The Arginine Biosynthesis Pathway of Candida albicans Regulates Its Cross-Kingdom Interaction with Actinomyces viscosus to Promote Root Caries.

The cross-kingdom interactions between Candida albicans and Actinomyces viscosus play critical roles in root caries. However, the key pathway by which C. albicans regulates its interactions with A. viscosus is unclear. Here, we first employed 39 volunteers with root caries and 37 caries-free volunteers, and found that the abundances of C. albicans and A. viscosus were significantly increased in the individuals with root caries and showed a strong positive correlation. Their dual-species combination synergistically promoted biofilm formation and root caries in rats. The arginine biosynthesis pathway of C. albicans was significantly upregulated in dual-species biofilms and dental plaques from another 10 root caries volunteers compared with the 10 caries-free volunteers. The exogenous addition of arginine increased the cariogenicity of the dual-species biofilm. The C. albicans ARG4, a key gene from the arginine biosynthesis pathway, null mutant failed to promote dual-species biofilm formation and root caries in rats; however, the addition of arginine restored its synergistic actions with A. viscosus. Our results identified the critical roles of the C. albicans arginine biosynthesis pathway in its cross-kingdom interactions with A. viscosus for the first time and indicated that targeting this pathway was a practical way to treat root caries caused by multiple species. IMPORTANCE Root caries is a critical problem that threatens the oral health of the elderly population. Our results identified the essential roles of the C. albicans arginine biosynthesis pathway in its cross-kingdom interactions with A. viscosus in root caries for the first time and indicated that targeting this pathway was a practical way to treat root caries caused by multiple species.

Clinical Characteristics of Actinomyces viscosus Bacteremia.

Background and Objectives: Actinomyces species are part of the normal flora of humans and rarely cause disease. It is an uncommon cause of disease in humans. The clinical features of actinomycosis have been described, and various anatomical sites (such as face, bones and joints, respiratory tract, genitourinary tract, digestive tract, central nervous system, skin, and soft tissue structures) can be affected. It is not easy to identify actinomycosis because it sometimes mimics cancer due to under-recognition. As new diagnostic methods have been applied, Actinomyces can now more easily be identified at the species level. Recent studies have also highlighted differences among Actinomyces species. We report a case of Actinomyces viscosus bacteremia with cutaneous actinomycosis. Materials and Methods: A 66 years old male developed fever for a day with progressive right lower-leg erythematous swelling. Blood culture isolates yielded Actinomyces species, which was identified as Actinomyces viscosus by sequencing of the 16S rRNA gene. In addition, we searched for the term Actinomyces or actinomycosis cross-referenced with bacteremia or "blood culture" or "blood stream" from January 2010 to July 2020. The infectious diseases caused by species of A. viscosus from January 1977 to July 2020 were also reviewed. Results: The patient recovered well after intravenous ampicillin treatment. Poor oral hygiene was confirmed by dental examination. There were no disease relapses during the following period. Most cases of actinomycosis can be treated with penicillin. However, clinical alertness, risk factor evaluation, and identification of Actinomyces species can prevent inappropriate antibiotic or intervention. We also compiled a total of 18 cases of Actinomyces bacteremia after conducting an online database search. Conclusions: In summary, we describe a case of fever and progressive cellulitis. Actinomyces species was isolated from blood culture, which was further identified as Actinomyces viscosus by 16S rRNA sequencing. The cellulitis improved after pathogen-directed antibiotics. Evaluation of risk factors in patients with Actinomyces bacteremia and further identification of the Actinomyces species are recommended for successful treatment.

[Polymicrobial liver abscesses and pleural empyema in a 40-year-old male after tooth extraction and closed periodontal treatment: A case report]. / Polymikrobielle Leberabszesse und Pleuraempyem bei einem 40-jährigen Mann nach Zahnextraktion und geschlossener Parodontitis-Behandlung: Ein Fallbericht.

We report on a 40-year-old patient who presented with fever, right upper abdominal pain, right-sided chest pain and acute dyspnea. Imaging revealed several liver abscesses, as well as extensive right pleural empyema. Sixteen weeks previously, the patient underwent tooth extraction of the third molars (18, 28, 38, 48) and a first molar (46), and systematic closed periodontitis treatment. Four different species of the physiological microbiota of the oral cavity were detected in the pleura or liver abscess punctate (Streptococcus anginosus, Streptococcus constellatus, Actinomyces odontolyticus, Prevotella denticola). An underlying immune defect was ruled out. Ultrasound-guided drainage of liver abscesses and surgical treatment of pleural empyema by video-assisted thoracoscopy (VATS) and insertion of thoracic suction drains was performed, accompanied by targeted antibiotic therapy. Over a course of 6 weeks, the patient recovered completely. The case report illustrates severe infectious side effects of major dental interventions, and it critically summarizes current dental guideline recommendations on peri-interventional antimicrobial therapy. Therefore, a good clinical follow up after major tooth extractions is imperative.

Cross-kingdom interaction of Candida albicans and Actinomyces viscosus elevated cariogenic virulence.

OBJECTIVE: How the interactions between Candida albicans and Actinomyces viscosus contributed to the root caries was not clear. This study aimed to investigate their cross-kingdom interactions on the biomass and the cariogenic virulence in dual-species biofilms. DESIGN: Suspensions of C. albicans and A. viscosus were formed the mono and polymicrobial biofilms in vitro. Crystal violet assay, viable plate count, scanning electron microscopy and fluorescence in situ hybridization were used to analyze the biomass and biofilm structure. Glycolytic pH drop and the spectrophotometric method were used to evaluate the acid production and hydroxyapatite dissolution, respectively. The exopolysaccharide production was measured by the anthrone-sulfuric acid method, while the adhesion force was measured by atomic force microscopy. RESULTS: The biomass and colony-forming units of mixed-species were significantly increased compared to that of the mono-species at 24 h, 48 h, 72 h. The structure of dual-species biofilm had more microcolonies and was much denser. The dual-species biofilms significantly decreased the pH value and damaged the hydroxyapatite compared with the mono-species biofilms at various time points, indicating the strong cariogenic virulence. Moreover, the dual-species biofilms significantly enhanced the exopolysaccharide production and adhesion force suggesting the increase of biofilm adhesion. CONCLUSIONS: Cross-kingdom interactions of C. albicans and A. viscosus significantly elevated the biomass and cariogenic virulence of dual-species biofilm.

Voriconazole inhibits cross-kingdom interactions between Candida albicans and Actinomyces viscosus through the ergosterol pathway.

Candida albicans and Actinomyces viscosus are prominent microbes associated with dental root caries. The aim of this study was to investigate the effect of C. albicans on A. viscosus biofilms and to identify the mechanisms associated with this interaction. A. viscosus and C. albicans strains (wide-type and mutants) were used to form biofilms in vitro and in vivo, which were subsequently analysed by crystal violet assay and scanning electron microscopy (SEM) to investigate the effect of C. albicans on A. viscosus growth. A viable plate count and survival curve for C. albicans mutants and A. viscosus combinations were used to identify which C. albicans pathway was crucial for cross-kingdom interactions. Voriconazole was used to block their interactions both in vitro and in vivo. SEM, fluorescence in situ hybridisation (FISH), quantitative PCR and survival curve analyses were performed to evaluate the activity of voriconazole on C. albicans and A. viscosus interactions. The biomass and virulence of mixed-species biofilms were significantly enhanced compared with the A. viscosus biofilm alone. However, this was not observed in the mixed-species biofilms with the C. albicans mutant erg11Δ/Δ in vitro and in vivo, indicating that azoles may work on the mixed-species biofilms. As expected, voriconazole can effectively reduce the biomass of mixed-species biofilms. A high concentration of voriconazole (1 µg/mL) reduced the abundance of C. albicans, whilst a low voriconazole concentration (0.25 µg/mL) blocked their interactions similar to the effect of the erg11Δ/Δ mutant. Voriconazole may be a candidate strategy to combat root caries pathogens.

Optimization of Microwave-assisted Extraction of Essential Oil from Lavender Using Response Surface Methodology.

A microwave-assisted hydrodistillation (MAHD) method was investigated for extraction of essential oils from lavender. The essential oil extracts at optimized MAHD conditions was compared with hydrodistillation (HD). Response surface methodology coupled with Box-Behnken design was applied to optimize the parameters for MAHD. The optimized MAHD conditions were 500 W microwave power, 17 mL/g liquid-to-solid ratio and 40 min microwave time. The ANOVA results revealed that microwave time had the greatest impact on the essential oil yield followed by liquid-to-solid ratio and microwave power. Under the MAHD optimized conditions, the essential oil yield was 3.19%, approximating the predicted yield (3.20%). MAHD was superior in terms of saving energy and extraction time (40 min, compared to 120 min in HD). The essential oil analyzed by GC-MS, presented 39 compounds constituting 98.37% and 97.51% of the essential oils obtained through MAHD and HD, respectively. No obvious differences were found in composition between MAHD oil and HD oil. Antimicrobial study showed that the lavender essential oil exhibited broad-spectrum antibacterial activity and the MAHD oil showed a higher antimicrobial activity than the HD oil. This study revealed that MAHD could be a good method for extracting essential oil in lavender and other aromatic plants.

Antimicrobial Effect of an Experimental Glass lonomer Cement against Pathogens associated with Deep Carious Lesions.

AIM: To study the antimicrobial effect of chlorhexidine diacetate (CHX-D)-modified type II glass ionomer cement (GIC) against the two predominant deep caries microorganisms, namely Lactobacillus casei and Actinomyces viscosus. MATERIALS AND METHODS: An experimental GIC (ex-GIC) was prepared by mixing CHX-D powder with the powder of type II GIC to obtain 1% (w/w) concentration of CHX-D in the GIC. Antibacterial activity of this ex-GIC was tested against L. casei and A. viscosus using the agar diffusion method. The ex-GIC specimens were tested in their unset and set forms for each bacterium. For the unset group, specimens were placed in each agar plate immediately after manipulation and for the set group, specimens were placed in each agar plate, 1 hour after manipulation. The inhibition zones on the agar plate were recorded in millimeters immediately on placement of the specimen in the agar plate and after 48 hours. The reading was recorded and statistically analyzed for significant difference. RESULTS: Mann-Whitney U test showed statistically significant difference in the inhibition zones produced by ex-GIC against L. casei and A. viscosus when both were compared in unset (p-value = 0.002) and set (p-value = 0.031) groups. For both the groups, the zone of inhibition against L. casei was greater. Though the unset group recorded wider zone of inhibition, the difference was not significant when compared with the respective set group. This was true for both the bacterial groups. CONCLUSION: The 1% CHX-D-modified type II GIC showed antibacterial property against L. casei and A. viscosus and significantly higher activity against L. casei. CLINICAL SIGNIFICANCE: Addition of 1% CHX-D to type II GIC showed evidence of antibacterial activity against organisms found in deep carious lesion and therefore may exhibit superior antimicrobial efficiency when used as an intermediate therapeutic restoration in deep cavities.

Stannous Fluoride Effects on Gene Expression of Streptococcus mutans and Actinomyces viscosus.

A genome-wide transcriptional analysis was performed to elucidate the bacterial cellular response of Streptococcus mutans and Actinomyces viscosus to NaF and SnF2. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of SnF2 were predetermined before microarray study. Gene expression profiling microarray experiments were carried out in the absence (control) and presence (experimental) of 10 ppm and 100 ppm Sn2+ (in the form of SnF2) and fluoride controls for 10-min exposures (4 biological replicates/treatment). These Sn2+ levels and treatment time were chosen because they have been shown to slow bacterial growth of S. mutans (10 ppm) and A. viscosus (100 ppm) without affecting cell viability. All data generated by microarray experiments were analyzed with bioinformatics tools by applying the following criteria: 1) a q value should be ≤0.05, and 2) an absolute fold change in transcript level should be ≥1.5. Microarray results showed SnF2 significantly inhibited several genes encoding enzymes of the galactose pathway upon a 10-min exposure versus a negative control: lacA and lacB (A and B subunits of the galactose-6-P isomerase), lacC (tagatose-6-P kinase), lacD (tagatose-1,6-bP adolase), galK (galactokinase), galT (galactose-1-phosphate uridylyltransferase), and galE (UDP-glucose 4-epimerase). A gene fruK encoding fructose-1-phosphate kinase in the fructose pathway was also significantly inhibited. Several genes encoding fructose/mannose-specific enzyme IIABC components in the phosphotransferase system (PTS) were also downregulated, as was ldh encoding lactate dehydrogenase, a key enzyme involved in lactic acid synthesis. SnF2 downregulated the transcription of most key enzyme genes involved in the galactose pathway and also suppressed several key genes involved in the PTS, which transports sugars into the cell in the first step of glycolysis.

In vitro studies of the antimicrobial effect of non-thermal plasma-activated water as a novel mouthwash.

The aim of this study was to evaluate the antimicrobial effects of non-thermal plasma-activated water (PAW) as a novel mouthwash in vitro. Three representative oral pathogens - Streptococcus mutans, Actinomyces viscosus and Porphyromonas gingivalis - were treated with PAW. The inactivation effect was evaluated using the colony-forming unit (CFU) method, and the morphological and structural changes of a cell were observed by scanning electron microscopy and transmission electron microscopy (TEM). The physicochemical properties of PAW were analysed, and its influence on the leakage of intracellular proteins and DNA was evaluated. The results showed significant reduction of Streptococcus mutans within 60 s, of Actinomyces viscosus within 40 s, and of Porphyromonas gingivalis in less than 40 s. Scanning electron microscopy and TEM images showed that the normal cell morphology changed by varying degrees after treatment with PAW. Intracellular proteins (280 nm) and DNA (260 nm) leaked from all three species of bacteria after treatment with PAW. Reactive oxygen species (ROS), especially atomic oxygen (O), hydroxyl radical (˙OH), and hydrogen peroxide (H2 O2 ), were generated and led to strong oxidative stress and cell damage. These results suggest that PAW has potential use as a novel antimicrobial mouthwash.

Infección por Actinomyces viscosus en trasplantado de riñón-páncreas / Actinomyces viscosus infection in a kidney-pancreas trasplanted patient

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Antimicrobial efficiency of mouthrinses versus and in combination with different photodynamic therapies on periodontal pathogens in an experimental study.

BACKGROUND AND OBJECTIVE: In the therapy of destructive periodontal disease, chemical antimicrobial agents and increasingly photodynamic therapy (PDT) play an important adjunctive role to standard mechanical anti-infective treatment procedures. However, both antiseptic methods have their shortcomings in terms of eliminating periodontal pathogens. The aim of the study was to compare the antibacterial efficacy of different antiseptic mouthrinses, of a conventional and a new, modified PDTplus as well as of the different antiseptic mouthrinses combined with either the conventional or the modified PDTplus against periopathogens. MATERIAL AND METHODS: Six representative periodontitis-associated bacterial strains were grown for 24 h under anaerobic conditions. After mixing the individual cell pellets they were exposed to 10 different antiseptic mouthrinse formulations: chlorhexidine (0.2%, 0.06%, CHX); CHX + cetylpyridinium chloride (each 0.05%); sodium hypochlorite (0.05%); polyhexanide (0.04%, PHMB1; 0.1%, PHMB2); octenidine dihydrochloride (0.1%); fluoride (250 ppm); essential oils; povidone iodine (10%); and saline (0.9%, NaCl) as control. Furthermore, the bacteria were treated with conventional PDT based on light-emitting diodes and a new modified photodisinfection combining photosensitizer with hydrogen peroxide to PDTplus also based on light-emitting diodes. In addition to the single treatments, a combined application of antiseptic exposure followed by use of PDT or PDTplus was performed. The microbial viability was characterized by analyzing colony growth and fluorescence-based vitality proportions. RESULTS: Nearly all mouthrinses caused a statistically significant growth inhibition. The most effective antiseptics, CHX (0.2%), CHX/cetylpyridinium chloride and octenidine dihydrochloride, inhibited bacterial growth completely. Conventional PDT resulted in moderate reduction of colony growth. The modified PDTplus achieved maximum antimicrobial effect. The combination of antiseptic exposure and PDT against periopathogens predominantly increased antibacterial efficacy compared to the single applications. The mouthrinse containing essential oil seemed to interfere with PDT. CONCLUSION: A combination therapy of preceding chemotherapeutical exposure and subsequent photodisinfection may be a more effective and promising antibacterial treatment than single applications of the antiseptic methods. The modified PDTplus using oxygen-enriched toluidine showed a superior antibacterial effect on periodontal pathogens to conventional PDT and to the majority of the investigated mouthrinses.

In vitro antibacterial effect of Argentine propolis extracts on Streptococcus mutans and Actinomyces viscosus / Efecto antibacteriano in vitro de extractos de propóleos argentinos sobre Streptococcus mutans y Actinomyces viscosus / Efeito antibacteriano in vitro de extratos de própolis argentinos sobre Streptococcus mutans e Actinomyces viscosus

Aim: In the present study, the antibacterial activity of the Ethanol Extract of Propolis (EEP), collected from various regions (Mendoza, Santiago del Estero, and Corrientes) in Argentina, against Streptococcus mutans ATCC® 35668™ and Actinomyces viscosus ATCC® 15987™ (MicroBioLogics Inc., USA) was investigated. Methods: Identification of geographic and botanical origin was based on a reconnaissance survey. Phytochemical screening of propolis was carried out on ethanolic extracts using standard methods to identify the constituents (aluminum chloride colorimetric method, Folin-Ciocalteu colorimetric method, thin layer chromatography). The agar diffusion method (discs and wells) and serial dilution method (plates and tubes) were used to evaluate the antibacterial activity of EEP. Results: EEP exerted various degrees of antibacterial activity against S. mutans and A. viscosus, depending on the geographic area of collection. Phytochemical screening showed that the bioactive compounds correspond to phenolic compounds and flavones. EEP from Tunuyán (Mendoza), where the most abundant vegetation belongs to Populus sp., showed the highest content of phenolic compounds (220.92±2.01 mg/g) and flavonoids (30.39±0.25 mg/g). This sample showed the most profound antibacterial activity among the EEP tested. By the agar-well diffusion method, we found a high susceptibility with an inhibitory halo of 11.25 ± 4.68 mm and 10.90 ± 4.21 mm against S. mutans and A. viscosus, respectively. It also presented low Minimum Inhibitory Concentration and Minimum Bactericidal Concentration values against S. mutans (MIC 0.05 mg/mL - MBC 0.46 mg/mL) followed by A. viscosus (MIC 0.11 mg/mL - MBC 0.93 mg/mL). Conclusions: The combined results from all methods indicated that S. mutans is more susceptible to the effect of the Tunuyán EEP than A. viscosus.(AU)

Objetivo: En el presente estudio, fue investigada la actividad antibacteriana de los Extractos Etanólicos de Propóleos (EEP), coleccionados de diversas regiones (Mendoza, Santiago del Estero, Corrientes) de Argentina, contra Streptococcus mutans ATCC® 35668™ y Actinomyces viscosus ATCC® 15987™ (MicroBioLogics Inc., USA.). Métodos: La identificación del origen geográfico y botánico se basó en el estudio de reconocimiento. El tamizaje fitoquímico de propóleos se llevó a cabo en extractos etanólicos utilizando métodos estándar para identificar los componentes (método colorimétrico de cloruro de aluminio, método colorimétrico de Folin-Ciocalteu, cromatografía en capa fina). El método de difusión en agar (discos y pocillos) y métodos de diluciones en serie (placas y tubos) se llevaron a cabo para evaluar la actividad antibacteriana de los EEP. Resultados: EEP ejercieron diversos grados de actividad antibacteriana contra S. mutans y A. viscosus, dependiendo de la zona geográfica de recolección de propóleos. El tamizaje fitoquímico mostró que los compuestos bioactivos corresponden a compuestos fenólicos y flavonoides. El EEP de Tunuyán (Mendoza), donde la vegetación más abundante pertenece a Populus sp., mostró el mayor contenido de compuestos fenólicos (220.92±2.01 mg/g) y flavonoides (30.39±0.25 mg/g) y la más importante actividad antibacteriana entre los EEP estudiados. Por el método de difusión en agar en pocillos, se apreció una alta susceptibilidad con un halo inhibidor de 11,25 ± 4,68 mm y 10,90 ± 4,21 mm frente a S. mutans y A. viscosus, respectivamente. Se observaron valores bajos de Concentración Inhibitoria Mínima y valores mínimos de concentración bactericida contra S. mutans (CIM 0,05 mg/ml - CBM 0,46 mg/ml) seguido de A. viscosus (CIM 0,11 mg/ml - CBM 0,93 mg/ml). Conclusiones: Los resultados combinados de todos los métodos indicaron que S. mutans es más susceptible a los efectos de EEP que A. viscosus.(AU)

Design of a hydroxyapatite-binding antimicrobial peptide with improved retention and antibacterial efficacy for oral pathogen control.

Controlling and reducing the formation of pathogenic biofilm on tooth surface is the key to the prevention and treatment of the biofilm-associated oral diseases. Antimicrobial peptides (AMPs), considered as possible future alternatives for conventional antibiotics, have been extensively studied for the control of bacterial infection. Due to the rapid dilution and degradation by human saliva, AMP preparations designed for oral use with longer retention and higher efficacy are in urgent need. To this end, a hydroxyapatite (HAp)-binding antimicrobial peptide (HBAMP), which is based on the fusion of a specific HAp-binding heptapeptide (HBP7) domain and a broad-spectrum antimicrobial peptide (KSLW) domain, has been developed in our laboratory. HBAMP was supposed to form a contact-active antibacterial interface on tooth surface to inhibit the formation of biofilms. In this study, we investigated its binding behaviour, antibacterial activity against bacteria in both planktonic and sessile states, enzymatic stability in human saliva, and cytocompatibility to human gingival fibroblasts (HGFs). Our findings suggest that HBAMP could adsorb on tooth surface to provide effective antibacterial activity with improved retention. This study provides a proof-of-concept on using conjugated molecules to promote antibacterial efficacy by synergistically actions of HBAMP free in solution and bound on tooth surface.

The Starvation Resistance and Biofilm Formation of Enterococcus faecalis in Coexistence with Candida albicans, Streptococcus gordonii, Actinomyces viscosus, or Lactobacillus acidophilus.

INTRODUCTION: Enterococcus faecalis is the most frequently detected species in root canal-treated teeth, and it is able to survive under starvation conditions. However, persistent periapical disease is often caused by multispecies. The aim of this study was to explore the survival of E. faecalis in starvation conditions and biofilm formation with the 4 common pathogenic species. METHODS: A dual-species model of Candida albicans, Streptococcus gordonii, Actinomyces viscosus, or Lactobacillus acidophilus in combination with E. faecalis was established and allowed to grow in phosphate-buffered saline for the examination of starvation survival. Cefuroxime sodium and vancomycin at a concentration of 100 mg/L were added into brain-heart infusion plate agar to count the 2 bacteria separately in the dual species. Scanning electron microscopy was used to observe the dual species and multiple species on the root canal dentin of bovine teeth for 48 hours. A confocal laser scanning microscope was used to show the 4 groups of dual-species biofilms on substrates with glass bottoms for 48 hours. RESULTS: E. faecalis was more resistant to starvation in coexistence with C. albicans, S. gordonii, A. viscosus, or L. acidophilus, and S. gordonii was completely inhibited in coexistence with E. faecalis. The dual-species biofilm showed that E. faecalis formed thicker and denser biofilms on the root canal dentin and glass slides in coexistence with S. gordonii and A. viscosus than C. albicans and L. acidophilus. CONCLUSIONS: The multispecies community is conducive to the resistance to starvation of E. faecalis and biofilm formation in root canals.

Anti-plaque effect of a synergistic combination of green tea and Salvadora persica L. against primary colonizers of dental plaque.

OBJECTIVE: Green tea (Gt), leafs of Camellia sinensis var. assamica, is widely consumed as healthy beverage since thousands of years in Asian countries. Chewing sticks (miswak) of Salvadora persica L. (Sp) are traditionally used as natural brush to ensure oral health in developing countries. Both Gt and Sp extracts were reported to have anti-bacterial activity against many dental plaque bacteria. However, their combination has never been tested to have anti-bacterial and anti-adherence effect against primary dental plaque colonizers, playing an initial role in the dental plaque development, which was investigated in this study. METHODS: Two-fold serial micro-dilution method was used to measure minimal inhibitory concentration (MIC) of aqueous extracts of Gt, Sp and their combinations. Adsorption to hexadecane was used to determine the cell surface hydrophobicity (CSH) of bacterial cells. Glass beads were used to mimic the hard tissue surfaces, and were coated with saliva to develop experimental pellicles for the adhesion of the primary colonizing bacteria. RESULTS: Gt aqueous extracts exhibited better anti-plaque effect than Sp aqueous extracts. Their combination, equivalent to 1/4 and 1/2 of MIC values of Gt and Sp extracts respectively, showed synergistic anti-plaque properties with fractional inhibitory concentration (FIC) equal to 0.75. This combination was found to significantly reduce CSH (p<0.05) and lower the adherence ability (p<0.003) towards experimental pellicles. CONCLUSION: Combination between Gt and Sp aqueous extracts exhibited synergistic anti-plaque activity, and could be used as a useful active agent to produce oral health care products.

Antibacterial effect of composite resin foundation material incorporating quaternary ammonium polyethyleneimine nanoparticles.

STATEMENT OF PROBLEM: As caries is the most frequent cause of the failure of composite resin-based restorations, composite resins with antibacterial properties are desirable. However, whether quaternary ammonium polyethyleneimine nanoparticles can be effectively incorporated is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the antibacterial activity against Streptococcus mutans and Actinomyces viscosus of a foundation material incorporating quaternary ammonium polyethyleneimine (QPEI) nanoparticles. MATERIAL AND METHODS: QPEI antimicrobial nanoparticles were incorporated in a commercially available foundation material (Q Core; BJM Laboratories Ltd) at 1% wt/wt. Antibacterial efficacy against S mutans (106 colony-forming units [CFU]/mL) and A viscosus (106 CFU/mL) was examined by the direct contact test (DCT), and the agar diffusion test (ADT) with and without surface polishing. Bacterial outgrowth was recorded with a spectrophotometer. RESULTS: Growth of S mutans and A viscosus was inhibited, showing a decrease by 6 orders of magnitude in bacterial viability in specimens incorporating the nanoparticles, even after polishing the foundation material (P<.05). Growth inhibition was not observed in specimens without nanoparticles. CONCLUSIONS: Antibacterial properties can be achieved in a commercially available foundation material by incorporating polycationic antibacterial nanoparticles. This antibacterial effect did not diminish after surface polishing.

An in-vitro evaluation of antibacterial effect of Amalgomer CR and Fuji VII against bacteria causing severe early childhood caries.

OBJECTIVE: To evaluate the antibacterial action of Amalgomer CR and Fuji VII against bacteria causing S-early childhood caries. MATERIALS AND METHODS: Antibacterial activity of Amalgomer CR and Fuji VII was assessed using the agar diffusion test in triplicate. The powder and liquid of each test material was mixed and inserted in the punched wells (6 mm × 2 mm). A composition of 0.2% chlorhexidine digluconate acted as control. The agar plates were incubated at 37°C for 24 h for Streptococcus mutans, S. salivarius, S. parasanguinis and Actinomyces viscosus, whereas Lactobacillus casei was incubated for 48 h. Sizes of the inhibition zones were calculated by subtracting the diameter of the specimen (6 mm) from the average of the three measurements of the halo. For each test material against each bacteria, 9 measurements were made (3 measurements × 3 times). Kruskal-Wallis test was done to compare the zones of inhibition of test materials against individual bacteria. Pair-wise comparison was done by Mann-Whitney U-test. RESULTS: Amalgomer CR had the most antibacterial against S. mutans (31.0 mm), followed by A. viscosus (21.87 mm), S. salivarius (13.87 mm), S. parasanguinis (10.80 mm), and L. casei (9.69 mm). Fuji VII had the most antibacterial action against S. salivarius (10.65 mm), followed by A. viscosus (9.10 mm). However, it did not inhibit the growth of S. mutans (0 mm), S. parasanguinis (0 mm), and L. casei (0 mm). CONCLUSION: Amalgomer CR and Fuji VII showed wide variation in antibacterial action against all test organisms.

[Study of antimicrobial activity of carboxymethyl chitosan zinc complex material against cariogenic bacteria].

PUPPOSE: To evaluate the antimicrobial activity of carboxymethyl chitosan zinc (CMCSZ) and carboxymethyl chitosan zinc-active peptide complex material (CMCSZP) on oral cariogenic bacteria. METHODS: Agar dilution method and K-B disk diffusion susceptibility agents were used to measure the antimicrobial activity of two agents against S.mutans, Lactobacillus, S.sanguinis and Actinomyces viscosus. The former method was used to measure the minimal inhibitory concentration (MIC) and latter was used to measure the inhibitory zone. The effects of pH value, temperature, light, ultraviolet and storage temperature on the active substances were investigated to determine the stability of CMCSZ and CMCSZP. SPSS17.0 software package was used for statistical analysis. RESULTS: All the bacteria were susceptible to active peptide, CMCSZ and CMCSZP with the MIC of CMCSZ/CMCSZP being 625, 1250, 1250 and 2500 mg/L, respectively. At the same concentration, the inhibitory zone of CMCSZP was significantly bigger than that of CMCSZ. Acidic conditions were conducive to increase the antimicrobial activity of CMCSZ, while the effect on CMCSZP was not significant. CMCSZ and CMCSZP exhibited good stability against light, but their antimicrobial activity gradually weakened as the bath temperature rising. In the temperature of 85 degrees centigrade, their antibacterial activity disappeared. CONCLUSIONS: CMCSZ have CMCSZP had strong antimicrobial activity against 4 kinds of cariogenic bacteria. They have good stability against light, but poor thermal stability. This study provides theoretical foundation for the application of CMCSZ/CMCSZP in prevention of cariogenic diseases.

[Effects of Yili dark bee propolis on oral cariogenic biofilm in vitro].

OBJECTIVE: To evaluate the effects of Yili dark bee propolis on the main cariogenic biofilm and mechanisms. METHODS: Susceptibilities to the ethanolic extract of propolis against Streptococcus mutans (S. mutans), Streptococcus sobrinus (S. sobrinus), Streptococcus sanguis (S. sanguis), Actinomyces viscosus (A. viscosus), and Actinomyces naeslundii (A. naeslundii) were analyzed by crystal violet stain method to determine the minimum biofilm eradication concentration (MBEC). The biofilm was initially cultivated for 24 h. Subsequently, the propolis groups with different concentration MBEC and initial pH 7.0 were cultured for 24 h. Moreover, the pH value was measured to evaluate the acid-producing ability of the tested plaque biofilm. The effects of propolis on the insoluble extracellular polysaccharide synthesis of S. mutans biofilm were evaluated by anthrone method. RESULTS: The MBEC of Yili propolis on S. mutans, S. sobrinus, S. sanguis, A. viscosus, and A. naeslundii were 6.25, 1.56, 3.13, 0.78, and 0.78 mg.mL-1, respectively. Propolis could decrease the ΔpH of the tested plaque biofilm, and the differences between the control and propolis groups were statistically significant (P<0.05). At MBEC, propolis could reduce the ability of S. mutans in synthesizing insoluble extracellular polysaccharides. CONCLUSION: Yili propolis demonstrate remarkable eradicative effects on the cariogenic plaque biofilm, showing inhibition of the synthesis of biofilm-produced acids and insoluble extracellular polysaccharides.

[The efficacy of cold-light tooth bleaching on the formation of bacteria biofilm on the enamel surfaces].

PURPOSE: To evaluate the efficacy of Beyond cold-light tooth bleaching on the formation of main cariogenic bacteria biofilm on enamel surfaces. METHODS: Twenty enamel discs with the size of 4 mm×4 mm×1 mm in size, were made. The enamel discs were divided into 4 groups randomly: cold-light bleaching group, bleaching gel group, cold-light group and control group. Five discs were in each group. Cold-light bleaching group was whitened 3 times with bleaching gel and cold-light, and 12 min per session. Bleaching gel was smeared on the surface of enamel in bleaching gel group for 3 times and 12 min per session. Enamel discs of cold-light group were treated with cold-light for 12 min and 3 sessions. Control group was treated without any processing. The 4 groups were incubated in mixed bacteria liquid, including Streptococcus mutans(SM), Actinomyces viscosus (Av) and Fusobacterium nucleatum (Fn), within the artificial oral cavity model. After 36 h, the samples were observed under confocal laser scanning microscopy(CLSM). The data was analyzed with SAS8.2 software package. RESULTS: The biofilms in 3 experimental groups were sparser than the control group under CLSM, and the thickness significantly decreased after treatment (P<0.05), while no significant difference was found among 3 experimental groups (P>0.05).Compared with the control group, the percentage of vital bacteria in biofilm of the experimental groups decreased significantly after treatment (P<0.001). CONCLUSIONS: Cold-light tooth bleaching can inhibit the formation of mixed bacteria biofilm, damage the structure of biofilm and reduce the number of vital bacteria. Supported by Research Fund of Ninth People's Hospital of Shanghai Jiao Tong University School of Medicine (2013-06).