Journal of Oral Microbiology最新文献

Background: Periodontitis is caused by a dysbiotic shift in the dental plaque microbiome. Fusobacterium nucleatum is involved in the colonization of Porphyromonas gingivalis, which plays a key role in dysbiosis, via coaggregation and synergy with this microorganism.

Aim: We investigated the effect of diffusible signaling molecules from P. gingivalis ATCC 33277 on F. nucleatum TDC 100 to elucidate the synergistic mechanisms involved in dysbiosis.

Methods: The two species were cocultured separated with an 0.4-µm membrane in tryptic soy broth, and F. nucleatum gene expression profiles in coculture with P. gingivalis were compared with those in monoculture.

Results: RNA sequencing revealed 139 genes differentially expressed between the coculture and monoculture. The expression of 52 genes was upregulated, including the coaggregation ligand-coding gene. Eighty-seven genes were downregulated. Gene Ontology analysis indicated enrichment for the glycogen synthesis pathway and a decrease in de novo synthesis of purine and pyrimidine.

Conclusion: These results indicate that diffusible signaling molecules from P. gingivalis induce metabolic changes in F. nucleatum, including an increase in polysaccharide synthesis and reduction in de novo synthesis of purine and pyrimidine. The metabolic changes may accelerate biofilm formation by F. nucleatum with P. gingivalis. Further, the alterations may represent potential therapeutic targets for preventing dysbiosis.

Background: Many antimicrobial compounds in mouthwashes can have a negative impact on the oral microbiome. O-cymen-5-ol, a compound derived from a phytochemical, has a targeted mode of action and is being used as an alternative. However, its effect on the native oral microbiome is unknown.

Aim: To assess the effect of a mouthwash formulated with o-cymen-5-ol and zinc chloride on the oral microbiome of healthy individuals.

Methods: A mouthwash formulated with o-cymen-5-ol and zinc chloride was administered to a cohort of 51 volunteers for 14 days, while another cohort of 49 volunteers received a placebo. The evolution of the oral microbiome in both groups was analysed using a metataxonomic approach.

Results: Analysis of the oral microbiome showed that the mouthwash selectively targeted potential oral pathogens while maintaining the integrity of the rest of the microbiome. Specifically, the relative abundance of several potentially pathogenic bacterial taxa, namely Fusobacteriota, Prevotella, Actinomyces, Granulicatella, Abiotrophia, Lautropia, Lachnoanaerobaculum, Eubacterium (nodatum group) and Absconditabacteriales (SR1) decreased, while the growth of Rothia, a nitrate-reducing bacterium beneficial for blood pressure, was stimulated.

Conclusions: The use of o-cymen-5-ol and zinc chloride as antimicrobial agents in oral mouthwashes is a valuable alternative to classical antimicrobial agents.

Background: A growing body of evidence demonstrates a different bacterial composition in the oral cavity of patients with oral lichen planus (OLP).

Patients and methods: Buccal swab samples were collected from affected and non-affected sites of six patients with reticular OLP and the healthy oral mucosa of six control subjects. 16S rRNA gene MiSeq sequencing and mass spectrometry-based proteomics were utilised to identify the metataxonomic and metaproteomic profiles of the oral microbiome in both groups.

Results: From the metataxonomic analysis, the most abundant species in the three subgroups were Streptococcus oralis and Pseudomonas aeruginosa, accounting for up to 70% of the total population. Principal Coordinates Analysis showed differential clustering of samples from the healthy and OLP groups. ANCOM-BC compositional analysis revealed multiple species (including P. aeruginosa and several species of Veillonella, Prevotella, Streptococcus and Neisseria) significantly over-represented in the control group and several (including Granulicatella elegans, Gemella haemolysans and G. parahaemolysans) in patients with OLP. The metaproteomic data were generally congruent and revealed that several Gemella haemolysans-belonging peptidases and other proteins with inflammatory and virulence potential were present in OLP lesions.

Conclusion: Our data suggest that several bacterial species are associated with OLP. Future studies with larger cohorts should be conducted to determine their role in the aetiology of OLP and evaluate their potential as disease biomarkers.

Dental caries is an infectious disease that is a major concern for dentists. Streptococci and Lactobacilli were long thought to be the primary etiology responsible for caries. Candida albicans with acidogenic and aciduric characteristics has recently been implicated in the onset and progression of cariogenic lesions. Moreover, due to the increased resistance to common antimicrobials, the discovery of innovative candidates is in high demand. Therefore, our study might be the first report that explores the efficacy of glass ionomer cement (GIC) incorporated with a newly modified carboxylated chitosan derivative (CS-MC) against multidrug-resistant (MDR) and/or pandrug resistant (PDR) C. albicans isolated from the oral cavity. In this work, four CS-MC-GIC groups with different concentrations were formulated. Group four (CS-MC-GIC-4) gave a significant performance as an anticandidal agent against selected PDR Candida strain, with an obvious decrease in its cell viability and high antibiofilm activity. It also, enhanced all the mechanical properties and supports cell viability of Vero cells as a nontoxic compound. Moreover, CS-MC-GIC-4 inhibited neuraminidases completely, which might provide a novel mechanism to prevent dental/oral infections. Thus, findings in this study open up new prospect of the utilization of CS-MC-GIC as a novel dental filling material against oral drug-resistant Candida.

Background: We aimed to explore saliva microbiome alterations in dental fluorosis population.

Methods: The prevalence of dental fluorosis was examined in 957 college students. Dean's fluorosis index was used to evaluate the dental fluorosis status. Changes in the composition of the salivary microbiome were assessed in a subset of these patients (100 healthy controls, 100 dental fluorosis patients).

Results: Dental fluorosis affected 47% of the student sample, and incidence was unrelated to gender. Compared with healthy controls, the microbiota of patients with dental fluorosis exhibited increased diversity, with increased abundance of Treponema lecithinolyticum, Vibrio metschnikovii, Cupriavidus pauculus, Pseudomonas, Pseudomonadaceae, Pseudomonadales, and decreased abundance of Streptococcus mutans, Streptococcus sanguinis, Gemella, and Staphylococcales. Function analyses showed increases in arginine biosynthesis in patients affected by dental fluorosis, together with reductions in amino sugar and nucleotide sugar metabolism, fructose and mannose metabolism, and starch and sucrose metabolism.

Conclusions: These results suggest that there are striking differences in salivary microbiome between healthy controls and dental fluorosis patients. Dental fluorosis may contribute to periodontitis and systemic lung diseases. There is a need for cohort studies to determine whether altering the salivary microbiota in dental fluorosis patients can alter the development of oral or systemic diseases.

Background: Mfa1 fimbriae of the periodontal pathogen Porphyromonas gingivalis are responsible for biofilm formation and comprise five proteins: Mfa1-5. Two major genotypes, mfa1⁷⁰ and mfa1⁵³, encode major fimbrillin. The mfa1⁷⁰ genotype is further divided into the mfa1^70A and mfa1^70B subtypes. The properties of the novel mfa1^70B remain unclear.

Methods: Fimbriae were purified from P. gingivalis strains JI-1 (mfa1^70A), 1439 (mfa1^70B), and Ando (mfa1⁵³), and their components and their structures were analyzed. Protein expression and variability in the antigenic specificity of fimbrillins were compared using Coomassie staining and western blotting using polyclonal antibodies against Mfa1^70A, Mfa1^70B, and Mfa1⁵³ proteins. Cell surface expression levels of fimbriae were analyzed by filtration enzyme-linked immunosorbent assays.

Results: The composition and structures of the purified Mfa1 fimbriae of 1439 was similar to that of JI-1. However, each Mfa1 protein of differential subtype/genotype was specifically detected by western blotting. Mfa1^70B fimbriae were expressed in several strains such as 1439, JKG9, B42, 1436, and Kyudai-3. Differential protein expression and antigenic heterogeneities were detected in Mfa2-5 between strains.

Conclusion: Mfa1 fimbriae from the mfa170A and mfa170B genotypes indicated an antigenic difference suggesting the mfa170B, is to be utilized for the novel classification of P. gingivalis.

Background: Dysbiosis of oral microbiome causes chronic diseases including dental caries and periodontitis, which frequently affect older patient populations. Severely disabled individuals with impaired swallowing functions may require nutritional supply via nasogastric (NG) tubes, further impacting their oral condition and possibly microbial composition. However, little is known about the effect of NG tube on oral microbes and its potential ramification.

Methods: By using 16S rRNA amplicon sequencing, we characterized the tongue microbiome of 27 patients fed with NG tubes and 26 others fed orally.

Results: The microbial compositions of NG-tube and oral-feeding patients were substantially different, with more Gram-negative aerobes enriched in the presence of NG tube. Specifically, NG-tube patients presented more opportunistic pathogens like Pseudomonas and Corynebacterium associated with pneumonia and lower levels of commensal Streptococcus and Veillonella. Co-occurrence analysis further showed an inverse relationship between commensal and pathogenic species.

Conclusion: We present a systematic, high-throughput profiling of oral microbiome with regard to long-term NG tube feeding among the older patient population.

Introduction: The oral pathogen Porphyromonas gingivalis is not only associated with periodontitis but also with systemic diseases elsewhere in the body. The mechanisms by which P. gingivalis travels from the oral cavity to other organs in the body are largely unknown. This review describes the four putative mechanisms supported by experimental evidence, which enable translocation of P. gingivalis over the oral mucosa, endothelial barriers and subsequent dissemination into the bloodstream.

Mechanisms: The first mechanism: proteolytic enzymes secreted by P. gingivalis degrade adhesion molecules between tissue cells, and the extracellular matrix. This weakens the structural integrity of the mucosa and allows P. gingivalis to penetrate the tissue. The second is transcytosis: bacteria actively enter tissue cells and transfer to the next layer or the extracellular space. By travelling from cell to cell, P. gingivalis reaches deeper structures. Thirdly, professional phagocytes take up P. gingivalis and travel to the bloodstream where P. gingivalis is released. Lastly, P. gingivalis can adhere to the hyphae forming Candida albicans. These hyphae can penetrate the mucosal tissue, which may allow P. gingivalis to reach deeper structures.

Conclusion: More research could elucidate targets to inhibit P. gingivalis dissemination and prevent the onset of various systemic diseases.

Background: Streptococcus mutans (S. mutans) is a pivotal cariogenic pathogen contributing to its multiple virulence factors, one of which is synthesizing exopolysaccharides (EPS). VicK, a sensor histidine kinase, plays a major role in regulating genes associated with EPS synthesis and adhesion. Here we first identified an antisense vicK RNA (ASvicK) bound with vicK into double-stranded RNA (dsRNA).

Objective: This study aims to investigate the effect and mechanism of ASvicK in the EPS metabolism and cariogenesis of S. mutans.

Methods: The phenotypes of biofilm were detected by scanning electron microscopy (SEM), gas chromatography-mass spectrometery (GC-MS) , gel permeation chromatography (GPC) , transcriptome analysis and Western blot. Co-immunoprecipitation (Co-ip) assay and enzyme activity experiment were adopted to investigate the mechanism of ASvicK regulation. Caries animal models were developed to study the relationship between ASvicK and cariogenicity of S. mutans.

Results: Overexpression of ASvicK can inhibit the growth of biofilm, reduce the production of EPS and alter genes and protein related to EPS metabolism. ASvicK can adsorb RNase III to regulate vicK and affect the cariogenicity of S. mutans.

Conclusions: ASvicK regulates vicK at the transcriptional and post-transcriptional levels, effectively inhibits EPS synthesis and biofilm formation and reduces its cariogenicity in vivo.

Background: The oral cavity can be a reservoir for SARS-CoV-2 and may play a crucial role in the viral transmission in the hospital environment.

Objective: To investigate whether an oral hygiene protocol with chlorhexidine (CHX) used alone and in combination with hydrogen peroxide (HP) in the intensive care unit was effective in reducing the SARS-CoV-2 viral load in the oral cavity.

Methods: SARS-CoV-2 viral load was measured on oral fluid samples collected from patients undergoing orotracheal intubation. The study sample was randomly in: CHX group (n = 19) - oral rinse using only 0.12% CHX solution; HP+CHX group (n = 24) - oral rinse with 1.5% HP and 0.12% CHX. The samples were collected before the interventions (T0), immediately (T1), 30 minutes (T2) and 60 minutes (T3) after the procedure.

Results: A significant viral load reduction was observed at T1 (mean ± SD:-0.57 ± 0.19 log10;-73.2%;p = 0.022) in the HP+CHX group. No statistically significant differences between any time points were observed in the CHX group.

Conclusion: The HP+CHX oral rinses significantly reduced the SARS-CoV-2 viral load in the oral fluid immediately after the procedure. The CHX oral rinse alone did not result in any significant viral load reductions.