Taxonomic abundance in primary and secondary root canal infections

The potential regulatory role of mannose phosphotransferase system EII in alkaline resistance of Enterococcus faecalis

Objective

To investigate the role of mannose phosphotransferase system (Man-PTS) EII in the alkaline resistance of Enterococcus faecalis (E. faecalis).

Methods

The Man-PTS EIID (mptD) deletion (ΔmptD) and overexpressing (+mptD) strains of E. faecalis were constructed. The contribution of the Man-PTS EII to alkaline resistance was investigated by assessing growth and biofilm formation of E. faecalis at pH 7 and 10, as well as changes in intracellular ATP levels, pH, potassium ion concentration, membrane potential and membrane permeability. The effects of mptD on the expression of other Man-PTS EII components and membrane transport-related genes were evaluated by RT-qPCR at pH 10. In addition, six clinical strains were isolated. Three strains of E. faecalis with high to low alkaline resistance were screened, and RNA sequencing was performed to further explore the role of Man-PTS EII in the alkaline resistance.

Results

mptD enhanced the alkaline resistance of E. faecalis by maintaining pH homeostasis in an alkaline environment. Overexpression of mptD induced membrane hyperpolarization, reduced membrane permeability, decreased intracellular K+ levels, lowered cytoplasmic pH, and elevated ATP production, while the loss of mptD reversed these effects (p < 0.05). mptD coordinated the expression of Man-PTS EII components and upregulated genes encoding membrane transporter components (p < 0.01). All Man-PTS EII components were positively related to the degree of alkaline resistance of E. faecalis (p < 0.05).

Conclusion

Man-PTS EII is a key factor in the interaction between metabolism and ion membrane transport during the alkaline resistance process of E. faecalis. This study may provide new insights for understanding the alkaline resistance of E. faecalis.

Comparative analysis of deep dentinal caries microbiota in teeth with normal pulp, reversible pulpitis, symptomatic and asymptomatic irreversible pulpitis

AIM

To characterize the deep dentinal caries microbiota in teeth diagnosed with normal pulp with deep caries (NP), reversible pulpitis (RP), symptomatic irreversible pulpitis (SIP), and asymptomatic irreversible pulpitis (AIP), and to identify potential key pathogens associated with pulpitis progression, exploring their roles in disease advancement.

METHODOLOGY

In this cross-sectional study, we collected 108 dentinal caries samples, categorized into NP (n = 27), RP (n = 27), SIP (n = 27), and AIP (n = 27), according to the American Association of Endodontists' diagnostic criteria. 2 NP samples and 2 RP samples were excluded due to contamination. Samples were processed using Illumina MiSeq high-throughput sequencing. Alpha and beta diversity, taxa abundance differences, co-occurrence network analysis, and functional prediction were evaluated. Correlation analysis between the abundance of bacteria associated with clinical diagnosis, clinical signs, and pulp exposure status was performed with Spearman analysis and the Mantel test.

RESULTS

The bacteriome of deep dentinal caries exhibited statistically significant differences among NP, RP, SIP, and AIP groups. NP and RP showed similar microbial community structures, with comparable alpha diversity, beta diversity, bacterial phenotypes, functions, and network structures. In contrast, AIP and SIP displayed distinct microbial community profiles. AIP was characterized by higher alpha diversity and a greater abundance of gram-negative bacteria, with Propionibacterium and Prevotella_7 identified as bacteria associated with AIP pathogenesis. On the other hand, SIP showed lower alpha diversity and a higher abundance of facultative anaerobes, with Lactobacillus and Limosilactobacillus identified as bacteria associated with SIP pathogenesis. Fusobacterium, Prevotella, Treponema, and Selenomonas were identified as bacteria associated with both AIP and SIP. Compared to NP and RP, the microbial networks in AIP and SIP are more complex and contain more gram-negative endodontic pathogens. These pathogens form complex positive correlations with each other and numerous negative correlations with lactic acid bacteria.

CONCLUSIONS

The bacteriome of deep dentinal caries differs significantly across teeth diagnosed with NP, RP, AIP, and SIP. NP and RP exhibit similar microbial communities, whereas SIP and AIP display distinct microbial profiles.

Antibacterial effect of femtosecond laser against Enterococcus faecalis and Fusobacterium nucleatum biofilms on dentin: an in vitro study

BACKGROUND

Removing infectious bacteria biofilms from the root canal system is crucial for a successful endodontic treatment. This study investigated the antibacterial effect of femtosecond laser (fs-laser) against Enterococcus faecalis (E. faecalis) and Fusobacterium nucleatum (F. nucleatum) biofilms on dentin.

METHODS

The chemical composition of dentin slices from extracted human teeth was analyzed using FTIR and Raman probes. The morphology of fs-laser ablated dentin grooves was evaluated by an optical profiler, and the fs-laser ablation fluence threshold was obtained by a mathematical model. A correlation between dentin chemical composition and ablation threshold was established. The antibacterial effect of different fs-laser irradiation dosages within the safe threshold on E. faecalis and F. nucleatum biofilms was firstly evaluated using the growth curve method. The biofilm removal efficacy on dentin and antimicrobial effect in dentinal tubules was further evaluated by CLSM and SEM analysis. The effect of fs-laser irradiation on the microhardness of dentin surface was also evaluated. The fs-laser irradiation process was observed using a spectrometer.

RESULTS

The peak intensity of phosphate group showed a positive correlation to the fs-laser dentin ablation fluence threshold in both FTIR and Raman spectroscopy. The safe fluence threshold of 1.8 J/cm2 was determined by a prediction model on 20 dentin samples. The antimicrobial effect of fs-laser increased along with the irradiation fluence or time. Both E. faecalis and F. nucleatum biofilms on dentin could be effectively removed by the fs-laser with 1.5 J/cm2 fluence for 20 s without compromising the microhardness of dentin surface. Meanwhile, fs-laser could also eliminate the bacteria in dentinal tubules. The generation of plasma occurred during the fs-laser irradiation process, and the plasma spectra exhibited distinguishable characteristics between the two kinds of biofilms.

CONCLUSIONS

Fs-laser could effectively remove both E. faecalis and F. nucleatum biofilms on dentin, along with a notable antibacterial effect in dentinal tubules.

Reactivation of Epstein-Barr virus by n-butyric acid from Pseudoramibacter alactolyticus induces inflammatory cytokines in periapical granulomas

OBJECTIVES

This study investigates whether latent Epstein-Barr virus (EBV) can be reactivated by n-butyric acid from Pseudoramibacter alactolyticus, and if such reactivation induces expression of interleukin (IL)-1β and IL-6 in periapical granulomas.

METHODS

We analyzed periapical granulomas and healthy gingival tissues to detect the presence of EBV and P. alactolyticus. The concentration of n-butyric acid in P. alactolyticus culture supernatants was measured. BZLF-1 luciferase assays were conducted with or without these supernatants. Immunohistochemical detection of ZEBRA-, IL-1β-, and IL-6-expressing cells was performed in the tissue samples. Additionally, mRNA expression levels of BZLF-1, IL-1β, and IL-6 were quantified and statistically analyzed for correlation. The expression of these mRNAs was also measured in Daudi cells treated with or without the culture supernatants.

RESULTS

Both EBV and P. alactolyticus were detected in periapical granulomas, but not in healthy tissues. The concentration of n-butyric acid in the culture supernatants was ∼3.58 mmol/L. BZLF-1 luciferase activity in the presence of the culture supernatants was comparable to that of commercially available butyric acid, whereas no activity was detected without the supernatants. Cells expressing ZEBRA co-expressed IL-1β and IL-6. The mRNA levels of IL-1β and IL-6 in periapical granulomas were correlated with BZLF-1 mRNA levels. Daudi cells treated with the culture supernatants expressed BZLF-1, IL-1β, and IL-6 mRNA, while those without the supernatants did not.

CONCLUSIONS

The study concludes that EBV can be reactivated by n-butyric acid produced by P. alactolyticus, leading to the induction of IL-1β and IL-6 expression in periapical granulomas.

A Methodological Study on Microbial In Vivo Sampling Methods of Root Canal Microbiota for Next-Generation Gene Sequencing Analysis

INTRODUCTION

The aim was to evaluate the suitability of paper points or endodontic nickel-titanium files to sample microorganisms for in vivo investigation of endodontic microbiota by 16S ribosomal DNA (rDNA) sequencing.

METHODS

Forty-five patients presenting clinical and radiological signs of apical periodontitis were recruited for sampling, giving their written informed consent. Glide paths were assessed using C-Pilot Files and K-Files under electronic root canal length control under aseptic conditions. Microbial samples were taken from 84 root canals in duplicate, the first sample with a sterile paper point (size 15), the second with a sterile file (size 20/.06). After DNA extraction, the hypervariable region V4 of the bacterial 16 S rRNA gene was amplified and sequenced (Illumina MiSeq). Sequencing data were trimmed with Cutadapt and exact amplicon sequence variants generated by DADA2. Taxonomy was assigned based on the Human Oral Microbiome Database (eHOMD). Statistical analysis of diversity parameters comprised Wilcoxon signed-rank tests and permutational analysis of variance (PERMANOVA). Compositional differences were evaluated by differential abundance analysis (DESeq2). Microbial contamination during the sampling process and analysis were evaluated.

RESULTS

Concerning alpha diversity, richness and dissimilarity differed nonsignificantly between paper point and instrument samples (P > .05), whereas a significant difference was observed in the Shannon index (P < .05). Regarding beta diversity, paper point and instrument samples presented with similar microbial community compositions (P = 1.0, PERMANOVA). Paper point controls contained significantly higher proportions of Pseudomonadales (P < .05).

CONCLUSIONS

Paper point and endodontic instrument sampling generate valid specimens for 16S rDNA community profiling. Endodontic instrument sampling is easier to execute and, therefore, could be the technique of choice.

Microbial diversity in primary endodontic infections: demographics and radiographic characteristics

OBJECTIVE

To analyze if the microbiome community composition in primary endodontic infections is associated with clinical or radiographic factors.

MATERIALS AND METHODS

Seventy-one patients with primary endodontic infections were evaluated for percussion tenderness, presence of a sinus tract, presence of caries, sex, probing depth > 4 mm, and age. Samples from the root canals were obtained and the microbiome was subsequently characterized by 16 S rRNA amplicon sequencing. For the radiographic analysis, a subset of 12 samples with a periapical index (PAI) ≤ 2 were compared with 19 samples with PAI of 5. The Shannon and Chao1 indices were used to measure alpha diversity. Differences in abundances of genera were evaluated using the Kruskal-Wallis test with Bonferroni's correction. Differences in community composition were evaluated using analysis of similarity (ANOSIM) with Bray-Curtis dissimilarity matrices.

RESULTS

No significant differences in microbiome composition relative to clinical factors were found using ANOSIM. Teeth within the two categories of periapical index showed a similar number of species richness, and alpha diversity values P > 0.05. Community composition was significantly affected by the periapical index (ANOSIM P = 0.039, R = 0.10). Larger radiographic lesions demonstrated significant increase in Prevotellaceae, Olsenella, and the motile bacteria Oribacterium, Selenomonadaceae spp., and Treponema.

CONCLUSION

Clinical factors associated with apical periodontitis have a limited impact on the root canal microbiome composition. Community composition appears to be affected in teeth with large apical lesions.

Clinical Investigation of Bacteriome in Primary Endodontic Infections With Apical Periodontitis Using High-Throughput Sequencing Analysis

INTRODUCTION

This study characterized the bacteriome in primary endodontic infection (PEI) with apical periodontitis (AP), identified core and rare bacteriome species and community diversity metrics, and analyzed the relationship between the bacteriome composition, diversity and features, and patient variables.

METHODS

Twenty-seven patients with PEI and AP were sampled. The DNA was extracted and quantified using quantitative polymerase chain reaction. Raw V3-V4 amplicon sequencing data were processed with the DADA2 pipeline to generate amplicon sequence variants, and taxonomic assignment of the amplicon sequence variants up to the species level was done against the Human Oral Microbiome Database. Core bacteriome and differential abundance analyses were performed using ANCOM. Alpha diversity was determined using Chao1, Shannon, and Simpson indexes. LeFse analysis was used to identify abundant taxa. Sparse Estimation of Correlations among Microbiomes analysis estimated linear and nonlinear relationships among bacteria.

RESULTS

Of 27, 24 root canal samples were analyzed, and 3 root canal sampling were filtered out with a low read count. The bacterial phyla with top mean relative abundance were Bacteroidetes, Firmicutes, Synergistetes, Fusobacteria, and Actinobacteria. A total of 113 genera and 215 species were identified. The samples were gathered into 3 clusters. LefSe analysis identified differences in abundant taxa between distinct age, gender, symptomatology, and lesion size groups. Sparse Estimation of Correlations among Microbiomes distance analysis indicated Slackia exigua as the node with the highest degree.

CONCLUSIONS

The bacteriome in PEI with AP among the patients in this study was complex and displayed high microbial heterogeneity. Moreover, age, gender, symptomatology, and lesion size were associated with differences in bacteriome features in PEI with AP.

Comparative analysis of hydrophobicity and dentin adhesion ability in Candida albicans strains

OBJECTIVE

Adhesion to dentin is a first step for a successful microbial root canal colonization. Cell hydrophobicity seems to have some influence in the Candida species adhesion to surfaces. To measure cell surface hydrophobicity and to investigate the adherence ability to human dentin among Candida albicans strains isolated from root canal and lingual dorsum via an in vitro study.

METHODOLOGY

adhesion was quantified in function of dentin area covered by blastospores and/or hyphae presence detected by epifluorescence microscope. Cell surface hydrophobicity was estimated by assessing the percentage migration of cells from an aqueous phase to a hydrocarbon phase. Contact angles were measured by the sessile drop technique on the dentin surface using a contact angle measurements apparatus. We also examined the correlation between adhesion ability and hydrophobicity.

RESULTS

although there was some intra-species variation in cell surface hydrophobicity, most isolates were characterized by moderate hydrophobicity. There was no significant difference in this parameter when the isolation niche was considered. Both root canal and lingual dorsum yeasts were able to adhere to dentin. No association was found between the strains' site of isolation and adhesion. Moreover, cell surface hydrophobicity and adhesion ability were not correlated.

CONCLUSION

although hydrophobicity can influence Candida albicans virulence in many ways, this study suggests that this parameter by itself was not a good predictor of adhesion to dentin.

Impact of root canal disinfection on the bacteriome present in primary endodontic infection: A next generation sequencing study

AIM

To investigate the bacteriome present in teeth with primary endodontic infection (PEI) and apical periodontitis (AP) and to determine quantitatively and qualitatively the impact of chemomechanical preparation (CMP) using 2.5% sodium hypochlorite NAOCl on the bacteriome found in PEI with AP using the Illumina MiSeq platform.

METHODOLOGY

Thirty-six paired samples from 18 patients were successfully sequenced and analysed. Samples were collected at two sampling times: before (s1) and after (s2) CMP using 2.5% NaOCl. The DNA was extracted from s1 and s2 samples and quantified using quantitative PCR (qPCR). All 36 samples were sequenced using the Illumina MiSeq platform. Raw V3-V4 amplicon sequencing data were processed with the DADA2 pipeline to generate amplicon sequence variants (ASVs). Alpha diversity metrics representing abundance (Chao1) and diversity and evenness (Shannon, Simpson) were computed. The paired-sample Wilcoxon's test was used to compare alpha diversity metrics and qPCR counts between s1 and s2. The PERMANOVA method (with 999 permutations) was applied to compare community composition between sample types (s1 versus s2) and between patient IDs. ALDEx2 (ANOVA-like differential expression tool for high-throughput sequencing data) to investigate differentially abundant taxa between s1 and s2. A paired-sample Wilcoxon's test was used to compare alpha diversity metrics and qPCR counts between s1 and s2.

RESULTS

The qPCR counts were significantly higher in s1 compared to s2 (p = .0007). The Chao1 index indicated no difference in alpha diversity (p < .7019); whereas Shannon (p = .0056) and Simpson (p = .02685) indexes showed higher values in s2. The PERMANOVA test using Adonis2 showed a significant effect of sample time on community composition (R2 = .0630, p = .012). Patient ID also showed a significant effect on community composition (R2 = .6961, p = .001). At the genus level, Dialister, Mogibacterium, Prevotella, and Olsenella were differentially enriched at s1, while Actinomyces, Stenotrophomonas_unclassified, Enterococcus_unclassified, and Actinomyces_unclassified were differentially enriched in s2.

CONCLUSION

The bacteriome present in teeth with PEI with AP is complex and diverse. CMP using 2.5% NaOCl showed a high quantitatively and qualitatively disinfectant impact on the bacteriome present in PEI with AP.

Microbiota Association and Profiling of Gingival Sulci and Root Canals of Teeth with Primary or Secondary/Persistent Endodontic Infections

INTRODUCTION

Microbiota associated with primary endodontic infection (PEI) and secondary/persistent endodontic infection (SPEI) must be characterized to elucidate pathogenesis in apical periodontitis and bacterial biomarkers identified for diagnostic and therapeutic applications.

METHODS

This study analyzed the microbial community profiles of root canals and gingival sulci (sulcus-E) for teeth with PEI (n = 10) or SPEI (n = 10), using the Illumina MiSeq platform. Bacterial samples from gingival sulci (sulcus-C) of healthy contralateral teeth served as controls.

RESULTS

There were 15 phyla, 177 genera, and 340 species identified. The number and diversity of bacteria in root canals did not differ significantly between PEI and SPEI. Proteobacteria, Firmicutes, Fusobacteria, Bacteroidetes, and Actinobacteria were the dominant phyla in both groups. At the genus level, Lancefieldella, Bifidobacterium, Stomatobaculum, and Schaalia were enriched in root canals with SPEI. Of significance, Lancefieldella was observed in both root canals and sulcus-E of teeth with SPEI. At the species level, Neisseria macacae, Streptococcus gordonii, Bifidobacterium dentium, Stomatobaculum longum, and Schaalia odontolytica were increased significantly in root canals with SPEI compared to PEI. Oribacterium species, Streptococcus salivarius, Lancefieldella parvula, Prevotella denticola, and Oribacterium asaccharolyticum were more abundant in sulcus-E of teeth with SPEI compared to PEI.

CONCLUSIONS

There were distinctive and differing predominant bacterial species associated with the root canals and gingival sulci between teeth with PEI and SPEI. Specific bacteria identified in sulcus-E and root canals of teeth with SPEI could serve as noninvasive diagnostic biomarkers for detecting SPEI.

Molecular analyses indicate profuse bacterial diversity in primary and post- treatment endodontic infections within a cohort from the United Arab Emirates-A preliminary study

OBJECTIVE

Endodontic microbiota appears to undergo evolutionary changes during disease progression from inflammation to necrosis and post-treatment. The aim of this study was to compare microbiome composition and diversity in primary and post-treatment endodontic infections from a cohort of patients from the UAE.

DESIGN

Intracanal samples were collected from primarily infected (n = 10) and post-treatment infected (n = 10) root canals of human teeth using sterile paper points. Bacterial DNA was amplified from seven hypervariable regions (V2-V4 and V6-V9) of the 16S rRNA gene, then sequenced using next-generation sequencing technology. The data was analyzed using appropriate bioinformatic tools.

RESULTS

Analyses of all the samples revealed eight major bacterial phyla, 112 genera and 260 species. Firmicutes was the most representative phylum in both groups and was significantly more abundant in the post-treatment (54.4%) than in primary (32.2%) infections (p>0.05). A total of 260 operational taxonomic units (OTUs) were identified, of which 126 (48.5%) were shared between the groups, while 83 (31.9%) and 51 (19.6%) disparate species were isolated from primary and post-treatment infections, respectively. A significant difference in beta, but not alpha diversity was noted using several different indices (p< 0.05). Differential abundance analysis indicated that, Prevotella maculosa, Streptococcus constellatus, Novosphigobium sediminicola and Anaerococcus octavius were more abundant in primary infections while Enterrococcus faecalis, Bifidobacterium dentium, Olsenella profusa and Actinomyces dentalis were more abundant in post-treatment infections (p <0.05).

CONCLUSION

Significant differences in the microbiome composition and diversity in primary and post-treatment endodontic infections were noted in our UAE cohort. Such compositional differences of microbiota at various stages of infection could be due to both intrinsic and extrinsic factors impacting the root canal ecosystem during disease progression, as well as during their therapeutic management. Identification of the key microbiota in primarily and secondarily infected root canals can guide in the management of these infections.

Exploring the root canal microbiome in previously treated teeth: A comparative study of diversity and metabolic pathways across two geographical locations

AIM

To analyse and compare the root canal microbiome present in root-filled teeth of two different geographical populations, and to study their functional potential using a next-generation sequencing approach.

METHODOLOGY

Sequencing data obtained from surgical specimens from previously treated teeth with periapical bone loss from Spain and USA were included in the study. Taxa were classified using SILVA v.138 database. Differences in genera abundances among the 10 most abundant genera were evaluated using a Kruskal-Wallis test. Alpha diversity indices were calculated in mothur. The Shannon and Chao1 indices were used. Analyses of similarity (ANOSIM) to determine differences in community composition were done in mothur, with Bonferroni correction for multiple comparisons. p-Values < .05 were considered statistically significant. Identification of enriched bacteria function prediction in the study groups (KEGG pathways) was carried out by linear discriminant analysis effect size (LEfSe) via Python 3.7.6.

RESULTS

A greater alpha-diversity (Shannon and Chao1 indices) was observed from samples obtained in Spain (p = .002). Geography showed no significant effects on community composition via an ANOSIM using Bray-Curtis dissimilarities (R = 0.03, p = .21). Bacterial functional analysis prediction obtained by PICRUSt showed that 5.7% KEGG pathways differed between the Spain and US samples.

CONCLUSIONS

The taxonomic assessment alone does not fully capture the microbiome's differences from two different geographical locations. Carbohydrate and amino acid metabolism were enriched in samples from Spain, while samples from USA had a higher representation of pathways related to nitrogen, propanoate metabolism, and secretion systems.

Identification of keystone taxa in root canals and periapical lesions of post-treatment endodontic infections: Next generation microbiome research

AIM

The aim of this study was to analyse and compare the microbiome present in root canals and periapical lesions of teeth with post-treatment infections, and to identify the presence of keystone taxa in both habitats using next-generation sequencing analysis.

METHODOLOGY

Apices and periapical lesions of patients with post-treatment apical periodontitis were surgically extracted. Specimens were cryo-pulverized, bacterial DNA was extracted, and the V3-V4 hypervariable regions of the 16S rRNA gene were sequenced using the Illumina Miseq platform. Bioinformatic analysis was carried out with Mothur software, whilst diversity indices were obtained using operational taxonomic units (OTUs). The diversity indices were compared with the Kruskal-Wallis test, and community composition differences were explored with Permutational Multivariate Analysis of Variance (PERMANOVA). A bacterial functional study was performed with the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. Co-occurrence network analyses were performed using the Sparse Correlations for Compositional data (SparCC). Eigencentrality, clr-based abundance and ubiquitousness were applied to infer keystone taxa. P values <.05 were considered statistically significant.

RESULTS

Thirty-two apices and thirty-nine periapical lesions were sequenced and analysed. A similar alpha-diversity (p < .05) and community composition (p = .91) was observed for apices and lesion samples. The most abundant OTUs identified amongst all samples included Fusobacterium nucleatum, Prevotella loescheii, Streptococcus intermedius, Porphyromonas gingivalis, Parvimonas micra, Synergistetes bacterium, Tannerella forsythia and Peptostreptococcus stomatis. The metabolic pathways with >0.81% abundances included membrane transport, genetic information processing and metabolic pathways. F. nucleatum was identified as a keystone taxon as it showed ubiquitousness, an eigenvector centrality value of 0.83 and a clr-based abundance >4.

CONCLUSIONS

The microbiome in apices and periapical lesions of post-treatment endodontic infections showed a similar diversity and taxonomic composition. Co-occurrence network analyses at OTU level identified F. nucleatum as a keystone taxon candidate in these infections.

The root canal microbiome diversity and function. A whole-metagenome shotgun analysis

AIM

To evaluate the root canal microbiome composition and bacterial functional capability in cases of primary and secondary apical periodontitis utilizing whole-metagenome shotgun sequencing.

METHODOLOGY

Twenty-two samples from patients with primary root canal infections, and 18 samples obtained from previously treated teeth currently diagnosed with apical periodontitis were analysed with whole-metagenome shotgun sequencing at a depth of 20 M reads. Taxonomic and functional gene annotations were made using MetaPhlAn3 and HUMAnN3 software. The Shannon and Chao1 indices were utilized to measure alpha diversity. Differences in community composition were evaluated utilizing analysis of similarity (ANOSIM) using Bray-Curtis dissimilarities. The Wilcoxon rank sum test was used to compare differences in taxa and functional genes.

RESULTS

Microbial community variations within a community were significantly lower in secondary relative to primary infections (alpha diversity p = .001). Community composition was significantly different in primary versus secondary infection (R = .11, p = .005). The predominant taxa observed among samples (>2.5%) were Pseudopropionibacterium propionicum, Prevotella oris, Eubacterium infirmum, Tannerella forsythia, Atopobium rimae, Peptostreptococcus stomatis, Bacteroidetes bacterium oral taxon 272, Parvimonas micra, Olsenella profusa, Streptococcus anginosus, Lactobacillus rhamnosus, Porphyromonas endodontalis, Pseudoramibacter alactolyticus, Fusobacterium nucleatum, Eubacterium brachy and Solobacterium moorei. The Wilcoxon rank test revealed no significant differences in relative abundances of functional genes in both groups. Genes with greater relative abundances (top 25) were associated with genetic, signalling and cellular processes including the iron and peptide/nickel transport system. Numerous genes encoding toxins were identified: exfoliative toxin, haemolysins, thiol-activated cytolysin, phospholipase C, cAMP factor, sialidase, and hyaluronic glucosaminidase.

CONCLUSIONS

Despite taxonomic differences between primary and secondary apical periodontitis, the functional capability of the microbiomes was similar.

Prevalence and virulence factors of haemolytic Enterococcus faecalis isolated from root filled teeth associated with periradicular lesions: A laboratory investigation in Thailand

AIM

Previous endodontic research has provided limited understanding of the prevalence and roles of haemolytic and non-haemolytic Enterococcus faecalis strains in root filled teeth. This study aimed to determine the prevalence of these strains in root filled teeth with periradicular lesions and investigate their associated virulence factors.

METHODOLOGY

A total of 36 root canal samples were collected from 36 subjects. The prevalence of E. faecalis was determined using culture and PCR methods. Antibiotic susceptibility of haemolytic and non-haemolytic E. faecalis strains was assessed using the broth dilution assay. The cytokine stimulation in periodontal ligament (PDL) cells and neutrophil migration were evaluated using real-time PCR and migration assay, respectively. Cell invasion ability of the strains was assessed using a cell culture model. Additionally, the virulence gene expression of the haemolytic and non-haemolytic strains was investigated using real-time PCR. The Mann-Whitney U and Spearman's ρ tests were used to examine the significant difference between the two strains and to analyse the correlation between phenotype and gene expression, respectively.

RESULTS

Enterococcus faecalis was detected in 33.3% and 88.9% of samples by culture and real-time PCR, respectively. Haemolytic strains were found in 36.4% of subjects. Non-haemolytic strains exhibited susceptibility to erythromycin and varying susceptibility to tetracycline, while all haemolytic strains were resistant to both antibiotics. Haemolytic strains significantly upregulated the expression of IL-8, OPG and RANKL in PDL cells (p < .05). Notably, the fold increases in these genes were higher: IL-8 (556.1 ± 82.9 vs. 249.6 ± 81.8), OPG (2.2 ± 0.5 vs. 1.3 ± 0.2) and RANKL (1.8 ± 0.3 vs. 1.2 ± 0.1). Furthermore, haemolytic strains had a greater effect on neutrophil migration (68.7 ± 15.2% vs. 46.9 ± 11.4%) and demonstrated a higher level of internalization into oral keratinocyte cells (68.6 ± 0.4% vs. 33.8 ± 0.5%) (p < .05). They also showed enhanced expression of virulence genes associated with haemolysin, surface proteins, collagen-binding and aggregation substances. Gelatinase activity was only detectable in non-haemolytic strains.

CONCLUSIONS

This study revealed that haemolytic strains E. faecalis possessed enhanced abilities in host invasion and a higher abundance of virulence factors, suggesting their potential contribution to more severe disease manifestations.

Odontogenic infections in the antibiotic era: approach to diagnosis, management, and prevention

PURPOSE

The prevalence of odontogenic infections remains one of the highest in the world. If untreated, odontogenic infections can break through the limitation, disseminate to other organs or spaces, and cause high mortality rates. However, it is still difficult to rapidly target limited or disseminated infections in clinical practice. The type of disseminated odontogenic infections and the responsible bacteria have not been described in detail.

METHODS

Search databases (e.g., PubMed, MEDLINE, Web of Science, Embase) for reports published from 2018.1 to 2022.9. Use search strategies: ("odontogenic infections" OR "pulpitis" OR "periapical lesions" OR "periodontal diseases") AND ("disseminated infections" OR "complication").

RESULTS

Fourteen different types of disseminated odontogenic infections, most of which are polymicrobial infections, can spread through the body either direct or through hematogenous diffusion. Multiple microbial infections can be more invasive in the transmission of infection. Secondary infections are commonly associated with bacteria like Fusobacterium spp., Streptococcus spp., Peptostreptococcus spp., Prevotella spp., and Staphylococcus spp. Antibiotics with broad-spectrum activity are fundamental as first-line antimicrobial agents based on the microorganisms isolated from disseminated infections.

CONCLUSION

This review elaborates on the epidemiology, microorganisms, risk factors, and dissemination routes, and provides evidence-based opinions on the diagnosis, multidisciplinary management, and prevention of odontogenic infections for dentists and clinicians.