Treponema species associated with abscesses of endodontic origin

The association between gingivitis and oral spirochetes in young cats and dogs

Although gingivitis frequently occurs in young cats, spirochetes are often found in the early stages of periodontal disease. This study was conducted to determine the association between gingivitis and oral spirochetes in young cats and dogs. The degree of gingivitis was evaluated in a total of 68 cats and 31 dogs under one year of age, and plaques were collected from each carnassial. To detect spirochetes or Porphyromonas gulae in plaque samples, 16S rRNA gene was amplified by polymerase chain reaction (PCR) using specific primers. All data were analyzed using Fisher's exact probability test and odds ratio (OR) with a 95% confidence interval (95% CI). The prevalence of gingivitis was significantly higher in young cats (92.6%) than in young dogs (45.2%). The positive rate of spirochetes by PCR in gingivitis cases was 85.4% in young cats and 15.4% in young dogs, and the positive rate of P. gulae was 66.7% in young cats and 15.4% in young dogs. Both results were significantly higher in young cats than in young dogs. In young cats, spirochetes were significantly associated with gingivitis (OR = 7.95; 95% CI = 1.17, 53.83; P < 0.05), but P. gulae was not (OR = 2.44; 95% CI = 0.38, 15.66; P = 0.23). These results suggest that spirochetes may be associated with the early stages of periodontal disease in cats.

Multimodal Data Integration Reveals Mode of Delivery and Snack Consumption Outrank Salivary Microbiome in Association With Caries Outcome in Thai Children

Early childhood caries (ECC) is not only the most common chronic childhood disease but also disproportionately affects underserved populations. Of those, children living in Thailand have been found to have high rates of ECC and severe ECC. Frequently, the cause of ECC is blamed on a handful of cariogenic organisms, such as Streptococcus mutans and Streptococcus sobrinus. However, ECC is a multifactorial disease that results from an ecological shift in the oral cavity from a neutral pH (~7.5) to an acidic pH (&lt;5.5) environment influenced by the host individual’s biological, socio-behavioral, and lifestyle factors. Currently, there is a lack of understanding of how risk factors at various levels influence the oral health of children at risk. We applied a statistical machine learning approach for multimodal data integration (parallel and hierarchical) to identify caries-related multiplatform factors in a large cohort of mother-child dyads living in Chiang Mai, Thailand (N=177). Whole saliva (1 mL) was collected from each individual for DNA extraction and 16S rRNA sequencing. A set of maternal and early childhood factors were included in the data analysis. Significantly, vaginal delivery, preterm birth, and frequent sugary snacking were found to increase the risk for ECC. The salivary microbial diversity was significantly different in children with ECC or without ECC. Results of linear discriminant analysis effect size (LEfSe) analysis of the microbial community demonstrated that S. mutans, Prevotella histicola, and Leptotrichia hongkongensis were significantly enriched in ECC children. Whereas Fusobacterium periodonticum was less abundant among caries-free children, suggesting its potential to be a candidate biomarker for good oral health. Based on the multimodal data integration and statistical machine learning models, the study revealed that the mode of delivery and snack consumption outrank salivary microbiome in predicting ECC in Thai children. The biological and behavioral factors may play significant roles in the microbial pathobiology of ECC and warrant further investigation.

A critical analysis of research methods and experimental models to study the root canal microbiome

Endodontic microbiology deals with the study of the microbial aetiology and pathogenesis of pulpal and periradicular inflammatory diseases. Research in endodontic microbiology started almost 130 years ago and since then has mostly focussed on establishing and confirming the infectious aetiology of apical periodontitis, identifying the microbial species associated with the different types of endodontic infections and determining the efficacy of treatment procedures in eradicating or controlling infection. Diverse analytical methods have been used over the years, each one with their own advantages and limitations. In this review, the main features and applications of the most used technologies are discussed, and advice is provided to improve study designs in order to properly address the scientific questions and avoid setbacks that can compromise the results. Finally, areas of future research are described.

Borreliae Part 1: Borrelia Lyme Group and Echidna-Reptile Group

Simple Summary

Borreliae are spirochaetes, which represent a heterogeneous phylum within bacteria. Spirochaetes are indeed distinguished from other bacteria for their spiral shape, which also characterizes Borreliae. This review describes briefly the organization of the phylum Spirocheteales with a digression about its pathogenicity and historical information about bacteria isolation and characterization. Among spirochaetes, Borrelia genus is here divided into three groups, namely the Lyme group (LG), the Echidna-Reptile group (REPG) and the Relapsing Fever group (RFG). Borreliae Part 1 deals with Lyme group and Echidna-Reptile group Borreliae, while the subject of Borreliae Part 2 is Relapsing Fever group and unclassified Borreliae. Lyme group Borreliae is organized here in sections describing ecology, namely tick vectors and animal hosts, epidemiology, microbiology, and Borrelia genome organization and antigen characterization. Furthermore, the main clinical manifestations in Lyme borreliosis are also described. Although included in the Lyme group due to their particular clinical features, Borrelia causing Baggio Yoshinari syndrome and Borrelia mayonii are described in dedicated paragraphs. The Borrelia Echidna-Reptile group has been recently characterized including spirochaetes that apparently are not pathogenic to humans, but infect reptiles and amphibians. The paragraph dedicated to this group of Borreliae describes their vectors, hosts, geographical distribution and their characteristics.

Abstract

Borreliae are divided into three groups, namely the Lyme group (LG), the Echidna-Reptile group (REPG) and the Relapsing Fever group (RFG). Currently, only Borrelia of the Lyme and RF groups (not all) cause infection in humans. Borreliae of the Echidna-Reptile group represent a new monophyletic group of spirochaetes, which infect amphibians and reptiles. In addition to a general description of the phylum Spirochaetales, including a brief historical digression on spirochaetosis, in the present review Borreliae of Lyme and Echidna-Reptile groups are described, discussing the ecology with vectors and hosts as well as microbiological features and molecular characterization. Furthermore, differences between LG and RFG are discussed with respect to the clinical manifestations. In humans, LG Borreliae are organotropic and cause erythema migrans in the early phase of the disease, while RFG Borreliae give high spirochaetemia with fever, without the development of erythema migrans. With respect of LG Borreliae, recently Borrelia mayonii, with intermediate characteristics between LG and RFG, has been identified. As part of the LG, it gives erythema migrans but also high spirochaetemia with fever. Hard ticks are vectors for both LG and REPG groups, but in LG they are mostly Ixodes sp. ticks, while in REPG vectors do not belong to that genus.

Treponema spp. Isolated from Bovine Digital Dermatitis Display Different Pathogenicity in a Murine Abscess Model

Digital dermatitis (DD) causes lameness in cattle with substantial negative impact on sustainability and animal welfare. Although several species of Treponema bacteria have been isolated from various DD stages, their individual or synergistic roles in the initiation or development of lesions remain largely unknown. The objective of this study was to compare effects of the three most common Treponema species isolated from DD lesions in cattle (T. phagedenis, T. medium and T. pedis), both as individual and as mixed inoculations, in a murine abscess model. A total of 109 or 5 × 108Treponema spp. were inoculated subcutaneously, and produced abscess was studied after 7 days post infection. There were no synergistic effects when two or three species were inoculated together; however, T. medium produced the largest abscesses, whereas those produced by T. phagedenis were the smallest and least severe. Treponema species were cultured from skin lesions at 7 days post infection and, additionally, from the kidneys of some mice (2/5), confirming systemic infection may occur. Taken together, these findings suggest that T. medium and T. pedis may have more important roles in DD lesion initiation and development than T. phagedenis.

Cefazolin versus ampicillin/sulbactam as an empiric antibiosis in severe odontogenic neck infection descending from the lower jaw-retrospective analysis of 350 cases

OBJECTIVES

Odontogenic infections descending from the lower jaw may lead to severe health conditions. Commonly, a biphasic treatment of surgical drainage and antibiotic therapy is conducted. The choice of the administered empiric antibiotic agent remains debatable.

MATERIAL AND METHODS

Retrospectively, we analyzed 350 medical records of patients who were consecutively treated with odontogenic infections descending from the lower jaw. All patients received surgical drainage and either cefazolin or ampicillin/sulbactam as empiric antibiosis. In particular, the number of secondary operations, infectious parameters, and length of in-hospital stay were investigated.

RESULTS

The most frequently infected space was the perimandibular/buccal space for both groups followed by the submandibular space. Number of revision procedures, early recurrence, and length of stay presented no significant difference between both groups (p > 0.05). Inflammatory parameters (c-reactive protein, leukocytes) similarly decreased in both groups.

CONCLUSION

Cefazolin targets the majority of the pathogens detected in severe odontogenic neck infections descending from the lower jaw and reveals comparable results to AMP/S in regard to the inflammatory parameters and in-hospital stay.

CLINICAL RELEVANCE

Cefazolin is a feasible empiric antibiosis for odontogenic neck infections descending from the lower jaw if surgical drainage is performed.

Treponema spp., the dominant pathogen in the lesion of bovine digital dermatitis and its characterization in dairy cattle

This study examined the presence of Treponema in lesions using conventional PCR detection methods and investigated the microbiome by performing high-throughput DNA sequencing. Twenty-nine bovine digital dermatitis (BDD) lesions were collected from 25 dairy farms in South Korea that were tested by PCR amplification using sets of one universal, one genus-specific, and three species specific Treponema PCR primers. Three BDD samples were randomly selected and normal tissue samples were submitted for 16S rRNA sequencing using the Illumina MiSeq platform. The dominant phylum present in all tested BDD lesions was Spirochaetes with a mean relative abundance of 46.9 %, and Treponema was the most abundant genus. Spirochaetes abundance was followed by the phyla Tenericutes and Bacteroidetes with 14.1 % and 11.8 % mean abundances, respectively. Co-infecting bacteria from phyla Tenericutes and Bacteroidetes may be involved in the progression of BDD. Bovine digital dermatitis infection is polymicrobial in nature, but Treponema spp. are the main etiologic agents of the disease. In the microbiome results, Treponema pedis had the highest mean relative abundance (20.9 %) in the BDD lesions in this study followed by T. denticola, T. medium, T. lecithinolyricum, Spirochaeta africana, and Sediminispirochaeta bajacalifoniensis. All 29 samples were positive in the genus-specific Treponema PCR results. The species-specific PCR resulted in 75.9 %, 86.2 %, and 69.0 % of samples in groups T. medium/T. vincentii-like, T. phagedenis-like, and T. pedis, respectively. Understanding how these microorganisms mutually interact in the host during certain stages of infection may help in the development of better practices for controlling BDD.

16S rRNA amplicon sequencing reveals a polymicrobial nature of complicated claw horn disruption lesions and interdigital phlegmon in dairy cattle

Lameness represents an intractable problem for the dairy industry. Complicated claw horn disruption lesions, interdigital hyperplasia, and interdigital phlegmon are important lameness causing foot lesions. Their aetiology is multifactorial, but infectious processes are likely implicated in disease pathogenesis. Our aim was to investigate the bacterial profiles of these lesions using 16S rRNA gene sequencing of samples obtained from 51 cattle across ten farms in the UK. In this study, interdigital hyperplasia, interdigital hyperplasia with signs of interdigital dermatitis, interdigital phlegmon, complicated sole ulcers, complicated toe ulcers lesions, and complicated white line lesions were investigated; corresponding healthy skin control samples were also analysed. All diseased tissues displayed reduced microbial richness and diversity (as described by Chao1, Shannon, and Simpson alpha-diversity indices) compared to their healthy skin control samples. Our results confirm the association of Treponema spp with some of these disorders. Other anaerobic bacteria including Fusobacterium spp., Fastidiosipila spp. and Porphyromonas spp. were implicated in the aetiology of all these lesions with the exception of interdigital hyperplasia. Complicated claw horn disruption lesions, and interdigital phlegmon were found to have similar bacterial profiles. Such sharing of bacterial genera suggests many of the infectious agents detected in these foot lesions are acting opportunistically; this finding could contribute towards future treatment and control strategies.

Illumina MiSeq Sequencing for Preliminary Analysis of Microbiome Causing Primary Endodontic Infections in Egypt

The use of high throughput next generation technologies has allowed more comprehensive analysis than traditional Sanger sequencing. The specific aim of this study was to investigate the microbial diversity of primary endodontic infections using Illumina MiSeq sequencing platform in Egyptian patients. Samples were collected from 19 patients in Suez Canal University Hospital (Endodontic Department) using sterile # 15K file and paper points. DNA was extracted using Mo Bio power soil DNA isolation extraction kit followed by PCR amplification and agarose gel electrophoresis. The microbiome was characterized on the basis of the V3 and V4 hypervariable region of the 16S rRNA gene by using paired-end sequencing on Illumina MiSeq device. MOTHUR software was used in sequence filtration and analysis of sequenced data. A total of 1858 operational taxonomic units at 97% similarity were assigned to 26 phyla, 245 families, and 705 genera. Four main phyla Firmicutes, Bacteroidetes, Proteobacteria, and Synergistetes were predominant in all samples. At genus level, Prevotella, Bacillus, Porphyromonas, Streptococcus, and Bacteroides were the most abundant. Illumina MiSeq platform sequencing can be used to investigate oral microbiome composition of endodontic infections. Elucidating the ecology of endodontic infections is a necessary step in developing effective intracanal antimicrobials.

Frequency and levels of candidate endodontic pathogens in acute apical abscesses as compared to asymptomatic apical periodontitis

Introduction

Acute apical abscess is caused by bacteria that leave the infected dental root canal to invade the periodontal tissues. Most species occurring in abscesses are also found in asymptomatic infections; therefore, the possibility exists that not only the presence of certain species but also their specific counts influence the appearance of symptoms. This molecular study compared the frequency and levels of several candidate endodontic pathogens in teeth with acute apical abscesses and asymptomatic apical periodontitis.

Methods

Samples were taken from the root canals of teeth with asymptomatic apical periodontitis (n = 73) and by aspiration of purulent exudate from acute abscesses (n = 55). DNA was extracted from samples and bacterial identifications were performed by a closed-ended semi-quantitative reverse-capture checkerboard approach targeting 40 bacterial species/phylotypes.

Results

Bacterial DNA was detected in all cases. In abscesses, the most prevalent taxa were Fusobacterium nucleatum (60%), Porphyromonas endodontalis (53%), Parvimonas micra (51%), and Streptococcus species (45%). The most frequently detected taxa in asymptomatic teeth were P. endodontalis (63%), Dialister invisus (58%), Olsenella uli (56%), and F. nucleatum (51%). None of the targeted taxa were significantly associated with abscesses when only mere presence was evaluated (p>0.05). However, semi-quantitative data demonstrated that P. endodontalis, Prevotella baroniae, Treponema denticola and Streptococcus species were significantly more frequent at levels >10⁵ in abscesses than in asymptomatic cases (p<0.05).

Conclusion

None of the target species/phylotypes were associated with abscesses in terms of frequency. However, some taxa were significantly found in higher levels in abscesses. Presence of a potentially virulent pathogen in high counts may increase the collective pathogenicity of the bacterial community and give rise to symptoms.

Gene Regulation, Two Component Regulatory Systems, and Adaptive Responses in Treponema Denticola

The oral microbiome consists of a remarkably diverse group of 500-700 bacterial species. The microbial etiology of periodontal disease is similarly complex. Of the ~400 bacterial species identified in subgingival plaque, at least 50 belong to the genus Treponema. As periodontal disease develops and progresses, T. denticola transitions from a low to high abundance species in the subgingival crevice. Changes in the overall composition of the bacterial population trigger significant changes in the local physical, immunological and physiochemical conditions. For T. denticola to thrive in periodontal pockets, it must be nimble and adapt to rapidly changing environmental conditions. The purpose of this chapter is to review the current understanding of the molecular basis of these essential adaptive responses, with a focus on the role of two component regulatory systems with global regulatory potential.

Novel Bacterial Phylotypes in Endodontic Infections

Although molecular studies have revealed potential oral pathogens among the phyla Spirochaetes and Deferribacteres, their occurrence in endodontic infections has not been consistently investigated. In this study, we devised a nested PCR-DGGE approach to survey samples from infected root canals for the presence of members of these two phyla, and to examine their diversity. The primers used also amplified DNA from Atopobium species. Eight of 10 cases showed bands representative of the target bacterial groups. DGGE profiles revealed a mean number of 6.5 intense and faint bands. No single band occurred in all profiles. Sequences from intense bands excised from the gel showed similarities to species/phylotypes of all target groups— Flexistipes species ( Deferribacteres phylum), uncharacterized spirochetes, and Atopobium species. Analysis of these data indicates that uncultivated Spirochaetes and Deferribacteres phylotypes are frequent members of the endodontic microbiota and may be potential pathogens involved with the etiology of periradicular diseases.

The Treponema denticola FhbB Protein Is a Dominant Early Antigen That Elicits FhbB Variant-Specific Antibodies That Block Factor H Binding and Cleavage by Dentilisin

The Treponema denticola FhbB protein contributes to immune evasion by binding factor H (FH). Cleavage of FH by the T. denticola protease, dentilisin, may contribute to the local immune dysregulation that is characteristic of periodontal disease (PD). Although three FhbB phyletic types have been defined (FhbB1, FhbB2, and FhbB3), the in vivo expression patterns and antigenic heterogeneity of FhbB have not been assessed. Here, we demonstrate that FhbB is a dominant early antigen that elicits FhbB type-specific antibody (Ab) responses. Using the murine skin abscess model, we demonstrate that the presence or absence of FhbB or dentilisin significantly influences Ab responses to infection and skin abscess formation. Competitive binding analyses revealed that α-FhbB Ab can compete with FH for binding to T. denticola and block dentilisin-mediated FH cleavage. Lastly, we demonstrate that dentilisin cleavage sites reside within critical functional domains of FH, including the complement regulatory domain formed by CCPs 1 to 4. Analysis of the FH cleavage products revealed that they lack cofactor activity. The data presented here provide insight into the in vivo significance of dentilisin, FhbB and its antigenic diversity, and the potential impact of FH cleavage on the regulation of complement activation.

Isolation of digital dermatitis treponemes from hoof lesions in Wild North American Elk (Cervus elaphus) in Washington State, USA

Since 2008, a large increase in the numbers of cases of lameness have been seen in wild North American elk (Cervus elaphus) from Washington State, USA. The most recent cases manifested as foot lesions similar both clinically and pathologically to those seen in digital dermatitis (DD) in cattle and sheep, a disease with a bacterial etiopathogenesis. To determine whether the same bacteria considered responsible for DD are associated with elk lameness, lesion samples were subjected to bacterial isolation studies and PCR assays for three phylogroups of relevant DD treponemes. The DD treponemes were isolated from lesional tissues but not from control feet or other areas of the diseased foot (including the coronary band or interdigital space), suggesting that the bacteria are strongly associated with DD lesions and may therefore be causal. In addition, PCR analysis revealed that all three unique DD treponeme phylotypes were found in elk hoof disease, and in 23% of samples, all 3 DD-associated treponemes were present in lesions. Sequence analysis of the 16S rRNA gene showed that the elk lesion treponemes were phylogenetically almost identical to those isolated from cattle and sheep DD lesions. The isolates were particularly similar to two of the three culturable DD treponeme phylotypes: specifically, the Treponema medium/Treponema vincentii-like and Treponema phagedenis-like DD spirochetes. The third treponeme culturable phylogroup (Treponema pedis), although detected by PCR, was not isolated. This is the first report describing isolation of DD treponemes from a wildlife host, suggesting that the disease may be evolving to include a wider spectrum of cloven-hoofed animals.

Periodontal disease bacteria specific to tonsil in IgA nephropathy patients predicts the remission by the treatment

Background

Immunoglobulin (Ig)A nephropathy (IgAN) is the most common form of primary glomerulonephritis in the world. Some bacteria were reported to be the candidate of the antigen or the pathogenesis of IgAN, but systematic analysis of bacterial flora in tonsil with IgAN has not been reported. Moreover, these bacteria specific to IgAN might be candidate for the indicator which can predict the remission of IgAN treated by the combination of tonsillectomy and steroid pulse.

Methods and Findings

We made a comprehensive analysis of tonsil flora in 68 IgAN patients and 28 control patients using Denaturing gradient gel electrophoresis methods. We also analyzed the relationship between several bacteria specific to the IgAN and the prognosis of the IgAN. Treponema sp. were identified in 24% IgAN patients, while in 7% control patients (P = 0.062). Haemophilus segnis were detected in 53% IgAN patients, while in 25% control patients (P = 0.012). Campylobacter rectus were identified in 49% IgAN patients, while in 14% control patients (P = 0.002). Multiple Cox proportional-hazards model revealed that Treponema sp. or Campylobactor rectus are significant for the remission of proteinuria (Hazard ratio 2.35, p = 0.019). There was significant difference in remission rates between IgAN patients with Treponema sp. and those without the bacterium (p = 0.046), and in remission rates between IgAN patients with Campylobacter rectus and those without the bacterium (p = 0.037) by Kaplan-Meier analysis. Those bacteria are well known to be related with the periodontal disease. Periodontal bacteria has known to cause immune reaction and many diseases, and also might cause IgA nephropathy.

Conclusion

This insight into IgAN might be useful for diagnosis of the IgAN patients and the decision of treatment of IgAN.

Microbiology and treatment of acute apical abscesses

Acute apical abscess is the most common form of dental abscess and is caused by infection of the root canal of the tooth. It is usually localized intraorally, but in some cases the apical abscess may spread and result in severe complications or even mortality. The reasons why dental root canal infections can become symptomatic and evolve to severe spreading and sometimes life-threatening abscesses remain elusive. Studies using culture and advanced molecular microbiology methods for microbial identification in apical abscesses have demonstrated a multispecies community conspicuously dominated by anaerobic bacteria. Species/phylotypes commonly found in these infections belong to the genera Fusobacterium, Parvimonas, Prevotella, Porphyromonas, Dialister, Streptococcus, and Treponema. Advances in DNA sequencing technologies and computational biology have substantially enhanced the knowledge of the microbiota associated with acute apical abscesses and shed some light on the etiopathogeny of this disease. Species richness and abundance and the resulting network of interactions among community members may affect the collective pathogenicity and contribute to the development of acute infections. Disease modifiers, including transient or permanent host-related factors, may also influence the development and severity of acute abscesses. This review focuses on the current evidence about the etiology and treatment of acute apical abscesses and how the process is influenced by host-related factors and proposes future directions in research, diagnosis, and therapeutic approaches to deal with this disease.

Variability of Actinobacteria, a minor component of rumen microflora

Actinobacteria (Actinomycetes) are a significant and interesting group of gram-positive bacteria. They are regular, though infrequent, members of the microbial life in the rumen and represent up to 3 % of total rumen bacteria; there is considerable lack of information about ecology and biology of rumen actinobacteria. During the characterization of variability of rumen treponemas using non-cultivation approach, we also noted the variability of rumen actinobacteria. By using Treponema-specific primers a specific 16S rRNA gene library was prepared from cow and sheep rumen total DNA. About 10 % of recombinant clones contained actinobacteria-like sequences. Phylogenetic analyses of 11 clones obtained showed the high variability of actinobacteria in the ruminant digestive system. While some sequences are nearly identical to known sequences of actinobacteria, we detected completely new clusters of actinobacteria-like sequences, representing probably new, as yet undiscovered, group of rumen Actinobacteria. Further research will be necessary for understanding their nature and functions in the rumen.

Treponema denticola chymotrypsin-like proteinase (CTLP) integrates spirochaetes within oral microbial communities

Treponema denticola is found ubiquitously in the human oral cavity and is mainly associated with bacterial communities implicated in the establishment and development of periodontal disease. The ability to become integrated within biofilm communities is crucial to the growth and survival of oral bacteria, and involves inter-bacterial coaggregation, metabolic cooperation, and synergy against host defences. In this article we show that the chymotrypsin-like proteinase (CTLP), found within a high-molecular-mass complex on the cell surface, mediates adherence of T. denticola to other potential periodontal pathogens, Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia and Parvimonas micra. Proteolytic activity per se did not appear to be required for the interactions, and expression of the major outer-sheath protein (Msp) was not necessary, except for binding Parv. micra. Biofilms of densely packed cells and matrix, up to 40 µm in depth, were formed between T. denticola and P. gingivalis on salivary pellicle, with T. denticola cells enriched in the upper layers. Expression of CTLP, but not Msp, was critical for dual-species biofilm formation with P. gingivalis. T. denticola did not form dual-species biofilms with any of the other three periodontal bacterial species under various conditions. Synergy between T. denticola and P. gingivalis was also shown by increased inhibition of blood clotting, which was CTLP-dependent. The results demonstrate the critical role of CTLP in interactions of T. denticola with other oral micro-organisms, leading to synergy in microbial community development and host tissue pathogenesis.

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.

Molecular characterization of Treponema denticola infection-induced bone and soft tissue transcriptional profiles

Treponema denticola is associated with subgingival biofilms in adult periodontitis and with acute necrotizing ulcerative gingivitis. However, the molecular mechanisms by which T. denticola impacts periodontal inflammation and alveolar bone resorption remain unclear. Here, we examined changes in the host transcriptional profiles during a T. denticola infection using a murine calvarial model of inflammation and bone resorption. T. denticola was injected into the subcutaneous soft tissue over the calvaria of BALB/c mice for 3 days, after which the soft tissues and the calvarial bones were excised. RNA was isolated and analysed for transcript profiling using Murine GeneChip arrays. Following T. denticola infection, 2905 and 1234 genes in the infected calvarial bones and soft tissues, respectively, were differentially expressed (P <or= 0.05). Biological pathways significantly impacted by T. denticola infection in calvarial bone and calvarial tissue included leukocyte transendothelial migration, cell adhesion (immune system) molecules, cell cycle, extracellular matrix-receptor interaction, focal adhesion, B-cell receptor signaling and transforming growth factor-beta signaling pathways resulting in proinflammatory, chemotactic effects, and T-cell stimulation. In conclusion, localized T. denticola infection differentially induces transcription of a broad array of host genes, the profiles of which differed between inflamed calvarial bone and soft tissues.

Diversity of endodontic microbiota revisited

Although fungi, archaea, and viruses contribute to the microbial diversity in endodontic infections, bacteria are the most common micro-organisms occurring in these infections. Datasets from culture and molecular studies, integrated here for the first time, showed that over 460 unique bacterial taxa belonging to 100 genera and 9 phyla have been identified in different types of endodontic infections. The phyla with the highest species richness were Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria. Diversity varies significantly according to the type of infection. Overall, more taxa have been disclosed by molecular studies than by culture. Many cultivable and as-yet-uncultivated phylotypes have emerged as candidate pathogens based on detection in several studies and/or high prevalence. Now that a comprehensive inventory of the endodontic microbial taxa has been established, future research should focus on the association with different disease conditions, functional roles in the community, and susceptibility to antimicrobial treatment procedures.

Diversity of spirochetes in endodontic infections

The diversity of spirochetes in primary endodontic infections of teeth with chronic apical periodontitis or acute apical abscesses was investigated using 16S rRNA gene clone library analysis. The prevalences of three common cultivable oral Treponema species were also determined using species-specific nested PCR. All detected spirochetes belonged to the genus Treponema. Overall, 28 different taxa were identified from the 431 clones sequenced: 9 cultivable and validly named species, 1 cultivable as-yet-uncharacterized strain, and 18 as-yet-uncultivated phylotypes, 17 of which were novel. The large majority of clones (94%) were from cultivable named species. The numbers of Treponema species/phylotypes per selected positive sample ranged from 2 to 12. Species-specific nested PCR detected T. denticola, T. socranskii, and T. maltophilum in 59 (66%), 33 (37%), and 26 (29%) of the 90 cases of primary endodontic infections, respectively. Clone library analysis revealed diverse Treponema species/phylotypes as part of the microbiota associated with asymptomatic and symptomatic (abscess) endodontic infections. Although several as-yet-uncultivated Treponema phylotypes were disclosed, including novel taxa, cultivable named species were more abundant and frequently detected.

The microbiology of the acute dental abscess

The acute dental abscess is frequently underestimated in terms of its morbidity and mortality. The risk of potential serious consequences arising from the spread of a dental abscess is still relevant today with many hospital admissions for dental sepsis. The acute dental abscess is usually polymicrobial comprising facultative anaerobes, such as viridans group streptococci and the Streptococcus anginosus group, with predominantly strict anaerobes, such as anaerobic cocci, Prevotella and Fusobacterium species. The use of non-culture techniques has expanded our insight into the microbial diversity of the causative agents, identifying such organisms as Treponema species and anaerobic Gram-positive rods such as Bulleidia extructa, Cryptobacterium curtum and Mogibacterium timidum. Despite some reports of increasing antimicrobial resistance in isolates from acute dental infection, the vast majority of localized dental abscesses respond to surgical treatment, with antimicrobials limited to spreading and severe infections. The microbiology and treatment of the acute localized abscess and severe spreading odontogenic infections are reviewed.

The microbiota of acute apical abscesses

As the breadth of bacterial diversity in the oral cavity has been deciphered by molecular studies, several newly identified species/phylotypes have emerged as potential pathogens. We hypothesized that many of these species/phylotypes could also be involved with the etiology of endodontic abscesses. Abscess aspirates from 42 persons were analyzed for the presence of 81 species/phylotypes by means of a reverse-capture checkerboard hybridization assay. Associations between the most frequently detected taxa were calculated. The most prevalent taxa were Fusobacterium nucleatum, Parvimonas micra, and Porphyromonas endodontalis. Other frequently found taxa included Olsenella uli, streptococci, Eikenella corrodens, some as-yet-uncultivated phylotypes (Bacteroidetes clone X083 and Synergistes clone BA121), and newly named species (Prevotella baroniae and Dialister invisus). Several positive bacterial associations were disclosed. Findings not only strengthen the association of many cultivable species with abscesses, but also include some newly named species and uncultivated phylotypes in the set of candidate pathogens associated with this disease.

Association of unique, isolated treponemes with bovine digital dermatitis lesions

This study used a PCR-based approach targeting 16S rRNA gene fragments to determine the occurrence and association of the three bovine digital dermatitis (BDD) treponeme phylogroups within lesions found in cattle from the United Kingdom. Examination of 51 BDD lesions collected from infected cattle across the United Kingdom revealed that BDD treponeme group 1 (Treponema medium/Treponema vincentii-like), group 2 (Treponema phagedenis-like), and group 3 (Treponema putidum/Treponema denticola-like) were present in 96.1%, 98%, and 76.5% of BDD lesions, respectively. The three phylogroups were present together in 74.5% of lesions. The PCR assays enabled the isolation of further treponeme strains from previously mixed primary BDD lesion cultures. Here a representative from each of the three distinct treponeme phylogroups was isolated from a single BDD lesion for the first time. These data highlight the extent to which this disease is polytreponemal. Immunohistochemistry and electron microscopy were used to investigate lesional hoof tissues, resulting in treponemes being identified copiously in hair follicles and sebaceous glands, suggesting a potential route of exit and/or entry for these pathogens. This study gives further evidence for the importance of the three treponeme groups in BDD pathogenesis and reiterates the value of molecular genetic approaches for isolating and identifying fastidious anaerobes.

Native cellular architecture of Treponema denticola revealed by cryo-electron tomography

Using cryo-electron tomography, we are developing a refined description of native cellular structures in the pathogenic spirochete Treponema denticola. Tightly organized bundles of periplasmic flagella were readily observed in intact plunge-frozen cells. The periplasmic space was measured in both wild-type and aflagellate strains, and found to widen by less than the diameter of flagella when the latter are present. This suggests that a structural change occurs in the peptidoglycan layer to accommodate the presence of the flagella. In dividing cells, the flagellar filaments were found to bridge the cytoplasmic cylinder constriction site. Cytoplasmic filaments, adjacent to the inner membrane, run parallel to the tightly organized flagellar filaments. The cytoplasmic filaments may be anchored by a narrow plate-like structure. The tapering of the cell ends was conserved between cells, with a patella-shaped structure observed in the periplasm at the tip of each cytoplasmic cylinder. Several incompletely characterized structures have been observed in the periplasm between dividing cells, including a cable-like structure linking two cytoplasmic cylinders and complex foil-shaped structures.

The correlation between serum immunoglobulin A and immunoglobulin G levels and the presence of Treponema denticola in human periapical lesions

The aim of this study was to compare the serum immunoglobulin A (IgA) and immunoglobulin G (IgG) levels and the presence of Treponema denticola in the root canals in a group of teeth with/without periapical lesion. A total of 66 children aged 8 to 13 years old were involved in this study. Five milliliters of blood samples were taken to detect the serum IgA and IgG levels. Sixty-six endodontic samplings were also obtained to determine the presence of T. denticola by polymerase chain reaction. The presence of T. denticola between the groups with/without periapical lesion was statistically significant (p = 0.026). A significant negative correlation was found between serum IgG and IgA levels and the presence of T. denticola (p = 0.023 and 0.038, respectively). This study may support the hypothesis that the presence of T. denticola in the root canals is mainly related to the periapical lesions, and the higher levels of serum IgG and IgA levels may protect against T. denticola.

Treponema denticola in disseminating endodontic infections

Treponema denticola is a consensus periodontal pathogen that has recently been associated with endodontic pathology. In this study, the effect of mono-infection of the dental pulp with T. denticola and with polymicrobial "red-complex" organisms (RC) (Porphyromonas gingivalis, Tannerella forsythia, and T. denticola) in inducing disseminating infections in wild-type (WT) and severe-combined-immunodeficiency (SCID) mice was analyzed. After 21 days, a high incidence (5/10) of orofacial abscesses was observed in SCID mice mono-infected with T. denticola, whereas abscesses were rare in SCID mice infected with the red-complex organisms or in wild-type mice. Splenomegaly was present in all groups, but only mono-infected SCID mice had weight loss. T. denticola DNA was detected in the spleen, heart, and brain of mono-infected SCID mice and in the spleen from mono-infected wild-type mice, which also had more periapical bone resorption. The results indicate that T. denticola has high pathogenicity, including dissemination to distant organs, further substantiating its potential importance in oral and linked systemic conditions.

Catonella morbi and Granulicatella adiacens: new species in endodontic infections

OBJECTIVE

This study intended to examine samples from primary endodontic infections for the presence of Catonella morbi and Granulicatella adiacens, 2 species that have been recently suggested to be involved with infections in other oral sites.

STUDY DESIGN

Genomic DNA was isolated directly from samples taken from teeth with different forms of apical periodontitis, and a devised culture-independent 16S rRNA gene-based heminested PCR assay was used to determine the prevalence of these 2 target species. Species-specific primers were developed by aligning closely related 16S rRNA gene sequences. Species-specificity for each primer pair was confirmed by running PCR against a panel of oral bacteria and by sequencing of DNA from representative positive samples.

RESULTS

C morbi and G adiacens were detected in 33% and 19%, respectively, of the root canals associated with chronic apical periodontitis; 30% and 10%, respectively, of the cases diagnosed as acute apical periodontitis, and 16% and 11%, respectively, of the pus samples taken from acute apical abscesses. Overall, C morbi occurred in 26% and G adiacens in 14% of the samples taken from primary endodontic infections.

CONCLUSIONS

Our findings demonstrate that C morbi and G adiacens can take part in the microbiota associated with primary endodontic infections, and their specific role in the disease process warrants further elucidation.

Species-directed 16S rRNA gene nested PCR detection of Olsenella species in association with endodontic diseases

AIMS

To investigate the occurrence of Olsenella uli and Olsenella profusa in samples taken from infections of endodontic origin using a devised 16S RNA gene-based nested PCR protocol.

METHODS AND RESULTS

DNA extracted from clinical samples was initially amplified using universal 16S rRNA gene primers followed by a second round of amplification using the first PCR products to detect a specific fragment of either O. uli or O. profusa 16S rRNA gene. Olsenella uli was detected in 27% of samples from teeth with asymptomatic periradicular lesions and in 20% of pus samples taken from symptomatic (abscess) lesions. Olsenella profusa was detected in 7% of asymptomatic teeth and in 13% of symptomatic teeth. A new Olsenella phylotype was also detected.

CONCLUSIONS

Olsenella species can take part in the microbiota associated with infections of the root canal of human teeth and a role in the pathogenesis of periradicular diseases is suspected.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study demonstrates that molecular genetic methods keep expanding the list of candidate endodontic pathogens to include Olsenella species.

Searching for Archaea in infections of endodontic origin

Archaea is a highly diverse group of prokaryotes, whose members have been traditionally recognized as extremophiles. Recently, some of these microorganisms have also been found to thrive in nonextreme environments, including the human body. Methanogenic archaea have been detected in samples from subgingival plaque associated with periodontal disease and a pathogenetic role is suspected. The purpose of this study was to survey samples taken from different types of endodontic infections for the presence of archaea. Samples were taken from untreated and treated root canals associated with asymptomatic chronic periradicular lesions as well as from cases diagnosed as acute periradicular abscesses. Overall, 96 samples were obtained. DNA from samples was extracted by using two different protocols and used as template for polymerase chain reaction amplification using oligonucleotide universal primers for the domains Archaea or Bacteria. Samples were also checked for the presence of spirochetes by making use of a group-specific primer. While bacteria were present in all samples, no case yielded archaeal DNA. Spirochetes occurred in a high number of cases. Our findings suggested that members of the Archaea domain are not members of the microbiota present in different types of endodontic infections and thereby may not be implicated in the etiology of apical periodontitis.

Occurrence of two newly named oral treponemes -Treponema parvum and Treponema putidum- in primary endodontic infections

BACKGROUND/AIMS

Recent evidence from molecular genetic studies has revealed that oral Treponema species are involved in infections of endodontic origin. This study assessed the occurrence of two newly named oral treponemes - Treponema parvum and Treponema putidum - in primary endodontic infections using a culture-independent identification technique.

METHODS

Genomic DNA was isolated directly from clinical samples, and a 16S rRNA gene-based nested polymerase chain reaction (PCR) assay was used to determine the presence of T. parvum and T. putidum. Species-specific primer pairs were developed by aligning closely related 16S rRNA gene sequences. The specificity for each primer pair was validated by running PCR against a panel of oral bacteria and by sequence analysis of PCR products from positive clinical samples.

RESULTS

T. parvum was detected in 52% of the root canals associated with chronic apical periodontitis, in 20% of the cases diagnosed as acute apical periodontitis, and in no abscessed case. In general, T. parvum was detected in 26% of the samples from primary endodontic infections. T. putidum was found in only one case of acute apical periodontitis (2% of the total number of cases investigated).

CONCLUSIONS

The devised nested PCR protocol was able to identify both T. parvum and T. putidum directly in clinical samples and demonstrated that these two treponemes can take part in endodontic infections.

Detection of bacteria in endodontic samples by polymerase chain reaction assays and association with defined clinical signs in Italian patients

BACKGROUND/AIMS

The presence of selected bacteria (Enterococcus faecalis, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, Treponema denticola) in infected root canals was studied using polymerase chain reaction (PCR) assays, and the association of bacteria with clinical signs of endodontic disease was assessed. The null hypothesis, that no difference could be observed between clinical signs of apical periodontitis and a specific bacterial strain, was tested.

METHODS

Microbial samples were obtained from 62 teeth in 54 patients with endodontic disease. For each tooth, clinical data including patient symptoms were collected. Teeth were categorized by diagnosis as having acute apical periodontitis (AAP, teeth with clinical symptoms but no periapical radiolucency, n=22), chronic apical periodontitis (CAP, teeth with radiolucency but no clinical symptoms, n=15) or exacerbated apical periodontitis (EAP, teeth with symptoms and radiolucency, n=25). Seventy-one percent of cases were primary endodontic infections, and 29% were recurrent ('secondary') endodontic infections (failing cases). PCR assays were used to detect the presence of the selected bacteria.

RESULTS

T. denticola and E. faecalis were each detected in 15 of 62 samples (24%), P. gingivalis in 8 samples (13%), P. intermedia in 5 samples (8%), and T. forsythensis in 4 samples (7%). T. denticola was detected in 56% of teeth with EAP. E. faecalis was found in 60% of teeth with CAP and in 72% of teeth with secondary infection. Statistical analysis demonstrated an association of CAP and secondary endodontic infection with the presence of E. faecalis. (P<0.01). EAP was associated with the presence of T. denticola (P<0.01).

CONCLUSION

T. denticola was associated with symptomatic endodontic disease in the presence of apical bone resorption. E. faecalis was associated with treatment failures. We suggest that these species may play critical roles in endodontic pathology.

Detection of novel oral species and phylotypes in symptomatic endodontic infections including abscesses

This study was undertaken to investigate the occurrence of several uncultivated phylotypes and newly named bacterial species in symptomatic endodontic infections. Samples taken from cases clinically diagnosed as acute periradicular abscesses or acute periradicular periodontitis were surveyed for the presence of 12 taxa by means of a 16S rRNA-gene-based nested or hemi-nested PCR assay. The most prevalent of the target taxa were Dialister invisus, Olsenella uli, Granulicatella adiacens, and Synergistes clones BA121 and E3_33. Findings revealed that novel phylotypes and newly named species can take part in the microbiota associated with symptomatic endodontic infections and a pathogenetic role is suspected.

Exploiting Molecular Methods to Explore Endodontic Infections: Part 2—Redefining the Endodontic Microbiota

The second part of this review discusses the application of molecular methods in endodontic microbiology research for a comprehensive characterization of the microbiota associated with different types of endodontic infections. Despite their recent introduction in endodontic research, molecular methods have already given a significant contribution to the understanding of endodontic infections and the future holds the perspective of a still better refinement of the knowledge about these infections. Molecular methods have revealed a higher complexity of the endodontic microbiota than previously reported by cultivation approaches. In addition to detecting some cultivable species in increased prevalence, molecular methods have also expanded the list of putative endodontic pathogens by inclusion of some fastidious bacterial species or even uncultivated bacteria that have never been previously found in endodontic infections.