Differences in the subgingival microbiota of Swedish and USA subjects who were periodontally healthy or exhibited minimal periodontal disease

Characterization of oral microbiota in 6-8-month-old small breed dogs

BACKGROUND

Periodontitis is the most common oral disease in dogs, and its progression and severity are influenced by risk factors, such as age and body size. Recent studies have assessed the canine oral microbiota in relation to different stages of periodontitis and niches within the oral cavity. However, knowledge of the bacterial composition at different ages and body sizes, especially in puppies, is limited. This study aimed to characterize the oral microbiota in the healthy gingiva of small breed puppies using next-generation sequencing. Additionally, we assessed the impact of dental care practices and the presence of retained deciduous teeth on the oral microbiota.

RESULTS

In this study, plaque samples were collected from the gingival margin of 20 small breed puppies (age, 6.9 ± 0.6 months). The plaque samples were subjected to next-generation sequencing targeting the V3-V4 region of the 16 S rRNA. The microbiota of the plaque samples was composed mostly of gram-negative bacteria, primarily Proteobacteria (54.12%), Bacteroidetes (28.79%), and Fusobacteria (5.11%). Moraxella sp. COT-017, Capnocytophaga cynodegmi COT-254, and Bergeyella zoohelcum COT-186 were abundant in the oral cavity of the puppies. In contrast, Neisseria animaloris were not detected. The high abundance of Pasteurellaceae suggests that this genus is characteristic of the oral microbiota in puppies. Dental care practices and the presence of retained deciduous teeth showed no effects on the oral microbiota.

CONCLUSIONS

In this study, many bacterial species previously reported to be detected in the normal oral cavity of adult dogs were also detected in 6-8-month-old small breed dogs. On the other hand, some bacterial species were not detected at all, while others were detected in high abundance. These data indicate that the oral microbiota of 6-8-month-old small breed dogs is in the process of maturating in to the adult microbiota and may also have characteristics of the small dog oral microbiota.

Comparative 16S rRNA gene sequencing study of subgingival microbiota of healthy subjects and patients with periodontitis from four different countries

AIM

To investigate the differences between the subgingival microbiota of healthy subjects (HS) and periodontitis patients (PP) from four different countries through a metagenomic approach.

MATERIALS AND METHODS

Subgingival samples were obtained from subjects from four different countries. Microbial composition was analysed through high-throughput sequencing of the V3-V4 region of the 16S rRNA gene. The country of origin, diagnosis and clinical and demographic variables of the subjects were used to analyse the microbial profiles.

RESULTS

In total, 506 subgingival samples were analysed: 196 from HS and 310 from patients with periodontitis. Differences in richness, diversity and microbial composition were observed when comparing samples pertaining to different countries of origin and different subject diagnoses. Clinical variables, such as bleeding on probing, did not significantly affect the bacterial composition of the samples. A highly conserved core of microbiota associated with periodontitis was detected, while the microbiota associated with periodontally HS was much more diverse.

CONCLUSIONS

Periodontal diagnosis of the subjects was the main variable explaining the composition of the microbiota in the subgingival niche. Nevertheless, the country of origin also had a significant impact on the microbiota and is therefore an important factor to consider when describing subgingival bacterial communities.

Simultaneous detection and evaluation of Prevotella intermedia, Prevotella nigrescens, Prevotella loescheii, and Prevotella melaninogenica in subgingival plaque samples of chronic periodontitis and healthy individuals through multiplex polymerase chain reaction

Background

Prevotella is a Gram-negative anaerobic bacilli. The phenotypic characteristics of the various species of Prevotella are similar, which often makes it difficult in routine differentiation and identification of all the species.

Aim

The purpose of the study was to detect and compare presence of Prevotella intermedia, Prevotella nigrescens, Prevotella melaninogenica, and Prevotella loescheii in subgingival plaque samples of chronic periodontitis and healthy individuals.

Materials and Methods

Two hundred and thirty-six subjects were considered consisting of chronic periodontitis (128) and healthy (108) individuals. Subgingival plaque sample was collected in reduced transport fluid and analyzed. DNA extraction and polymerase chain reaction (PCR) were performed for genus Prevotella followed by positive samples were considered for the detection of selected species through multiplex PCR using specific primers.

Results

Out of 236 samples, 94.1% were positive for genus Prevotella. Out of 222 cases P. nigrescens showed the highest number of cases positive (59.5%) followed by P. melaninogenica (57.2%), P. intermedia (55.4%), and P. loescheii (40.1%). Species were analyzed individually between chronic periodontitis and healthy, P. intermedia, P. nigrescens, and P. loescheii showed greater positivity in healthy compared to chronic periodontitis. Positivity for P. melaninogenica was high in chronic periodontitis compared to healthy.

Conclusion

The number of positive cases for species, when correlated with clinical parameters showed an increase in mean score for all clinical parameters assessed, suggesting the presence of variation in the prevalence of Prevotella species and geographic variation do exist in oral microflora. Findings suggest that they can be normal commensals and opportunistic.

Prevalence and abundance of 9 periodontal pathogens in the saliva of periodontally healthy adults and patients undergoing supportive periodontal therapy

PURPOSE

This study aimed to examine the prevalence and abundance of 9 representative periodontal pathogens in the saliva samples of periodontally healthy subjects (PH) and patients with periodontitis who underwent supportive periodontal therapy (SPT). The age-specific distribution of these pathogens in periodontally healthy individuals was also analyzed.

METHODS

One hundred subjects (aged >35 years) were recruited (50 each in the PH and SPT groups) between August 2016 and April 2019. The prevalence and abundance of periodontal pathogens in the PH group were compared with those in periodontally healthy young subjects (94 subjects; aged <35 years), who were included in our previous study. DNA copy numbers of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Campylobacter rectus (Cr), Peptostreptococcus anaerobius (Pa), and Eikenella corrodens (Ec) were analyzed using real-time polymerase chain reaction.

RESULTS

The detection frequencies of all pathogens, except Aa, were high in the PH and SPT groups. The ranking order of pathogen DNA copy numbers was similar in both groups. In both groups, Fn had the highest abundance, Aa had the lowest abundance. Additionally, Td was significantly more abundant in men than in women in both groups (P<0.05). Compared with the PH group, the SPT group exhibited significantly lower total bacteria and Fn abundance and higher Pg abundance (P<0.05). The age-specific pathogen distribution analysis revealed a significantly low Aa abundance and high Tf and Cr abundance in the PH group.

CONCLUSIONS

The clinical parameters and microbial profiles were similar between the SPT and PH groups. However, patients with periodontitis require supportive care to prevent recurrence. As the abundance of some bacteria varied with age, future studies must elucidate the correlation between age-related physiological changes and periodontal bacterial composition.

Comparison of subgingival and gingival margin plaque microbiota from dogs with healthy gingiva and early periodontal disease

The purpose of the investigation was to determine whether canine gingival margin (GM) plaque is a reliable surrogate for subgingival (SG) plaque from a microbial community (microbiota) perspective. SG and GM plaque samples were collected from 381 dogs visiting pet hospitals in the USA, China and Thailand. Dogs with clinically healthy gingivae through to early periodontitis were included in the study. The samples were subject to next generation Illumina sequence analysis to allow microbiota comparisons to be made between the two plaque sources. Overall, the SG and GM samples indicated commonality via the majority community that were shared between them; health associations led to the identification of some significant taxa-specific differences. GM microbiota exhibited lower variability and diversity and were shown to reflect a sub-population of those associated with SG plaque. Both plaque niches, however, demonstrated similar changes in microbial signatures with health and early periodontal disease and did not indicate divergent trends. The key, most abundant microbiota of GM plaque strongly reflect those observed with SG plaque across health and early periodontitis. Microbiota in plaque from above the gum line may therefore be employed as a biomarker of oral health. This opens up the potential to use plaque, sampled from conscious dogs, to define oral health status and improve the diagnosis, treatments and interventions for periodontal disease.

Subgingival microbiota of dogs with healthy gingiva or early periodontal disease from different geographical locations

BACKGROUND

Periodontal disease is the most common oral disease of dogs worldwide and results from a complex interplay between plaque bacteria, the host and environmental factors. Recent studies have enhanced our understanding of the associations between the plaque microbiota and canine periodontal disease. These studies, however, were limited in their geographical reach. Thus associations between the canine oral microbiota and geographical location were investigated by determining the composition of subgingival plaque samples from 587 dogs residing in the United Kingdom (UK), United States of America (USA), China and Thailand using 454-pyrosequencing.

RESULTS

After quality filtering 6,944,757 sequence reads were obtained and clustering of these at ≥98% sequence resulted in 280 operational taxonomic units (OTUs) following exclusion of rare OTUs (present at < 0.05% in all four countries). The subgingival plaque from dog populations located in the UK, USA, China and Thailand had a similar composition although the abundance of certain taxa varied significantly among geographical locations. Exploration of the effect of clinical status and age revealed a marked similarity among the bacteria associated with increased age and those associated with gingivitis: Young dogs and those with no gingivitis were dominated by taxa from the phyla Bacteroidetes and Proteobacteria whereas older dogs and those with moderate gingivitis were dominated by members of the Firmicutes. The plaque microbiota of small breed dogs was found to significantly differ to medium and large breeds and was dominated by species belonging to the Firmicutes.

CONCLUSIONS

The bacterial associations with health, gingivitis and periodontitis were conserved across dogs from the UK, USA, China and Thailand. These bacterial signatures of periodontal health and disease have potential as biomarkers for disease detection.

A cross-sectional study on the periodontal status and prevalence of red complex periodontal pathogens in a Japanese population

This large-scale study cross-sectionally examined the periodontal status and prevalence of "red complex" bacteria (Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia) in Japanese adults. A total of 977 participants were enrolled in the study. Probing depth (PD), bleeding on probing (BOP), and bone crest level (BCL) were recorded, and the presence of red complex bacteria in the saliva was examined using polymerase chain reaction. The mean BCL value and the percentage of sites with a PD ≥4 mm or the presence of BOP were significantly higher in older participants. The detection rates of P. gingivalis, T. denticola, and T. forsythia were 46.3%, 76.4%, and 61.1%, respectively. The P. gingivalis detection rate significantly increased with age, while those of T. denticola and T. forsythia were comparably high for all age groups. A close correlation between P. gingivalis and the percentage of sites with PD ≥4 mm was indicated by nonlinear canonical correlation analysis. Current smokers exhibited a more advanced disease condition and a significantly higher P. gingivalis detection rate than non-smokers. In conclusion, periodontal condition worsens with age, and P. gingivalis appears to be the red complex bacterium most closely associated with periodontitis.

Real-time PCR quantification of 9 periodontal pathogens in saliva samples from periodontally healthy Korean young adults

Purpose

Few studies have examined periodontal pathogens from saliva samples in periodontally healthy young adults. The purposes of this study were to determine the prevalence of periodontopathic bacteria and to quantify periodontal pathogens in saliva samples using real-time polymerase chain reaction (PCR) assays in periodontally healthy Korean young adults under 35 years of age.

Methods

Nine major periodontal pathogens were analyzed by real-time PCR in saliva from 94 periodontally healthy young adults. Quantification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Peptostreptococcus anaerobius, and Eikenella corrodens was performed by DNA copy number measurement.

Results

F. nucleatum and E. corrodens were detected in all subjects; the numbers of positive samples were 87 (92.6%), 91 (96.8%), and 90 (95.7%) for P. gingivalis, P. anaerobius, and C. rectus, respectively. Other pathogens were also detected in periodontally healthy subjects. Analysis of DNA copy numbers revealed that the most abundant periodontal pathogen was F. nucleatum, which was significantly more prevalent than all other bacteria (P<0.001), followed by P. anaerobius, P. gingivalis, E. corrodens, C. rectus, and T. denticola. There was no significant difference in the prevalence of each bacterium between men and women. The DNA copy number of total bacteria was significantly higher in men than in women.

Conclusions

Major periodontal pathogens were prevalent in the saliva of periodontally healthy Korean young adults. Therefore, we suggest that the development of periodontal disease should not be overlooked in periodontally healthy young people, as it can arise due to periodontal pathogen imbalance and host susceptibility.

Systemic antibiotics in the treatment of periodontitis

Despite the fact that several clinical studies have shown additional benefits when certain systemic antibiotics are used as adjuncts to periodontal treatment, clear guidelines for the use of these agents in the clinical practice are not yet available. Basic questions concerning the use of systemic antibiotics to treat periodontitis remain unanswered, such as: which drug(s) should be used; which patients would most benefit from treatment; which are the most effective protocols (i.e. doses and durations); and in which phase of the mechanical therapy should the drug(s) be administered? Although not all of those questions have been directly addressed by controlled randomized clinical trials, recent concepts related to the ecology of periodontal diseases, as well as the major advances in laboratory and clinical research methods that have occurred in the past decade, have significantly broadened our knowledge in this field. This article endeavored to provide a 'state of the art' overview on the use of systemic antibiotics in the treatment of periodontitis, based on the most recent literature on the topic as well as on a compilation of data from studies conducted at the Center of Clinical Trials at Guarulhos University (São Paulo, Brazil) from 2002 to 2012.

Bacterial diversity in medication-related osteonecrosis of the jaw

OBJECTIVE

The aim was to study the association between microflora and medication-related osteonecrosis of the jaw (MRONJ) by using culture-independent molecular techniques to detect bacteria in necrotic bone lesions.

STUDY DESIGN

Included were 18 consecutive patients with MRONJ, 10 with osteoporosis and 8 cancer patients. Bone biopsies were retrieved from the center of the necrotic bone and from visually healthy bone, and 16 S rRNA gene fragments from bacterial DNA were amplified with polymerase chain reaction.

RESULTS

The study revealed a diversity of bacteria represented by 16 S rRNA sequences in all the necrotic bone samples and in 60% of the visually healthy bone. Eight dominating taxa groups were identified at the genus level: Porphyromonas, Lactobacillus, Tannerella, Prevotella, Actinomyces, Treponema, Streptococcus, and Fusobacterium.

CONCLUSIONS

The necrotic bone lesions contained mainly anaerobic bacteria, representative of periodontal microflora, suggesting that a periodontal infection in combination with antiresorptive treatment could initiate osteonecrosis.

On putative periodontal pathogens: an epidemiological perspective

The current understanding on the role of microbiology on periodontitis causation is reviewed. An appraisal of the literature reveals several issues that have limited the attempts to investigate candidate periodontal pathogens as causes of periodontitis and confirms that only limited epidemiological evidence is available. Several aspects of the contemporary understanding on causal inference are discussed with examples for periodontitis.

Early canine plaque biofilms: characterization of key bacterial interactions involved in initial colonization of enamel

Periodontal disease (PD) is a significant problem in dogs affecting between 44% and 63.6% of the population. The main etiological agent for PD is plaque, a microbial biofilm that colonizes teeth and causes inflammation of the gingiva. Understanding how this biofilm initiates on the tooth surface is of central importance in developing interventions against PD. Although the stages of plaque development on human teeth have been well characterized little is known about how canine plaque develops. Recent studies of the canine oral microbiome have revealed distinct differences between the canine and human oral environments and the bacterial communities they support, particularly with respect to healthy plaque. These differences mean knowledge about the nature of plaque formation in humans may not be directly translatable to dogs. The aim of this study was to identify the bacterial species important in the early stages of canine plaque formation in vivo and then use isolates of these species in a laboratory biofilm model to develop an understanding of the sequential processes which take place during the initial colonization of enamel. Supra-gingival plaque samples were collected from 12 dogs at 24 and 48 hour time points following a full mouth descale and polish. Pyrosequencing of the 16S rDNA identified 134 operational taxonomic units after statistical analysis. The species with the highest relative abundance were Bergeyella zoohelcum, Neisseria shayeganii and a Moraxella species. Streptococcal species, which tend to dominate early human plaque biofilms, had very low relative abundance. In vitro testing of biofilm formation identified five primary colonizer species, three of which belonged to the genus Neisseria. Using these pioneer bacteria as a starting point, viable two and three species communities were developed. Combining in vivo and in vitro data has led us to construct novel models of how the early canine plaque biofilm develops.

Subgingival microbiome in smokers and non-smokers in Korean chronic periodontitis patients

Smoking is a major environmental factor associated with periodontal diseases. However, we still have a very limited understanding of the relationship between smoking and subgingival microflora in the global population. Here, we investigated the composition of subgingival bacterial communities from the pooled plaque samples of smokers and non-smokers, 134 samples in each group, in Korean patients with moderate chronic periodontitis using 16S rRNA gene-based pyrosequencing. A total of 17,927 reads were analyzed and classified into 12 phyla, 126 genera, and 394 species. Differences in bacterial communities between smokers and non-smokers were examined at all phylogenetic levels. The genera Fusobacterium, Fretibacterium, Streptococcus, Veillonella, Corynebacterium, TM7, and Filifactor were abundant in smokers. On the other hand, Prevotella, Campylobacter, Aggregatibacter, Veillonellaceae GQ422718, Haemophilus, and Prevotellaceae were less abundant in smokers. Among species-level taxa occupying > 1% of whole subgingival microbiome of smokers, higher abundance (≥ 2.0-fold compared to non-smokers) of seven species or operational taxonomic units (OTUs) was found: Fusobacterium nucleatum, Neisseria sicca, Neisseria oralis, Corynebacterium matruchotii, Veillonella dispar, Filifactor alocis, and Fretibacterium AY349371. On the other hand, lower abundance of 11 species or OTUs was found in smokers: Neisseria elongata, six Prevotella species or OTUs, Fusobacterium canifelinum, Aggregatibacter AM420165, Selenomonas OTU, and Veillonellaceae GU470897. Species richness and evenness were similar between the groups whereas diversity was greater in smokers than non-smokers. Collectively, the results of the present study indicate that differences exist in the subgingival bacterial community between smoker and non-smoker patients with chronic moderate periodontitis in Korea, suggesting that cigarette smoking considerably affects subgingival bacterial ecology.

A cross-sectional survey of bacterial species in plaque from client owned dogs with healthy gingiva, gingivitis or mild periodontitis

Periodontal disease is the most widespread oral disease in dogs which if left untreated results in significant pain to the pet and loss of dentition. The objective of this study was to identify bacterial species in canine plaque that are significantly associated with health, gingivitis and mild periodontitis (<25% attachment loss). In this survey subgingival plaque samples were collected from 223 dogs with healthy gingiva, gingivitis and mild periodontitis with 72 to 77 samples per health status. DNA was extracted from the plaque samples and subjected to PCR amplification of the V1-V3 region of the 16S rDNA. Pyrosequencing of the PCR amplicons identified a total of 274 operational taxonomic units after bioinformatic and statistical analysis. Porphyromonas was the most abundant genus in all disease stages, particularly in health along with Moraxella and Bergeyella. Peptostreptococcus, Actinomyces, and Peptostreptococcaceae were the most abundant genera in mild periodontitis. Logistic regression analysis identified species from each of these genera that were significantly associated with health, gingivitis or mild periodontitis. Principal component analysis showed distinct community profiles in health and disease. The species identified show some similarities with health and periodontal disease in humans but also major differences. In contrast to human, healthy canine plaque was found to be dominated by Gram negative bacterial species whereas Gram positive anaerobic species predominate in disease. The scale of this study surpasses previously published research and enhances our understanding of the bacterial species present in canine subgingival plaque and their associations with health and early periodontal disease.

Molecular detection of Aggregatibacter actinomycetemcomitans on metallic brackets by the checkerboard DNA-DNA hybridization technique

INTRODUCTION

The purpose of this randomized clinical study was to evaluate the presence of the periodontal pathogen Aggregatibacter actinomycetemcomitans on metallic brackets and the effectiveness of a 0.12% chlorhexidine digluconate mouthwash in inhibiting this microorganism.

METHODS

The study involved 35 patients of both sexes having orthodontic treatment with fixed appliances between the ages of 14 and 22 years, randomized into 2 groups: experimental (n = 17) and control (n = 18). Two new metallic brackets were placed on the patients' premolars, and the subjects rinsed with a solution of 0.12% chlorhexidine digluconate or a placebo solution twice a week for 30 days. After that, the brackets were removed and underwent microbiologic analysis with the checkerboard DNA-DNA hybridization technique. Data were analyzed by using the Student t, Fisher exact, and Mann-Whitney tests at the significance level of 5%.

RESULTS

The results showed that A actinomycetemcomitans was present in all brackets from the subjects in the control group vs 83% of the subjects who rinsed with chlorhexidine digluconate (P <0.0001). There were also significantly lower levels of this species in the chlorhexidine digluconate group compared with the control group (P = 0.0003).

CONCLUSIONS

We concluded that 0.12% chlorhexidine digluconate rinsing, twice a week for 30 days during orthodontic treatment, is effective in reducing the presence and levels of A actinomycetemcomitans on metallic brackets.

Genome-wide association study of periodontal pathogen colonization

Pathological shifts of the human microbiome are characteristic of many diseases, including chronic periodontitis. To date, there is limited evidence on host genetic risk loci associated with periodontal pathogen colonization. We conducted a genome-wide association (GWA) study among 1,020 white participants of the Atherosclerosis Risk in Communities Study, whose periodontal diagnosis ranged from healthy to severe chronic periodontitis, and for whom "checkerboard" DNA-DNA hybridization quantification of 8 periodontal pathogens was performed. We examined 3 traits: "high red" and "high orange" bacterial complexes, and "high" Aggregatibacter actinomycetemcomitans (Aa) colonization. Genotyping was performed on the Affymetrix 6.0 platform. Imputation to 2.5 million markers was based on HapMap II-CEU, and a multiple-test correction was applied (genome-wide threshold of p < 5 × 10(-8)). We detected no genome-wide significant signals. However, 13 loci, including KCNK1, FBXO38, UHRF2, IL33, RUNX2, TRPS1, CAMTA1, and VAMP3, provided suggestive evidence (p < 5 × 10(-6)) of association. All associations reported for "red" and "orange" complex microbiota, but not for Aa, had the same effect direction in a second sample of 123 African-American participants. None of these polymorphisms was associated with periodontitis diagnosis. Investigations replicating these findings may lead to an improved understanding of the complex nature of host-microbiome interactions that characterizes states of health and disease.

Multilevel analysis of clinical parameters in chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results

AIM

Find the periodontal treatment that best maintained clinical results over time evaluated by changes in pocket depth (PD) and clinical attachment level (CAL).

METHODS

229 patients with chronic periodontitis from USA (n=134) and Sweden (n=95) were randomly assigned to eight groups receiving (1) scaling+root planing (SRP) alone or combined with (2) surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+local tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately after SRP. Plaque, gingival redness, bleeding on probing, suppuration, PD, and CAL were recorded at baseline and after 3, 6, 12, 18, and 24 months. Treatment effects were evaluated by linear multilevel regression and logistic multilevel regression models. We considered only data from sites with a baseline PD of at least 5 mm of 187 patients completing the study.

RESULTS

Surgically treated patients experienced most CAL loss. Adjunctive therapy including SURG was most effective in reducing PD. Combining SURG with AMOX, MET, and TET gave significant clinical benefits. Past and current smoking habits were significant predictors of deeper PD. Only current smoking was a significant predictor of CAL loss. Bleeding, accumulation of plaque, gingival redness, and suppuration were significant predictors of further CAL loss and deeper PD.

CONCLUSIONS

Both surgical and non-surgical therapies can be used to arrest chronic periodontitis. SURG+AMOX+MET+TET gave best maintenance of clinical results.

Can oral pathogens influence allergic disease?

The hygiene hypothesis contends that fewer opportunities for infections and microbial exposures have resulted in more widespread asthma and atopic disease. Consistent with that hypothesis, decreases in infectious oral diseases over the past half century have coincided with increases in the prevalence of asthma and other allergic diseases. This observation has led some researchers to speculate that exposures to oral bacteria, including pathogens associated with periodontal diseases, such as gingivitis and periodontitis, might play a protective role in the development of asthma and allergy. Colonization of the oral cavity with bacteria, including some species of periodontal pathogens, begins shortly after birth, and the detection of serum antibodies to oral pathogens in early childhood provides evidence of an early immune response to these bacteria. Current knowledge of the immune response to oral bacteria and the immunologic pathogenesis of periodontal diseases suggests biologically plausible mechanisms by which oral pathogens could influence the risk of allergic disease. However, studies investigating the association between oral pathogen exposures and allergic disease are few in number and limited by cross-sectional or case-control design, exclusion of young children, and use of surrogate measures of oral bacterial colonization. Additional studies, particularly well-designed case-control studies among very young children and prospective birth cohort studies, are needed.

Smoking and periodontal disease: discrimination of antibody responses to pathogenic and commensal oral bacteria

Smoking is an independent risk factor for the initiation, extent and severity of periodontal disease. This study examined the ability of the host immune system to discriminate commensal oral bacteria from pathogens at mucosal surfaces, i.e. oral cavity. Serum immunoglobulin (Ig)G antibody reactive with three pathogenic and five commensal oral bacteria in 301 current smokers (age range 21-66 years) were examined by enzyme-linked immunosorbent assay. Clinical features of periodontal health were used as measures of periodontitis. Antibody to the pathogens and salivary cotinine levels were related positively to disease severity; however, the antibody levels were best described by the clinical disease unrelated to the amount of smoking. The data showed a greater immune response to pathogens than commensals that was related specifically to disease extent, and most noted in black males. Significant correlations in individual patient responses to the pathogens and commensals were lost with an increasing extent of periodontitis and serum antibody to the pathogens. Antibody to Porphyromonas gingivalis was particularly distinct with respect to the discriminatory nature of the immune responses in recognizing the pathogens. Antibody responses to selected pathogenic and commensal oral microorganisms differed among racial groups and genders. The antibody response to the pathogens was related to disease severity. The level of antibody to the pathogens, and in particular P. gingivalis, was correlated with disease severity in black and male subsets of patients. The amount of smoking did not appear to impact directly serum antibody levels to these oral bacteria.

Short-term benefits of the adjunctive use of metronidazole plus amoxicillin in the microbial profile and in the clinical parameters of subjects with generalized aggressive periodontitis

AIM

The aim of this study was to evaluate the clinical and microbiological effects of scaling and root planing (SRP) alone or combined with metronidazole (MTZ) and amoxicillin (AMX) in the treatment of subjects with generalized aggressive periodontitis (GAgP).

MATERIALS AND METHODS

A double-blind, placebo-controlled, randomized clinical trial was conducted in 30 subjects receiving SRP alone or combined with MTZ (400 mg 3 x per day) and AMX (500 mg 3 x per day) for 14 days. Clinical and microbiological examinations were performed at baseline and 3 months post-SRP. Nine subgingival plaque samples per subject were analysed using checkerboard DNA-DNA hybridization.

RESULTS

Subjects receiving MTZ and AMX showed the greatest improvements in the mean full-mouth probing depth and clinical attachment level and at initially intermediate and deep sites. The most beneficial changes in the microbial profile were also observed in the MTZ+AMX group, which showed the lowest proportions of the red complex as well as a significant decrease in the proportions of the orange complex after treatment. The antibiotic therapy also reduced the levels of Aggregatibacter actinomycetemcomitans at initially deep sites.

CONCLUSION

Subjects with GAgP significantly benefit from the adjunctive use of MTZ and AMX. The short-term advantages are observed in the clinical and microbiological parameters.

Use of the DNA Checkerboard hybridization method for detection and quantitation of Candida species in oral microbiota

The DNA Checkerboard method enables the simultaneous identification of distinct microorganisms in a large number of samples and employs up to 45 whole genomic DNA probes to gram-negative and gram-positive bacterial species present in subgingival biofilms. Collectively, they account for 55%-60% of the bacteria in subgingival biofilms. In this study, we present the DNA Checkerboard hybridization as an alternative method for the detection and quantitation of Candida species in oral cavities. Our results reveal that DNA Checkerboard is sensitive enough and constitutes a powerful and appropriate method for detecting and quantifying Candida species found in the oral cavity.

Leptotrichia buccalis: A rare cause of bacteraemia in non-neutropenic patients

The anaerobic bacterium, Leptotrichia buccalis (Lb), belongs to the normal oral flora of humans and is seldom found in clinically significant specimens. However, on rare occasions, Lb has been isolated from blood cultures from patients with lesions of the oral mucosa, in particular from patients with neutropenia. Over a period of 6 months, Lb was isolated from blood cultures in our laboratory from 2 immunocompetent patients. The identification characteristics of Lb are described including the typical morphology at microscopy. Furthermore, we review the bacteraemic cases reported so far together with present knowledge of the pathogenicity and epidemiology of Lb.

Relation of body mass index, periodontitis and Tannerella forsythia

OBJECTIVE

To determine if there were differences in periodontal status and the composition of the subgingival microbiota in individuals who exhibited different body mass indices (BMI).

MATERIAL AND METHODS

One hundred and twenty-one periodontally healthy/gingivitis and 574 chronic periodontitis subjects had height and weight determined and were measured for probing pocket depth, clinical attachment level, bleeding on probing, gingival redness and presence of visible plaque. Subgingival plaque samples taken from each tooth were individually analysed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization.

RESULTS

Crude odds ratios (ORs) [95% confidence interval (CI)] of overweight and obese individuals exhibiting periodontitis were 3.1 (1.9-4.8) and 5.3 (2.8-9.5), respectively, when compared with subjects with normal BMI. Logistic regression analysis indicated an OR (95% CI) of 2.3 (1.2-4.5) for an obese subject to exhibit periodontitis after adjusting for age, gender and smoking status. Individuals <46.8 years (median age) were responsible for this association. Only Tannerella forsythia differed significantly in proportions among BMI groups and was significantly higher in obese periodontally healthy/gingivitis individuals.

CONCLUSION

The data suggest that an overgrowth of T. forsythia occurs in the subgingival biofilms of periodontally healthy, overweight and obese individuals that might put them at risk for initiation and progression of periodontitis.

The vaginal microflora in relation to gingivitis

BACKGROUND

Gingivitis has been linked to adverse pregnancy outcome (APO). Bacterial vaginosis (BV) has been associated with APO. We assessed if bacterial counts in BV is associated with gingivitis suggesting a systemic infectious susceptibilty.

METHODS

Vaginal samples were collected from 180 women (mean age 29.4 years, SD +/- 6.8, range: 18 to 46), and at least six months after delivery, and assessed by semi-quantitative DNA-DNA checkerboard hybridization assay (74 bacterial species). BV was defined by Gram stain (Nugent criteria). Gingivitis was defined as bleeding on probing at >or= 20% of tooth sites.

RESULTS

A Nugent score of 0-3 (normal vaginal microflora) was found in 83 women (46.1%), and a score of > 7 (BV) in 49 women (27.2%). Gingivitis was diagnosed in 114 women (63.3%). Women with a diagnosis of BV were more likely to have gingivitis (p = 0.01). Independent of gingival conditions, vaginal bacterial counts were higher (p < 0.001) for 38/74 species in BV+ in comparison to BV- women. Counts of four lactobacilli species were higher in BV- women (p < 0.001). Independent of BV diagnosis, women with gingivitis had higher counts of Prevotella bivia (p < 0.001), and Prevotella disiens (p < 0.001). P. bivia, P. disiens, M. curtisii and M. mulieris (all at the p < 0.01 level) were found at higher levels in the BV+/G+ group than in the BV+/G- group. The sum of bacterial load (74 species) was higher in the BV+/G+ group than in the BV+/G- group (p < 0.05). The highest odds ratio for the presence of bacteria in vaginal samples (> 1.0 x 104 cells) and a diagnosis of gingivitis was 3.9 for P. bivia (95% CI 1.5-5.7, p < 0.001) and 3.6 for P. disiens (95%CI: 1.8-7.5, p < 0.001), and a diagnosis of BV for P. bivia (odds ratio: 5.3, 95%CI: 2.6 to 10.4, p < 0.001) and P. disiens (odds ratio: 4.4, 95% CI: 2.2 to 8.8, p < 0.001).

CONCLUSION

Higher vaginal bacterial counts can be found in women with BV and gingivitis in comparison to women with BV but not gingivitis. P. bivia and P. disiens may be of specific significance in a relationship between vaginal and gingival infections.

Prevalence and distribution of principal periodontal pathogens worldwide

BACKGROUND

Detailed genetic analysis of bacteria has demonstrated an unanticipated genetic diversity within species, which often reveals evolutionary lineages that are disproportionately associated with infection. There is evidence that some evolutionary lineages of bacteria have adapted to particular ethnic groups.

AIM

This review analyzes to what extent observed differences in periodontal disease prevalence among ethnically or geographically distinct populations may be explained by restricted host adaptation of clones of principal periodontal pathogens.

RESULTS

Carriage rates of several putative periodontal pathogens and particular subsets of these species vary between ethnic groups. Few of these differences can, with the limited information available, be directly related to differences in periodontal disease prevalence. Asian populations are regularly colonized with Actinobacillus actinomycetemcomitans serotype c with questionable pathogenic potential. Conversely, the JP2 clone of A. actinomycetemcomitans has enhanced virulence and causes significantly higher prevalence of aggressive periodontitis in adolescents whose descent can be traced back to the Mediterranean and Western parts of Africa. Some genetically distinct types of Porphyromonas gingivalis are more associated with disease than others, but additional work is required to relate this to clinical differences.

CONCLUSIONS

Studies that take into account differences linked to the genetics of both patients and potential pathogens are likely to give better insight into the aetiology of periodontal diseases.

Differences in subgingival microflora of Korean and German periodontal patients

PURPOSE

The goal of this study was to characterize the microbiological profile in samples of subgingival plaque taken from periodontal patients with different ethnic origin.

METHODS

178 patients (n=90 from South Korea and n=88 from Germany; age: 45.4 +/- 10.4 years) were diagnosed with severe generalized periodontitis. In all patients the deepest pocket of each quadrant was sampled for subgingival plaque. The four samples per patient were pooled and subsequently analysed with a 16s-RNA-gene probe test.

RESULTS

Prevalence of Aggregatibacter actinomycetemcomitans was significantly higher in German patients (47.7%) compared to Korean patients (26.7%) (p < 0.01, chi(2)-test). For Tannerella forsythia and porphyromonas gingivalis, differences between Germans and Koreans were not as pronounced. A statistically significant difference could also be found for Treponema denticola (Germans: 95.5%, Koreans: 81.1%, p < 0.01, chi(2)-test). After logarithmic transformation, bacterial counts differed for all microorganisms under investigation between Germans and Koreans, even after using a General Linear Model/Analysis of Covariance (GLM/ANCOVA) to adjust for gender, age, smoking status, pocket probing depths (PPD) of sampled teeth, and gingival bleeding index (GBI).

CONCLUSION

Depending on their ethnic origin, the microbiological profile of pooled subgingival plaque sample seems to differ significantly between patients of Caucasian and Asian ethnic origin.

Profiling of root canal bacterial communities associated with chronic apical periodontitis from Brazilian and Norwegian subjects

The aim of this study was to compare the bacterial community profiles of the root canal microbiota associated with chronic apical periodontitis from Brazilian and Norwegian patients using the denaturing gradient gel electrophoresis (DGGE) and the ribosomal intergenic spacer analysis (RISA) approaches. DNA extracted from root canal samples was subjected to polymerase chain reaction using primers appropriate for further DGGE or RISA analysis. The resulting banding patterns representative of the bacterial community structures in samples from the two locations were compared. DGGE and RISA fingerprints showed a great interindividual variability in the bacterial community profiles, irrespective of the geographic location of the patient. However, similarities among the bacterial community DGGE profiles revealed the existence of a geography-related pattern.

The use of fluorescein for labeling genomic probes in the checkerboard DNA–DNA hybridization method

Molecular methods that permit the simultaneous detection and quantification of a large number of microbial species are currently employed in the evaluation of complex ecosystems. The checkerboard DNA-DNA hybridization technique enables the simultaneous identification of distinct bacterial species in a large number of dental samples. The original technique employed digoxigenin-labeled whole genomic DNA probes which were detected by chemiluminescence. In this study, we present an alternative protocol for labeling and detecting whole genomic DNA probes in the Checkerboard DNA-DNA hybridization method. Whole genomic DNA was extracted from five bacterial species and labeled with fluorescein. The fluorescein labeled whole genomic DNA probes were hybridized against whole genomic DNA or subgingival plaque samples in a checkerboard hybridization format, followed by chemiluminescent detection. Our results reveal that fluorescein is a viable and adequate alternative labeling reagent to be employed in the checkerboard DNA-DNA hybridization technique.

Diversity of the human gastrointestinal tract microbiota revisited

Since the early days of microbiology, more than a century ago, representatives of over 400 different microbial species have been isolated and fully characterized from human gastrointestinal samples. However, during the past decade molecular ecological studies based on ribosomal RNA (rRNA) sequences have revealed that cultivation has been able only to access a small fraction of the microbial diversity within the gastrointestinal tract. The increasing number of deposited rRNA sequences calls for the setting up a curated database that allows handling of the excessive degree of redundancy that threatens the usability of public databases. The integration of data from cultivation-based studies and molecular inventories of small subunit (SSU) rRNA diversity, presented here for the first time, provides a systematic framework of the microbial diversity in the human gastrointestinal tract of more than 1000 different species-level phylogenetic types (phylotypes). Such knowledge is essential for the design of high-throughput approaches such as phylogenetic DNA microarrays for the comprehensive analysis of gastrointestinal tract microbiota at multiple levels of taxonomic resolution. Development of such approaches is likely to be pivotal to generating novel insights in microbiota functionality in health and disease.

Occurrence of Periodontopathic and Superinfecting Bacteria in Chronic and Aggressive Periodontitis Subjects in a Colombian Population

BACKGROUND

Differences in the composition of subgingival microbiota in periodontitis have been observed in different geographic locations. Some of these microbial differences could have clinical significance. This study describes clinical parameters and the composition of the subgingival microbiota in chronic periodontitis (CP) and aggressive periodontitis (AgP) patients in a Colombian population.

METHODS

Clinical parameters (probing depth, clinical attachment level, bleeding on probing, and plaque index) and plaque samples from 68 CP, 12 AgP, and 30 periodontally healthy subjects were analyzed. Subgingival samples were processed using culture, biochemical tests, and polymerase chain reaction for the detection of periodontal and superinfecting pathogens. The analysis of variance, chi(2), and Kruskal-Wallis tests were used to evaluate differences between groups for clinical parameters and microbiologic composition (P <or=0.05).

RESULTS

Clinical parameters were significantly increased in CP and AgP patients compared to healthy subjects (P <0.001), but no differences were found between periodontitis groups. Porphyromonas gingivalis, Tannerella forsythensis, and Eikenella corrodens showed higher frequencies in AgP compared to CP and healthy subjects (P <0.05). Extension (localized and generalized) of the periodontal destruction had no effect on the composition of the subgingival microbiota. Gram-negative enteric rods were more frequent in AgP patients (P <0.01).

CONCLUSIONS

This study demonstrated a high prevalence of P. gingivalis, T. forsythensis, and E. corrodens in AgP patients. Gram-negative enteric rods were frequent in AgP and CP patients. Differences in the composition of subgingival microbiota in periodontitis patients need to be taken into account when considering the best therapeutic approach for each individual, including the use of antibiotics.

A three-year prospective study of adult subjects with gingivitis II: microbiological parameters

AIM

To investigate whether the clinical benefits obtained with a periodontal prevention programme in subjects with periodontal health or minimal disease were accompanied by beneficial changes in the subgingival microbiota.

MATERIAL AND METHODS

One hundred and twenty-four subjects completed the study. Subjects were clinically and microbiologically monitored at baseline, 1, 2 and 3 years. Subgingival plaque samples were taken from the mesiobuccal aspect of every tooth and were analysed for the levels of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples=13,477). The mean counts of each of the 40 test species were calculated for each subject at each time point. Significance of differences over time was sought using the Friedman test. p values were adjusted for multiple comparisons.

RESULTS

All clinical parameters, at the microbiologically sampled sites, improved over time. The clinical changes were accompanied by statistically significant decreases in the mean counts of 35 of the 40 test species. Major reductions occurred by year 2 for Actinomyces, Capnocytophaga, Campylobacter, Fusobacterium and Prevotella species. At year 3, there was a modest re-growth of the majority of the species.

CONCLUSIONS

The clinical improvements obtained through preventive measures were accompanied by a shift to a more host-compatible subgingival microbiota.

Bacterial community profiles of endodontic abscesses from Brazilian and USA subjects as compared by denaturing gradient gel electrophoresis analysis

This study compared the bacterial community profiles of the microbiota associated with acute apical abscesses from Brazilian and USA patients using denaturing gradient gel electrophoresis (DGGE). DNA was extracted from purulent exudate aspirates and part of the 16S rRNA gene was amplified by polymerase chain reaction and separated by DGGE. The resulting banding patterns, which were representative of the bacterial community structures in samples from the two locations, were then compared. Distinct DGGE banding patterns were observed from different samples. Ninety-nine bands with distinct positions in the gels were detected, of which 27 were found only in the USA samples and 13 were exclusive to Brazilian samples. Four of the 59 shared bands showed very discrepant findings with regard to prevalence in the two locations. Cluster analysis of DGGE banding profiles showed a great variability in the bacterial populations associated with teeth with abscesses regardless of the geographical location. Two big clusters, one for each location, were observed. Other clusters contained a mixture of samples from the two locations. The results of the present study demonstrated a great variability in the bacterial community profiles among samples. This indicates that the bacterial communities of abscesses are unique for each individual in terms of diversity. The composition of the microbiota in some samples showed a geography-related pattern. Furthermore, several bands were exclusive for each location and others were shared by the two locations and showed great differences in prevalence.

Hemorrhagic Necrotizing Splenitis in a Slaughter Pig Infected with Arcanobacterium Species

A 6-month-old barrow presented with lethargy, inappetence and dysstasia. At necropsy, multiple coalescing hemorrhagic foci were detected in the margins of the spleen. Gram-positive bacilli were isolated from the spleen, kidney, muscle and liver. Comparative 16S rDNA gene sequencing analysis of the isolates (TO16177) revealed that they would be the same species of unpublished Arcanobacterium species strain HJ57-14E (accession no. gi 18873551) (99.7% similarity based on a comparison of 675 bp). Histologic examination of the splenic tissue sections revealed extensive necrosis and inflammation, and gram-positive bacilli were discernible. Multifocal necrosis was also detected in the liver. Immunohistochemically, the isolates were cross-reacted with polyclonal antibodies against Arcanobacterium pyogenes and Actinomyces naeslundii, and the reaction was strong for the latter. Similar reactions were found in the suppurative lesions of the tonsil, and occasionally in the spleen and lymph nodes. The present results indicate that the unpublished Arcanobacterium species induced multiple organ failure accompanied by acute hemorrhagic necrotizing splenitis in this growing-finishing pig.

Association of Eubacterium nodatum and Treponema denticola with human periodontitis lesions

BACKGROUND

The purpose of the present investigation was to compare the levels, proportions and percentage of sites colonized by 40 bacterial species in subgingival plaque samples from periodontally healthy subjects and patients with chronic periodontitis to seek possible pathogens other than the consensus pathogens Porphyromonas gingivalis and Tannerella forsythia.

METHOD

Subgingival plaque samples were taken from the mesial aspect of each tooth in 635 subjects with chronic periodontitis and 189 periodontally healthy subjects. The samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples = 21,832). Mean counts, % DNA probe counts and percentage of sites colonized at >10(5) were determined for each species in each subject and then averaged in each clinical group. Significance of difference between groups was determined using the Mann-Whitney test. Association between combinations of species and periodontal status was examined by stepwise logistic regression analysis. Analyses were repeated using a subset of subjects from both clinical groups who had proportions of P. gingivalis plus T. forsythia less than the median (4.42%) found in periodontally healthy subjects. All analyses were adjusted for multiple comparisons.

RESULTS

For the 824 subjects the consensus pathogens P. gingivalis and T. forsythia as well as Eubacterium nodatum and Treponema denticola had significantly higher mean counts, proportions and percentage of sites colonized in samples from subjects with periodontitis than from periodontally healthy subjects. There were significantly more Capnocytophaga gingivalis, Streptococcus gordonii and Veillonella parvula in periodontally healthy subjects. E. nodatum, T. denticola, Streptococcus oralis, Streptococcus intermedius, Fusobacterium nucleatum ssp. vincentii all had higher counts and proportions in diseased than healthy subjects who had low proportions of P. gingivalis and T. forsythia. Logistic regression analysis indicated that the same species groups were associated with disease status after adjusting for the proportions of the other species.

CONCLUSIONS

This investigation confirmed the strong association of P. gingivalis and T. forsythia with chronic periodontitis and emphasized a strong association of E. nodatum and T. denticola with periodontitis whether in the presence or absence of high levels of the consensus pathogens. Other species, including S. oralis, Eikenella corrodens, S. intermedius and F. nucleatum ssp. vincentii, were associated with disease when P. gingivalis and T. forsythia were present in low proportions.

Influence of Combinations of Bacteria on the Levels of Prostaglandin E2, Interleukin-1β, and Granulocyte Elastase in Gingival Crevicular Fluid and on the Severity of Periodontal Disease

BACKGROUND

The aim of this study was to investigate the simultaneous presence of periodontal microbiota on inflammatory markers in gingival crevicular fluid from individuals with periodontal diseases.

METHODS

A total of 82 individuals with periodontal disease (mean age: 54.3 +/- 3.0 years) and 31 periodontally healthy individuals (mean age: 53.2 +/- 3.0 years) were randomly chosen and underwent clinical oral examinations in 2003 with the determination of the dental plaque index (PI), gingival index (GI), and periodontal probing depth (PD). The simultaneous presence of polymerase chain reaction (PCR)-assessed periodontal bacteria, levels of prostaglandin E(2) (PGE(2)), granulocyte elastase, interleukin 1-beta (IL-1beta), and total protein concentration were determined from the pockets. Marginal bone height percent was measured on x-rays. Analysis of variance and chi(2) tests were used to analyze the results.

RESULTS

In sites with Tannerella forsythensis, levels of PGE(2) (pg/site), granulocyte elastase (monoclonal antibodies (mAbs)/site), and total protein (mg/ml) were significantly higher than in sites without T. forsythensis (P <0.05, P <0.01, and P <0.05, respectively). Those with periodontal disease with simultaneous presence of T. forsythensis and Porphyromonas gingivalis, or T. forsythensis and Prevotella nigrescens, showed significantly higher PI and GI, deeper PD, more loss of attachment, and more release of PGE(2) and granulocyte elastase than did periodontitis patients without these bacteria.

CONCLUSION

The simultaneous presence of T. forsythensis and P. gingivalis, or T. forsythensis and P. nigrescens, seemed to promote the release of subgingival inflammatory mediators and seemed to be associated with more severe periodontal disease.