammatory effects in primary PDLFs stimulated by oral pathogens. PDLFs were stimulated with F. nucleatum or P. gingivalis. We showed that pro-inflammatory cytokine (IL-6 and IL-8) expression was induced by LPS or bacterial infection but decreased by treatment with O. japonica extract following bacterial infection. We found that the activation of NF-κB, a transcription factor for pro-inflammatory cytokines, was modulated by O. japonica extract. Thus, O. japonica extract has immunomodulatory activity that can be harnessed to control inflammation.

Balanced oral pathogenic bacteria and probiotics promoted wound healing via maintaining mesenchymal stem cell homeostasis

ObjectivesThe homeostasis of oral pathogenic bacteria and probiotics plays a crucial role in maintaining the well-being and healthy status of human host. Our previous study confirmed that imbalanced oral microbiota could impair mesenchymal stem cell (MSC) proliferation capacity and delay wound healing. However, the effects of balanced oral pathogenic bacteria and probiotics on MSCs and wound healing are far from clear. Here, the balance of pathogenic bacteria Porphyromonas gingivalis and probiotics Lactobacillus reuteri extracts was used to investigate whether balanced oral microbiota modulate the physiological functions of MSCs and promote wound healing.MethodsThe effects of balanced pathogenic bacteria P. gingivalis and probiotics L. reuteri extracts on gingival MSCs (GMSCs) were tested using the migration, alkaline phosphatase activity, alizarin red staining, cell counting kit-8, real-time PCR, and western blot assays. To investigate the role of balanced pathogenic bacteria P. gingivalis and probiotics L. reuteri extracts in the wound of mice, the wounds were established in the mucosa of palate and were inoculated with bacteria every 2 days.ResultsWe found that the balance between pathogenic bacteria and probiotics enhanced the migration, osteogenic differentiation, and cell proliferation of MSCs. Additionally, local inoculation of the mixture of L. reuteri and P. gingivalis promoted the process of wound healing in mice. Mechanistically, we found that LPS in P. gingivalis could activate NLRP3 inflammasome and inhibit function of MSCs, thereby accelerating MSC dysfunction and delaying wound healing. Furthermore, we also found that reuterin was the effective ingredient in L. reuteri which maintained the balance of pathogenic bacteria and probiotics by neutralizing LPS in P. gingivalis, thus inhibiting inflammation and promoting wound healing.ConclusionsThis study revealed that the homeostasis of oral microbiomes played an indispensable role in maintaining oral heath, provided hopeful methods for the prevention and treatment of oral diseases, and had some referential value for other systemic diseases caused by dysfunction of microbiota and MSCs.

Prevotella intermedia produces two proteins homologous to Porphyromonas gingivalis HmuY but with different heme coordination mode.

As part of the infective process, Porphyromonas gingivalis must acquire heme which is indispensable for life and enables the microorganism to survive and multiply at the infection site. This oral pathogenic bacterium uses a newly discovered novel hmu heme uptake system with a leading role played by the HmuY hemophore-like protein, responsible for acquiring heme and increasing virulence of this periodontopathogen. We demonstrated that Prevotella intermedia produces two HmuY homologs, termed PinO and PinA. Both proteins were produced at higher mRNA and protein levels when the bacterium grew under low-iron/heme conditions. PinO and PinA bound heme, but preferentially under reducing conditions, and in a manner different from that of the P. gingivalis HmuY. The analysis of the three-dimensional structures confirmed differences between apo-PinO and apo-HmuY, mainly in the fold forming the heme-binding pocket. Instead of two histidine residues coordinating heme iron in P. gingivalis HmuY, PinO and PinA could use one methionine residue to fulfill this function, with potential support of additional methionine residue/s. The P. intermedia proteins sequestered heme only from the host albumin-heme complex under reducing conditions. Our findings suggest that HmuY-like family might comprise proteins subjected during evolution to significant diversification, resulting in different heme coordination modes. The newer data presented in this manuscript on HmuY homologs produced by P. intermedia sheds more light on the novel mechanism of heme uptake, could be helpful in discovering their biological function, and in developing novel therapeutic approaches.

The Role of Green Tea Extract on Inhibiting Porphyromonas gingivalis as a Major Periodontitis Pathogen: In Vitro Study

Porphyromonas gingivalisis one of the anaerobic bacteria that are found in patients with periodontitis. Green tea catechins have antibacterial activity against several oral pathogenic bacteria. This study aimed to determine the ability of the green tea extract fraction to inhibit the growth of P. gingivalis. The green tea powder was extracted with hexane by maceration, then the insoluble fraction of the hexane was extracted using high-pressure extraction with water as a solvent ratio of 1:10. Antibacterial activity test was carried out by agar dilution method and agar diffusion disk using Mueller-HintonAgar (MHA) media. The results showed that green tea extract had antibacterial activity against P. gingivaliswith an inhibitory value of at least 0.5% (5mg / ml) and an average diameter of the zone of inhibition at a concentration of 4 mg/disc of 16.16 mm. This study concludes that green tea extract can be made in a dosage form to prevent periodontitis.

Essential Oil from Psidium cattleianum Sabine (Myrtaceae) Fresh Leaves: Chemical Characterization and in vitro Antibacterial Activity Against Endodontic Pathogens

Endodontic infections result from oral pathogenic bacteria which reach and infect dental pulp, as well as surrounding tissues, through cracks, unrepaired caries and failed caries restorations. This study aims to determine the chemical composition of essential oil from Psidium cattleianum leaves (PC-EO) and to assess its antibacterial activity against endodontic bacteria. Antibacterial activity of PC-EO was evaluated in terms of its minimum inhibitory concentration (MIC) values by the broth microdilution method on 96-well microplates. Bacteria Porphyromonas gingivalis (MIC = 20 µg/mL), Prevotella nigrescens (MIC = 62.5 µg/mL), Fusobacterium nucleatum (MIC = 12.5 µg/mL), Actinomyces naeslundii (MIC = 50 µg/mL), Bacteroides fragilis (MIC = 12.5 µg/mL), Aggregatibacter actinomycetemcomitans (MIC = 6.25 µg/mL) and Peptostreptococcus anaerobius (MIC = 62.5 µg/mL) were evaluated and compared to chlorhexidine dihydrochloride (CDH), the positive control. PC-EO was obtained by hydrodistillation with the use of a Clevenger-type apparatus whereas its chemical composition was analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Viridiflorol (17.9%), β-caryophyllene (11.8%), 1,8-cineole (10.8%) and β-selinene (8.6%) were the major constituents found in PC-EO, which exhibited high antibacterial activity against all endodontic pathogens under investigation. Therefore, PC-EO, a promising source of bioactive compounds, may provide therapeutic solutions for the field of endodontics.

α-Mangostin-Rich Extract: A Potential Oral Antibacterial Agent Prepared by Green Extraction

The purpose of this study was to prepare α-mangostin-rich extract (AME) using a green microwave extraction together with a simple one-step green fractionation method on a hydrophobic resin column. Based on the established method, AME containing 95% w/w α-mangostin content was obtained with an extract yield of 0.46% w/w dry plant powder. In addition, investigation of its antibacterial activity against oral pathogenic bacteria, including Streptococcus mitis, S. mutans, S. pyogenes and Bacillus subtilis, compared with the standard marker, α-mangostin found that AME exhibited strong antibacterial activities, which were equivalent to those of α-mangostin (MICs and MBCs of 0.5-2 and 4-16 µg/mL, respectively). Moreover, AME exhibited equivalent antibacterial activity against Propionibacterium acnes when compared to the pure α-mangostin (MIC and MBC of 2 and 8 µg/mL, respectively). A chemical stability evaluation found that AME was stable through a period of 16 weeks, when kept in a well-closed container protected from light and stored either at 4 ± 2 or 30 ± 2°C. On the other hand, AME was instable when exposed to light after 3 weeks of storage. The stability evaluation under accelerated conditions (75% relative humidity, at 45°C) implied that AME has a shelf-life of at least two years.

Analysis of oral pathogenic bacteria in the patients of eosinophilic esophagitis

Analysis of oral pathogenic bacteria in the patients of eosinophilic esophagitis

On-line profiling of volatile compounds produced in vitro by pathogenic oral bacteria

Infections by oral pathogens are one of the most common health problems worldwide. Due to the intimate connection between exhaled breath and the oral cavity, breath analysis could potentially be used to diagnose these infections. However, little is known about the volatile emissions of important oral pathogens that are connected with gingivitis and periodontitis. In this study, we have performed in vitro headspace measurements on four important oral pathogens (P. gingivalis, T. forsythia, P. intermedia and P. nigrescens) using proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS). Some of the most abundant compounds produced by the bacteria include hydrogen sulphide, methanethiol, acetone, dimethylsulphide, isoprene, cyclopentanone and indole as tentatively assigned from the mass spectra. Several other abundant mass signals were recorded but the assignment of these is less certain. Some of the bacterial species can be separated from each other by the emitted volatile fingerprints. The results of this study can be used in potential development of a diagnostic breath test for oral infections. In addition, as several of the measured compounds are known to be toxic, the results point to an intriguing possibility of studying the connection between the bacterial virulence and the emitted volatile compounds.

Antibacterial Diterpenoid Against Pathogenic Oral Bacteria of Streptococcus Mutans ATCC 25175 Isolated From Sarang Semut (Myrmecodia Pendans)

Discovery of new antibacterial agent to treat oral disease caused by pathogenic oral bacteria is an attracted focus to more pay attention of researcher. The tropical natural product is the promising sources of new bioactive as antibacterial compounds. The epiphyte plant of Sarang Semut (M. pendans) empirically has been used as a drug to treat various diseases. Our previous research found that ethyl acetate extract of Sarang Semut inhibited the bacteria growth of Enterococcus faecalis. This study aims to isolate, structure determination and antibacterial activity evaluation of active compound against Streptococcus mutans ATCC 25175. The isolation by combination chromatography on normal and reverse phase resulted an antibacterial compound 1. Based on the analysis of the spectroscopic data including IR, FTIR, 1H-NMR, 13C-NMR, 2D-NMR as well as by mass spectroscopic (MS) and compare to reported data, structure of compound 1 was suggested as terpenoid type diterpene derivative. Antibacterial activity evaluation by Kirby-Bauer method of compound 1 against S. mutans ATCC 25175 showed inhibition zone values were 17.8, 14.5 and 11.1 mm at 10000, 5000 and 1000 ppm, respectively, while the MIC and MBC values were 18.125 ppm with MBC of 2500 ppm, respectively.

Susceptibility Pattern of Isolated Pathogenic Oral Bacteria to Some Commonly Prescribed Antibiotics in Dental and General Medical Practice

The current global rise in the morbidity and mortality rates of infectious diseases is due in part, to the problem of antimicrobial resistance. The global threat of antimicrobial resistance is also partly a consequence of widespread inappropriate prescription and use of antibiotics, sometimes on empirical basis, without any established antimicrobial susceptibility data-based guidelines on such empirical use. In the present study, we re-examined the susceptibility pattern of organisms isolated from active carious lesions to some commonly prescribed antibiotics and suggest a comprehensive data generation and establishment of guidelines based on a holistic assessment of susceptibility pattern of different organisms to the different classes of antibiotics commonly prescribed in various branches of medicine. For instance, our results revealed significant resistance of cariogenic organisms such as Streptococcus mutans and Lactobacillus to Amoxicillin, Gentamicin, Tarivid, Chloramphenicol and Sparfloxacin, with good susceptibility to Ciprofloxacin, Ofloxacin, Pefloxacin and Streptomycin. These findings suggest that the latter group of antibiotics could function better than Amoxicillin in the prophylactic and empirical management of dental caries and other oral infections prior to obtaining antimicrobial susceptibility test results. &#x0D; Keywords: Antimicrobial, Susceptibility, Empirical, Resistance.

Antibacterial Flavonoids Against Oral Bacteria of Enterococcus Faecalis ATCC 29212 from Sarang Semut (Myrmecodia pendans) and Its Inhibitor Activity Against Enzyme MurA.

A significant number of antibiotics are known to inhibit peptidoglycan synthesis in the cross-linking stage, while the drug fosfomycin is the only one known to inhibit MurA. Escalated antibiotic resistance has had an impact on the efficacy of fosfomycin, thus demanding the discovery of suitable substitutes with improved potential for MurA inhibition. The aim of this work is to isolate antibacterial compounds from Sarang Semut (Myrmecodia pendans) and to evaluate their antibacterial activity against pathogenic oral bacteria of Enterococcus faecalis ATCC 29212 and inhibitory activity against MurA enzyme. The antibacterial compounds from Sarang Semut were isolated by a bioactivity-guided separation method with various solvents and combination of column chromatography on normal and reverse phases. The compounds with concentrations of 1000 and 5000 ppm were assessed against E. faecalis ATCC 29212 by agar well diffusion method, with chlorhexidine and fosfomycin being used as positive controls. Two antibacterial compounds isolated from Sarang Semut were identified as two new flavonoids derivates of 1 (10 mg) and 2 (4 mg). Both compounds were tested for antibacterial activities against E. faecalis. MIC values of compounds 1 and 2 were 8.15 and 8.05 mm at 1000 ppm and 8.62 and 8.55 mm at 5000 ppm, respectively. MBC values were 156 and 625 ppm for 1 and 625 and 2500 ppm for 2, respectively. In an inhibitory murA enzyme activity assay, compounds 1 and 2 were shown to inhibit the enzyme activity by IC50 values of 21.7 and 151.3 ppm. The study demonstrated that ethyl acetate fraction of Sarang Semut contained antibacterial flavonoids as active constituents that showed activity against E. faecalis. These results showed the plant's potential in herbal medicine and the development of new antibacterial agent for pathogenic dental caries.

Antibacterial Properties of Citrus limon and Pineapple Extracts on Oral Pathogenic Bacteria (Streptococcus mutans and Streptococcus sanguis)

Background: Micro-organisms resistant to most of the commercial antibiotics are rapidly expanding and there is an urgent need for detection of novel antimicrobial compounds. Tooth decay is a dental infection with bacterial sources such as Streptococcus mutans and Streptococcus sanguis. Objectives: The present study aimed to evaluate the in vitro antibacterial effects of different concentrations of Citrus limon peel, pineapple fruit, and pineapple peel extracts on oral pathogens such as S. mutants and S. sanguis. Materials and Methods: In this experimental study, the hydroethanolic extracts of the selected plants were prepared by maceration method and their antibacterial effects were evaluated by agar well diffusion method. Results: Two-fold dilutions of plant extract solutions were tested to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against each selected microorganism. The results of the current study revealed that pineapple peel extracts had the highest antibacterial effect on S. sanguis (MIC: 1.56 mg/mL and MBC: 3.12 mg/mL). Pineapple fruit had the lowest antibacterial activity against S. mutans (MIC: 25 mg/mL and MBC: 100 mg/mL). C. limon peel had significant antibacterial activity against S. mutans and S. sanguis. Conclusion: The peel of C. limon and pineapple had significant antibacterial activity against cariogenic microorganisms such as S. mutans and S. sanguinis.

Commensal and pathogenic biofilms differently modulate peri-implant oral mucosa in an organotypic model.

The impact of oral commensal and pathogenic bacteria on peri‐implant mucosa is not well understood, despite the high prevalence of peri‐implant infections. Hence, we investigated responses of the peri‐implant mucosa to Streptococcus oralis or Aggregatibacter actinomycetemcomitans biofilms using a novel in vitro peri‐implant mucosa‐biofilm model. Our 3D model combined three components, organotypic oral mucosa, implant material, and oral biofilm, with structural assembly close to native situation. S. oralis induced a protective stress response in the peri‐implant mucosa through upregulation of heat shock protein (HSP70) genes. Attenuated inflammatory response was indicated by reduced cytokine levels of interleukin‐6 (IL‐6), interleukin‐8 (CXCL8), and monocyte chemoattractant protein‐1 (CCL2). The inflammatory balance was preserved through increased levels of tumor necrosis factor‐alpha (TNF‐α). A. actinomycetemcomitans induced downregulation of genes important for cell survival and host inflammatory response. The reduced cytokine levels of chemokine ligand 1 (CXCL1), CXCL8, and CCL2 also indicated a diminished inflammatory response. The induced immune balance by S. oralis may support oral health, whereas the reduced inflammatory response to A. actinomycetemcomitans may provide colonisation advantage and facilitate later tissue invasion. The comprehensive characterisation of peri‐implant mucosa‐biofilm interactions using our 3D model can provide new knowledge to improve strategies for prevention and therapy of peri‐implant disease.

Abstract 132: Direct interactions of oral bacteria and oral squamous cell carcinoma cells

Abstract Head and neck cancers (HNC) are the sixth most common cancer worldwide with more than 90% being squamous cell carcinoma. HNC can occur in the oral cavity, oropharynx, larynx or hypopharynx, or nasal cavities. Oral squamous cell carcinoma (OSCC) is estimated to be diagnosed in 50,000 patients this year with an overall 5-year survival rate of 64%. The tumor microenvironment has been shown to play a vital role in the progression of many human cancers, including OSCC. Given the complexity of the oral microbiome, we hypothesize that OSCC and oral bacteria interact to affect the tumorigenic properties of OSCC. Methods: OSCC cells were cultured in the presence of oral pathogenic (Streptococcus mutans, Enterococcus faecalis, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans) and non-pathogenic (Streptococcus parasanguinis) bacteria. OSCC cells (A253, Cal27, FaDu, SCC-4, SCC- 9, SCC-25, SCC-152) were assessed for changes in cell proliferation, gene expression, and capacity to invade. Results: Pathogenic oral bacteria increased proliferation in A253 OSCC cells. Enterococcus faecalis increased proliferation of SCC-4, SCC-25 and SCC-152 cells. No increase in proliferation was seen in FaDu and Cal27 cells. When examining changes in gene expression, oral bacteria increased MMP2 expression in A253 cells.Enterococcus faecalis increased JAG1, markers of hedgehog signaling (GLI1, GLI2), cell proliferation (CCDN1, CDKN1A), and cell invasion (MMP2) in SCC-4. In SCC-25 cells, Enterococcus faecalis increased JAG1, GLI1, and GLI2. Despite having no effect in total proliferation, Enterococcus faecalis increased HES1 (a marker of Notch activity), GLI1, and GLI2 in Cal27 cells. In SCC-9 cells, GLI1 expression was increased with all treatments. Streptococcus mutans increased MMP9 and HES1. Aggregatibacter actinomycetemcomitans increased MMP2 and MMP9. Enterococcus faecalis and Fusobacterium nucleatum also increased HES1. Conclusions: Both the chemical and spatial interactions between OSCC and oral bacterium may play a role in tumor progression and migration by regulating proliferation of cancer cells and cellular signaling. A direct infection model, as opposed to interactions with bacterial spent media, showed more potential in terms of affecting cell viability and likely gene regulation as well. Future experiments will further explore the interactions, including the complexity of the oral biofilm in cancer patients and the presence of multiple bacteria. Citation Format: Stefan Kovac, Tiara Napier, Jessica Scoffield, Hope Amm. Direct interactions of oral bacteria and oral squamous cell carcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 132.