Occurrence of Aggregatibacter actinomycetemcomitans in Brazilians with chronic periodontitis

Parkinson's disease alters the composition of subgingival microbiome

Aim

The current study aimed to test the hypothesis that Parkinson's disease exacerbates periodontitis by altering its microbiome.

Materials and Methods

Clinical periodontal parameters were recorded. Subgingival samples from healthy controls, periodontitis patients (PD), and Parkinson's patients with periodontitis (PA+PD) were analyzed using the checkerboard DNA-DNA hybridization technique for targeting 40 bacterial species typically associated with periodontal disease and health. Next-generation sequencing (NGS) of the 16S ribosomal RNA gene (V1-V3 regions) was performed to analyze the microbiome comprehensively.

Results

Parkinson's patients had mild-to-moderate motor dysfunctions. Bleeding on probing was significantly increased in the PA+PD group compared to PD (p < 0.05). With checkerboard analysis, PA was associated with increased Treponema socranskii (p = 0.0062), Peptostreptococcaceae_[G-6] [Eubacterium]_nodatum (p = 0.0439), Parvimona micra (p < 0.0001), Prevotella melaninogenica (p = 0.0002), Lachnoanaerobaculum saburreum (p < 0.0001), and Streptococcus anginosus (p = 0.0020). Streptococcus intermedia (p = 0.0042), P.nodatum (p = 0.0022), P. micra (p = 0.0002), Treponema denticola (p = 0.0045), L.saburreum (p = 0.0267), P.melaninogenica (p = 0.0017), Campylobacter rectus (p = 0.0020), and T.socranskii (p = 0.0002) were higher; Aggregatibacter actinomycetemcomitans (p = 0.0072) was lower in deep pockets in the PA+PD compared to PD. Schaalia odontolytica (p = 0.0351) and A.actinomycetemcomitans (p = 0.002) were lower; C.rectus (p = 0.0002), P. micra (p = 0065), Streptococcus constellatus (p = 0.0151), T.denticola (p = 0.0141), P.melaninogenica (p = 0.0057), and T.socranskii (p = 0.0316) were higher in shallow pockets in the PA+PD. Diversity decreased in PD (p = 0.001) and PA+PD (p = 0.026) compared to control, with minimal differences in alpha and beta diversities among PD and PA+PD based on NGS results.

Conclusion

These data demonstrated that Parkinson's disease modifies PD-associated subgingival microbiome.

Invasive Aggregatibacter infection: shedding light on a rare pathogen in a retrospective cohort analysis

Introduction. Aggregatibacter are Gram-negative, facultatively anaerobic rods or coccobacilli that are infrequently encountered as pathogens causing infection.Hypothesis/Gap Statement. The range of invasive infection that Aggregatibacter cause is poorly described. The pathogenicity of species such as Aggregatibacter segnis is debated.Aim. To identify invasive infection due to Aggregatibacter species in a large healthcare organization and to characterize clinical syndromes, co-morbidities and risk factors.Methodology. All microbiological samples positive for Aggregatibacter species were identified by conventional culture or 16S rRNA PCR between October 2017 and March 2021. Electronic records for all patients with positive samples were reviewed and the infection syndrome classified for patients with invasive disease.Results. Twenty-seven patients with invasive infection were identified, with a statistically significant difference in species-specific patterns of invasive infection (P=0.02) and a statistically significant association with residence in the 30 % most deprived households in the UK by postcode (P<0.01). The three most common co-morbidities were periodontitis or recent dental work (29.6%), cardiovascular disease (25.9%) and diabetes (18.5 %).Conclusion. We describe a novel association of Aggregatibacter segnis with skin and soft tissue infection. The propensity of the Aggregatibacter species to cause invasive infection at different body sites and be associated with deprivation is reported. Aggregatibacter actinomycetemcomitans bacteraemia was associated with infective endocarditis, and Aggregatibacter aphrophilus was implicated in severe appendicitis and noted to cause brain abscess. Areas warranting future research include exploring the risk-factors required for invasive infection and those that may determine the species-specific differences in patterns of invasive disease.

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

AIM

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

METHODOLOGY

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

RESULTS

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

CONCLUSION

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

Prevalence of target anaerobes associated with chronic periodontitis

Introduction

Periodontal diseases are a group of chronic infections that destroy tissues surrounding and supporting the teeth. Data on the anaerobes associated with periodontal infections in Kuwait is lacking.

Aim

To investigate the target anaerobes associated with chronic periodontitis (CP) in patients admitted to Dental Clinics in Kuwait University Health Sciences Center, Kuwait.

Methodology

Patients with CP (severe and moderate) were recruited into this study during a period of 15 months. Samples were collected directly from inside the gingival pockets and subjected to semi-quantitative PCR assays.

Results

A total of 30 patients, stratified into moderate and severe CP and 31 healthy individuals, used as controls, were studied. Nine (30 %) of the 30 patients were in the 50–59-year age group. The detection rate of Aggregatibacter actinomycetemcomitans between the patients (9 : 30 %) versus the controls (5 : 16.1 %) was non-significant (P >0.05). Fusobacterium spp., were detected in all patients versus 29 (93.1 %) controls, (P >0.05). However, four target anaerobes were significantly associated with CP patients; Porphyromonas gingivalis was detected in ten (33.3 %) patients versus two (6.4 %) controls (P <0.0001); Tannerella forsythia 25 (83.3 %) versus 16 (51.6 %) controls (P <0.0001); Parvimonas micra 27 (90 %) versus 16 (51.6 %) controls (P <0.0001) and Treponema denticola, 18 (60 %) versus nine (29 %) controls (P <0.0001), respectively. Prevotella spp. were detected in 27 (90 %) patients and 30 (96.7 %) controls (P>0.5). There was no significant difference in the burden of Prevotella spp. between patients and controls determined by semi-quantitative PCR assays.

Conclusion

Some (4/7) of the target anaerobes were significantly associated with CP in our study. P. gingivalis was the most strongly associated anaerobe with CP, although not the keystone bacteria, while Prevotella spp. was similar to the healthy controls.

Qualitative, quantitative and genotypic evaluation of Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum isolated from individuals with different periodontal clinical conditions

Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are strongly associated with periodontitis, and their evaluations are relevant to understand their role in the etiology and progression of periodontal diseases. In this study, the qualitative and quantitative detection of A. actinomycetemcomitans and F. nucleatum, as well as their genetic diversity, were evaluated in individuals with gingivitis, chronic periodontitis and periodontally healthy. In addition, the biotyping, serotyping, and prevalence of the ltx and cdt genes in A. actinomycetemcomitans were also determined. Subgingival biofilms obtained from gingivitis (70), periodontitis (75) and healthy (95) individuals were analyzed by cultures and PCR. Bacterial typing and presence of ltx and cdt genes in A. actinomycetemcomitans were also verified. DNA from A. actinomycetemcomitans and F. nucleatum was detected respectively, in 65.7% and 57.1% of gingivitis, 80% and 68% of periodontitis, and 57.8% and 37.8% of healthy. A. actinomycetemcomitans from gingivitis were biotypes I, II, IV, V, and X, and serotypes a, c, and e. In periodontitis, biotypes II, VI, and X, and serotypes a, b, and c were found. In healthy subjects, biotypes II and X, and serotypes b and c were found. The LTX and ltxA were observed in strains from gingivitis and periodontitis pockets. Subsequently, our data also showed no direct relationship between ltxA gene expression and leukotoxin gene 530-bp presence. On the other hand, cdt gene predominated during the inflammatory disease process. Our results strongly support a role of A. actinomycetemcomitans and F. nucleatum in advanced stage of periodontal disease.

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.

Metabolic syndrome exacerbates inflammation and bone loss in periodontitis

Clinical studies have shown that metabolic syndrome (MetS) is associated with increased risk of developing periodontitis. However, the underlying mechanisms remain largely unknown. Since it is known that lipopolysaccharide (LPS)-activated toll-like receptor 4 signaling pathways play a crucial role in periodontitis, we hypothesized that MetS enhances LPS-induced periodontal inflammation and alveolar bone loss. In this study, we induced MetS in C57BL/6 mice by feeding them high-fat diet (HFD), and we induced periodontitis by periodontal injection of Aggregatibacter actinomycetemcomitans LPS. We found that mice fed a HFD had significantly increased body weight, plasma lipids, insulin, and insulin resistance when compared with mice fed regular chow, indicating that the mice developed MetS. We also found that a HFD markedly increased LPS-induced alveolar bone loss, osteoclastogenesis, and inflammatory infiltration. Analysis of gene expression in periodontal tissue revealed that HFD and LPS injection cooperatively stimulated expression of cytokines that are known to be involved in periodontal tissue inflammation and osteoclastogenesis-such as interleukin 6, monocyte-chemotactic protein 1, receptor activator of nuclear factor kappa-B ligand, and macrophage colony-stimulating factor. To further understand the potential mechanisms involved in MetS-boosted tissue inflammation, our in vitro studies showed that palmitic acid-the most abundant saturated fatty acid (SFA) and the major SFA in the HFD used in our animal study-potently enhanced LPS-induced proinflammatory gene expression in macrophages. In sum, this study demonstrated that MetS was associated with increased periodontal inflammation and alveolar bone loss in an LPS-induced periodontitis animal model. This study also suggests that SFA palmitic acid may play an important role in MetS-associated periodontitis by enhancing LPS-induced expression of inflammatory cytokines in macrophages.

Prevalence and distribution of Aggregatibacter actinomycetemcomitans and its cdtB gene in subgingival plaque of Chinese periodontitis patients

BACKGROUND

Aggregatibacter actinomycetemcomitans (A.actinomycetemcomitans) is an important periodontal pathogen that can participate in periodontitis and other non-oral infections. The cytolethal distending toxin (Cdt) is among the virulence factors produced by this bacterium. This study was to elucidate the distribution of A.actinomycetemcomitans and the prevalence of its cdtB gene in Chinese subjects.

METHODS

A total of 255 subgingival samples were obtained from 30 subjects. Samples were collected from periodontal healthy sites as well as shallow, moderate and deep pockets. The absolute quantity of A.actinomycetemcomitans and cdtB gene were determined by real-time polymerase chain reaction.

RESULTS

A.actinomycetemcomitans was detected in 92 of 105 (87.6%) samples of aggressive periodontitis (AgP) patients, in 73 of 79 (92.4%) samples of chronic periodontitis ( CP) patients and in 5 of 71 (7.0%) samples of periodontal healthy subjects. The cdtB gene was detected in 72 sites (78.3%) with AgP infected with A.actinomycetemcomitans, 54 sites (74.0%) with CP infected with A.actinomycetemcomitans and none in healthy sites infected with A.actinomycetemcomitans. In addition, quantity of A.actinomycetemcomitans and cdt gene in samples from deep pockets were significant larger than moderate, shallow and healthy sites (P < 0.05). In comparison to CP, AgP patients were infected with increased numbers of cdt genotype in deep pockets (P < 0.05).

CONCLUSION

This study suggests that the cdtB gene are prevalent in A.actinomycetemcomitans, and the distribution of cdt genotype strain may be correlated with AgP and serious periodontal inflammation.

Decreased phagocytic function in neutrophils and monocytes from peripheral blood in periodontal disease

Phagocytosis by neutrophils and monocytes constitutes the main defense mechanism against bacterial challenges in periodontitis. Phagocytosis by neutrophils has already been evaluated, whereas phagocytic function of monocytes has hardly been addressed so far.