Evaluation of the microbiota of primary endodontic infections using checkerboard DNA-DNA hybridization

Dental Pathophysiology of Odontogenic Sinusitis: Endodontic Infections

Bacterial odontogenic sinusitis (ODS) arises from maxillary dental issues or oral procedures, and affects at least the maxillary sinuses, with or without other paranasal sinus involvement. It has been historically underreported, in contrast to more recent findings attributing 25-40% of chronic maxillary sinusitis to dental causes. Endodontic infections represent one of the most common causes of ODS. Endodontic factors like root canal infection and microbial proximity to sinus cavities play pivotal roles. Host immunological responses further shape disease severity and progression. This article aims to explore the complexity of endodontic infections that cause ODS, elucidating anatomical, microbial, and immunological aspects.

Relationship of MMP-9 with the clinical course of apical periodontitis and the main bacterial species in the oral microbiota

Bacterial products, host immune cells and cytokines have been reported to play an important role in the pathogenesis of apical periodontitis (AP). This study aimed to determine the main bacterial species in the microbiota as gram positive and negative and to compare the relationship between matrix metalloproteinase (MMP)-9 and tumor necrosis factor (TNF)-α with controlled patient groups. 60 patients with AP and extraction indication were included in the study. 30 systemically healthy volunteers without AP were selected as the control group. After access cavity preparation, an initial microbiologic sample (S1) was taken from the root canal. After atraumatic extraction of the tooth, a second microbial sample (S2) was taken from the extraradicular region. After bacterial DNA extraction, 16S rRNA gene primer was designed for sequence analysis. Bacterial community profiling was made by Sanger sequencing of the PCR products. In addition, serum MMP-9 and TNF-α levels were measured from all patients. TNF-α levels of the AP group were higher than the control group, while MMP-9 levels were found to be lower (p = 0.0264 and p = 0.0146, respectively). There was no difference in the main bacterial species isolated from the samples taken from the intracanal and extraradicular region of the tooth with AP (p = 0.714). The main bacterial species in the intracanal region of the tooth with AP are similar to the main bacterial species in the extraradicular region. The pathophysiology of the tooth with AP is associated with low MMP-9 and high TNF-α, independent of the bacterial species in the intracanal and extraradicular regions.

Identification and antimicrobial susceptibility profile of bacteria isolated from primary endodontic infections

This study aimed to identify and characterize the antimicrobial susceptibility profile of bacteria found in primary endodontic infections in the teeth of patients treated at the Dental Clinic of the University of Ribeirão Preto, São Paulo, Brazil. From September to December 2019, samples were obtained from 21 patients with primary endodontic infections. The collections were carried out in triplicate using paper cones placed close to the total length of the root canal. Bacterial isolation was performed in Brain Heart Infusion agar, Blood agar, and other selective culture media cultured at 37°C for up to 48 h under aerobiosis and microaerophilic conditions. The bacterial species were identified using the Vitek 2 automated system. The disk diffusion method on agar Müeller-Hinton was used to assess antimicrobial susceptibility with the recommended antimicrobials for each identified bacterial species. A total of 49 antibiotics were evaluated. Fifteen of the 21 samples collected showed bacterial growth, and 17 bacterial isolates were found. There were 10 different bacterial species identified: Enterococcus faecalis (four isolates), Streptococcus mitis/oralis (three isolates), Streptococcus anginosus (three isolates) being the most common, followed by Staphylococcus epidermidis, Enterococcus faecium, Streptococcus constellatus, Streptococcus alactolyticus, Enterobacter cloacae, Klebsiella variicola, and Providencia rettgeri (one isolate of each species). The analysis demonstrated significant susceptibility to most of the tested antibiotics. However, some Enterococcus isolates resisted the antibiotic's erythromycin, ciprofloxacin, and tetracycline. A Staphylococcus epidermidis isolate was characterized as multidrug-resistant. Five Streptococcus isolates were non-susceptible to all antibiotics tested.

Prevalence of Fusobacterium Species in Endodontic Infections Detected With Molecular Methods: Systematic Review and Meta-Analysis

INTRODUCTION

Endodontic infections are polymicrobial; however, investigating the role of bacterial species is critical because they may influence pathogenesis, the development of symptoms, or the persistence of disease. This systematic review aimed to determine the prevalence of Fusobacterium species and its association with different types of endodontic infections.

METHODS

MEDLINE (Ovid), PubMed, Scopus, Web of Science, and Cochrane Library databases were used as electronic databases to retrieve relevant studies. The studies were evaluated for eligibility criteria, and the certainty in evidence and risk of bias were evaluated using critical appraisal tools for prevalence studies from the Joanna Briggs Institute. Forty studies were selected for meta-analysis and statistically analyzed for the relationship between the prevalence of Fusobacterium species and both the presence of symptoms and the type of infections (primary vs secondary/persistent) using meta-regression analysis.

RESULTS

The prevalence of Fusobacterium spp. in endodontic infections ranged from 3%-100% (mean = 42.51%) in the 40 included studies. Calculated confidence intervals indicated that the presence of Fusobacterium spp. was not statistically associated with the presence of symptoms or with the type of infections (the set of 2 predictors was not significant; P < .05).

CONCLUSIONS

The prevalence of Fusobacterium infection, which was identified with molecular methods, was not significant for overall regression using both predictors (ie, symptoms [symptomatic vs asymptomatic] and types of infections [primary vs secondary/persistent]).

Microbial identification from traumatized immature permanent teeth with periapical lesions using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

BACKGROUND

This study aims at identifying the microbiota in traumatized immature permanent teeth with periapical lesions using Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

METHODS

The study included 16 immature maxillary central incisors with periapical lesions in 13 patients. Field decontamination and negative control samples were performed before and after access cavity preparation. Root canal samples were taken using sterile stainless-steel hand files following field decontamination. In-office inoculation and pure sub-cultures were performed. Bacterial isolates were prepared for MALDI-TOF MS (Bruker, Billerica, MA USA) analysis using the formic acid extraction method. A comparison of the prevalence of isolated microorganisms was done using a one-sample chi-square test. Comparisons between identified microbial species with the, cone beam computed tomography periapical index (CBCT PAI) scores and lesion volume were also conducted. The Chi-square test was applied to investigate the association between the categorical variables .

RESULTS

Out of the forty isolates recovered from the 16 traumatized teeth included in the present study with the mean patients' age of 10.93 ± 1.77, 37 isolates were reliably identified by MALDI-TOF MS. Twelve teeth (62.5%) were polymicrobial. The recovered bacteria belonged to five phyla, 15 genera and 25 species. Firmicutes were the predominant phylum (P < 0.001) over Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria. Gram positive bacteria were significantly more prevalent than Gram negative (p = 0.03). Facultative anaerobes were the most prevalent (P < 0.001) compared to the obligate anaerobes and the obligate aerobes. The latter were the least prevalent. Statistically, significant differences existed in the comparison between CBCT PAI scores according to bacterial gram staining.

CONCLUSION

Traumatized immature permanent teeth with periapical lesions showed a significant predominance of Gram-positive facultative anaerobes. MALDI-TOF MS provided accurate identification of numerous viable endodontic microbes.

Fluorescence characteristics of E. faecalis in dentine following treatment with oxidizing endodontic irrigants

INTRODUCTION

This study aimed to assess changes in the fluorescence characteristics of Enterococcus faecalis in human dentine over a period of 24 h following treatment with endodontic irrigants.

METHOD

Sterilised, non-functional extracted third molars were embedded in acrylic resin and uniformly sectioned into 2 mm thick dentine sections. After the removal of smear layer, the dentine sections were inoculated with E. faecalis and cultured for 7 days. The infected dentine sections were subsequently treated with different concentrations of sodium hypochlorite (NaOCl) and hydrogen peroxide (H₂O₂). Bacterial fluorescence readings were assessed at different time points using a calibrated laser device. All data were assessed for normality (Kolmogorov Smirnoff test) and analysed using ANOVA with Bonferroni post-hoc tests.

RESULTS

Fluorescence readings were quenched when E. faecalis infected human dentine sections were treated with oxidizing irrigants in vitro. Throughout a 24-hour period, fluorescence recovered in part but did not return to baseline level.

CONCLUSION

The fluorescence quenching effect of these oxidizing agents needs to be considered when using laser fluorescence in assessing the quality of root canal debridement or disinfection.

Resolution of Nasal Sinus Tract after Endodontic Therapy: A Case Report with Microbial Analysis

This case report describes the resolution of a 20-year misdiagnosed nasal sinus tract after root canal therapy with multiple sessions of calcium hydroxide (Ca[OH]₂) intracanal medication. Clinical evaluation, including diagnostic testing and sinus tract tracing, was performed followed by a cone-beam computed tomographic scan and 3-dimensional reconstruction of the apical lesion. Bacteria and endotoxin analyses were performed from the nasal sinus tract and paired root canal infection before (s1) and after instrumentation (s2) and after 7 (s3), 14 (s4), and 21 (s5) days of Ca(OH)₂ medication. The bacteria analysis was performed using the checkerboard DNA-DNA hybridization method and endotoxin quantified by the limulus amebocyte lysate method. A similar microbiota profile was found in the sinus tract and paired root canal infection. No target bacterial species were detected in the root canal at s2, s3, and s5. In contrast, Actinomyces israellii and Eubacterium nodatum were detected at s4. Differences in bacterial detection were found between s1 × s2, s3 × s4, and s4 × s5 (all P < .05). Endotoxin was detected in the root canal at all sampling times. Differences in the levels of endotoxin were found between s1 × s2, s2 × s3, and s3 × s4 (all P < .05).The bacterial analysis revealed similar microbiota profiles present in the nasal sinus tract and paired root canal infection with the participation of a wide variety of gram-positive and -negative species. Additionally, root canal therapy with multiple sessions of Ca(OH)₂ intracanal medication for 21 days was effective in disinfecting the root canal system and resolving the nasal sinus tract.

Identification of microorganisms in irreversible pulpitis and primary endodontic infections with respect to clinical and radiographic findings

OBJECTIVES

The aim of this study was to evaluate the composition of microbiota of irreversible pulpitis and primary endodontic infections with respect to clinical and radiographic findings by performing cultures and 16s rDNA sequencing in Iranian patients.

MATERIAL AND METHODS

In this prospective cross-sectional study, samples were collected from 41 root canals for 4 main groups of patients. Bacterial identification was performed by the polymerase chain reaction (PCR) and 16s rDNA sequencing of aerobic and anaerobic cultivable colonies taken from patients' culture plates. Additionally, the presence of 13 bacterial species and 3 nonbacterial species was also explored using PCR and species-specific primers.

RESULTS

Sixteen microbial species, 1 fungus (Candida albicans), and 1 virus (Herpes simplex virus) were discovered and isolated. Species with the highest prevalence were Dialister invisus (68.3%), Porphyromonas gingivalis (58.8%), Streptococcus salivarius (58.5%), and Treponema denticola (56.1%). Lysinibacillus fusiformis (19.1%) was detected in the root canals for the first time. Candida albicans was seen in 11 cases (26.8%). Herpes simplex virus (HSV) was seen in 4 patients (9.8%).

CONCLUSIONS

Our results suggest that Gram-negative anaerobic oral bacteria are the majority of the microbes in primary endodontic infections. Various combinations of bacterial species were related to different clinical and radiographic conditions. Lysinibacillus fusiformis was detected for the first time in primary endodontic infections.

CLINICAL RELEVANCE

The results of this investigation might help clinicians choose to identify suspected endodontic pathogens in the etiology of each form of pulpal and periradicular diseases to determine the best therapeutic measures.

Effect of aeration mode on aerosol characteristics from the same wastewater treatment plant

Aeration and mechanical agitation are the main drivers of aerosol generation in wastewater treatment plants (WWTPs). However, the effect of aeration mode on aerosol characteristics remains poorly understood. In this study, horizontal rotor aeration and fine bubble aeration in the same WWTP were selected to identify the effect on the emission, size distribution, microbial and chemical composition. For bacteria, fungi, Enterobacteriaceae, Staphylococcus aureus, and Pseudomonas aeruginosa in aerosols, the horizontal rotor aeration had higher contributions to the emissions than the fine bubble aeration. Horizontal rotor aeration generated a more coarse fraction (size > 7 μm) and a comparable respirable fraction (RF; size < 3.3 μm) compared with those of fine bubble aeration. More types of potential pathogens were generated by horizontal rotor aeration. The most easily aerosolized genera generated by horizontal rotor aeration and fine bubble aeration, were Trichosporon and Mycobacterium, with the aerosolization factors of 633.70 and 192.56, respectively. For Cl^-, SO₄^2-, NO₃^-, Zn, Ba, Cd, Sc, V, Rb, Ca, K, Ca, K, Mg, Na and Si in the aerosols, the contributions of fine bubble aeration were higher than those of horizontal rotor aeration. Due to the aerosol specialty from the different aeration modes, targeted manipulations should be employed to reduce the exposure risks.

Leptotrichia species in human infections II

Leptotrichia species are non-motile facultative anaerobic/anaerobic bacteria that are found mostly in the oral cavity and some other parts of the human body, in animals, and even in ocean sediments. Valid species include L. buccalis, L. goodfellowii, L. hofstadii, L. honkongensis, L. shahii, L. trevisanii, and L. wadei. Some species require serum or blood for growth. All species ferment carbohydrates and produce lactic acid that may be involved with tooth decay. Acting as opportunistic pathogens, they are involved in a variety of diseases, and have been isolated from immunocompromised but also immunocompetent individuals. Mucositis, oral lesions, wounds, and abscesses may predispose to Leptotrichia septicemia. Because identification of Leptotrichia species by phenotypic features occasionally lead to misidentification, genetic techniques such as 16S rRNA gene sequencing is recommended. Early diagnosis and treatment of leptotrichia infections is important for positive outcomes. Over the last years, Leptotrichia species have been associated with several changes in taxonomy and new associations with clinical diseases. Such changes are reported in this updated review.

First case of infectious endocarditis caused by Parvimonas micra

P. micra is an anaerobic Gram-positive cocci, and a known commensal organism of the human oral cavity and gastrointestinal tract. Although it has been classically described in association with endodontic disease and peritonsillar infection, recent reports have highlighted the role of P. micra as the primary pathogen in the setting of invasive infections. In its most recent taxonomic classification, P. micra has never been reported causing infectious endocarditis in humans. Here, we describe a 71 year-old man who developed severe native valve endocarditis complicated by aortic valvular destruction and perivalvular abscess, requiring emergent surgical intervention. Molecular sequencing enabled identification of P. micra.

Inter-Individual Differences in the Oral Bacteriome Are Greater than Intra-Day Fluctuations in Individuals

Given the advent of massively parallel DNA sequencing, human microbiome is analyzed comprehensively by metagenomic approaches. However, the inter- and intra-individual variability and stability of the human microbiome remain poorly characterized, particularly at the intra-day level. This issue is of crucial importance for studies examining the effects of microbiome on human health. Here, we focused on bacteriome of oral plaques, for which repeated, time-controlled sampling is feasible. Eighty-one supragingival plaque subjects were collected from healthy individuals, examining multiple sites within the mouth at three time points (forenoon, evening, and night) over the course of 3 days. Bacterial composition was estimated by 16S rRNA sequencing and species-level profiling, resulting in identification of a total of 162 known bacterial species. We found that species compositions and their relative abundances were similar within individuals, and not between sampling time or tooth type. This suggests that species-level oral bacterial composition differs significantly between individuals, although the number of subjects is limited and the intra-individual variation also occurs. The majority of detected bacterial species (98.2%; 159/162), however, did not fluctuate over the course of the day, implying a largely stable oral microbiome on an intra-day time scale. In fact, the stability of this data set enabled us to estimate potential interactions between rare bacteria, with 40 co-occurrences supported by the existing literature. In summary, the present study provides a valuable basis for studies of the human microbiome, with significant implications in terms of biological and clinical outcomes.

Antimicrobial peptide-based treatment for endodontic infections--biotechnological innovation in endodontics

The presence/persistence of microorganisms in the pulp and periapical area corresponds to the maintenance of an exacerbated immune response that leads to the start of periradicular bone resorption and its perpetuation. In endodontic treatment, the available intracanal medications do not have all the desirable properties in the context of endodontic infection and apical periodontitis; they need to include not only strong antimicrobial performance but also an immunomodulatory and reparative activity, without host damage. In addition, there are various levels of resistance to root canal medications. Thus, antimicrobial agents that effectively eliminate resistant species in root canals could potentially improve endodontic treatment. In the emergence of new therapies, an increasing number of studies on antimicrobial peptides (AMPs) have been seen over the past few years. AMPs are defense biomolecules produced in response to infection, and they have a wide spectrum of action against many oral microorganisms. There are some studies that correlate peptides and oral infections, including oral peptides, neuropeptides, and bacterial, fish, bovine and synthetic peptides. So far, there are around 120 published studies correlating endodontic microbiota with AMPs but, according to our knowledge, there are no registered patents in the American patent database. There are a considerable number of AMPs that exhibit excellent antimicrobial activity against endodontic microbiota at a small inhibitory concentration and modulate an exacerbated immune response, down-regulating bone resorption. All these reasons indicate the antimicrobial peptide-based endodontic treatment as an emerging and promising option.

Antimicrobial resistance and virulence traits of Enterococcus faecalis from primary endodontic infections

OBJECTIVES

To determine the phenotypic and molecular characteristics of Enterococcus faecalis recovered from primary endodontic infections in Brazilian patients.

METHODS

Twenty isolates of E. faecalis recovered from 43 Brazilian patients with primary endodontic infections were identified by biochemical profiling (API20Strep) and 16S rDNA sequencing. Antimicrobial susceptibility was ascertained by agar dilution, using the recommended protocol of the Clinical and Laboratory Standards Institute (CLSI). PCR with validated primers was used to detect genes associated with antibiotic resistance and specific virulence factors.

RESULTS

All isolates were deemed susceptible to penicillin G, erythromycin and vancomycin. However, nine isolates had a minimum inhibitory concentration of 4μg/mL to vancomycin (the resistance breakpoint). Fourteen isolates (70% of isolates) were also resistant to tetracycline with MICs of >64μg/mL. PCR products for tetracycline resistance genes were detected in test isolates, while erythromycin and vancomycin resistance genes were not evident. Gelatinase, aggregation substance and enteroccocal surface protein genes were detected in 20, 18 and 12 isolates, respectively.

CONCLUSIONS

Endodontic E. faecalis isolates exhibit high level of resistance to tetracycline, an antibiotic that has use in local treatment of dental infections. This opens up a much-needed debate on the role and efficacy of this antibiotic for oral infections. Furthermore, these isolates were shown to possess genes that could contribute to pathogenicity in the pulp cavity.

Evidence of an increased pathogenic footprint in the lingual microbiome of untreated HIV infected patients

Background

Opportunistic oral infections can be found in over 80% of HIV + patients, often causing debilitating lesions that also contribute to deterioration in nutritional health. Although appreciation for the role that the microbiota is likely to play in the initiation and/or enhancement of oral infections has grown considerably in recent years, little is known about the impact of HIV infection on host-microbe interactions within the oral cavity. In the current study, we characterize modulations in the bacterial composition of the lingual microbiome in patients with treated and untreated HIV infection. Bacterial species profiles were elucidated by microarray assay and compared between untreated HIV infected patients, HIV infected patients receiving antiretroviral therapy, and healthy HIV negative controls. The relationship between clinical parameters (viral burden and CD4+ T cell depletion) and the loss or gain of bacterial species was evaluated in each HIV patient group.

Results

In untreated HIV infection, elevated viremia was associated with significantly higher proportions of potentially pathogenic Veillonella, Prevotella, Megasphaera, and Campylobacter species in the lingual microbiome than observed in healthy controls. The upsurge in the prevalence of potential pathogens was juxtaposed by diminished representation of commensal Streptococcus and Veillonella species. Colonization of Neisseria flavescens was lower in the lingual microbiome of HIV infected patients receiving antiretroviral therapy than in uninfected controls.

Conclusions

Our findings provide novel insights into the potential impact of HIV infection and antiretroviral therapy on the community structure of the oral microbiome, and implicate potential mechanisms that may increase the capacity of non-commensal species to gain a stronger foothold.

Microbiologic profile of endodontic infections from HIV- and HIV+ patients using multiple-displacement amplification and checkerboard DNA-DNA hybridization

OBJECTIVE

To compare the microbiota of endodontic infections in necrotic pulp from HIV-negative and HIV-positive subjects.

MATERIALS AND METHODS

Root canal samples from necrotic pulp were collected from 40 HIV- and 20 HIV+ subjects. Pulps were amplified using multiple displacement amplification (MDA). Then, checkerboard DNA-DNA hybridization was employed to assess the levels of 107 microbial taxa. The percentage of DNA probe count and the percentage of teeth colonized by each test species were investigated. Significant differences between groups regarding proportions of taxa and prevalence of the test species were sought using the Mann-Whitney test and the Chi-square analysis, respectively.

RESULTS

The most prevalent taxa detected were Dialister pneumosintes, Stenotrophomonas maltophilia, Streptococcus sobrinus, Corynebacterium diphteriae, and Helicobacter pylori among HIV- subjects and D. pneumosintes, Prevotella tannerae, Porphyromonas gingivalis, Parvimonas micra, Prevotella nigrescens, and Corynebacterium diphtheriae among HIV+ individuals. D. pneumosintes, C. diphtheria, and C. albicans were the most abundant species in the HIV- group, whereas the predominant taxa in HIV+ samples were P. tannerae, D. pneumosintes and Olsenella uli. P. tannerae, O. uli, Veilonella dispar, Bacteroides fragilis, and Actinomyces meyeri were significantly more abundant in HIV+ samples.

CONCLUSIONS

There were significant differences in the prevalence and proportions of specific microbial taxa between HIV- and HIV+ individuals. The root canal microbiota may represent a reservoir of important oral and medical pathogens, mainly in HIV+ individuals.

Polymerase chain reaction of enterococcus faecalis and candida albicans in apical periodontitis from Turkish patients

Aim: The aim of this study was to determine the frequency of two important pathogenic microorganisms associated with endodontic infections, Enterococcus faecalis and Candida albicans, in root canal samples from patients with necrotic pulps or failed canal therapy by polymerase chain reaction method. Method: Microbial samples were obtained from 117 teeth with necrotic pulp tissues and 114 teeth with failed endodontic treatment. Results: E.faecalis were identified in 16% of the necrotic and 10% of the retreated root canal infections by PCR. C.albicans genome were identified in 20% and 11% of the necrotic and retreated root canal infections, respectively, by PCR. The frequencies of microbiota were not statistically different between necrotic and retreatment groups (p > 0.05, chi squared test). Conclusions: PCR analysis of teeth with periapical lesions revealed that E.faecalis was found in fewer patients than in previous studies. The C.albicans prevelance was consistent with previous reports. No statistical difference was found between primary and secondary root canal infections for C.albicans or E.faecalis.

Key words:Primary root canal infection, secondary root canal infection, E.faecalis, C.albicans.

Real-time polymerase chain reaction of "red complex" (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) in periradicular abscesses

OBJECTIVE

The red complex bacteria (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) have been implicated, either singly or in combination, in the development of various forms of periodontal diseases. The aim of this study was to investigate the presence of "red complex" in acute periradicular abscesses by real-time polymerase chain reaction (PCR) method.

STUDY DESIGN

Microbial samples were collected by aspiration from 32 cases diagnosed as acute periradicular abscess. DNA was extracted from the samples by using a QIAamp DNA mini-kit and analyzed with real-time PCR.

RESULTS

At least 1 member of the red complex was found in 84% of the cases. In general T. denticola, P. gingivalis, and T. forsythia were detected in 65.6%, 43.7%, and 40.6% of the cases, respectively. Red complex was detected in 15.6% of samples taken from acute periradicular abscesses.

CONCLUSIONS

Our findings suggest that "red complex" can participate in the pathogenesis of acute periradicular abscesses.

Microbiota of deciduous endodontic infections analysed by MDA and Checkerboard DNA-DNA hybridization

AIMS

To evaluate the microbiota of endodontic infections in deciduous teeth by Checkerboard DNA-DNA hybridization after uniform amplification of DNA in samples by multiple displacement amplification (MDA).

METHODOLOGY

Forty samples from the root canal system of deciduous teeth exhibiting pulp necrosis with or without radiographically detectable periradicular/interradicular bone resorption were collected and 32 were analysed, with three individuals contributing two samples; these were MDA-amplified and analysed by Checkerboard DNA-DNA hybridization for levels of 83 bacterial taxa. Two outcome measures were used: the percentage of teeth colonized by each species and the mean proportion of each bacterial taxon present across all samples.

RESULTS

The mean amount of DNA in the samples prior to amplification was 5.2 (±4.7) ng and 6.1 (±2.3) μg after MDA. The mean number of species detected per sample was 19 (±4) (range: 3-66) to the nearest whole number. The most prevalent taxa were Prevotella intermedia (96.9%), Neisseria mucosa (65.6%), Prevotella nigrescens (56.2%) and Tannerella forsythia (56.2%). Aggregatibacter (Haemophilus) aphrophilus and Helicobacter pylori were not detected. P. intermedia (10%), Prevotella tannerae (7%) and Prevotella nigrescens (4.3%) presented the highest mean proportions of the target species averaged across the positive samples.

CONCLUSION

Root canals of infected deciduous teeth had a diverse bacterial population. Prevotella sp. were commonly found with P. intermedia, Prevotella tannerae and Prevotella nigrescens amongst the most prominent species detected.

Characterization of virulence factors and clonal diversity of Enterococcus faecalis isolates from treated dental root canals

The high prevalence of Enterococcus faecalis in root canal treated teeth with post-treatment disease, as evidenced by both molecular and traditional culturing methods, suggests that this species may be a key player in endodontic treatment failure. This study aimed to detect virulence factors by phenotypic and western blotting tests, and virulence genes by PCR from 20 clinical strains of E. faecalis isolated from treated root canals of teeth with (10) or without (10) apical periodontitis. Moreover, genomic diversity of these strains was assessed by pulsed-field gel electrophoresis (PFGE) and rep-PCR. All 20 strains presented the gelE gene (gelatinase), but 10 of them did not hydrolyze gelatin. Seven of the 10 gelatinase-producing isolates were recovered from root canals with lesions, which suggests a role for this virulence factor in the pathogenesis of post-treatment disease. The esp gene was expressed only in cases where gelatinase production was negative. The other virulence genes were found in 90% (efaA and ace genes), 45% (agg gene) and 95% (cpd gene) of the E. faecalis isolates. As for PFGE and rep-PCR, no specific clonal type of E. faecalis was found in association with teeth with or without disease, revealing the interindividual clonal diversity of endodontic infections.

Propionibacterium acnes and Staphylococcus epidermidis isolated from refractory endodontic lesions are opportunistic pathogens

The predominant cultivable microbiota from 20 refractory endodontic lesions (9 with abscesses and 11 without abscesses) were determined, and Propionibacterium acnes and Staphylococcus epidermidis were among the most predominant organisms. The number of species identified from lesions with abscesses (14.1 ± 2.6) was significantly greater (P < 0.001) than the number from lesions without abscesses (7.4 ± 5.9). Comparison of perioral isolates using repetitive extragenic palindromic PCR of the same species from the same subjects demonstrated that the endodontic and skin populations were significantly different. The P. acnes isolates were typed on the basis of recA gene sequence comparison, and only three types (types I, II, and III) were identified among 125 isolates examined. However, we found that type I (type IA and IB) isolates were primarily isolated from the skin, while types II and III were significantly more likely to be isolated from the endodontic lesions (P < 10(-10)). We found that the robustness of the recA phylotypes was not strong by comparing the partial gene sequences of six putative virulence determinants, PAmce, PAp60, PA-25957, PA-5541, PA-21293, and PA-4687. The resulting neighbor-joining trees were incongruent, and significant (phi test; P = 2.2 × 10(-7)) evidence of recombination was demonstrated, with significant phylogenetic heterogeneity being apparent within the clusters. P. acnes and S. epidermidis isolated from refractory endodontic infections, with or without periapical abscesses, are likely to be nosocomial infections.

Distribution of Porphyromonas gingivalis fimA genotypes in primary endodontic infections

OBJECTIVE

Long fimbriae (FimA) are important virulence factors of Porphyromonas gingivalis. Based on the diversity of the fimA gene, this species is classified into 6 genotypes. This study surveyed samples from primary endodontic infections for the presence of these P. gingivalis fimA variants.

STUDY DESIGN

Genomic DNA isolated from samples taken from 25 root canals of teeth with chronic apical periodontitis and 25 aspirates from acute apical abscess was used as template in polymerase chain reaction (PCR) assays directed toward the detection of the different P. gingivalis fimA genotypes.

RESULTS

Porphyromonas gingivalis was detected by a 16S rRNA gene-based PCR in 36% of the total number of cases sampled (44% of chronic apical periodontitis and 28% of abscess aspirates). In cases of chronic apical periodontitis, P. gingivalis variant type IV was the most prevalent (24%), followed by types I (20%), II (16%), and III (8%). In acute abscess samples, variant type II was the most prevalent (12%), followed by types III and IV (8% of each) and type I (4%). Combinations of up to 3 different genotypes were detected in a few cases. No single fimA genotype variant or combination thereof was significantly associated with symptoms. Overall, fimA types IV (16%), II (14%), and I (12%) were the most prevalent.

CONCLUSIONS

Findings demonstrated that different P. gingivalis fimA genotypes can be present in primary endodontic infections.

Analysis of Enterococcus faecalis in samples from Turkish patients with primary endodontic infections and failed endodontic treatment by real-time PCR SYBR green method

Objective:

The aims of this study were to investigate the presence of Enterococcus faecalis in primary endodontic infections and failed endodontic treatments using real-time PCR and to determine the statistical importance of the presence of E. faecalis in a Turkish population with endodontic infections.

Material and Methods:

E. faecalis was investigated from 79 microbial samples collected from patients who were treated at the Endodontic Clinic of the Dental School of Atatürk University (Erzurum, Turkey). Microbial samples were taken from 43 patients (Group 1) with failed endodontic treatments and 36 patients (Group 2) with chronic apical periodontitis (primary endodontic infections). DNA was extracted from the samples by using a QIAamp^® DNA mini-kit and analyzed with real-time PCR SYBR Green.

Results:

E. faecalis was detected in 41 out of 79 patients, suggesting that it exists in not less than 61% of all endodontic infections when the proportion test (z= -1.645, <x= 0.05) was applied. Real-time PCR SYBR Green allowed for the detection of E. faecalis in 32 out of 43 (74.4%) in Group 1, and in 9 out of 36 (25%) in Group 2.

Conclusions:

These results suggest that E. faecalis is a frequent isolate for endodontic infections in Turkish patients, and is more often associated with failed endodontic treatments than primary endodontic infections.

Prevalence and clonal analysis of Porphyromonas gingivalis in primary endodontic infections

This study investigated the prevalence of Porphyromonas gingivalis in 62 teeth with primary endodontic infections by using a species-specific 16S rRNA gene-based nested polymerase chain reaction assay. P. gingivalis isolates recovered from 2 infected root canals were also analyzed for clonal diversity by using arbitrarily primed PCR. Overall, P. gingivalis was found in 48% of the samples. This species was specifically detected in 36% of canals of teeth with chronic apical periodontitis, in 46% of the cases of acute apical periodontitis, and in 67% of acute apical abscesses. P. gingivalis was significantly more frequent in abscess aspirates than in canals of teeth with chronic apical periodontitis (P < .05). Typing of colonies retrieved from 2 infected canals revealed 2 clones per individual. These findings confirmed that P. gingivalis can be an important endodontic pathogen, mostly associated with acute abscesses, and demonstrated that different clonal types of this species can colonize the root canal in the same individual.

Root canal microbiota of teeth with chronic apical periodontitis

Samples from infected root canals of 43 teeth with chronic apical periodontitis were analyzed for the presence and relative levels of 83 oral bacterial species and/or phylotypes using a reverse-capture checkerboard hybridization assay. Associations between the most frequently detected taxa were also recorded. The most prevalent taxa were Olsenella uli (74%), Eikenella corrodens (63%), Porphyromonas endodontalis (56%), Peptostreptococcus anaerobius (54%), and Bacteroidetes oral clone X083 (51%). When prevalence was considered only for bacteria present at levels >10(5), Bacteroidetes clone X083 was the most frequently isolated bacterium (37%), followed by Parvimonas micra (28%), E. corrodens (23%), and Tannerella forsythia (19%). The number of target taxa per canal was directly proportional to the size of the apical periodontitis lesion, with lesions >10 mm in diameter harboring a mean number of approximately 20 taxa. Several positive associations for the most prevalent taxa were disclosed for the first time and may have important ecological and pathogenic implications. In addition to strengthening the association of several cultivable named species with chronic apical periodontitis, the present findings using a large-scale analysis allowed the inclusion of some newly named species and as-yet-uncultivated phylotypes in the set of candidate pathogens associated with this disease.

Gemella morbillorum in primary and secondary/persistent endodontic infections

OBJECTIVE

To investigate the presence of Gemella morbillorum by culture or nested PCR in primary and secondary/persistent endodontic infections.

STUDY DESIGN

Microbial samples were taken from 50 cases with primary and 50 cases with secondary/persistent endodontic infections. Microbiologic techniques were used for culture and identification. The DNA extracted from the samples was analyzed for the presence of the target species using species-specific primers.

RESULTS

Culture and polymerase chain reaction (PCR) identified the species in 23 and 77, respectively, of 100 root canals. Culture yielded the test organism in 19 of 50 (38%) of root canal samples from primary and in 4 of 50 (8%) from secondary/persistent infections. PCR yielded the test organisms in 41 of 50 (82%) and 36 of 50 (72%) of the, respectively, primary and secondary/persistent root canal infections studied.

CONCLUSION

Gemella morbillorum was identified more frequently in primary endodontic infections than in secondary/persistent ones. A higher frequency of the target species was detected by PCR than by culture.