CLINICAL SIGNIFICANCE OF STREPTOCOCCUS MEMBERS IN DEVELOPING PERIODONTITIS

Bacteria of the genus Streptococcus are one of the most numerous and diverse representatives in the normal biocenosis of human organs and systems particularly being abundant as obligatory inhabitants of the oral cavity. All streptococci are divided into six groups: S.mitis, S.anginosus, S.salivarius, S.mutans, S.bovis and S.pyogenic groups, among which their certain number may potentially participate in the infectious process of developing periodontitis. Owing to the presence of a wide range of adhesion, invasion and colonization factors, they are capable of performing a protective function such as, e.g., colonization resistance, but they may also cause formation of a pathological process in the tooth tissues and dento-facial system. The most prominent adhesion factors are antigens I / II (Ag I / II), fibronectin, collagen, laminin, fibrinogen binding proteins, serine-rich glycoproteins, pili, protein M, proteases, C5a peptidases, and the presence of a tooth capsule. Among the complex of proteolytic enzymes, it is important to note that streptococci contain enzymes hyaluronidase and lyase, which cleave the β1,4 bond between N-acetylglucosamine and d-glucuronic acid as the components of hyaluronic acid being a part of the connective tissues. The members of the S.anginosus group are able to release chondroitin sulfatase, which destroys chondroitin sulfates as specific components in cartilage, ligaments and other connective tissue structures. The enzymes noted contribute to a deeper spread of microorganisms in host tissues. Pathological processes associated with the development of periodontitis comprise a complex problem, wherein several important elements take part, including an infectious agent, a macroorganismal response in the form of nonspecific and adaptive immunity, as well as involvement of anti-inflammatory components. A great body of studies in research literature are dedicated to describe to participation of the members within the "red, orange and green" complexes as the principal components in developing periodontitis. Whereas the "yellow" and the "purple" complex plays a more protective role by acting as antagonists while interacting with periodontopathogens, but it should not be ruled out a potential participation for some representatives, particularly S. intermedius, S. gordonii, Actinomyces odontolyticus, Actinomyces naeslundii in developing periodontal disease. Altogether, it poses a problem, which may be solved solely based on a multidisciplinary approach by inviting not only dentists and bacteriologists but also researchers of other specialties. Here we review the studies found in international and national data bases such as Scopus, Web of Science, Springer, RINC.

In Vitro Evaluation of the Effect of Oral Probiotic Weissella cibaria on the Formation of Multi-Species Oral Biofilms on Dental Implant Surfaces

Oral probiotics are beneficial bacteria that can help prevent periodontal disease. However, little is known about the effects of oral probiotics on the formation of implant biofilms. This study aimed to evaluate the effects of oral probiotics Weissella cibaria CMU and CMS1 in an in vitro complex biofilm model on titanium implant surfaces. First, it was identified through colony biofilm assay that W. cibaria CMU and CMS1 inhibit the formation of multi-species biofilms formed by eight types of bacteria. Two types of saliva-coated titanium discs inoculated with early (Streptococcus gordonii, Streptococcus oralis, Streptococcus sanguinis, Actinomyces naeslundii, and Veillonella parvula), secondary (Fusobacterium nucleatum and Prevotella intermedia), and late (Porphyromonas gingivalis) colonizers were treated with the oral probiotics and then incubated anaerobically for three days. The effects of oral probiotics on titanium disc biofilm formation were analyzed using culture methods, quantitative polymerase chain reaction (qPCR), and microscopic analysis. Both probiotics significantly inhibited the formation of biofilm, and all eight bacterial species were significantly reduced. The effectiveness of both probiotic strains was confirmed by all the methods used. Oral probiotics may have dramatically reduced the biofilm formation of secondary colonizers that act as bridges, thus inhibiting biofilm formation on the titanium surface. Our results suggest that the probiotic W. cibaria offers new possibilities for the prevention of peri-implant mucositis.

Influence of cigarette smoking on oral microbiota in patients with recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS) is a common recurrent ulcerative disease of the oral mucosa which is closely related to oral microbial composition. However, the specific effect and the mechanism of smoking in RAS are unclear. In this study, 16S rRNA sequencing technology was used to compare the differences in saliva microbial community between 28 non-smoking healthy controls (NSctrl), 31 non-smoking RAS patients (NSras), and 19 smoking RAS patients (Sras). The results showed that the bacterial community diversity in patients with RAS (NSras and Sras) was lower than that of NSctrl. The microbial community in smoking-associated RAS is less diverse and distinct from that of non-smokers. The RAS groups have higher abundance of Veillonella, Rothia, and Sneathia and lower abundance of Bacteroidales, Bacteroides, Wolinella, Moryella, Pyramidobacter, and Christensenellaceae at the genera level. A significantly different abundance of Anaerovorax, Candidatus Endomicrobium, Lactococcus, Sneathia, Veillonella, and Cloacibacterium was observed between the Sras and the NSras group. Notably, there was a significant difference in many species from the genus Prevotella and Treponema between the NSras and the Sras group. Further, the relative abundance of several taxa is correlated with smoking age or frequency, including Megasphaera, Haemophilus, Leptotrichia, and Rothia at the genera level, and Prevotella melaninogenica, Prevotella salivae, Megasphaera micronuciformis, Haemophilus parainfluenzae, Alloprevotella tannerae, Actinomyces naeslundii, Lautropia mirabilis, and Capnocytophaga sputigena at the species level. Among patients with RAS, smoking aggravated the pathways of respiration and human pathogens. Our results suggest that smoking is closely related to changes in the oral microbiota, which may contribute an opposite effect to the pathogenesis of RAS. This study provides new insight and theoretical basis for the cause and pathogenesis of RAS and better prevention and treatment.

Microbial Adhesion and Biofilm Formation on Bioactive Surfaces of Ti-35Nb-7Zr-5Ta Alloy Created by Anodization

This study evaluated the microbial colonization (adhesion and biofilm) on modified surfaces of a titanium alloy, Ti-35Nb-7Zr-5Ta, anodized with Ca and P or F ions, with and without silver deposition. The chemical composition, surface topography, roughness (Ra), and surface free energy were evaluated before and after the surface modifications (anodizing). Adhesion and biofilm formation on saliva-coated discs by primary colonizing species (Streptococcus sanguinis, Streptococcus gordonii, Actinomyces naeslundii) and a periodontal pathogen (Porphyromonasgingivalis) were assessed. The surfaces of titanium alloys were modified after anodizing with volcano-shaped micropores with Ca and P or nanosized with F, both with further silver deposition. There was an increase in the Ra values after micropores formation; CaP surfaces became more hydrophilic than other surfaces, showing the highest polar component. For adhesion, no difference was detected for S. gordonii on all surfaces, and some differences were observed for the other three species. No differences were found for biofilm formation per species on all surfaces. However, S. gordonii biofilm counts on distinct surfaces were lower than S. sanguinis, A. naeslundii, and P. gingivalis on some surfaces. Therefore, anodized Ti-35Nb-7Zr-5Ta affected microbial adhesion and subsequent biofilm, but silver deposition did not hinder the colonization of these microorganisms.

Assessment of Disinfection Potential of Q-Switch Nd: YAG Laser on Contaminated Titanium Implant Surfaces

Peri-implantitis (PI) is a relatively frequent pathology that compromises the overall survival of the dental implant. Adjunctive approaches for the conventional mechanical debridement are being suggested to optimize the treatment of PI. The goal of the study was the assessment of the disinfection potential of the Q-Switch Nd: YAG laser on contaminated titanium implant surfaces. A total of 72 sterile titanium discs were used and divided into three groups: 24 contaminated titanium discs treated with the laser (study Group L), 24 contaminated titanium discs with no treatment (control 1—Group C), and 24 sterile titanium discs with no treatment (control 2—Group S). Multi-species biofilm was used: Porphyromonas gingivalis, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, Streptococcus sobrinus, and Prevotella intermedia. Commensal bacteria were included also: Actinomyces naeslundii, Actinomyces viscosus, Streptococcus cristatus, Streptococcus gordonii, Streptococcus mitis, Streptococcus oralis, Streptococcus sanguinis, Streptococcus parasanguinis, and Veillonella parvula. Parameters delivered per pulse on the targeted surfaces of the titanium discs were an energy density of 0.597 J/cm2 each pulse, a pulse power of 270 mW, a laser beam spot of 2.4 mm in diameter, and a rate of repetition of 10 Hertz (Hz) for a pulse duration of 6 nanoseconds (ns). The mode was no contact, and a distance of 500 micrometers was used with a total time of irradiation equal to 2 s (s). The collection of microbiological samples was made for all groups; colony-forming units (CFU) were identified by two different practitioners, and the average of their examinations was considered for each sample. The average of the TBC (CFU/mL) was calculated for each group. Values were 0.000 CFU/mL, 4767 CFU/mL, and 0.000 CFU/mL for Group L, Group C, and Group S, respectively. Therefore, the suggested treatment protocol was able to provoke a total disinfection of the contaminated titanium surfaces. A statistical difference was only found between Group L vs. Group C and between Group S vs. Group C. The difference was not significant between Group S and Group L. In conclusion, the present study confirmed that the Q-Switch Nd: YAG laser under our specific conditions can provide a total disinfection of the contaminated titanium surfaces.

Identification of Substances Produced by Cercospora brachiata in Absence of Light and Evaluation of Antibacterial Activity

Cercospora brachiata is a phytopathogenic fungus. To know more about the metabolites produced by this fungus, the objective of this work was to identify, isolate and characterize substances present in extracts of the growth broth and mycelium, using gas chromatography with mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). It was also objective to evaluate the antibacterial activity of the extracts. Among the compounds identified, fatty acids, esters, and steroids can be highlighted. The main compounds identified are 9-hexadecenoic, hexadecenoic, oleic, octadecanoic, lauric, myristic, palmitic, doceno-13-enoic, stearic, linoleic, and nonadecanoic acids present in almost all extracts. For the antibacterial activity, the broth microdilution method was used. The ethyl acetate extract of the mycelium presented inhibitory concentrations (MICs) against the bacterium Actinomyces naeslundii (100 μg mL−1) and Streptococcus sanguinis (200 μg mL−1). Finally, two steroids were isolated and identified in the hexane extract of mycelium: ergosta-6,22-dien-3β,5α,8α-triol and brassicasterol.

ANALYSIS OF MICROBLE LANDSCAPE IN CHILDREN WITH DISEASES

Выявляемость патогенных и условно- патогенных микроорганизмов было в два раза выше в основной группе (24 изолята), чем в контрольной- 12 изолят. Немаловажное значение имеет, что у детей с гастродуоденальной патологией отмечается симбиоз патогенных анаэробных микроорганизмов: Escherichia coli5,5%, Enterobacter cloacae2,7%, Enterobacter aerogenes2,7%, Pantoea agglomerans2,7%, Pseudomonas putida2,7%, Veillonella spp. 2,7%, Parvimonas micra 2,7%, Actinomyces naeslundii2,7%, Actinomyces meyeri2,7%, Clostridium histolyticum2,7% , которые усугубляют течение заболевания. При этом сравнительная характеристика показало, анаэробных штаммов высеяно в основной группе в 84,6% случаях по сравнению с контрольной - 15,4%. The detectability of pathogenic and opportunistic microorganisms was twice as high in the main group (24 isolates) than in the control group (12 isolates). It is also important that children with gastroduodenal pathology have a symbiosis of pathogenic anaerobic microorganisms: Escherichia coli 5.5%, Enterobacter cloacae 2.7%, Enterobacter aerogenes 2.7%, Pantoea agglomerans 2.7%, Veudomonas putidaon 2.7%. 2.7%, Parvimonas micra 2.7%, Actinomyces naeslundii 2.7%, Actinomyces meyeri 2.7%, Clostridium histolyticum 2.7%, which aggravate the course of the disease. At the same time, the comparative characteristics showed that anaerobic strains were sown in the main group in 84.6% of cases compared to the control group - 15.4%.

Synergistic Effect of Plant Extracts on Endodontic Pathogens Isolated from Teeth with Root Canal Treatment Failure: An In Vitro Study

Background and objectives: This study aimed to evaluate the synergistic antimicrobial activity of extracts obtained from Salvadora persica (Miswak), Commiphora molmol (myrrh) and Azadirachta indica (neem) in combination with commercially available antimicrobial agents: penicillin, tetracycline, ofloxacin and fluconazole on endodontic pathogens such as Enterococcus faecalis, Streptococcus mitis, Actinomyces naeslundii and Candida albicans. Materials and Methods: Microbiological samples from the root canals of the teeth undergoing retreatment were taken using sterile paper points kept at full length in the canal for 30 seconds. The disc diffusion method was used to check the susceptibility of microbes to the plant extracts and antimicrobials by measuring the diameter of the inhibition zones. Against the microbes, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)/minimum fungicidal concentration (MFC) of the plant extracts were assessed. The fractional inhibitory concentration index (FICI) was used to estimate the synergistic effect of plant extracts combined with antimicrobials against the resistant endodontic microbes. Results: The findings clearly indicate the effectiveness of all the three plant extracts, Commiphora molmol, Azadirachta indica, Salvadora persica, against all the experimental pathogenic microorganisms except for the ineffectiveness of Azadirachta indica, Salvadora persica against Candida albicans. Maximum antimicrobial activity was displayed by Azadirachta indica against Enterococcus faecalis (MIC = 0.09 ± 1.2 mg/mL, MBC = 0.78 ± 1.25 mg/mL) and the minimum antimicrobial activity was displayed by Commiphora molmol against Actinomyces naeslundii (MIC = 12.5 ± 3.25 mg/mL, MBC = 100 ± 3.75 mg/mL). The best synergy was displayed by Commiphora molmol with fluconazole against Candida albicans (FICI = 0.45). Conclusions: The current study delineates the variable antimicrobial activity of plant extracts against the experimental endodontic pathogenic microorganisms. Plant extracts in conjunction with various antimicrobials can be valuable aids in combating relatively resistant endodontic microorganisms that have been the cause of worry in recent years, leading to failure even in treatment procedures following all required protocols.

Clonal Relationship within Two Oral Actinomyces Populations Collected from Plaque of Periodontitis Patients

Actinomyces naeslundii and A. oris are dental plaque formers involved in the pathogenesis of periodontitis. The aim of the study was to investigate the clonal relationship within two oral Actinomyces populations collected from plaque of patients with chronic periodontitis. The 223 clinical strains of A. naeslundii and A. oris were isolated from biofilm samples collected supra and subgingivally from teeth with shallow (probing depth (PD) = 3-4 mm), deep (PD = 5-6 mm) and very deep (PD ≥7 mm) pockets from 20 chronic periodontitis patients. All strains were submitted to repetitive sequence-based PCR typing using DiversiLab (BioMerieux,Marcy l´Étoile, France). Seven patients harboured only unrelated (<95% similarity) multiple isolates, while 13 harboured both similar (>95% similarity) and unrelated isolates at different sites. Identical (>98% similarity) strains were found to be present in the subgingival shallow depths more often than in the other subgingival depths. The number of clones in individual patients varied from 2 to 17 different rep-PCR genotypes. The clonal relationship within the oral populations of A. naeslundii and A. oris in an individual was unpredictable, ranging from the presence of multiple genotypes with no clonal similarity to only two different clones supra or subgingivally at different sites.

Antibacterial effect of silver diamine fluoride and potassium iodide against E. faecalis, A. naeslundii and P. micra

Background The aim of this study was to determine in vitro the bactericidal potential of 38% silver diamine fluoride (SDF) alone, potassium iodide (PI) alone, and the two in combination (SDF + PI) against three bacterial species commonly found in root canal samples (Enterococcus faecalis, Actinomyces naeslundii and Parvimonas micra). Methods The potential bactericidal rates for SDF, PI and SDF + PI against E. faecalis, A. naeslundii and P. micra were calculated as reduction of bacteria colony forming units. Results The bactericidal potential of SDF was at 99.97–100% against E. faecalis and 100% against A. naeslundii and P. micra. SDF + PI showed a 100% bactericidal effect against P. micra, 99.89–99.98% against E. faecalis and 99.98–100% against A. naeslundii. The bactericidal effect of PI was 99.51–99.98% against E. faecalis, 99.27–99.95% against A. naeslundii and 99.93–100% against P. micra. The differences between controls and bacteria exposed to the antibacterial agents were statistically significant (p < 0.05). Conclusions SDF had an effective bactericidal effect against the examined bacteria. However, the limitations of this in vitro study do not allow a recommendation of the employment of these solutions as root canal irrigants. Additional investigations are necessary to assess their endodontic clinical applicability.