Actinobacillus actinomycetemcomitans in human periodontal disease. Prevalence in patient groups and distribution of biotypes and serotypes within families

Periodontal Molecular Diagnostics: State of Knowledge and Future Prospects for Clinical Application

Periodontitis leads to immunologically mediated loss of periodontium and, if untreated, can result in tooth loss. Periodontal diseases are the most prevalent in the world and have a very strong impact on patients' well-being and general health. Their treatment generates enormous costs. Given the above, precise, prompt, and predictive diagnosis of periodontal disease is of paramount importance for clinicians. The aim of the study was to summarize the state-of-the-art knowledge of molecular periodontal diagnostics and the utility of its clinical application. There is a great need to have diagnostic tests that not only describe the periodontal destruction that has occurred in the tissues but also allow clinicians to detect disease at a subclinical level before the changes occur. A test that would enable clinicians to follow the course of the disease and detect areas prone to exacerbation could be used to evaluate the effectiveness of ongoing periodontal therapies. Unfortunately, there is no such diagnostic method yet. A hopeful prospect is molecular diagnostics. There are numerous studies on biomarkers of periodontal disease. Point-of-care tests are also emerging. There are possibilities for processing large biological datasets (omics data). However, all of the above have a minor role in the overall single-patient diagnostics process. Despite advances in microbiological, molecular, and genetic research, the basis of periodontal diagnosis is still clinical examination enriched by the evaluation of radiological images.

Unravelling the Oral-Gut Axis: Interconnection Between Periodontitis and Inflammatory Bowel Disease, Current Challenges, and Future Perspective

As the opposite ends of the orodigestive tract, the oral cavity and the intestine share anatomical, microbial, and immunological ties that have bidirectional health implications. A growing body of evidence suggests an interconnection between oral pathologies and inflammatory bowel disease [IBD], implying a shift from the traditional concept of independent diseases to a complex, reciprocal cycle. This review outlines the evidence supporting an 'oral-gut' axis, marked by a higher prevalence of periodontitis and other oral conditions in IBD patients and vice versa. We present an in-depth examination of the interconnection between oral pathologies and IBD, highlighting the shared microbiological and immunological pathways, and proposing a 'multi-hit' hypothesis in the pathogenesis of periodontitis-mediated intestinal inflammation. Furthermore, the review underscores the critical need for a collaborative approach between dentists and gastroenterologists to provide holistic oral-systemic healthcare.

Grade C Molar-Incisor Pattern Periodontitis in Young Adults: What Have We Learned So Far?

Grade C molar-incisor pattern periodontitis (C-MIP) is a disease that affects specific teeth with an early onset and aggressive progression. It occurs in systemically healthy patients, mostly African descendants, at an early age, with familial involvement, minimal biofilm accumulation, and minor inflammation. Severe and rapidly progressive bone loss is observed around the first molars and incisors. This clinical condition has been usually diagnosed in children and young adults with permanent dentition under 30 years of age. However, this disease can also affect the primary dentition, which is not as frequently discussed in the literature. Radiographic records have shown that most patients diagnosed in the permanent dentition already presented disease signs in the primary dentition. A hyperresponsive immunological profile is observed in local (gingival crevicular fluid-GCF) and systemic environments. Siblings have also displayed a heightened inflammatory profile even without clinical signs of disease. A. actinomycetemcomitans has been classified as a key pathogen in C-MIP in both dentitions. Scaling and root planning associated with systemic antibiotics is the current gold standard to treat C-MIP, leading to GCF biomarker reduction, some systemic inflammatory response modulation and microbiome profile changes to a healthy-site profile. Further studies should focus on other possible disease-contributing risk factors.

Therapeutic Strategies and Genetic Implications for Periodontal Disease Management: A Systematic Review

The objective of this review is to identify the microbiological alterations caused by various therapy modalities by critically analyzing the current findings. We limited our search to English-language papers published between 1 January 2004 and 7 May 2024 in PubMed, Scopus, and Web of Science that were relevant to our topic. In the search approach, the Boolean keywords "microbio*" AND "periodontitis" were used. A total of 5152 papers were obtained from the databases Web of Science (2205), PubMed (1793), and Scopus (1154). This resulted in 3266 articles after eliminating duplicates (1886), and 1411 entries were eliminated after their titles and abstracts were examined. The qualitative analysis of the 22 final articles is included in this study. Research on periodontal disease shows that periodontitis alters the oral microbiome and increases antibiotic resistance. Treatments like scaling and root planing (SRP), especially when combined with minocycline, improve clinical outcomes by reducing harmful bacteria. Comprehensive mechanical debridement with antibiotics, probiotics, EMD with bone grafts, and other adjunctive therapies enhances periodontal health. Personalized treatment strategies and advanced microbial analyses are crucial for effective periodontal management and antibiotic resistance control.

Study of various therapeutic strategies for the treatment of rapidly progressive periodontitis in experimental models

Rapidly progressive periodontitis is a serious disease that leads to rapid degradation of periodontal tissues and can lead to tooth loss at a relatively young age. The purpose of this article is to study the effectiveness of various modern methods in the treatment of this disease on an experimental model. A model of the studied pathology was created - a rat with a destroyed circular ligament of the tooth and a ligature applied to the base of the teeth. 5 study groups were formed, where various treatment methods were used: the appointment of soft food, the combination of intramuscular administration of vitamin C and prednisolone, the combination of tocilizumab and dexamethasone, and the combination of photodynamic therapy and tocilizumab. Histological material was taken from experimental animals and evaluated. The best results were noted in the group of photodynamic therapy and tocilizumab, where there was a better histological picture with minimal signs of the inflammatory process and satisfactory indicators of clinical dynamics, this approach showed high efficiency in resolving inflammation in the area of the affected foci. The 2nd place was taken by the combination of tocilizumab and dexamethasone, in this group, accelerated positive dynamics were noted compared to other groups, but the results of histological examination were worse than in group 1. In 3rd place - the combination of ascorbic acid with dexamethasone and the appointment of soft food, where there were almost no differences in terms of histological results and clinical picture compared to the control group. The combination of tocilizumab with photodynamic therapy is promising in the treatment of patients with rapidly progressive periodontitis, but additional human studies are required to include this type of treatment in clinical guidelines.

Pattern of grade C molar-incisor pattern periodontitis in families

BACKGROUND

The aim of this study was to determine the clinical and inflammatory response patterns for individual siblings diagnosed with grade C molar-incisor pattern periodontitis (C-MIP) and between the related siblings within families.

METHODS

Sixty-nine siblings within 28 families with moderate-to-severe C-MIP were included. Clinical parameters were evaluated for symmetry regarding the affected type of teeth, side and/or arch, and bone loss pattern. The protein concentrations from in vitro whole blood cultures for 14 different lipopolysaccharide-stimulated inflammatory markers were correlated with the extent and severity of disease, within an individual sibling and among siblings within a family.

RESULTS

A similar disease pattern was observed among all siblings and within families. The most common teeth affected were first molars and incisors or first molars only within the permanent dentition and only molars within the primary dentition (p < 0.001). Symmetry involving molars was higher than in incisors in siblings, regardless of arch or side affected (p = 0.020). Arc-shape/vertical bone defects were the most common (p = 0.006) and higher symmetry was found for these defects in the permanent dentition (p = 0.005). Positive correlations were found between age, clinical attachment loss, and percent affected sites with several inflammatory markers. The inflammatory responses for several inflammatory markers were correlated within and among families (p < 0.050). Specifically, the intraclass correlation coefficient within families was highest (>0.5) for interleukin (IL)-8, IL-6, and IL-10.

CONCLUSIONS

Families with C-MIP presented similar patterns of disease. The level of an inflammatory response to bacteria seemed to play a role in the extent and severity of this disease, exemplified by the high degree of correlation in these families.

The Involvement of Photobiology in Contemporary Dentistry-A Narrative Review

Light is an emerging treatment approach that is being used to treat many diseases and conditions such as pain, inflammation, and wound healing. The light used in dental therapy generally lies in visible and invisible spectral regions. Despite many positive results in the treatment of different conditions, this therapy still faces some skepticism, which has prevented its widespread adoption in clinics. The main reason for this skepticism is the lack of comprehensive information about the molecular, cellular, and tissular mechanisms of action, which underpin the positive effects of phototherapy. However, there is currently promising evidence in support of the use of light therapy across a spectrum of oral hard and soft tissues, as well as in a variety of important dental subspecialties, such as endodontics, periodontics, orthodontics, and maxillofacial surgery. The merging of diagnostic and therapeutic light procedures is also seen as a promising area for future expansion. In the next decade, several light technologies are foreseen as becoming integral parts of modern dentistry practice.

Periodontitis: An Oral Disease with Severe Consequences

Periodontitis, being a multifactorial disorder is found to be the most common oral disease denoted by the inflammation of gingiva and resorption of tooth supporting alveolar bone. The disease being closely linked with fast life style and determined by unhygienic behavioural factors, the internal milieu of oral cavity and formation of plaque biofilm on the dental and gingival surfaces. Porphyromonas gingivalis, being the major keystone pathogen of the periodontal biofilm evokes host immune responses that causes damage of gingival tissues and resorption of bones. The biofilm associated microbial community progressively aggravates the condition resulting in chronic inflammation and finally tooth loss. The disease often maintains bidirectional relationship with different systemic, genetic, autoimmune, immunodeficiency diseases and even psychological disorders. The disease can be diagnosed and predicted by various genetic, radiographic and computer-aided design (CAD) & computer-aided engineering (CAE) and artificial neural network (ANN). The elucidation of genetic background explains the inheritance of the disease. The therapeutic approaches commonly followed include mechanical removal of dental plaque with the use of systemic antibiotics. Awareness generation amongst local people, adoption of good practice of timely tooth brushing preferably with fluoride paste or with nanoconjugate pastes will reduce the chance of periodontal plaque formation. Modern tissue engineering technology like 3D bioprinting of periodontal tissue may help in patient specific flawless regeneration of tooth structures and associated bones.

Regulation of LL-37 in Bone and Periodontium Regeneration

The goal of regenerative therapy is to restore the structure and function of the lost tissues in the fields of medicine and dentistry. However, there are some challenges in regeneration therapy such as the delivery of oxygen and nutrition, and the risk of infection in conditions such as periodontitis, osteomyelitis, etc. Leucine leucine-37 (LL-37) is a 37-residue, amphipathic, and helical peptide found only in humans and is expressed throughout the body. It has been shown to induce neovascularization and vascular endothelial growth factor (VEGF) expression. LL-37 also stimulates the migration and differentiation of mesenchymal stem cells (MSCs). Recent studies have shown that LL-37 plays an important role in the innate defense system through the elimination of pathogenic microbes and the modulation of the host immune response. LL-37 also manifests other functions such as promoting wound healing, angiogenesis, cell differentiation, and modulating apoptosis. This review summarizes the current studies on the structure, expression, and function of LL-37 and highlights the contributions of LL-37 to oral cavity, periodontium, and bone regeneration.

Clinical laboratory diagnostics in dentistry: Application of microbiological methods

Diagnosis and treatment in dentistry are based on clinical examination of the patients. Given that the major oral diseases are of microbial biofilm etiology, it can be expected that performing microbiological analysis on samples collected from the patient could deliver supportive evidence to facilitate the decision-making process by the clinician. Applicable microbiological methods range from microscopy, to culture, to molecular techniques, which can be performed easily within dedicated laboratories proximal to the clinics, such as ones in academic dental institutions. Periodontal and endodontic infections, along with odontogenic abscesses, have been identified as conditions in which applied clinical microbiology may be beneficial for the patient. Administration of antimicrobial agents, backed by microbiological analysis, can yield more predictable treatment outcomes in refractory or early-occurring forms of periodontitis. Confirming a sterile root canal using a culture-negative sample during endodontic treatment may ensure the longevity of its outcome and prevent secondary infections. Susceptibility testing of samples obtained from odontogenic abscesses may facilitate the selection of the appropriate antimicrobial treatment to prevent further spread of the infection.

Computational modeling and druggability assessment of Aggregatibacter actinomycetemcomitans leukotoxin

The leukotoxin (LtxA) of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a protein exotoxin belonging to the repeat-in-toxin family (RTX). Numerous studies have demonstrated that LtxA may play a critical role in the pathogenicity of A. actinomycetemcomitans since hyper-leukotoxic strains have been associated with severe disease. Accordingly, considerable effort has been made to elucidate the mechanisms by which LtxA interacts with host cells and induce their death. However, these attempts have been hampered by the unavailability of a tertiary structure of the toxin, which limits the understanding of its molecular properties and mechanisms. In this paper, we used homology and template free modeling algorithms to build the complete tertiary model of LtxA at atomic level in its calcium-bound Holo-state. The resulting model was refined by energy minimization, validated by Molprobity and ProSA tools, and subsequently subjected to a cumulative 600ns of all-atom classical molecular dynamics simulation to evaluate its structural aspects. The druggability of the proposed model was assessed using Fpocket and FTMap tools, resulting in the identification of four putative cavities and fifteen binding hotspots that could be targeted by rational drug design tools to find new ligands to inhibit LtxA activity.

An in vitro model for studies of attenuation of antibiotic-inhibited growth of Aggregatibacter actinomycetemcomitans Y4 by polyamines

Polyamines are ubiquitous polycationic molecules that are present in all prokaryotic and eukaryotic cells, and they serve as important modulators of cell growth, stress, and cell proliferation. Polyamines are present at high concentrations in the periodontal pocket and could potentially affect the stress response of periodontal bacteria to antibiotics. The effects of polyamines on inhibition of growth by amoxicillin (AMX), azithromycin (AZM), and doxycycline (DOX) were investigated with the Y4 strain of Aggregatibacter actinomycetemcomitans (Aa). Bacteria were grown in brain heart infusion broth under the following conditions: (1) Aa only, (2) Aa + polyamine mix (1 mM putrescine, 0.4 mM spermidine, and 0.4 mM spermine), (3) Aa + antibiotic, and (4) Aa + antibiotic + polyamines. Growth curve analysis, minimal inhibitory concentration determination, and transcriptomic studies were conducted. The presence of exogenous polyamines produced a small, but significant increase in Aa growth, and polyamines attenuated the inhibitory effects of AMX, AZM, and DOX on growth. Transcriptomic analysis revealed that polyamines upregulate expression of ribosomal biogenesis proteins and small subunits, attenuate the bacterial stress response to antibiotics, and modulate bacterial nutritional pathways in a manner that could potentially increase the virulence of Aa. In summary, the polyamine‐rich environment found in periodontal pockets appears to protect Aa and reduce its susceptibility to several antimicrobial agents in this in vitro model.

Optical profile: A key determinant of antibacterial efficacy of photodynamic therapy in dentistry

BACKGROUND

Periodontal disease effects 20-50% of the population worldwide, posing a global health challenge. It has been reported to be more prevalent among adults. Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) is an important organism associated with localized juvenile periodontitis. Photodynamic therapy (PDT) has been widely utilized for the treatment of periodontal disease; however, the effect of laser (light) profile on the antibacterial efficacy of PDT remains to be established. The quantitative measurement of laser profile is required to confirm the in vitro efficacy of PDT.

AIM

In the present study, a low cost PDT system comprising of six copper tube waveguides (CTW) was developed to provide more uniform irradiation of the culture plate.

METHODS

The antibacterial effect of PDT, in combination with 200 μg/mL methylene blue (MB) as photosensitizer and 60 sec of irradiation, was studied on A. actinomycetemcomitans and Streptococcus mutans (S. mutans). In the present case, 660 nm laser guided with unpolished CTW, polished CTW, and optical fiber waveguide (OFW) provided radiant exposure of 0.86, 1.38, and 1.36 J/cm², respectively, for a 24-well culture plate.

RESULTS

The designed PDT system provided antimicrobial efficacy of 98% and 91% for A. actinomycetemcomitans and S. mutans, respectively, which was significantly higher as compared to OFW guided PDT.

CONCLUSION

The results of the study highlighted the importance of laser profile as a key parameter that determines the survival rate of bacteria at the edge of the culture plate. Thus, the dose of PDT at the margin of optical profile is important for antibacterial activity for in vitro evaluation.

The composition of microbial communities in inflammatory periodontal diseases in young adults Tatars

Host susceptibility and environmental factors are important for the development of gingivitis and periodontitis, but bacterial biofilms attached to the teeth and gingival tissues play a crucial role. We have analyzed and compared the subgingival microbial communities between subjects with dental plaque biofilm-induced generalized chronic gingivitis (CG), localized initial (Stage I) periodontitis (IP) and healthy controls (HC) of young people aged 18-19 years permanently residing in the city of Kazan (Tatarstan, Russia). The results showed that the α-diversity in groups with CG and IP was higher than in the healthy group. In a course of periodontal disease, a decrease in the relative abundance of dominates genera Rothia and Streptococcus was observed along with increase of class TM7-3 (Candidatus Saccharibacteria phylum) representatives. Also, the increase of red complex representatives Porphyromonadeceae, Treponema and Tannerella was detected together with statistically significant increase of Filifactor, Parvimonas, Peptostreptococcaceae, Veillonellaceae, Tissierelaceae and Mogibacteriaceae. Analysis of our data suggests that transition from HC to IP may be accompanied by a decrease in microbial diversity and a reduction in the abundance of family Rs-045 (Candidatus Saccharibacteria phylum), Desulfovibrionaceae Corynebacterium, Campylobacter and Selenomonas in young adults Kazan Tatars.

Oral and Fecal Microbiome in Molar-Incisor Pattern Periodontitis

In order to improve our understanding on the microbial complexity associated with Grade C/molar-incisor pattern periodontitis (GC/MIP), we surveyed the oral and fecal microbiomes of GC/MIP and compared to non-affected individuals (Control). Seven Afro-descendants with GC/MIP and seven age/race/gender-matched controls were evaluated. Biofilms from supra/subgingival sites (OB) and feces were collected and submitted to 16S rRNA sequencing. Aggregatibacter actinomycetemcomitans (Aa) JP2 clone genotyping and salivary nitrite levels were determined. Supragingival biofilm of GC/MIP presented greater abundance of opportunistic bacteria. Selenomonas was increased in subgingival healthy sites of GC/MIP compared to Control. Synergistetes and Spirochaetae were more abundant whereas Actinobacteria was reduced in OB of GC/MIP compared to controls. Aa abundance was 50 times higher in periodontal sites with PD≥ 4 mm of GC/MIP than in controls. GC/MIP oral microbiome was characterized by a reduction in commensals such as Kingella, Granulicatella, Haemophilus, Bergeyella, and Streptococcus and enrichment in periodontopathogens, especially Aa and sulfate reducing Deltaproteobacteria. The oral microbiome of the Aa JP2-like+ patient was phylogenetically distant from other GC/MIP individuals. GC/MIP presented a higher abundance of sulfidogenic bacteria in the feces, such as Desulfovibrio fairfieldensis, Erysipelothrix tonsillarum, and Peptostreptococcus anaerobius than controls. These preliminary data show that the dysbiosis of the microbiome in Afro-descendants with GC/MIP was not restricted to affected sites, but was also observed in supragingival and subgingival healthy sites, as well as in the feces. The understanding on differences of the microbiome between healthy and GC/MIP patients will help in developing strategies to improve and monitor periodontal treatment.

Grade C molar-incisor pattern periodontitis subgingival microbial profile before and after treatment

Aim: This study evaluated the influence of periodontal therapy on the microbiological profile of individuals with Grade C Molar-Incisor Pattern Periodontitis (C/MIP).

Methods: Fifty-three African-American participants between the ages of 5–25, diagnosed with C/MIP were included. Patients underwent full mouth mechanical debridement with systemic antibiotics (metronidazole 250 mg + amoxicillin 500 mg, tid, 7 days). Subgingival samples were collected from a diseased and a healthy site from each individual prior to treatment and at 3, 6, 12, 18 and 24 months after therapy from the same sites. Samples were subjected to a 16S rRNA gene based-microarray.

Results: Treatment was effective in reducing the main clinical parameters of disease. Aggregatibacter actinomycetemcomitans (A.a.) was the strongest species associated with diseased sites. Other species associated with diseased sites were Treponema lecithinolyticum and Tannerella forsythia. Species associated with healthy sites were Rothia dentocariosa/mucilaginosa, Eubacterium yurii, Parvimonas micra, Veillonella spp., Selenomonas spp., and Streptococcus spp. Overall, treatment was effective in strongly reducing A.a. and other key pathogens, as well as increasing health-associated species. These changes were maintained for at least 6 months.

Conclusions:Treatment reduced putative disease-associated species, particularly A.a., and shifted the microbial profile to more closely resemble a healthy-site profile. (Clinicaltrials.gov registration #NCT01330719).

Differences in the periodontal microbiome of successfully treated and persistent aggressive periodontitis

AIMS

The primary aim of this investigation was to analyse the periodontal microbiome in patients with aggressive periodontitis (AgP) following treatment.

METHODS

Sixty-six AgP patients were recalled on average 7 years after completion of active periodontal treatment and had subgingival plaque samples collected and processed for 16S rRNA gene sequencing analyses.

RESULTS

Of 66 participants, 52 showed persistent periodontal disease, while 13 participants were considered as "successfully treated AgP" (no probing pocket depths >4 mm) and 1 was fully edentulous. Genera associated with persistent generalized disease included Actinomyces, Alloprevotella, Capnocytophaga, Filifactor, Fretibacterium, Fusobacterium, Leptotrichia, Mogibacterium, Saccharibacteria [G-1], Selenomonas and Treponema. "Successfully treated" patients harboured higher proportions of Haemophilus, Rothia, and Lautropia and of Corynebacterium, Streptococcus and Peptidiphaga genera. Overall, patients with persistent generalized AgP (GAgP) revealed higher alpha diversity compared to persistent localized AgP (LAgP) and stable patients (p < .001). Beta diversity analyses revealed significant differences only between stable and persistent GAgP groups (p = .004).

CONCLUSION

Patients with persistent AgP showed a more dysbiotic subgingival biofilm than those who have been successfully treated. It remains to be established whether such differences were predisposing to disease activity or were a result of a dysbiotic change associated with disease recurrence in the presence of sub-standard supportive periodontal therapy or other patient-related factors.

Do patients with aggressive and chronic periodontitis exhibit specific differences in the subgingival microbial composition? A systematic review

BACKGROUND

The 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions grouped the diseases previously recognized as chronic (CP) or aggressive (AgP) periodontitis under a single category named periodontitis. The rationale for this decision was the lack of specific patterns of immune-inflammatory response or microbial profiles associated with CP or AgP. However, no previous studies have compiled the results of all studies comparing subgingival microbial data between these clinical conditions. Thus, this systematic review aimed to answer the following focused question: "Do patients with AgP periodontitis present differences in the subgingival microbiota when compared with patients with CP?"

METHODS

A systematic review was conducted according to the PRISMA statement. The MEDLINE, EMBASE, and Cochrane databases were searched up to June 2019 for studies of any design (except case reports, case series, and reviews) comparing subgingival microbial data from patients with CP and AgP.

RESULTS

A total of 488 articles were identified and 56 were included. Thirteen studies found Aggregatibacter actinomycetemcomitans elevated in AgP in comparison with CP, while Fusobacterium nucleatum, Parvimonas micra, and Campylobacter rectus were elevated in AgP in a few studies. None of these species were elevated in CP. However, the number of studies not showing statistically significant differences between CP and AgP was always higher than that of studies showing differences.

CONCLUSION

These results suggested an association of A. actinomycetemcomitans with AgP, but neither this species nor the other species studied to date were unique to or could differentiate between CP and AgP (PROSPERO #CRD42016039385).

Salivary markers of oxidative stress and periodontal pathogens in patients with periodontitis from Santander, Colombia

Introduction:

Periodontitis affects more than 20% of the Latin American population. Oxidative markers are associated with greater progression of periodontitis; therefore, its role in pathogenesis should be studied.

Objective:

To determine the prevalence of the main oral bacteria and viruses associated with periodontitis and estimate the total antioxidant capacity and lipid peroxidation in saliva from patients with periodontitis.

Materials and methods:

We conducted systemically a cross-sectional study in 101 healthy subjects, 87 of whom had been diagnosed with periodontitis (P), according to the criteria of the Centers of Disease Control and Prevention and the American Academy of Periodontology, and 14 without periodontal pockets as controls (C). In subgingival samples, major viruses and dental pathogenic bacteria were identified using PCR techniques. The levels of total antioxidant capacity and malon-di-aldehyde (MDA) were determined by spectrophotometry in samples of unstimulated saliva.

Results:

The mean of periodontal depth pocket and clinical attachment loss in patients with periodontitis was 5.6 ± 1.7 and 6.1 ± 3.1 mm, respectively. The most prevalent microorganisms were Aggregatibacter actinomycetemcomitans (32.5%) and Porphyromonas gingivalis (18.6%). The patients from rural areas showed a higher percentage of A. actinomycetemcomitans (urban: 17.9% vs. rural: 48.9%, p=0.0018). In patients with periodontitis, the frequency of EBV, HSV1 & 2, and HCMV genes was 2.3%. Periodontitis patients had higher levels of MDA (P: 2.1 ± 1.5; C: 0.46 ± 0.3 µmol/g protein; p=0.0001) and total antioxidant capacity (P: 0.32 ± 0.2; C: 0.15 ± 0.1 mM; p< 0.0036). Oxidative markers showed no modifications due to the presence of periodontopathic bacteria.

Conclusions:

Aggregatibacter actinomycetemcomitans was the most prevalent bacteria; its presence did not modify the levels of oxidative markers in the saliva of patients with periodontitis.

Insights into the study and origin of the citrullinome in rheumatoid arthritis

The presence of autoantibodies and autoreactive T cells to citrullinated proteins and citrullinating enzymes in patients with rheumatoid arthritis (RA), together with the accumulation of citrullinated proteins in rheumatoid joints, provides substantial evidence that dysregulated citrullination is a hallmark feature of RA. However, understanding mechanisms that dysregulate citrullination in RA has important challenges. Citrullination is a normal process in immune and non-immune cells, which is likely activated by different conditions (eg, inflammation) with no pathogenic consequences. In a complex inflammatory environment such as the RA joint, unique strategies are therefore required to dissect specific mechanisms involved in the abnormal production of citrullinated proteins. Here, we will review current models of citrullination in RA and discuss critical components that, in our view, are relevant to understanding the accumulation of citrullinated proteins in the RA joint, collectively referred to as the RA citrullinome. In particular, we will focus on potential caveats in the study of citrullination in RA and will highlight methods to precisely detect citrullinated proteins in complex biological samples, which is a confirmatory approach to mechanistically link the RA citrullinome with unique pathogenic pathways in RA.

Rheumatoid Arthritis-Associated Mechanisms of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans

Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology characterized by immune-mediated damage of synovial joints and antibodies to citrullinated antigens. Periodontal disease, a bacterial-induced inflammatory disease of the periodontium, is commonly observed in RA and has implicated periodontal pathogens as potential triggers of the disease. In particular, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans have gained interest as microbial candidates involved in RA pathogenesis by inducing the production of citrullinated antigens. Here, we will discuss the clinical and mechanistic evidence surrounding the role of these periodontal bacteria in RA pathogenesis, which highlights a key area for the treatment and preventive interventions in RA.

Effects of Monolaurin on Oral Microbe-Host Transcriptome and Metabolome

The aim of this in vitro study was to evaluate the effects of monolaurin against Aggregatibacter actinomycetemcomitans (Aa) and determine their effects on the host transcriptome and metabolome, using an oral cell/bacteria co-culture dual-chamber model to mimic the human periodontium. For this, the Aa, was applied to cross the monolayer of epithelial keratinocytes (OBA-9) to reach the fibroblasts layer (HGF-1) in the basal chamber. The Monolaurin treatments (25 or 50 μM) were added immediately after the inoculation of the dual-chamber with Aa. After 24 h, the transcriptional factors and metabolites produced were quantified in the remaining cell layers (insert and basal chamber) and in supernatant released from the cells. The genes IL-1α, IL-6, IL-18, and TNF analyzed in HGF-1 concentrations showed a decreased expression when treated with both concentration of Monolaurin. In keratinocytes, the genes IL-6, IL-18, and TNF presented a higher expression and the expression of IL-1α decreased when treated with the two cited concentrations. The production of glycerol and pyruvic acid increased, and the 2-deoxytetronic acid NIST, 4-aminobutyric acid, pinitol and glyceric acid, presented lower concentrations because of the treatment with 25 and/or 50 μM of Monolaurin. Use of monolaurin modulated the immune response and metabolite production when administered for 24 h in a dual-chamber model inoculated with A. actinomycetemcomitans. In summary, this study indicates that monolaurin had antimicrobial activity and modulated the host immune response and metabolite production when administered for 24 h in a dual-chamber model inoculated with A. actinomycetemcomitans.

Periodontal disease susceptible matrilines in the Cayo Santiago Macaca mulatta macaques

OBJECTIVE AND BACKGROUND

The expression of periodontitis, including age of onset, extent, and severity is considered to represent an interaction of the individual's oral microbiome and host response to the microbial challenge that is modified by both genetics and environmental factors. The aim of this study was to determine the distribution of periodontitis in a population of nonhuman primates, to document features of familial distribution that could reflect heritability and transmission of microbes with enhanced virulence.

MATERIAL AND METHODS

This report presents our findings from evaluation of periodontal disease bone defects in skulls from 569 animals (5-31 years of age) derived from the skeletons of the rhesus monkeys (Macaca mulatta) of Cayo Santiago derived from eight matrilines over 6-9 generations. The distance from the base of alveolar bone to the cemento-enamel junction on 1^st /2^nd premolars and 1^st /2^nd molars from all four quadrants was evaluated as a measure of periodontal disease. Additionally, we documented the presence of periodontitis in 79 living descendants within these matrilines.

RESULTS

The results demonstrated an increased extent and severity of periodontitis with aging across all matrilines. Extensive heterogeneity in disease expression was observed among the animals and this was linked to specific periodontitis susceptible matrilines. Moreover, we identified some matrilines in which the members appeared to show some resistance to more severe disease, even with aging.

CONCLUSION

Linking these disease variations to multigenerational matriarchal family units supported familial susceptibility of periodontitis. This familial disease relationship was reinforced by the distribution of naturally-occurring periodontitis in the living descendants.

Drinking alcohol is associated with variation in the human oral microbiome in a large study of American adults

BACKGROUND

Dysbiosis of the oral microbiome can lead to local oral disease and potentially to cancers of the head, neck, and digestive tract. However, little is known regarding exogenous factors contributing to such microbial imbalance.

RESULTS

We examined the impact of alcohol consumption on the oral microbiome in a cross-sectional study of 1044 US adults. Bacterial 16S rRNA genes from oral wash samples were amplified, sequenced, and assigned to bacterial taxa. We tested the association of alcohol drinking level (non-drinker, moderate drinker, or heavy drinker) and type (liquor, beer, or wine) with overall microbial composition and individual taxon abundance. The diversity of oral microbiota and overall bacterial profiles differed between heavy drinkers and non-drinkers (α-diversity richness p = 0.0059 and β-diversity unweighted UniFrac p = 0.0036), and abundance of commensal order Lactobacillales tends to be decreased with higher alcohol consumption (fold changes = 0.89 and 0.94 for heavy and moderate drinkers, p trend = 0.005 [q = 0.064]). Additionally, certain genera were enriched in subjects with higher alcohol consumption, including Actinomyces, Leptotrichia, Cardiobacterium, and Neisseria; some of these genera contain oral pathogens, while Neisseria can synthesize the human carcinogen acetaldehyde from ethanol. Wine drinkers may differ from non-drinkers in microbial diversity and profiles (α-diversity richness p = 0.048 and β-diversity unweighted UniFrac p = 0.059) after controlling for drinking amount, while liquor and beer drinkers did not. All significant differences between drinkers and non-drinkers remained after exclusion of current smokers.

CONCLUSIONS

Our results, from a large human study of alcohol consumption and the oral microbiome, indicate that alcohol consumption, and heavy drinking in particular, may influence the oral microbiome composition. These findings may have implications for better understanding the potential role that oral bacteria play in alcohol-related diseases.

Dual action of highbush blueberry proanthocyanidins on Aggregatibacter actinomycetemcomitans and the host inflammatory response

Background

The highbush blueberry (Vaccinium corymbosum) has a beneficial effect on several aspects of human health. The present study investigated the effects of highbush blueberry proanthocyanidins (PACs) on the virulence properties of Aggregatibacter actinomycetemcomitans and macrophage-associated inflammatory responses.

Methods

PACs were isolated from frozen highbush blueberries using solid-phase chromatography. A microplate dilution assay was performed to determine the effect of highbush blueberry PACs on A. actinomycetemcomitans growth as well as biofilm formation stained with crystal violet. Tight junction integrity of oral keratinocytes was assessed by measuring the transepithelial electrical resistance (TER), while macrophage viability was determined with a colorimetric MTT assay. Pro-inflammatory cytokine and MMP secretion by A. actinomycetemcomitans-stimulated macrophages was quantified by ELISA. The U937-3xκB-LUC monocyte cell line transfected with a luciferase reporter gene was used to monitor NF-κB activation.

Results

Highbush blueberry PACs reduced the growth of A. actinomycetemcomitans and prevented biofilm formation at sub-inhibitory concentrations. The treatment of pre-formed biofilms with the PACs resulted in a loss of bacterial viability. The antibacterial activity of the PACs appeared to involve damage to the bacterial cell membrane. The PACs protected the oral keratinocytes barrier integrity from damage caused by A. actinomycetemcomitans. The PACs also protected macrophages from the deleterious effect of leukotoxin Ltx-A and dose-dependently inhibited the secretion of pro-inflammatory cytokines (IL-1β, IL-6, CXCL8, TNF-α), matrix metalloproteinases (MMP-3, MMP-9), and sTREM-1 by A. actinomycetemcomitans-treated macrophages. The PACs also inhibited the activation of the NF-κB signaling pathway.

Conclusion

The antibacterial and anti-inflammatory properties of highbush blueberry PACs as well as their ability to protect the oral keratinocyte barrier and neutralize leukotoxin activity suggest that they may be promising candidates as novel therapeutic agents.

Himar1 Transposon for Efficient Random Mutagenesis in Aggregatibacter actinomycetemcomitans

Aggregatibacter actinomycetemcomitans is the primary etiological agent of aggressive periodontal disease. Identification of novel virulence factors at the genome-wide level is hindered by lack of efficient genetic tools to perform mutagenesis in this organism. The Himar1 mariner transposon is known to yield a random distribution of insertions in an organism’s genome with requirement for only a TA dinucleotide target and is independent of host-specific factors. However, the utility of this system in A. actinomycetemcomitans is unknown. In this study, we found that Himar1 transposon mutagenesis occurs at a high frequency (×10^-4), and can be universally applied to wild-type A. actinomycetemcomitans strains of serotypes a, b, and c. The Himar1 transposon inserts were stably inherited in A. actinomycetemcomitans transconjugants in the absence of antibiotics. A library of 16,000 mutant colonies of A. actinomycetemcomitans was screened for reduced biofilm formation. Mutants with transposon inserts in genes encoding pilus, putative ion transporters, multidrug resistant proteins, transcription regulators and enzymes involved in the synthesis of extracellular polymeric substance, bacterial metabolism and stress response were discovered in this screen. Our results demonstrated the utility of the Himar1 mutagenesis system as a novel genetic tool for functional genomic analysis in A. actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans in African Americans with Localized Aggressive Periodontitis

This study aims to investigate the prevalence of the highly leukotoxic JP2 sequence versus the minimally leukotoxic non-JP2 sequence of Aggregatibacter actinomycetemcomitans within a cohort of 180 young African Americans, with and without localized aggressive periodontitis (LAP), in north Florida. The study included patients aged 5 to 25 y: 60 LAP patients, 60 healthy siblings (HS), and 60 unrelated healthy controls (HC). Subgingival plaque was collected from LAP sites-diseased (PD ≥5 mm with bleeding on probing) and healthy (PD ≤3 mm with no bleeding on probing)-and from healthy sites of HS and HC. Plaque DNA was extracted and analyzed by polymerase chain reaction for the detection of the JP2 and non-JP2 sequences of A. actinomycetemcomitans. Overall, 90 (50%) subjects tested positive for the JP2 sequence. Fifty (83.33%) LAP subjects were carriers of the highly leukotoxic JP2 sequence, detected in 45 (75%) diseased sites and 34 (56.67%) healthy sites. Additionally, JP2 carriage was found in 16 HS (26.67%) and 24 HC (40%; P < 0.0001, among groups). The non-JP2 sequence was detected in 26 (14.44%) total subjects: 17 (28.33%) LAP patients detected in equal amounts of diseased and healthy sites (n = 11, 18.33%), 6 (10%) HS sites, and 3 (5%) HC sites (P < 0.05, among groups). The JP2 sequence was strongly associated with LAP-diseased sites in young African Americans, significantly more so than the non-JP2 (ClinicalTrials.gov NCT01330719). Knowledge Transfer Statement: Clinicians may use the results of this study to identify susceptible individuals to aggressive periodontitis, potentially leading to more appropriate selection of therapeutic choices.

Defining Genetic Fitness Determinants and Creating Genomic Resources for an Oral Pathogen

Periodontitis is a microbial infection that destroys the structures that support the teeth. Although it is typically a chronic condition, rapidly progressing, aggressive forms are associated with the oral pathogen Aggregatibacter actinomycetemcomitans One of this bacterium's key virulence traits is its ability to attach to surfaces and form robust biofilms that resist killing by the host and antibiotics. Though much has been learned about A. actinomycetemcomitans since its initial discovery, we lack insight into a fundamental aspect of its basic biology, as we do not know the full set of genes that it requires for viability (the essential genome). Furthermore, research on A. actinomycetemcomitans is hampered by the field's lack of a mutant collection. To address these gaps, we used rapid transposon mutant sequencing (Tn-seq) to define the essential genomes of two strains of A. actinomycetemcomitans, revealing a core set of 319 genes. We then generated an arrayed mutant library comprising >1,500 unique insertions and used a sequencing-based approach to define each mutant's position (well and plate) in the library. To demonstrate its utility, we screened the library for mutants with weakened resistance to subinhibitory erythromycin, revealing the multidrug efflux pump AcrAB as a critical resistance factor. During the screen, we discovered that erythromycin induces A. actinomycetemcomitans to form biofilms. We therefore devised a novel Tn-seq-based screen to identify specific factors that mediate this phenotype and in follow-up experiments confirmed 4 mutants. Together, these studies present new insights and resources for investigating the basic biology and disease mechanisms of a human pathogen.IMPORTANCE Millions suffer from gum disease, which often is caused by Aggregatibacter actinomycetemcomitans, a bacterium that forms antibiotic-resistant biofilms. To fully understand any organism, we should be able to answer: what genes does it require for life? Here, we address this question for A. actinomycetemcomitans by determining the genes in its genome that cannot be mutated. As for the genes that can be mutated, we archived these mutants into a library, which we used to find genes that contribute to antibiotic resistance, leading us to discover that antibiotics cause A. actinomycetemcomitans to form biofilms. We then devised an approach to find genes that mediate this process and confirmed 4 genes. These results illuminate new fundamental traits of a human pathogen.

Oral microbe-host interactions: influence of β-glucans on gene expression of inflammatory cytokines and metabolome profile

Background

The aim of this study was to evaluate the effects of β-glucan on the expression of inflammatory mediators and metabolomic profile of oral cells [keratinocytes (OBA-9) and fibroblasts (HGF-1) in a dual-chamber model] infected by Aggregatibacter actinomycetemcomitans. The periodontopathogen was applied and allowed to cross the top layer of cells (OBA-9) to reach the bottom layer of cells (HGF-1) and induce the synthesis of immune factors and cytokines in the host cells. β-glucan (10 μg/mL or 20 μg/mL) were added, and the transcriptional factors and metabolites produced were quantified in the remaining cell layers and supernatant.

Results

The relative expression of interleukin (IL)-1-α and IL-18 genes in HGF-1 decreased with 10 μg/mL or 20 μg/mL of β-glucan, where as the expression of PTGS-2 decreased only with 10 μg/mL. The expression of IL-1-α increased with 20 μg/mL and that of IL-18 increased with 10 μg/mL in OBA-9; the expression of BCL 2, EP 300, and PTGS-2 decreased with the higher dose of β-glucan. The production of the metabolite 4-aminobutyric acid presented lower concentrations under 20 μg/mL, whereas the concentrations of 2-deoxytetronic acid NIST and oxalic acid decreased at both concentrations used. Acetophenone, benzoic acid, and pinitol presented reduced concentrations only when treated with 10 μg/mL of β-glucan.

Conclusions

Treatment with β-glucans positively modulated the immune response and production of metabolites.

Localized aggressive periodontitis immune response to healthy and diseased subgingival plaque

AIM

The objective of this case-control study was to compare the inflammatory response of peripheral blood from localized aggressive periodontitis (LAP) patients when stimulated with healthy or diseased plaque samples.

MATERIALS AND METHODS

Whole blood and subgingival plaque samples were collected from 13 LAP subjects, 14 siblings of LAP subjects and six periodontally healthy individuals. Whole blood was stimulated for 24 h with plaque samples generated from healthy or diseased sites. The levels of 14 cyto/chemokines were detected using multiplex technology.

RESULTS

Localized aggressive periodontitis-derived cultures displayed higher levels of G-CSF, INFγ, IL10, IL12p40, IL1β, IL-6, IL-8, MCP-1, MIP-1α, and TNFα, than control cultures regardless of stimulus used. Whole blood from healthy siblings displayed higher levels of IL-6 compared to control subjects, but lower levels than those observed in cultures from LAP participants.

CONCLUSIONS

This study suggests that although bacteria is an important factor in eliciting the hyper-inflammatory response observed in LAP patients, the predisposition of host's response to bacterial presence may play a more significant role than the components of the stimulatory plaque.

Occurrence of Aggregatibacter actinomycetemcomitans in Indian chronic periodontitis patients and periodontally healthy adults

Background:

Aggregatibacter actinomycetemcomitans (Aa), an important primary periodontal pathogen, is known for its strong virulence characteristics that cause periodontal disease. We investigated Aa occurrence in Indian individuals using culture and 16 s rDNA polymerase chain reaction (PCR).

Materials and Methods:

A cross-sectional study with 100 participants each in the healthy and chronic periodontitis (CP) groups was conducted. The subgingival plaque was collected and immediately plated on selective media for Aa. The remaining plaque samples were used for DNA extraction. PCR was performed using specific primers for Aa.

Statistical Analysis Used:

The detection of bacteria and the clinical parameters between the groups were compared using the Mann–Whitney U-test. For assessing the agreement between the results of anaerobic culture and PCR, Kappa analyses were performed.

Results:

Aa levels using culture and PCR was 51% and 69% in the CP group and 12% and 30% in the healthy group, respectively. The two groups showed significant differences (P < 0.00001). The detection accuracy of culture and PCR was assessed, and the coefficient of accuracy (k) was highly significant in the healthy (0.3103; P < 0.0001) and CP groups (0.1536; P < 0.0497).

Conclusions:

Aa was predominantly found in the CP group compared with the healthy group, which is consistent with previous findings. Our results showed that both techniques can be used for detecting Aa. An ideal technique for detecting subgingival microorganisms should be carefully selected depending on the scope of the intended future work.

Organic Nanomaterials and Their Applications in the Treatment of Oral Diseases

There is a growing interest in the development of organic nanomaterials for biomedical applications. An increasing number of studies focus on the uses of nanomaterials with organic structure for regeneration of bone, cartilage, skin or dental tissues. Solid evidence has been found for several advantages of using natural or synthetic organic nanostructures in a wide variety of dental fields, from implantology, endodontics, and periodontics, to regenerative dentistry and wound healing. Most of the research is concentrated on nanoforms of chitosan, silk fibroin, synthetic polymers or their combinations, but new nanocomposites are constantly being developed. The present work reviews in detail current research on organic nanoparticles and their potential applications in the dental field.

Aggressive Periodontitis: microbes and host response, who to blame?

A paradigm shift several decades ago elucidated that aggressive periodontitis (AgP) was not a degenerative disorder but a rapid progressive form of plaque-induced inflammatory periodontal disease. Ensuing years of research have led to linkage analysis identification of specific genetic defects responsible for AgP in some families and to the finding that subgingival detection of A. actinomycet-emcomitans JP2 clone is a predictive factor for disease onset and progression. However, rather disappointingly, these ‘proven’ risk factors are only detected in a small subset of AgP cases. Recent advances are leading to a new paradigm shift, with the realization that genetically-driven dysbiotic changes in the subgingival microbiota may predispose to a cascade of events leading to the rapid periodontal tissue destruction seen in AgP. This review tries to dissect the existing literature on the host response-microbial axis of AgP and to propose possible pathogenic pathways in line with current theories.

Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans

Mixed-phase TiO₂ nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The topology was assessed by White Light Optical Profiling (WLOP) in the Vertical Scanning Interferometer (VSI) mode. Representative height descriptive parameters of roughness R_a and R_z were calculated. The photocatalytic activity of the resulting TiO₂ films was evaluated by the photodegradation of Rhodamine B (RhB) dye solution. The antibacterial ability of the photocatalyst was examined by  Aggregatibacter actinomycetemcomitans suspensions in a colony-forming assay. XRD showed that anatase/rutile mixed-phase TiO₂ thin films were predominantly in anatase and rutile that were 54.6 wt% and 41.9 wt%, respectively. Craters (2–5 µm) and protruding hills (10–50 µm) on Ti substrates were produced after electrochemical anodization with higher R_a and R_z surface roughness values. Anatase/rutile mixed-phase TiO₂ thin films showed 26% photocatalytic decolorization toward RhB dye solution. The number of colonizing bacteria on anatase/rutile mixed-phase TiO₂ thin films was decreased significantly in vitro. The photocatalyst was effective against A. actinomycetemcomitans colonization.

Oxidative Stress Parameters in Saliva and Its Association with Periodontal Disease and Types of Bacteria

Objective. To determine the association between oxidative stress parameters with periodontal disease, bleeding, and the presence of different periodontal bacteria. Methods. A cross-sectional study in a sample of eighty-six patients, divided into three groups depending on their periodontal status. Thirty-three with chronic periodontitis, sixteen with gingivitis, and thirty-seven with periodontal healthy as control. Oxidative stress biomarkers (8-OHdG and MDA), total antioxidant capacity (TAOC), and the activity of two antioxidant enzymes (GPx and SOD) were determined in saliva. Subgingival plaque samples were obtained from the deepest periodontal pocket and PCR was used to determine the presence of the 6 fimA genotypes of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia, and Treponema denticola. Results. Periodontal disease was found to be associated with increased oxidative stress parameter levels. These levels rose according to the number and type of different periodontal bacteria found in the periodontal pockets. The presence of different types of periodontal bacteria is predictive independent variables in linear regresion models of oxidative stress parameters as dependent variable, above all 8-OHdG. Conclusions. Oxidative stress parameter levels are correlated with the presence of different types of bacteria. Determination of these levels and periodontal bacteria could be a potent tool for controlling periodontal disease development.

Familial periodontal disease in the Cayo Santiago rhesus macaques

Substantial ongoing research continues to explore the contribution of genetics and environment to the onset, extent and severity of periodontal disease(s). Existing evidence supports that periodontal disease appears to have an increased prevalence in family units with a member having aggressive periodontitis. We have been using the nonhuman primate as a model of periodontal disease for over 25 years with these species demonstrating naturally occurring periodontal disease that increases with age. This report details our findings from evaluation of periodontal disease in skulls from 97 animals (5-31 years of age) derived from the skeletons of the rhesus monkeys (Macaca mulatta) on Cayo Santiago. Periodontal disease was evaluated by determining the distance from the base of the alveolar bone defect to the cemento-enamel junction on 1st/2nd premolars and 1st/2nd molars from all four quadrants. The results demonstrated an increasing extent and severity of periodontitis with aging across the population of animals beyond only compensatory eruption. Importantly, irrespective of age, extensive heterogeneity in disease expression was observed among the animals. Linking these variations to multi-generational matriarchal family units supported familial susceptibility of periodontitis. As the current generations of animals that are descendants from these matrilines are alive, studies can be conducted to explore an array of underlying factors that could account for susceptibility or resistance to periodontal disease.

Clinical and microbiological characterization of localized aggressive periodontitis: a cohort study

BACKGROUND

Localized aggressive periodontitis (LAgP) is an infectious periodontal disease which generally affects young people. Recent data suggest the involvement of different bacterial species in different populations. The causative bacterial species in Israel has never been identified despite a high prevalence of LAgP in this population. The objectives of this study were to characterize the bacterial microbiota of periodontal pockets within an Israeli LAgP population who were also clinically assessed.

METHODS

Twenty-one LAgP patients (test) and 12 chronic periodontitis patients (control) were examined. Bacterial samples were collected from periodontal pockets and analysed by both culture and polymerase chain reaction techniques. Mann-Whitney U test and chi-square test were used to compare results between the groups.

RESULTS

Higher levels of Parvimonas micra (>10(6) ), Aggregatibacter actinomycetemcomitans (>10(5) ), Fusobacterium nucleatum/F. periodonticum (>10(6) ), and Tannerella forsythia (levels of 10(5) to 10(6) bacteria) were detected in the LAgP group compared to the control (p < 0.05), while levels of Porphyromonas gingivalis and Prevotella intermedia were higher in the CP group.

CONCLUSIONS

The characteristic periodontal bacterial flora of LAgP patients in Israel is mainly comprised of P. micra, A. actinomycetemcomitans, F. nucleatum/F. periodonticum and T. forsythia. Similar population based studies of each population will improve the quality of treatment of LAgP when individual sampling is not possible.

Aggregatibacter actinomycetemcomitans - a tooth killer?

Strong evidence is available on Aggregatibacter actinomycetemcomitans (A.a) on its role as the causative agent of localised juvenile periodontitis (LJP), a disease characterised by rapid destruction of the tooth-supporting tissues. This organism possesses a large number of virulence factors with a wide range of activities which enable it to colonise the oral cavity, invade periodontal tissues, evade host defences, initiate connective tissue destruction and interfere with tissue repair. Adhesion to epithelial and tooth surfaces is dependent on the presence of surface proteins and structures such as microvesicles and fimbriae. Invasion has been demonstrated in vivo and in vitro. The organism has a number of means of evading host defences which include: (i) production of leukotoxin; (ii) producing immunosuppressive factors; (iv) secreting proteases capable of cleaving IgG; and (v) producing Fc-binding.

Pathogenicity of the highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans and its geographic dissemination and role in aggressive periodontitis

For decades, Aggregatibacter actinomycetemcomitans has been associated with aggressive forms of periodontitis in adolescents. In the middle of the 1990s, a specific JP2 clone of A. actinomycetemcomitans, belonging to the cluster of serotype b strains of A. actinomycetemcomitans and having a number of other characteristics, was found to be strongly associated with aggressive forms of periodontitis, particularly in North Africa. Although several longitudinal studies still point to the bacterial species, A. actinomycetemcomitans as a risk factor of aggressive periodontitis, it is now also widely accepted that the highly leukotoxic JP2 clone of A. actinomycetemcomitans is implicated in rapidly progressing forms of aggressive periodontitis. The JP2 clone strains are highly prevalent in human populations living in Northern and Western parts of Africa. These strains are also prevalent in geographically widespread populations that have originated from the Northwest Africa. Only sporadic signs of a dissemination of the JP2 clone strains to non-African populations have been found despite Africans living geographically widespread for hundreds of years. It remains an unanswered question if a particular host tropism exists as a possible explanation for the frequent colonization of the Northwest African population with the JP2 clone. Two exotoxins of A. actinomycetemcomitans are known, leukotoxin (LtxA) and cytolethal distending toxin (Cdt). LtxA is able to kill human immune cells, and Cdt can block cell cycle progression in eukaryotic cells and thus induce cell cycle arrest. Whereas the leukotoxin production is enhanced in JP2 clone strains thus increasing the virulence potential of A. actinomycetemcomitans, it has not been possible so far to demonstrate such a role for Cdt. Lines of evidence have led to the understanding of the highly leukotoxic JP2 clone of A. actinomycetemcomitans as an aetiological factor of aggressive periodontitis. Patients, who are colonized with the JP2 clone, are likely to share this clone with several family members because the clone is transmitted through close contacts. This is a challenge to the clinicians. The patients need intense monitoring of their periodontal status as the risk for developing severely progressing periodontal lesions are relatively high. Furthermore, timely periodontal treatment, in some cases including periodontal surgery supplemented by the use of antibiotics, is warranted. Preferably, periodontal attachment loss should be prevented by early detection of the JP2 clone of A. actinomycetemcomitans by microbial diagnostic testing and/or by preventive means.

Characterization and serotype distribution of Aggregatibacter actinomycetemcomitans isolated from a population of periodontitis patients in Spain

OBJECTIVE

There is no study characterizing the variability of Aggregatibacter actinomycetemcomitans isolates in periodontitis patients in Spain. It is therefore the aim of this investigation to study the serotype distribution of A. actinomycetemcomitans strains isolated from periodontitis patients in Spain. The polymorphism of the genes that codifies the leukotoxin and the operon of the cytolethal-distending toxin (cdt) will also be investigated.

DESIGN

From a total of 701 patients samples, 40 A. actinomycetemcomitans-positive periodontitis patients were included in the study (mean age 45.3, 62.5% females) and their clinical periodontal status was assessed. On average, 1-3 isolates from each patient were sub-cultured and characterized by PCR.

RESULTS

Using culture the prevalence of A. actinomycetemcomitans was 5.7%. The most frequent serotype was "b", being 30 patients infected by a unique serotype, while 7 patients showed co-colonization, mostly with serotypes "a" and "b". From the 79 pure isolates obtained, 24 were from serotype "a", 30 from serotype "b", 12 from serotype "c" and 4 from serotype "d". Further characterization of these samples showed that none of these 79 isolates demonstrated the 530-bp deletion in the leukotoxin's promoter region that characterizes the JP2 strain. Conversely 65.8% of the isolates were cdt+.

CONCLUSIONS

The most common serotypes were "a" and "b", being serotype "b" the most prevalent in mono-colonization, while serotypes "e" and "f" were not detected. In the majority of samples, operon that codifies the cdt (65.8%) and the genes responsible for the codification of leukotoxin (100%) were found. None of the isolates were JP2 strains.

Clinical and microbiological effects of systemic azithromycin in adjunct to nonsurgical periodontal therapy in treatment of Aggregatibacter actinomycetemcomitans associated periodontitis: a randomized placebo-controlled clinical trial

OBJECTIVE

This study aimed to evaluate clinical and microbiological effects of systemic azithromycin (AZM) in adjunct to nonsurgical periodontal therapy (NSPT; or scaling root planing - SRP) in treatment of Aggregatibacter actinomycetemcomitans associated periodontitis (AAAP).

METHODS AND MATERIALS

Seventy individuals with moderate to severe periodontitis and subgingival detection of A. actinomycetemcomitans were randomly allocated to two groups. Thirty-five individuals were allocated to full mouth SRP+AZM (500 mg oral delivery (OD) × 3 days) while 35 individuals were allocated to SRP+Placebo (OD × 3 days) group. The clinical variables evaluated were probing depth (PD), clinical attachment level (CAL), gingival index (GI), plaque index (PI), and percent bleeding on probing sites (%BOP), while microbiologic variables included percentage of subjects positive for A. actinomycetemcomitans at baseline, 3, 6, and 12 months.

RESULTS

The AZM group showed statistically significant reduction in mean PD (2.91 ± 0.88 mm) as compared to placebo (1.51 ± 0.98 mm) (P < 0.001), while CAL gain was significant in the AZM group (2.71 ± 1.15 mm) as compared to the placebo group (1.71 ± 1.29 mm) (P < 0.001). There was also a statistically significant reduction in the number of subjects positive for A. actinomycetemcomitans in the AZM group (P < 0.0001).

CONCLUSION

Azithromycin was found to significantly improve the clinical and microbiological parameters in AAAP individuals.

Periodontal pathogens and associated factors in aggressive periodontitis: results 5-17 years after active periodontal therapy

OBJECTIVES

To assess the association between presence of periodontal pathogens and recurrence of disease in patients with aggressive periodontitis (AgP) after active periodontal therapy (APT) and further influencing factors.

MATERIAL & METHODS

Microbiological samples were taken from 73 patients with AgP 5-17 years after APT at 292 sites (deepest site per quadrant). Real-time polymerase chain reactions were used to detect the periodontal pathogens Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola. Uni- and multivariate analyses evaluated the associations between pathogens and recurrence of disease, smoking and adjunctive antibiotic therapy.

RESULTS

At re-examination A. actinomycetemcomitans could be detected in six patients (8.2%), P. gingivalis in 24 (32.9%), T. forsythia in 31 (42.5%) and T. denticola in 35 (48.0%). Increased levels of T. forsythia and T. denticola at re-examination were significantly associated with recurrence of disease in multivariate analyses (OR: 12.72, p < 0.001; OR 5.55, p = 0.002 respectively). Furthermore, high counts of T. denticola were found in patients with increased percentage of sites with clinical attachment levels (CAL) ≥ 6 mm compared to those with low counts (13.8% versus 3.2%, p = 0.005).

CONCLUSION

In patients with recurrence of disease T. forsythia and T. denticola were detected more frequently and in higher counts. Furthermore, T. denticola was found more frequently in patients with increased CAL.