Oral Microbiota Transplant in Dogs with Naturally Occurring Periodontitis

In periodontitis patients, dysbiosis of the oral microbiota is not only found at clinically diseased periodontal sites but also at clinically healthy periodontal sites, buccal mucosae, tongue, and saliva. The present study evaluated the safety and efficacy of an oral microbiota transplant (OMT) for the treatment of periodontitis in dogs. Eighteen systemically healthy beagle dogs with naturally occurring periodontitis were enrolled in the study and randomly assigned to a test or control group. A 4-y-old, periodontally healthy female beagle dog served as a universal OMT donor. To reduce periodontal inflammation, all dogs received full-mouth mechanical debridement of teeth and mucosae 2 wk before baseline. At baseline, full-mouth mechanical debridement was repeated and followed by adjunctive subgingival and oral irrigation with 0.1% NaOCl. Subsequently, test dogs were inoculated with an OMT from the healthy donor. No daily oral hygiene was performed after OMT transplantation. Adverse events were assessed throughout the observation period. Clinical examinations were performed and whole-mouth oral microbiota samples were collected at week 2, baseline, week 2, and week 12. The composition of oral microbiota samples was analyzed using high-throughput 16S ribosomal RNA gene amplicon sequencing followed by taxonomic assignment and downstream bioinformatic and statistical analyses. Results demonstrated that the intergroup difference in the primary outcome measure, probing pocket depth at week 12, was statistically insignificant. However, the single adjunctive OMT had an additional effect on the oral microbiota composition compared to the full-mouth mechanical and antimicrobial debridement alone. The OMT resulted in an "ecological shift" toward the composition of the donor microbiota, but this was transient in nature and was not observed at week 12. No local or systemic adverse events were observed throughout the study period. The results indicate that OMT may modulate the microbiota composition in dogs with naturally occurring periodontitis and can be applied safely.

Prevalence of Aggregatibacter actinomycetemcomitans and Periodontal Findings among 14 to 15-Year Old Danish Adolescents: A Descriptive Cross-Sectional Study

Aggregatibacter actinomycetemcomitans (Aa) is a keystone pathogen associated with periodontitis in adolescents. The knowledge on the prevalence of Aa and periodontitis among adolescents in Northern Europe is sparse. A total of 525 14- to 15-year-old adolescents from the municipality of Aarhus, Denmark, underwent a full-mouth clinical examination. Plaque score (PS), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment loss (CAL) were recorded. Subgingival plaque samples (SPS) and stimulated saliva samples (SSS) were collected and analyzed for the presence of JP2 and non-JP2 genotypes of Aa using real-time PCR. A total of 70 (13.3%) individuals were positive for Aa, with 17 found in SPS, 19 in SSS, and 35 in both. The highly leukotoxic JP2 genotype of Aa was not detected. The individuals positive for Aa in both SPS and SSS had poorer periodontal outcomes (PPD and CAL) than individuals without Aa and individuals carrying Aa in either SPS or SSS only. In conclusion, 13% of 14- to 15-year-old Danish adolescents were positive for Aa, and the presence of Aa in both SPS and SSS was associated with poorer periodontal outcomes.

Aggregatibacter Actinomycetemcomitans: Clinical Significance of a Pathobiont Subjected to Ample Changes in Classification and Nomenclature

Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium that is part of the oral microbiota. The aggregative nature of this pathogen or pathobiont is crucial to its involvement in human disease. It has been cultured from non-oral infections for more than a century, while its portrayal as an aetiological agent in periodontitis has emerged more recently. A. actinomycetemcomitans is one species among a plethora of microorganisms that constitute the oral microbiota. Although A. actinomycetemcomitans encodes several putative toxins, the complex interplay with other partners of the oral microbiota and the suppression of host response may be central for inflammation and infection in the oral cavity. The aim of this review is to provide a comprehensive update on the clinical significance, classification, and characterisation of A. actinomycetemcomitans, which has exclusive or predominant host specificity for humans.

Antimicrobial susceptibilities of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis strains from periodontitis patients in Morocco

BACKGROUND AND OBJECTIVE

Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis have been frequently isolated in periodontitis patients in Morocco. Its persistence after the subgingival debridement of the biofilm has been correlated with worse clinical outcomes. The aim of this study was to evaluate the antimicrobial susceptibilities of A. actinomycetemcomitans and P. gingivalis, to amoxicillin, amoxicillin plus clavulanate, metronidazole, and azithromycin. In addition, microbiological profiles of patients harbouring A. actinomycetemcomitans, P. gingivalis, or both were compared.

MATERIAL AND METHODS

In 45 consecutive periodontitis Moroccan patients, subgingival samples were taken and processed by culture. Twenty-four A. actinomycetemcomitans and 30 P. gingivalis colonies were isolated (54 strains) and susceptibility tests, using the epsilometric method, were run for amoxicillin, amoxicillin plus clavulanate, metronidazole, and azithromycin. Minimum inhibitory concentrations for 50 (MIC50) and 90% (MIC90) of the organisms were calculated.

RESULTS

The prevalence of A. actinomycetemcomitans and P. gingivalis was 79.5 and 84.4%, respectively. A. actinomycetemcomitans showed susceptibility to amoxicillin, amoxicillin plus clavulanate, while 28% of the isolated strains were resistant to azithromycin and 61.7% towards metronidazole. No P. gingivalis resistance towards amoxicillin, amoxicillin plus clavulanate, metronidazole, and azithromycin was found.

CONCLUSION

A. actinomycetemcomitans and P. gingivalis were frequently detected in Moroccan patients with periodontitis, while antimicrobial resistance was only detected for A. actinomycetemcomitans to metronidazole and azithromycin.

CLINICAL RELEVANCE

A. actinomycetemcomitans resistance against some antimicrobials in periodontitis patients in Morocco can influence the selection of the therapeutic approaches.

Aggregatibacter (Actinobacillus) actimycetemcomitans leukotoxin and human periodontitis - A historic review with emphasis on JP2

Aggregatibacter (Actinobacillus) actimycetemcomitans (Aa) is a gram-negative bacterium that colonizes the human oral cavity and is causative agent for localized aggressive (juvenile) periodontitis (AgP). In the middle of 1990s, a specific JP2 clone of belonging to the cluster of serotype b strains of Aa with highly leukotoxicity (leukotoxin, LtxA) able to kill human immune cells was isolated. JP2 clone of Aa was strongly associated with in particularly in rapidly progressing forms of aggressive periodontitis. The JP2 clone of Aa is transmitted through close contacts. Therefore, AgP patients need intense monitoring of their periodontal status as the risk for developing severely progressing periodontitis lesions are relatively high. Furthermore, timely periodontal treatment, including periodontal surgery supplemented by the use of antibiotics, is warranted. More importantly, periodontal attachment loss should be prevented by early detection of the JP2 clone of Aa by microbial diagnosis testing and/or preventive means.

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.

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.

Leukotoxicity of Aggregatibacter actinomycetemcomitans in generalized aggressive periodontitis in Brazilians and their family members

OBJECTIVE

The purpose of this study was to examine the leukotoxin promoter types of Aggregatibacter actinomycetemcomitans clones in subjects with generalized aggressive periodontitis (GAgP) and in their family members (FM).

MATERIAL AND METHODS

Thirty-five patients with GAgP (33.9±7.1 years), 33 of their FM (22.8±11.4 years), and 41 patients with chronic periodontitis (CP) (44.1±9.4 years) were clinically analyzed using the plaque index, gingival index, probing depth (PD), and clinical attachment level (CAL). Subgingival biofilm samples were collected from four interproximal periodontal sites (>PD and >CAL) of each patient. The presence of A. actinomycetemcomitans and its leukotoxic clone was confirmed by polymerase chain reaction (PCR).

RESULTS

A. actinomycetemcomitans was observed in 23 (51.1%) GAgP patients and 16 (30.1%) CP patients. Thirty-seven (94.8%) patients showed minimally leukotoxic strains and 2 (5.1%) showed highly leukotoxic strains. In the FM group, 10 (30.3%) had aggressive periodontitis (AgP), 12 (36.3%) had CP, 11 (33.3%) were periodontally healthy or had gingivitis, and 12.2% were A. actinomycetemcomitans positive. Greater full mouth PD and CAL were observed in GAgP patients positive for the bacteria than those negative for it (p<;0.05), and the presence of A. actinomycetemcomitans positively correlated with GAgP (Odds ratio, 3.1; confidence interval, 1.4-7.0; p=0.009).

CONCLUSIONS

The presence of A. actinomycetemcomitans was associated with the clinical condition of GAgP, with most patients exhibiting a generalized form of the disease and minimally leukotoxic clones. Most of the relatives of GAgP patients presented either CP or AgP.

Salivary carriage of periodontal pathogens in generalized aggressive periodontitis families

BACKGROUND

Generalized aggressive periodontitis (GAP) is a multifactorial disease that shows a specific microbial profile and a familial aggregation.

AIM

This study evaluated the salivary microbial profile of families with a history of GAP and compared them with healthy families.

DESIGN

Fifteen families with parents presenting periodontal health and 15 with parents with a history of GAP were selected. Each family had a child aged 6-12 years. Stimulated saliva was collected from all subjects, and Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), and Aggregatibacter actinomycetemcomitans (Aa) amounts were determined.

RESULTS

Children of GAP families showed higher detection of Aa (90%) than children of healthy families (45%) (P < 0.05). Parents with GAP showed a Pg salivary concentration statistically higher than that of healthy parents (P < 0.05).Children of GAP families, however, exhibited similar Pg concentration than healthy children (P > 0.05). Tf amounts did not differ either in parents or in children (P > 0.05) The infection risk calculation indicates that children who have one parent who is positive for Aa have 16.3 times (95% CI 3.1-87.2) more risk of being infected with Aa (P < 0.05) than children from an Aa-negative family.

CONCLUSION

It may be concluded that children of parents with aggressive periodontitis have higher levels and higher risk of Aa infection.

Quantitative discrimination of Aggregatibacter actinomycetemcomitans highly leukotoxic JP2 clone from non-JP2 clones in diagnosis of aggressive periodontitis

BACKGROUND

Aggregatibacter actinomycetemcomitans is the etiological agent of periodontitis, and there is a strong association between clone JP2 and aggressive periodontitis in adolescents of African descent. The JP2 clone has an approximately 530-bp deletion (∆530) in the promoter region of the lkt/ltx gene, which encodes leukotoxin, and this clone has high leukotoxic activity. Therefore, this clone is very important in aggressive periodontitis. To diagnose this disease, culture methods and conventional PCR techniques are used. However, quantitative detection based on qPCR for the JP2 clone has not been developed due to genetic difficulties. In this study, we developed a qPCR-based quantification method specific to the JP2 clone.

METHODS

Based on our analysis of the DNA sequence of the lkt/ltx gene and its flanking region, we designed a reverse primer specific for the ∆530 deletion border sequence and developed a JP2-specific PCR-based quantification method using this primer. We also analyzed the DNA sequence of the ∆530 locus and found it to be highly conserved (97-100%) among 17 non-JP2 strains. Using the ∆530 locus, we designed a qPCR primer-probe set specific to non-JP2 clones. Next, we determined the numbers of JP2 and non-JP2 clone cells in the periodontal pockets of patients with aggressive periodontitis.

RESULTS

The JP2-specific primers specifically amplified the genomic DNA of the A. actinomycetemcomitans JP2 clone and did not react with other bacterial DNA, whereas the non-JP2 specific primers reacted only with A. actinomycetemcomitans non-JP2 clones. Samples from the 88 periodontal sites in the 11 patients with aggressive periodontitis were analyzed. The bacterial cell numbers in 88 periodontal sites ranged from 0 to 4.8 × 10(8) (mean 1.28 × 10(7)) for JP2 clones and from 0 to 1.6 × 10(6) for non-JP2 clones (mean 1.84 × 10(5)). There were significant differences in the JP2 cell number between a clinical attachment level (CAL) ≤6 mm and a level ≥7 mm (p < 0.01). Our new qPCR-based JP2- and non-JP2-specific quantitative detection assay is applicable to the diagnosis of aggressive periodontitis with A. actinomycetemcomitans.

CONCLUSIONS

We successfully developed a quantitative and discriminative PCR-based method for the detection of A. actinomycetemcomitans JP2 and non-JP2 clones. This technique will contribute to future analyses of the quantitative relationship between this organism and aggressive periodontitis.

The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans in localized and generalized forms of aggressive periodontitis

OBJECTIVE

To investigate the presence of A. actinomycetemcomitans, including the highly virulent JP2 clone, in young adult patients with aggressive periodontitis, and associate the findings with the two forms of the disease.

MATERIALS AND METHODS

Seventy Moroccan subjects with aggressive periodontitis, aged less than 35 years, were recruited. Among these, 41 had LAgP and 29 had GAgP. Plaque samples were collected from periodontal pockets and examined using a PCR that detects the presence of A. actinomycetemcomitans and which differentiates between JP2 and non-JP2 genotypes of the bacterium.

RESULTS

total of 58 (83%) from the 70 AgP patients were positive for A. actinomycetemcomitans, among whom 77% were positives for the JP2 clone. The JP2 clone was detected in 34 (83%) of the LAgP patients compared to 20 (69%) of the GAgP patients (p = 0.17). Fourteen (20%) of the patients harbored non-JP2 genotypes of A. actinomycetemcomitans, although most of these patients (10/14) also harbored the JP2 clone.

CONCLUSIONS

The presence of the JP2 clone of A. actinomycetemcomitans is strongly associated with both LAgP and GAgP in young adults in Morocco. This implies that treatment of AgP in this population should include microbiological screening and aim at eradication of the bacterium when present.

Microbiological and immunological characteristics of young Moroccan patients with aggressive periodontitis with and without detectable Aggregatibacter actinomycetemcomitans JP2 infection

Cross-sectional and longitudinal studies identify the JP2 clone of Aggregatibacter actinomycetemcomitans as an aetiological agent of aggressive periodontitis (AgP) in adolescents of northwest African descent. To gain information on why a significant part of Moroccan adolescents show clinical signs of periodontal disease in the absence of this pathogen we performed comprehensive mapping of the subgingival microbiota of eight young Moroccans, four of whom were diagnosed with clinical signs of AgP. The analysis was carried out by sequencing and phylogenetic analysis of a total of 2717 cloned polymerase chain reaction amplicons of the phylogenetically informative 16S ribosomal RNA gene. The analyses revealed a total of 173 bacterial taxa of which 39% were previously undetected. The JP2 clone constituted a minor proportion of the complex subgingival microbiota in patients with active disease. Rather than identifying alternative aetiologies to AgP, the recorded infection history of the subjects combined with remarkably high concentrations of antibodies against the A. actinomycetemcomitans leukotoxin suggest that disease activity was terminated in some patients with AgP as a result of elimination of the JP2 clone. This study provides information on the microbial context of the JP2 clone activity in a JP2-susceptible population and suggests that such individuals may develop immunity to AgP.

Occurrence of Aggregatibacter actinomycetemcomitans serotypes in subgingival plaque from United States subjects

This study examined the distribution pattern of Aggregatibacter actinomycetemcomitans serotypes in the subgingival plaque of subjects residing in the United States. A. actinomycetemcomitans was identified in 256 subgingival plaque samples from 161 subjects. For 190 of the 256 samples, the total cultivable bacteria and selected periodontal pathogenic species were determined. A. actinomycetemcomitans isolates were confirmed by a16S rDNA-based PCR analysis, genotyped by arbitrarily-primed PCR, and serotyped by PCR analysis of serotype-specific gene clusters. A total of 82 distinct A. actinomycetemcomitans strains were identified. The serotype distribution pattern of the strains was 21 (25.6%) serotype a, 12 (14.6%) b, 41 (50%) c, 6 (7.3%) e, 1 (1.2%) f, and 1 (1.2%) non-typeable. For 14 subjects where multiple colonies of A. actinomycetemcomitans were identified, 11 subjects (78.6%) were each infected by a single serotype, while the remaining three subjects (21.3%) were each infected by two serotypes of A. actinomycetemcomitans. There was an inverse relationship between the level of cultivable A. actinomycetemcomitans and Porphyromonas gingivalis. Within subgingival plaque of study cohort A. actinomycetemcomitans serotype c was the dominant serotype and comprised 50% of all strains, followed by (in order of detection frequency) serotypes a and b. Serotypes d, e, and f strains were either not detected or less frequently found. Serotype distribution patterns of subgingival A. actinomycetemcomitans may vary among subjects of different race orethnicity.