Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia and Prevotella nigrescens in endodontic lesions detected by culture and by PCR

Porphyromonas endodontalis HmuY differentially participates in heme acquisition compared to the Porphyromonas gingivalis and Tannerella forsythia hemophore-like proteins

Introduction

Porphyromonas gingivalis and Porphyromonas endodontalis belong to the Bacteroidota phylum. Both species inhabit the oral cavity and can be associated with periodontal diseases. To survive, they must uptake heme from the host as an iron and protoporphyrin IX source. Among the best-characterized heme acquisition systems identified in members of the Bacteroidota phylum is the P. gingivalis Hmu system, with a leading role played by the hemophore-like HmuY (HmuYPg) protein.

Methods

Theoretical analysis of selected HmuY proteins and spectrophotometric methods were employed to determine the heme-binding mode of the P. endodontalis HmuY homolog (HmuYPe) and its ability to sequester heme. Growth phenotype and gene expression analysis of P. endodontalis were employed to reveal the importance of the HmuYPe and Hmu system for this bacterium.

Results

Unlike in P. gingivalis, where HmuYPg uses two histidines for heme-iron coordination, other known HmuY homologs use two methionines in this process. P. endodontalis HmuYPe is the first characterized representative of the HmuY family that binds heme using a histidine-methionine pair. It allows HmuYPe to sequester heme directly from serum albumin and Tannerella forsythia HmuYTf, the HmuY homolog which uses two methionines for heme-iron coordination. In contrast to HmuYPg, which sequesters heme directly from methemoglobin, HmuYPe may bind heme only after the proteolytic digestion of hemoglobin.

Conclusions

We hypothesize that differences in components of the Hmu system and structure-based properties of HmuY proteins may evolved allowing different adaptations of Porphyromonas species to the changing host environment. This may add to the superior virulence potential of P. gingivalis over other members of the Bacteroidota phylum.

Evaluation of loop-mediated isothermal amplification method for efficient detection of the periodontopathic bacteria Porphyromonas gingivalis

Background

Periodontitis is a multifactorial, polymicrobial oral inflammatory illness brought on by oral pathogens. Porphyromonas gingivalis is a Gram-negative, obligatory anaerobic, black-pigmented coccobacillus and is regarded as a primary etiological factor in the progression of periodontitis. Rapid, highly senstitive and specific detection methods are emerging. The present study aimed to evaluate the loop-mediated isothermal amplification (LAMP) technique for efficiently detecting P. gingivalis from subgingival plaque samples of chronic periodontitis patients.

Materials and Methods

This study included 50 subgingival plaque samples from patients suffering from chronic periodontitis. The DNA (Deoxyribonucleic acid) was extracted by the "modified proteinase K" method. A set of six primers, targeting the pepO gene of P. gingivalis, was used for conducting LAMP. The amplification was visualized by naked-eye detection and agarose electrophoresis. Conventional polymerase chain reaction (PCR) and real-time qantitative PCR (qPCR) were carried out by targeting the 16SrRNA (16S ribosomal ribonucleic acid) gene of P. gingivalis.

Results

The results showed that LAMP detected P. gingivalis in 40 out of 50 samples (80%). Whereas, qPCR and conventional PCR technique detected P. gingivalis in 38 (76%) and 33 (66%) samples respectively. The sensitivity and specificity of the LAMP method were 94.87% and 90.90%, respectively. With qPCR, the sensitivity and specificity were found to be 92.30% and 81.81%, respectively, whereas, with conventional PCR, it was found to be 76.92% and 72.72%, respectively.

Conclusion

LAMP is an efficient technique for quick, accurate, and reliable identification of P. gingivalis from subgingival plaque samples. The technique needs to be validated analytically, and further studies can be conducted by taking saliva and/or gingival crevicular fluid samples from periodontitis patients.

A novel experimental model to investigate fungal involvement shows expression of Dectin-1 in periapical lesion pathogenesis

BACKGROUND

Candida albicans is linked to persistent endodontic lesions. However, the recognition receptor that identifies it is not explored previously.

OBJECTIVES

The aim of this study was to (1) establish a zymosan-induced model of apical periodontitis in mouse, (2) observe the expression of Dectin-1 and its possible relationship with toll-like receptor (TLR) 2 and (3) observe relationship between Osteopontin (OPN) and inflammatory cytokines.

METHODS

A total of 138 Naval Medical Research Institute (NMRI) mice were randomly divided into; Experimental Group n = 69 and Zymosan Group n = 69. Periapical periodontitis was developed in right maxillary molar. The animals were sacrificed at 7, 21 and 42 days. Bone blocks containing the mesial root (n = 15 for qRT-PCR, n = 45 for enzyme-linked immune sorbent assay (ELISA)) were collected for mRNA expression and ELISA. While whole maxilla (n = 3 from each time interval) were used for histology and immunohistochemical analysis. One way analysis of variance (ANOVA) and Tuckey's posthoc was used for statistical analysis at p ≤ .05.

RESULTS

TLR-2, Dectin-1 and TLR4-positive cells was detected at all time intervals in both groups. A strong positive correlation was observed between TLR-2 and Dectin-1 in both lesions (regular r = .680, p = .015, zymosan (r = .861, p < .001)). A significant correlation was found between OPN and tumour necrosis factor-alpha (TNF-α) in zymosan lesion (r = .827, p = .001).

CONCLUSIONS

Immune cells of inflamed periapical tissue expressed Dectin-1 receptor in response to the microbial challenge from infected root canals and showed positive correlation with TLR-2 and OPN suggesting a possible receptor collaboration mediated by OPN. The expression of OPN and TNF-α showed positive correlation in response to fungal antigen, indicating a possible relationship.

Real-time optical detection of endodontic infection using bacterial autofluorescence

OBJECTIVES

For successful root canal treatment (RCT), it is essential to objectively assess the presence and activity of bacteria in the root canal system. However, current methods rely on subjective observations of root canal exudates. This study aimed to confirm whether real-time optical detection using bacterial autofluorescence can evaluate endodontic infection status by assessing the red fluorescence (RF) detected from root canal exudates.

METHODS

During RCT, endodontic paper points were used to collect root canal exudates scored using conventional organoleptic tests to assess the severity of root canal infections. RF on the paper points was assessed using quantitative light-induced fluorescence (QLF) technology. RF intensity and area from the paper points were quantified, and their correlations with infection severity were assessed using their organoleptic scores. The oral microbiome composition of RF samples was compared with non-red fluorescent (non-RF) samples.

RESULTS

The RF detection rate was nil and >98% in the non-infectious and severe groups. The RF intensity and area significantly increased with infection severity (p<0.001) and showed strong correlations with organoleptic scores (r=0.72, 0.82, respectively). The diagnostic accuracy for detecting root canal infection using RF intensity was good to excellent (AUC = 0.81-0.95) and increased with infection severity. The microbial diversity of the RF samples was significantly lower than that of the non-RF samples. Gram-negative anaerobic bacteria such as Prevotella and Porphyromonas were more predominant in RF samples.

CONCLUSIONS

Optical detection using bacterial autofluorescence can objectively evaluate endodontic infection status in real-time by assessing the RF of endodontic root canal exudates.

CLINICAL SIGNIFICANCE

This real-time optical technology can be utilised to detect endodontic bacterial infection without conventional incubation, allowing clinicians to determine the endpoint of chemomechanical debridement and increase the positive outcomes of RCTs.

Presence of zoonotic black-pigmented periodontal pathogens in the oral microbiota of pet and stray cats

Black-pigmented bacteria are one of the neglected species to cause periodontal disease in cats, and they are also zoonotic agents that pose an infection risk to humans. In this study, we aimed to determine the presence of Porphyromonas gingivalis, Porphyromonas gulae and Prevotella nigrescens in the oral microbiota of pet and stray cats. Dental swab samples were taken from 25 pet cats and 25 stray cats with symptoms of periodontal disease and then investigated by multiplex polymerase chain reaction using 16S rRNA species-specific primers. As a result of the multiplex PCR analysis, P. gingivalis 3/25 (12%), P. nigrescens 1/25 (4%), P. gingivalis + P. gulae 7/25 (28%), P. gingivalis + P. nigrescens 1/25 (4%), P. gulae + P. nigrescens 1/25 (4%), and P. gingivalis + P. gulae + P. nigrescens 2/25 (8%) were molecularly typed in the pet cats. In addition, 1/25 (4%) of P. gulae and 21/25 (84%) of P. gingivalis + P. gulae were typed in the stray cats. In 10/25 (40%) pet and 3/25 (12%) stray cat samples, no bacteria were detected by molecular typing. In summary, the results provide strong evidence that black-pigmented zoonotic pathogens are associated with cat periodontal disease.

Evaluation of hydrocortisone as a strain-dependent growth-regulator of Porphyromonasgingivalis

OBJECTIVE

Porphyromonas gingivalis is an oral key pathogen and known to be very diverse in geno- and phenotypes. It is a fastidious bacterium with low O₂-tolerance and 3-7 days of incubation are necessary. With growing interest in the field of microbial endocrinology we explored the potential growth-stimulating effect of hydrocortisone (HC, synonym cortisol) on P. gingivalis cultures.

MATERIAL AND METHODS

Six different P. gingivalis strains were pre-incubated in supplemented Brain-Heart-Infusion broth under appropriate conditions for 24 h, diluted and transferred into microplates. A newly developed and semi-automated spectrophotometric measurement in triplicate, applying a SpectraMax i3x microplate reader at an optical density of 600 nm, was conducted to test growth differences between test group (exposed to a supplement of either 1.25, 2.5, 5, 10, or 20 μg/ml of hydrocortisone) and control group over 48 h of anaerobic incubation (O₂ ≤ 1%). Furthermore, strains were also incubated on HC-supplemented blood agar to test for a possible growth-stimulating effect on solid media.

RESULTS

HC significantly stimulated the lag-phase growth of four out of six P. gingivalis strains. Our data suggest a concentration-dependent growth stimulatory effect of HC between 2.5 and 5 μg/ml, while below 1.25 μg/ml and above 10 μg/ml HC either did not stimulate or inhibited growth.

CONCLUSIONS

HC could reduce the incubation time when isolating P. gingivalis from clinical samples and could boost low biomass cultivations especially during their lag-phase. The growth-modulating effect might be via modulation of virulence factors/quorum sensing gene expression or by reactive oxygen species(ROS)-capturing during early stages of bacterial growth. Further experiments are necessary to explain the mechanism behind our observations.

Is the Addition of Anaerobic Coverage to Perioperative Antibiotic Prophylaxis During Soft Tissue Sarcoma Resection Associated With a Reduction in the Proportion of Wound Complications?

BACKGROUND

Wound complications are common after resection of soft tissue sarcomas, with published infection rates ranging from 10% to 35%. Multiple studies have reported on the atypical flora comprising these infections, which are often polymicrobial and contain anaerobic bacteria, and recent studies have noted the high prevalence of anaerobic bacterial infections after soft tissue sarcoma resection [ 26, 35 ]. Based on this, our institution changed clinical practice to include an antibiotic with anaerobic coverage in addition to the standard first-generation cephalosporin for prophylaxis during soft tissue sarcoma resections. The current study was undertaken to evaluate whether this change was associated with a change in major wound complications, and if the change should therefore be adopted for future patients.

QUESTIONS/PURPOSES

(1) After controlling for potentially confounding variables, was the broadening of the prophylactic antibiotic spectrum to cover anaerobic bacteria associated with a lower odds of major wound complications after soft tissue sarcoma resection? (2) Was the broadening of the prophylactic antibiotic spectrum to cover anaerobic bacteria associated with a lower odds of surgical site infections with polymicrobial or anaerobic infections after soft tissue sarcoma resection? (3) What are the factors associated with major wound complications after soft tissue sarcoma resection?

METHODS

We retrospectively identified 623 patients who underwent soft tissue sarcoma resection at a single center between January 2008 and January 2021 using procedural terminology codes. Of these, four (0.6%) pediatric patients were excluded, as were five (0.8%) patients with atypical lipomatous tumors and two (0.3%) patients with primary bone tumors; 5% (33 of 623) who were lost to follow-up, leaving 579 for final analysis. The prophylactic antibiotic regimen given at the resection and whether a wound complication occurred were recorded. Patients received the augmented regimen based on whether they underwent resection after the change in practice in July 2018. A total of 497 patients received a standard antibiotic regimen (usually a first-generation cephalosporin), and 82 patients received an augmented regimen with anaerobic coverage (most often metronidazole). Of the 579 patients, 53% (307) were male (53% [264 of 497] in the standard regimen and 52% [43 of 82] in the augmented regimen), and the mean age was 59 ± 17 years (59 ± 17 and 60 ±17 years in the standard and augmented groups, respectively). Wound complications were defined as any of the following within 120 days of the initial resection: formal wound debridement in the operating room, other interventions such as percutaneous drain placement, readmission for intravenous antibiotics, or deep wound packing for more than 120 days from the resection. Patients were considered to have a surgical site infection if positive cultures resulted from deep tissue cultures taken intraoperatively at the time of debridement. The proportion of patients with major wound complications was 26% (150 of 579); it was 27% (136 of 497) and 17% (14 of 82) in the standard and augmented antibiotic cohorts, respectively (p = 0.049). With the numbers we had, we could not document that the addition of antibiotics with anaerobic coverage was associated with lower odds of anaerobic (4% versus 6%; p = 0.51) or polymicrobial infections (9% versus 14%; p = 0.25). Patient, tumor, and treatment (surgical, radiotherapy, and chemotherapy) variables were collected to evaluate factors associated with overall infection and anaerobic or polymicrobial infection. Patient follow-up was 120 days to capture early wound complications. A multivariable analysis was performed for all variables found to be significant in the univariate analysis. A p value < 0.05 was used as the threshold for statistical significance for all analyses. No patients were found to have an adverse reaction to the augmented regimen, including allergic reactions or Clostridioides (formerly Clostridium) difficile infection.

RESULTS

After controlling for other potentially confounding factors such as neoadjuvant radiation, tumor size and anatomic location, as well as patient BMI, anaerobic coverage was associated with smaller odds of wound complications (OR 0.36 [95% confidence interval (CI) 0.18 to 0.68]; p = 0.003). Other factors associated with major wound complications were preoperative radiation (versus no preoperative radiation) (OR 2.66 [95% CI 1.72 to 4.15]; p < 0.001), increasing tumor size (OR 1.04 [95% CI 1.00 to 1.07]; p = 0.03), patient BMI (OR 1.07 [95% CI 1.04 to 1.11]; p < 0.001), and tumor in the distal upper extremity (versus proximal upper extremity, pelvis/groin/hip, and lower extremity) (OR 0.18 [95% CI 0.04 to 0.62]; p = 0.01).

CONCLUSION

The addition of anaerobic coverage to the standard prophylactic regimen during soft tissue sarcoma resection demonstrated an association with smaller odds of major wound complications and no documented adverse reactions. Treating physicians should consider these findings but note that they are preliminary, and that further work is needed to replicate them in a more controlled study design such as a prospective trial.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Evaluation of PCR primers to identify Porphyromonas endodontalis in apical periodontitis clinical samples

We aimed to evaluate whether two commonly used PCR primers are effective to identify P. endodontalis and discriminate from other prevalent black-pigmented bacteria in apical periodontitis (AP). Endodontic canal samples from patients with asymptomatic AP (n = 20) were collected and cultured in anaerobiosis. Two primer sets to detect P. endodontalis were selected from the literature and first analyzed for their specificity in silico; and then tested on clinical isolates in vitro and finally, in apical exudates ex vivo. The identity of P. endodontalis was verified by PCR and Sanger sequencing with universal primers for bacterial V3-V6 regions 16S rDNA. Only one primer set showed specificity only for P. endodontalis clones in silico and also was specific for P. endodontalis in vitro and ex vivo.

Effect of electronic cigarette and tobacco smoking on the human saliva microbial community

Increasing evidence demonstrated the oral microbial community profile characteristics affected by conventional cigarettes smoking, but few studies focus on oral microbiome in response to electronic cigarettes (E-cigarettes). This study aimed to investigate the effect of E-cigarettes on the oral microbiome and to describe the difference of oral community profiles between E-cigarette smokers and tobacco smokers. 16S rRNA V4 gene sequencing was performed to investigate the oral microbial profiles of 5 E-cigarette smokers, 14 tobacco smokers, 8 quitting tobacco smokers, and 6 nonsmokers. The Chao1, ACE, and Shannon diversity indexes increased significantly in saliva samples collected from E-cigarette smokers and tobacco smokers compared to the non-smokers, and no significant difference was found in alpha diversity between E-cigarette smokers and tobacco smokers. The main phyla Proteobacteria, Firmicutes, Bacteroidetes, and Fusobacteria and major genera Neisseria, Streptococcus, Prevotellaceae, Fusobacterium, and Porphyromonas dominated in the smoking groups, while Actinobacteria, Proteobacteria, Firmicutes, Bacteroidetes, and Fusobacteria became the dominant phyla along with the genera Corynebacterium, Neisseria, Streptococcus, Actinomyces, and Porphyromonas in the nonsmokers. The differences in the phylum Actinobacteria and genus Corynebacterium contributed to various functional differences between smokers and nonsmokers. The difference on oral microbial and composition between E-cigarettes and common tobacco were associated with increased Prevotellaceae and decreased Neisseria. Additionally, smoking cessation could lead to re-establishment of the oral microbiome to that of nonsmokers. Our data demonstrate that E-cigarette smoking had different effects on the structure and composition of the oral microbial community compared to tobacco smoking. However, the short- and long-term impact of E-cigarette smoking on microbiome composition and function needs further exploration.

Dataset of endodontic microorganisms killed at 265 nm wavelength by an ultraviolet C light emitting diode in root canals of extracted, instrumented teeth

Ultraviolet C (UVC) light emitting diode (LED) can kill the endodontic pathogen Enterococcus faecalis and has the potential to kill other oral microorganisms associated with endodontic infections. This same bacteriocidal device shows great promise in the stimulation of periapical healing and pain reduction resulting from inflammation in root canals. Previously, we found that 255 nm UVC LED killed E. faecalis and induced the production of cellular biomarkers in HEPM cells and gingival fibroblasts (Morio et al., 2019). Here, we extend those findings and hypothesize that UVC LED at other wavelengths and power levels kill microorganisms associated with root canal infections. Units emitting UVC LED at 265 nm (12 mW), 265 nm (22.5 mW), and 280 nm (8 mW) wavelenths were assembled and the energy levels of their emissions were measured. The energy doses in millijoules (mJ) were calculated from the power readings of the meter (µW) × time of exposure (seconds). Ex vivo models of root canals were prepared in extracted, instrumented, single canal human premolars. Five cultures of microorganisms were treated with 265 nm (12 mW), 265 nm (22.5 mW), or 280 nm (8 mW) UVC LED on discs in laboratory assays and 4 cultures of microorganisms were treated with 265 nm (22.5 mW) UVC LED in root canals of extracted, instrumented teeth. After UVC LED treatment, all microorganisms were cultivated on microbiological media. Colony forming units (CFU) of viable microorganisms treated with UVC LED were counted and compared with those of viable microorganisms not treated with UVC LED as controls. Tukey's Honestly Significant Difference was used to determine statistical significances (0.05). Units emitting UVC LED at 265 nm (12 mW), 265 nm (22.5 mW), and 280 nm (8 mW) killed Candida albicans, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), E. faecalis, and Streptococcus sanguinis after 30-90 seconds of exposure in laboratory assays (p < 0.05). Microbial killing differed among treatment times, UVC LED wavelengths, power levels of each unit, and specific microorganism. The unit emitting UVC LED at 265 nm (22.5 mW) killed C. albicans, S. aureus, MRSA, and E. faecalis in 30 s in root canals of extracted, instrumented teeth (p < 0.05). This dataset can be reused to assess the ability of other wavelengths and power levels to kill microorganisms as well as improve procedures for treating endodontic infections and inflammation in root canals.

The Antimicrobial Susceptibility of Porphyromonas gingivalis: Genetic Repertoire, Global Phenotype, and Review of the Literature

The in vitro antimicrobial susceptibility of 29 strains of the major periodontal pathogen Porphyromonas gingivalis and three P. gulae (as an ancestor) to nine antibiotics (amoxicillin, amoxicillin/clavulanate, clindamycin, metronidazole, moxifloxacin, doxycycline, azithromycin, imipenem, and cefoxitin) was evaluated by E-testing of minimal inhibitory concentration (MIC) according to international standards. The results were compared with 16 international studies reporting MICs from 1993 until recently. In addition, 77 currently available P. gingivalis genomes were screened for antimicrobial resistance genes. E-testing revealed a 100% sensitivity of P. gingivalis and P. gulae to all antibiotics. This was independent of the isolation year (1970 until 2021) or region, including rural areas in Indonesia and Africa. Regarding studies worldwide (675 strains), several method varieties regarding medium, McFarland inoculation standards (0.5-2) and incubation time (48-168 h) were used for MIC-testing. Overall, no resistances have been reported for amoxicillin + clavulanate, cefoxitin, and imipenem. Few strains showed intermediate susceptibility or resistance to amoxicillin and metronidazole, with the latter needing both confirmation and attention. The only antibiotics which might fail in the treatment of P. gingivalis-associated mixed anaerobic infections are clindamycin, macrolides, and tetracyclines, corresponding to the resistance genes erm(B), erm(F), and tet(Q) detected in our study here, as well as fluoroquinolones. Periodical antibiotic susceptibility testing is necessary to determine the efficacy of antimicrobial agents and to optimize antibiotic stewardship.

Association between bacteria other than Helicobacter pylori and the risk of gastric cancer

BACKGROUND

The gastric microbiota, including Helicobacter pylori (HP), has a remarkable role in gastric cancer (GC) occurrence. Evidence for the role of non-HP bacteria in GC risk is limited. We aimed to observe the association between bacteria other than HP and risk of GC in a Korean population.

METHODS

In this study, 268 GC cases and 288 healthy controls were included. Demographic data and total energy intake data were collected using a general questionnaire and a semiquantitative food frequency questionnaire, respectively. 16S rRNA gene sequencing was performed using DNA extracted from gastric biopsy samples.

RESULTS

Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and non-HP Proteobacteria were the five main phyla in the gastric environment. The five phyla were negatively related to the relative abundance of Helicobacter species (all p < 0.001). The Shannon index, richness, and Pilou-evenness were negatively correlated with Helicobacter species (all p < 0.001), while the microbial dysbiosis index was positively correlated with Helicobacter species (p < 0.001). Participants with a higher relative abundance of Actinobacteria species showed a significantly increased risk of GC (OR: 3.16, 95% CI = 1.92-5.19, p-trend<0.001). The non-HP microbiota composition among the four groups (HP+cases, HP- cases, HP+controls, and HP- controls) was significantly different (ANOSIM R = 0.10, p = 0.001).

CONCLUSION

Other than HP, several bacterial species might be associated with GC risk. HP status and GC status could determine the differences in microbial compositions. Further large prospective studies are warranted to confirm our findings.

Systemic burden and cardiovascular risk to Porphyromonas species in apical periodontitis

OBJECTIVE

Porphyromonas (P.) species (spp.) are a major etiological agent of apical periodontitis (AP), which in turn represents a risk factor for cardiovascular diseases. This study explored the associations between endodontic infection with Porphyromonas species, the systemic bacterial burden, and cardiovascular risk, based on high-sensitivity C-reactive protein (hsCRP), in young adults with AP.

MATERIALS AND METHODS

Cross-sectional study. Otherwise, healthy individuals with AP and controls (n = 80, ≤ 40 years) were recruited at the University Dental Clinic. Oral parameters and classic cardiovascular risk factors were registered. Endodontic Porphyromonas endodontalis and Porphyromonas gingivalis were identified using conventional PCR. Serum concentrations of anti-P. endodontalis and anti-P. gingivalis antibodies, and endotoxins were determined through ELISA and Limulus-amebocyte assays. Serum hsCRP was determined for cardiovascular risk stratification.

RESULTS

Intracanal detection of P. endodontalis and P. gingivalis in AP were 33.3% and 22.9%, respectively. Serum anti-P. endodontalis and anti-P. gingivalis IgG was higher in AP than controls (p < 0.05 and p = 0.057, respectively). Intracanal P. endodontalis associated with higher endotoxemia (p < 0.05). Among endodontic factors, the presence (OR 4.2-5.5, p < 0.05) and the number of apical lesions (OR 2.3, p < 0.05) associated with moderate-severe cardiovascular risk, whereas anti-P. endodontalis IgG were protective (OR 0.3, p > 0.05).

CONCLUSIONS

AP and infection with P. endodontalis positively associated with cardiovascular risk based on hsCRP levels and endotoxemia, respectively, whereas anti-P. endodontalis IgG response seems to be protective against low-grade systemic inflammation.

CLINICAL RELEVANCE

Apical periodontitis and endodontic P. endodontalis can influence the systemic burden with impact on the surrogate cardiovascular risk marker hsCRP, providing mechanistic links.

Investigation of a modified hydraulic calcium silicate-based material - Bio-C Pulpo

This study evaluated the physicochemical, biological, and antimicrobial properties of a new hydraulic calcium silicate-based modified material, and compared it with MTA Repair HP and MTA Angelus. The materials were assessed regarding color luminosity (L), color change, radiopacity, setting time, and ISO 6876:2012 linear flow. Volumetric filling and volume change were evaluated using microcomputed-tomography (µCT). Chemical characterization after 28 days in Hank's Balanced Salt Solution (HBSS) and pH analysis were also assessed. Biological characterization of cytotoxicity and microbiological assessment were also undertaken. Shapiro-Wilk, ANOVA, Levene and post hoc analyses with Bonferroni correction were performed, adopting a 5% significance level (p <0.05). Bio-C Pulpo exhibited the highest L values after 90 days. All tested materials demonstrated color change during the analyses, and had radiopacity above 5 mm Al. MTA Repair HP set faster than Bio-C Pulpo, whereas the latter had the highest linear flow. MTA Repair HP had the highest volumetric filling in µCT analysis. Bio-C Pulpo showed the highest alkalinity during all tested periods, and the highest volumetric loss (above 9%), in comparison with MTA Repair HP and MTA Angelus. Bio-C Pulpo did not form calcium hydroxide after hydration. MTA Repair HP demonstrated the highest cytocompatibility, and Bio-C Pulpo, the highest cytotoxicity. No inhibition halos were observed for any material, and similar higher turbidity values were seen after direct contact. Composition additives used in Bio-C Pulpo modified its properties, and both the absence of calcium hydroxide deposition after hydration, and the related cytotoxicity of this material are of particular concern.

Clinical significance of ragA, ragB, and PG0982 genes in Porphyromonas gingivalis isolates from periodontitis patients

Consistent detection of ragA, ragB, and PG0982 in the genome of Porphyromonas gingivalis (P. gingivalis) isolates from periodontitis patients suggests that genotypes containing these genes may influence virulence and P. gingivalis-associated periodontitis progression. This study evaluated the prevalence of these genes in P. gingivalis isolates from periodontitis patients (n = 28) and in isolates from periodontally healthy P. gingivalis carriers (n = 34). The association of these genes with progression of periodontitis, in vitro cell invasiveness, and bacterial survival following periodontal therapy was also assessed. Periodontal charting and microbiological sampling were done at baseline, and at 6, 12, and 24 months following subgingival debridement of the periodontitis patients. Healthy controls were assessed at baseline for comparison. P. gingivalis isolates were analysed by ragA, ragB, and PG0982 specific polymerase chain reaction (PCR) and Sanger sequencing. Primary human gingival fibroblasts were used for invasion experiments. Results showed that 25% of the tested isolates from the periodontitis group had ragB detected, whereas this gene was undetected in isolates from healthy participants. However, none of the selected genes was associated with an increased cell invasiveness in vitro, with bacterial survival, or with significant clinical periodontal parameter changes. Identification of genes that influence P.gingivalis virulence and therapeutic outcome may have a diagnostic or prognostic value.

Bacteria and virulence factors in periapical lesions associated with teeth following primary and secondary root canal treatment

AIM

This cross-sectional study aimed to investigate the microbial profile and to quantify the levels of endotoxins (LPS) and lipoteichoic acid (LTA) present in periapical lesions associated with root filled teeth and those that had received root canal retreatment. It also aimed to investigate the association between microorganisms and their virulence factors with clinical and radiographic features.

METHODOLOGY

Patients with periapical lesions in teeth with post-treatment endodontic disease following primary root canal treatment (n = 19) and unsuccessful root canal retreatment (n = 13) were treatment planned for endodontic microsurgery, where the periapical lesions were collected. Clinical and radiographic data were also collected. For microbiological analysis, nested polymerase chain reaction was used to detect 17 bacterial species. Levels of LPS and LTA were determined using limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively. The Student t-test or Wilcoxon-Mann-Whitney tests were applied to compare the data on LPS and LTA with clinical and radiographic features. The associations between the clinical and radiographic features and the bacterial species were analysed using the Fisher's exact test. A significance level of 5% was adopted.

RESULTS

Bacterial DNA, LPS and LTA were detected in all samples. Parvimonas micra was the most commonly detected species in all groups, followed by Enterococcus faecalis, Fusobacterium nucleatum and Porphyromonas endodontalis. The type of endodontic treatment, whether a primary root canal treatment or retreatment, was not associated with the presence of any bacterial species in periapical lesions. The levels of LPS and LTA in periapical lesions of root filled teeth were not significantly different from those that had been retreated. Associations between the levels of LPS and LTA with clinical signs and symptoms were found. No association was found between specific bacteria and clinical features.

CONCLUSION

Periapical lesions associated with teeth after primary root canal treatment and retreatment had similar polymicrobial composition. The levels of LPS and LTA in periapical lesions associated with teeth after primary root canal treatment and retreatment were similar, and both were associated with the same symptomatology.

The apical root canal system microbial communities determined by next-generation sequencing

The aim of this study was to explore the microbial communities of endodontic infections at their apical portion by 16S rRNA Illumina sequencing and delineate the core microbiome of root canal infections and that of their associated clinical symptomatology. Samples were collected from fifteen subjects presenting one tooth with a root canal infection, and their associated symptoms were recorded. Samples were collected from the apical third of roots using a #10 K file and then amplified using multiple displacement amplification and PCR-amplified with universal primers. Amplicons were sequenced (V3–V4 hypervariable region of the 16S rRNA gene) using MiSeq (Illumina, CA). The microbial composition of the samples was determined using QIIME and HOMINGS. Data were analyzed using t tests and ANOVA. A total of 1,038,656 good quality sequences were obtained, and OTUs were assigned to 10 bacterial phyla, led by Bacteroidetes (51.2%) and Firmicutes (27.1%), and 94 genera were represented primarily by Prevotella (17.9%) and Bacteroidaceae G-1 (14.3%). Symptomatic teeth were associated with higher levels of Porphyromonas (p < 0.05) and Prevotella. P. endodontalis and P. oris were present in both cores. The present study demonstrated the complexity of the root canal microbiome and the “common denominators” of root canal infections and identified taxa whose virulence properties should be further explored. The polymicrobial etiology of endodontic infections has long been established. However, few studies have focused on expanding the breadth and depth of coverage of microbiome-infected root canals at their apical portion.

Clinical Detection of Chronic Rhinosinusitis through Next-Generation Sequencing of the Oral Microbiota

Chronic rhinosinusitis (CRS) is the chronic inflammation of the sinus cavities of the upper respiratory tract, which can be caused by a disrupted microbiome. However, the role of the oral microbiome in CRS is not well understood. Polymicrobial and anaerobic infections of CRS frequently increased the difficulty of cultured and antibiotic therapy. This study aimed to elucidate the patterns and clinical feasibility of the oral microbiome in CRS diagnosis. Matched saliva and nasal swabs were collected from 18 CRS patients and 37 saliva specimens from normal volunteers were collected for 16S rRNA sequencing. The α-diversity of the saliva displayed no significant difference between control and CRS patients, whereas the β-diversity was significantly different (p = 0.004). Taxonomic indices demonstrated that Veillonella dispar, Rothia mucilaginosa, and Porphyromonas endodontalis were enriched, while Campylobacter and Cardiobacterium were reduced in the saliva of CRS patients. These microbial markers could significantly distinguish CRS patients from control (AUC = 0.939). It is noted that the 16S rRNA results of the nasal swab were consistent with the nasopharynx aerobic culture, and additionally detected multiple pathogens in CRS patients. In summary, these results indicated these oral microbiomes may provide a novel signal for CRS detection and that NGS may be an alternative approach for CRS diagnosis.

Next-Generation Sequencing to Assess Potentially Active Bacteria in Endodontic Infections

INTRODUCTION

Because active bacteria present a higher abundance of ribosomal RNA (rRNA) than DNA (rRNA gene), the rRNA/DNA ratio of next-generation sequencing (NGS) data was measured to search for active bacteria in endodontic infections.

METHODS

Paired complementary DNA and DNA samples from 5 root canals of teeth with apical periodontitis were subjected to polymerase chain reaction with bar-coded primers amplifying the 16S rRNA gene hypervariable regions V4-V5. High-throughput sequencing was performed using MiSeq (Illumina, San Deigo, CA), and data were analyzed using Quantitative Insights Into Microbial Ecology and Human Oral Microbiome Database. Statistical analysis was performed for relative abundance of bacteria in the DNA- and rRNA-based NGS data using the Mann-Whitney test, whereas differences in the diversity and richness indexes were assessed using a nonparametric 2-sample t test (P < .05). For bacterial taxa detected in both approaches, the rRNA/DNA ratios were calculated by dividing the average abundance of individual species in the respective analysis.

RESULTS

Although no significant difference was found in the indexes of bacterial richness and diversity, the relative abundance of bacterial members varied in both analyses. Comparing rRNA with DNA data, there was a significant decrease in the relative abundance of Firmicutes (P < .05). The bacterial taxa Bacteroidales [G-2] bacterium HMT 274, Porphyromonas endodontalis, Tannerella forsythia, Alloprevotella tannerae, Prevotella intermedia, Pseudoramibacter alactolyticus, Olsenella sp. HMT 809, Olsenella sp. HMT 939, Olsenella uli, and Fusobacterium nucleatum subsp. animalis were both dominant (DNA ≥ 1%) and active (rRNA/DNA ≥ 1).

CONCLUSIONS

The integrated DNA- and rRNA-based NGS strategy was particularly important to disclose the activity of as-yet-uncultivated or difficult-to-culture bacteria in endodontic infections.

Endodontic-Like Oral Biofilms as Models for Multispecies Interactions in Endodontic Diseases

Oral bacteria possess the ability to form biofilms on solid surfaces. After the penetration of oral bacteria into the pulp, the contact between biofilms and pulp tissue may result in pulpitis, pulp necrosis and/or periapical lesion. Depending on the environmental conditions and the availability of nutrients in the pulp chamber and root canals, mainly Gram-negative anaerobic microorganisms predominate and form the intracanal endodontic biofilm. The objective of the present study was to investigate the role of different substrates on biofilm formation as well as the separate and collective incorporation of six endodontic pathogens, namely Enterococcus faecalis, Staphylococcus aureus, Prevotella nigrescens, Selenomonas sputigena, Parvimonas micra and Treponema denticola into a nine-species "basic biofilm". This biofilm was formed in vitro as a standard subgingival biofilm, comprising Actinomyces oris, Veillonella dispar, Fusobacterium nucleatum, Streptococcus anginosus, Streptococcus oralis, Prevotella intermedia, Campylobacter rectus, Porphyromonas gingivalis, and Tannerella forsythia. The resulting endodontic-like biofilms were grown 64 h under the same conditions on hydroxyapatite and dentin discs. After harvesting the endodontic-like biofilms, the bacterial growth was determined using quantitative real-time PCR, were labeled using fluorescence in situ hybridization (FISH) and analyzed by confocal laser scanning microscopy (CLSM). The addition of six endodontic pathogens to the "basic biofilm" induced a decrease in the cell number of the "basic" species. Interestingly, C. rectus counts increased in biofilms containing E. faecalis, S. aureus, P. nigrescens and S. sputigena, respectively, both on hydroxyapatite and on dentin discs, whereas P. intermedia counts increased only on dentin discs by addition of E. faecalis. The growth of E. faecalis on hydroxyapatite discs and of E. faecalis and S. aureus on dentin discs were significantly higher in the biofilm containing all species than in the "basic biofilm". Contrarily, the counts of P. nigrescens, S. sputigena and P. micra on hydroxyapatite discs as well as counts of P. micra and T. denticola on dentin discs decreased in the all-species biofilm. Overall, all bacterial species associated with endodontic infections were successfully incorporated into the standard multispecies biofilm model both on hydroxyapatite and dentin discs. Thus, future investigations on endodontic infections can rely on this newly established endodontic-like multispecies biofilm model.

The human oral cavity microbiota composition during acute tonsillitis: a cross-sectional survey

BACKGROUND

Microbial culture-based investigations of inflamed tonsil tissues have previously indicated enrichment of several microorganisms such as Streptococcus, Staphylococcus and Prevotella. These taxa were also largely reflected in DNA sequencing studies performed using tissue material. In comparison, less is known about the response of the overall oral cavity microbiota to acute tonsillitis despite their role in human health and evidence showing that their compositions are correlated with diseases such as oral cancers. In addition, the influence of subject-specific circumstances including consumption of prescription antibiotics and smoking habits on the microbiology of acute tonsillitis is unknown.

METHODS

We collected oral rinse samples from 43 individuals admitted into hospital for acute tonsillitis and 165 non-disease volunteers recruited from the public, and compared their microbial community compositions using 16S rRNA gene sequencing. We assessed the impact of tonsillitis, whether subjects were prescribed antibiotics, the presence of oral abscesses and their smoking habits on community composition, and identified specific microbial taxa associated with tonsillitis and smoking.

RESULTS

Oral rinse community composition was primarily associated with disease state (tonsillitis vs non-tonsillitis) although its effect was subtle, followed by smoking habit. Multiple Prevotella taxa were enriched in tonsillitis subjects compared to the non-tonsillitis cohort, whereas the non-tonsillitis cohort primarily showed associations with several Neisseria sequence variants. The presence of oral abscesses did not significantly influence community composition. Antibiotics were prescribed to a subset of individuals in the tonsillitis cohort but we did not observe differences in community composition associated with antibiotics consumption. In both tonsillitis and non-tonsillitis cohorts, smoking habit was associated with enrichment of several Fusobacterium variants.

CONCLUSIONS

These findings show that the oral cavity microbial community is altered during acute tonsillitis, with a consistent enrichment of Prevotella during tonsillitis raising the possibility of targeted interventions. It also supports the possible link between smoking, Fusobacteria and oral cancers.

Saliva and Serum Immune Responses in Apical Periodontitis

Apical periodontitis is an inflammatory reaction at the apex of an infected tooth. Its microbiota resembles that of marginal periodontitis and may induce local and systemic antibodies binding to bacteria- and host-derived epitopes. Our aim was to investigate the features of the adaptive immune response in apical periodontitis. The present Parogene cohort (n = 453) comprises patients with cardiac symptoms. Clinical and radiographic oral examination was performed to diagnose apical and marginal periodontitis. A three-category endodontic lesion score was designed. Antibodies binding to the bacteria- and host-derived epitopes were determined from saliva and serum, and bacterial compositions were examined from saliva and subgingival samples. The significant ORs (95% CI) for the highest endodontic scores were observed for saliva IgA and IgG to bacterial antigens (2.90 (1.01-8.33) and 4.91 (2.48-9.71)/log10 unit), saliva cross-reacting IgG (2.10 (1.48-2.97)), serum IgG to bacterial antigens (4.66 (1.22-10.1)), and Gram-negative subgingival species (1.98 (1.16-3.37)). In a subgroup without marginal periodontitis, only saliva IgG against bacterial antigens associated with untreated apical periodontitis (4.77 (1.05-21.7)). Apical periodontitis associates with versatile adaptive immune responses against both bacterial- and host-derived epitopes independently of marginal periodontitis. Saliva immunoglobulins could be useful biomarkers of oral infections including apical periodontitis-a putative risk factor for systemic diseases.

Frequency of bacetrial content finding in persistant periapical lesions

Objectives

To determine the percentage of persistant apical lesions positive for bacterial nucleic acids, to detect microorganisms difficult to cultivate in persistant apical lesions by PCR and relate them to endodontic failure, clinical symptoms and diabetes mellitus.

Materials and methods

The samples of persistent apical lesions were collected during apicoectomy. Bacterial ubiquitous primer 16S rRNA was used to detect 16S ribosomal RNA in 36 samples. A species–specific PCR was performed with primers targeted to the bacterial 16S rRNA genes of Prevotella Nigrescens, Pseudoramibacter alactolyticus, and Propionobacterium propionicum.

Results

Six samples (16.67%) were positive for bacterial ribosomal RNA. Pseudoramibacter alactolyticus was detected in three samples. Propionibacterium propionicum and Prevotella nigrescens were detected in one sample each. The prevalence of infection of such lesions with P. intermedia, P. propionicum and P. alactolyticus is low.

Conslusion

The study we conducted gave insufficient data about extraradicular infection and its connection with diabetes mellitus and clinical symptoms.

Conclusions

Apical lesions persisting after endodontic treatment could harbor microorganisms other than Actinomyces and Propionicum species.

Can the Enterococcus faecalis identified in the root canals of primary teeth be a cause of failure of endodontic treatment?

OBJECTIVE

This study investigated the presence of Enterococcus faecalis in primary teeth with primary root canal infections and related to the possible failure of pulpectomy outcome after 36 months.

MATERIAL AND METHODS

Root canal samples were obtained from 25 out of 244 patients using the sterile paper cone method. The identification of E. faecalis was done with culture and molecular tests using species-specific 16S rRNA gene-based polymerase chain reaction (PCR). After 36 months, the pulpectomy outcome was evaluated.

RESULTS

Enterococcus faecalis was found in five (20%) samples, and dental caries were the cause of primary infection in all of them. Pulpectomy outcome was evaluated only in teeth that completed the entire clinical protocol and were followed up to 36 months (n = 8). From these, 75% (n = 6) were successful and 25% (n = 2) failed. E. faecalis was present in 50% of both successful and failed cases.

CONCLUSIONS

Enterococcus faecalis was not related to the failure of endodontic treatment of primary teeth.

Analysis of the expression of NLRP3 and AIM2 in periapical lesions with apical periodontitis and microbial analysis outside the apical segment of teeth

OBJECTIVE

To detect the distribution and expression levels of the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) and the absent in Melanoma 2 (AIM2) inflammasomes in periapical lesions and to analyse the possible microbial stimuli outside of teeth.

DESIGN

The distribution of NLRP3 and AIM2 inflammasomes in sixteen periapical lesions was investigated by immunohistochemistry. Meanwhile, the relative gene expression levels of NLRP3 and AIM2 in sixteen periapical lesions and three health periodontal tissue were quantified by real-time polymerase chain reaction (PCR). Moreover, forty-seven teeth without sinus tracts were obtained in the clinic and included in bacterial analysis using PCR. Then, the mRNA levels of apoptosis-associated speck-like protein (ASC), caspase-1, interleukin-1β (IL-1β), NLRP3 and AIM2 in THP-1-derived macrophages treated with lipopolysaccharides (LPS) of Porphyromonas were also quantified by real-time PCR, and the IL-1β secretion level was investigated using enzyme-linked immunosorbent assay (ELISA).

RESULTS

NLRP3 and AIM2 were positively expressed in periapical lesions and were mainly distributed in inflammatory cells. Most of the samples that demonstrated up-regulation of NLRP3 mRNA also demonstrated up-regulation of caspase-1 mRNA. Microbial analysis revealed that Porphyromonas endodontalis was the most commonly detected species and was detected in 27 of 47 cases (57.4%), followed by Fusobacterium nucleatum (20/47, 42.6%), Porphyromonas gingivalis (19/47, 40.4%), Tannerella forsythia (19/47, 40.4%), Actinomyces sp. (17/47, 36.17%), Treponema denticola (10/47,21.28%), Actinomyces israelii (9/47,19.15%), Prevotella intermedia (6/47, 12.77%), Enterococcus faecalis (1/47,2.13%) and Enterococcus faecium (0/47,0). Furthermore, we found that LPS of P. gingivalis induced THP-1 cells to produce IL-1β and to activate NLRP3 and AIM2 inflammasomes.

CONCLUSIONS

Our results suggest that the NLRP3 and AIM2 proteins play a part in the pathogenesis of periapical periodontitis. Anaerobes, such as P. endodontalis, P. gingivalis, F. nucleatum and T. forsythia, were the main detected microbial stimuli that might activate inflammasomes in periapical tissues.

Culture-based identification of pigmented Porphyromonas and Prevotella species in primary endodontic infections

Background. The most common species isolated from primary endodontic infections are black-pigmented bacteria. These species are implicated in apical abscess formation due to their proteolytic activity and are fastidious in nature. Therefore, the present study was carried out to evaluate the presence and identification of various pigmented Porphyromonas and Prevotella species in the infected root canal through culture-based techniques.

Methods. Thirty-one patients with primary endodontic infections were selected. Using sterile paper points, samples were collected from the root canals after access opening and prior to obturation, which were cultured using blood and kanamycin blood agar. Subsequently, biochemical test was used to identify the species and the results were analyzed using percentage comparison analysis, McNemar and chi-squared tests, Wilcoxon match pair test and paired t-test.

Results. Out of 31 samples 26 were positive for black-pigmented organisms; the predominantly isolated species were Prevotella followed by Porphyromonas. In Porphyromonas only P. gingivalis was isolated. One of the interesting features was isolation of P. gingivalis through culture, which is otherwise very difficult to isolate through culture.

Conclusion. The presence of Prevotella and Porphyromonas species suggests that a significant role is played by these organisms in the pathogenesis of endodontic infections.

Design and evaluation of multifunctional antibacterial ion-doped β-dicalcium silicate cements favorable for root canal sealing

Cu or Zn-doping dicalcium silicate-based cements exhibit multifunctional physiochemical and biological performances and meet some challenging criteria in root canal treatment.

Comparative genome analysis of Prevotella intermedia strain isolated from infected root canal reveals features related to pathogenicity and adaptation

Background

Many species of the genus Prevotella are pathogens that cause oral diseases. Prevotella intermedia is known to cause various oral disorders e.g. periodontal disease, periapical periodontitis and noma as well as colonize in the respiratory tract and be associated with cystic fibrosis and chronic bronchitis. It is of clinical significance to identify the main drive of its various adaptation and pathogenicity. In order to explore the intra-species genetic differences among strains of Prevotella intermedia of different niches, we isolated a strain Prevotella intermedia ZT from the infected root canal of a Chinese patient with periapical periodontitis and gained a draft genome sequence. We annotated the genome and compared it with the genomes of other taxa in the genus Prevotella.

Results

The raw data set, consisting of approximately 65X-coverage reads, was trimmed and assembled into contigs from which 2165 ORFs were predicted. The comparison of the Prevotella intermedia ZT genome sequence with the published genome sequence of Prevotella intermedia 17 and Prevotella intermedia ATCC25611 revealed that ~14% of the genes were strain-specific. The Preveotella intermedia strains share a set of conserved genes contributing to its adaptation and pathogenic and possess strain-specific genes especially those involved in adhesion and secreting bacteriocin. The Prevotella intermedia ZT shares similar gene content with other taxa of genus Prevotella. The genomes of the genus Prevotella is highly dynamic with relative conserved parts: on average, about half of the genes in one Prevotella genome were not included in another genome of the different Prevotella species. The degree of conservation varied with different pathways: the ability of amino acid biosynthesis varied greatly with species but the pathway of cell wall components biosynthesis were nearly constant. Phylogenetic tree shows that the taxa from different niches are scarcely distributed among clades.

Conclusions

Prevotella intermedia ZT belongs to a genus marked with highly dynamic genomes. The specific genes of Prevotella intermedia indicate that adhesion, competing with surrounding microbes and horizontal gene transfer are the main drive of the evolution of Prevotella intermedia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1272-3) contains supplementary material, which is available to authorized users.

Identification of Dipeptidyl-Peptidase (DPP)5 and DPP7 in Porphyromonas endodontalis, Distinct from Those in Porphyromonas gingivalis

Dipeptidyl peptidases (DPPs) that liberate dipeptides from the N-terminal end of oligopeptides are crucial for the growth of Porphyromonas species, anaerobic asaccharolytic gram negative rods that utilize amino acids as energy sources. Porphyromonas endodontalis is a causative agent of periapical lesions with acute symptoms and Asp/Glu-specific DPP11 has been solely characterized in this organism. In this study, we identified and characterized two P. endodontalis DPPs, DPP5 and DPP7. Cell-associated DPP activity toward Lys-Ala-4-methylcoumaryl-7-amide (MCA) was prominent in P. endodontalis ATCC 35406 as compared with the Porphyromonas gingivalis strains ATCC 33277, 16-1, HW24D1, ATCC 49417, W83, W50, and HNA99. The level of hydrolysis of Leu-Asp-MCA by DPP11, Gly-Pro-MCA by DPP4, and Met-Leu-MCA was also higher than in the P. gingivalis strains. MER236725 and MER278904 are P. endodontalis proteins belong to the S9- and S46-family peptidases, respectively. Recombinant MER236725 exhibited enzymatic properties including substrate specificity, and salt- and pH-dependence similar to P. gingivalis DPP5 belonging to the S9 family. However, the kcat/Km figure (194 µM-1·sec-1) for the most potent substrate (Lys-Ala-MCA) was 18.4-fold higher as compared to the P. gingivalis entity (10.5 µM-1·sec-1). In addition, P. endodontalis DPP5 mRNA and protein contents were increased several fold as compared with those in P. gingivalis. Recombinant MER278904 preferentially hydrolyzed Met-Leu-MCA and exhibited a substrate specificity similar to P. gingivalis DPP7 belonging to the S46 family. In accord with the deduced molecular mass of 818 amino acids, a 105-kDa band was immunologically detected, indicating that P. endodontalis DPP7 is an exceptionally large molecule in the DPP7/DPP11/S46 peptidase family. The enhancement of four DPP activities was conclusively demonstrated in P. endodontalis, and remarkable Lys-Ala-MCA-hydrolysis was achieved by qualitative and quantitative potentiation of the DPP5 molecule.

Comparison of the bacterial composition and structure in symptomatic and asymptomatic endodontic infections associated with root-filled teeth using pyrosequencing

Residual microorganisms and/or re-infections are a major cause for root canal therapy failure. Understanding of the bacterial content could improve treatment protocols. Fifty samples from 25 symptomatic and 25 asymptomatic previously root-filled teeth were collected from Sudanese patients with periradicular lesions. Amplified 16S rRNA gene (V1-V2) variable regions were subjected to pyrosequencing (FLX 454) to determine the bacterial profile. Obtained quality-controlled sequences from forty samples were classified into 741 operational taxonomic units (OTUs) at 3% dissimilarity, 525 at 5% dissimilarity and 297 at 10% dissimilarity, approximately corresponding to species-, genus- and class levels. The most abundant phyla were: Firmicutes (29.9%), Proteobacteria (26.1%), Actinobacteria (22.72%), Bacteroidetes (13.31%) and Fusobacteria (4.55%). Symptomatic patients had more Firmicutes and Fusobacteria than asymptomatic patients, while asymptomatic patients showed more Proteobacteria and Actinobacteria. Interaction of disease status and age was observed by two-way ANOSIM. Canonical correspondence analysis for age, tooth restoration and disease status showed a correlation of disease status with the composition and prevalence of different members of the microbial community. The pyrosequencing analysis revealed a distinctly higher diversity of the microbiota compared to earlier reports. The comparison of symptomatic and asymptomatic patients showed a clear association of the composition of the bacterial community with the presence and absence of symptoms in conjunction with the patients’ age.

An investigation of the presence of specific anaerobic species in necrotic primary teeth

Different microbial identification methods have shown that the microbial community profiles in endodontic infections are diverse and assorted. The aim of this study was to evaluate the frequency of selected endodontic pathogens in the pulp chambers (PCs) and root canals (RCs) of infected primary teeth using PCR methods. Paired PC and RC samples were collected from 15 subjects and analyzed by PCR for the presence of Filifactor alocis, Fusobacterium nucleatum, Parvimonas micra, Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Prevotella tannerae, Tanerella forsythia, Treponema denticola, and Treponema socranskii. The frequency of each species was determined in the PC and RC of each case. The species most frequently detected in PCs were P. nigrescens (86.7%), P. gingivalis (73.3%), and F. alocis (73.3%). Of the PC samples, 13.3% contained P. micra and T. denticola, and 6.7% contained T. forsythia. The species most frequently detected in RCs were P. gingivalis (100%) and P. nigrescens (93.3%). P. tannerae, P. micra, and T. denticola were found in 40% of the RC samples; T. forsythia was found in 26.7% of the RC samples. The "red complex", which comprises P. gingivalis, T. denticola, and T. forsythia, was not found in the PC of any tooth but was found in 30% of the RC samples. The detection of P. nigrescens in the PC was statistically associated with the presence of P. nigrescens in the RC (p = 0.04). The results suggest high heterogeneity among the samples, even among those from the same subject.

Comprehensive analysis of secondary dental root canal infections: a combination of culture and culture-independent approaches reveals new insights

Persistence of microorganisms or reinfections are the main reasons for failure of root canal therapy. Very few studies to date have included culture-independent methods to assess the microbiota, including non-cultivable microorganisms. The aim of this study was to combine culture methods with culture-independent cloning methods to analyze the microbial flora of root-filled teeth with periradicular lesions. Twenty-one samples from previously root-filled teeth were collected from patients with periradicular lesions. Microorganisms were cultivated, isolated and biochemically identified. In addition, ribosomal DNA of bacteria, fungi and archaea derived from the same samples was amplified and the PCR products were used to construct clone libraries. DNA of selected clones was sequenced and microbial species were identified, comparing the sequences with public databases. Microorganisms were found in 12 samples with culture-dependent and -independent methods combined. The number of bacterial species ranged from 1 to 12 in one sample. The majority of the 26 taxa belonged to the phylum Firmicutes (14 taxa), followed by Actinobacteria, Proteobacteria and Bacteroidetes. One sample was positive for fungi, and archaea could not be detected. The results obtained with both methods differed. The cloning technique detected several as-yet-uncultivated taxa. Using a combination of both methods 13 taxa were detected that had not been found in root-filled teeth so far. Enterococcus faecalis was only detected in two samples using culture methods. Combining the culture-dependent and –independent approaches revealed new candidate endodontic pathogens and a high diversity of the microbial flora in root-filled teeth with periradicular lesions. Both methods yielded differing results, emphasizing the benefit of combined methods for the detection of the actual microbial diversity in apical periodontitis.

Molecular profiling of oral microbiota in jawbone samples of bisphosphonate-related osteonecrosis of the jaw

OBJECTIVE

Infection has been hypothesized as a contributing factor to bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ). The objective of this study was to determine the bacterial colonization of jawbone and identify the bacterial phylotypes associated with BRONJ.

MATERIALS AND METHODS

Culture-independent 16S rRNA gene-based molecular techniques were used to determine and compare the total bacterial diversity in bone samples collected from 12 patients with cancer (six, BRONJ with history of BP; six, controls without BRONJ, no history of BP but have infection).

RESULTS

Denaturing gradient gel electrophoresis profile and Dice coefficient displayed a statistically significant clustering of profiles, indicating different bacterial population in BRONJ subjects and control. The top three genera ranked among the BRONJ group were Streptococcus (29%), Eubacterium (9%), and Pseudoramibacter (8%), while in the control group were Parvimonas (17%), Streptococcus (15%), and Fusobacterium (15%). H&E sections of BRONJ bone revealed layers of bacteria along the surfaces and often are packed into the scalloped edges of the bone.

CONCLUSION

This study using limited sample size indicated that the jawbone associated with BRONJ was heavily colonized by specific oral bacteria and there were apparent differences between the microbiota of BRONJ and controls.

Synergistic growth effect among bacteria recovered from root canal infections

The objective of this study was to determine the ecological relationships between bacterial species that colonize infected root canals. Root canal bacteria recovered from one patient with pulp canal necrosis were evaluated in vitro for synergistic and antagonistic activities determined by mono and co-culture growth kinetics and the production of bacteriocin-like substances using the double layer diffusion method. Peptostreptococcus prevotii triggered a significant increase of Fusobacterium nucleatum growth, while the former bacteria did not affect the growth of P. prevotii. The bacterial species did not produce antagonism activity against itself or against any of the other two species. Despite many studies have demonstrated the capability of root canal microorganisms to produce antagonistic substances, these in vitro experimental tests show the synergistic effect of P. prevotii on the growth of F. nucleatum.

Detection and clonal analysis of anaerobic bacteria associated to endodontic-periodontal lesions

BACKGROUND

Microbial agents in root canal systems can induce periodontal inflammation. The aims of this study are to detect anaerobic microorganisms in endodontic-periodontal lesions, determine the genetic diversity among them, and assess the simultaneous colonization of the pulp and periodontal microenvironments by a single clone.

METHODS

Twenty-seven teeth of patients with endodontic-periodontal lesions were selected. Samples were spread on an agar-blood medium, the detection of each species was performed using a polymerase chain reaction, and the determination of the simultaneous presence of the same species in the microenvironments by one or more clones was determined using arbitrarily primed PCR.

RESULTS

Prevotella intermedia (Pi) was the most prevalent species of the colonies in periodontal pockets, whereas Porphyromonas gingivalis (Pg) and Pi were the more prevalent in root canals. Isolates of Pi and Pg were simultaneously identified in root canals and periodontal pockets. Eighteen percent of teeth exhibited the simultaneous colonization by Pg, Tannerella forsythia (previously T. forsythensis), and Porphyromonas endodontalis in the pulp and periodontal microenvironments. The presence of these species was noted even in niches from which no colonies were isolated. Seventeen different genotypes were found in periodontal and pulp sites, with the majority of sites colonized by one or two different genotypes. A high degree of genotype similarity was found for samples of Pg isolated from only one site as well as for those isolated from both microenvironments.

CONCLUSION

Different clones of Pi and Pg with a high intraspecific genotype similarity were found to colonize the same anatomic sites in endodontic-periodontal infections.