Intra-familial transmission and distribution of Prevotella intermedia and Prevotella nigrescens

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.

Microbiomics: Were we all wrong before?

Periodontal microbiology has historically been based on an "us against them" paradigm, one that focuses mainly on identifying microbes and viruses that cause disease. However, such a bottom-up approach limits our appreciation of the incredible diversity of this ecosystem and the essential ways in which microbial interactions contribute to health and homeostasis of the subgingival niche. Microbiomics-the science of collectively characterizing and quantifying molecules responsible for the structure, function, and dynamics of a microbial community-has enabled us to study these communities in their natural habitat, thereby revolutionizing our knowledge of host-associated microbes and reconceptualizing our definition of "human." When this systems-biology approach is combined with ecologic principles, it explicates the complex relationship that exist between microbiota and between them and us, the human. In this volume of Periodontology 2000, a group of 12 female scientists take the lead in investigating how metagenomics, genomics, metatranscriptomics, proteomics, metaproteomics, and metabolomics have achieved the following: (a) widened our view of the periodontal microbiome; (b) expanded our understanding of the evolution of the human oral microbiome; (c) shone a light on not just bacteria, but also other prokaryotic and eukaryotic members of the community; (d) elucidated the effects of anthropogenic behavior and systemic diseases on shaping these communities; and (e) influenced traditional patterns of periodontal therapeutics.

Clinical and Microbiological Evaluation of the Periodontal Status of Children with Unilateral Complete Cleft Lip and Palate

Objective

To compare periodontal conditions in children with and without cleft.

Design

Clinical examinations and microbiological analysis of 57 selected children, including 30 with unilateral complete cleft lip and palate (experimental group) and 27 without clefts (control group).

Setting

Hospital of Rehabilitation of Craniofacial Anomalies (HRCA) in Bauru, Sao Paulo, Brazil.

Patients, Participants

All children examined were healthy and between the ages of 5 and 6 years.

Results

The mean plaque index (PI) in the experimental group was higher (1.82 ± 0.3) than in the control group (1.63 ± 0.38), although this difference was not statistically significant. The mean gingival index (GI) in the experimental group (1.82 ± 0.38) was found to be significantly higher (p < .05) than that of the control group (0.79 ± 0.33). The cleft area in the experimental group, with a mean PI of 2.04 ± 0.58 and mean GI of 1.11 ± 0.26, compared with the posterior area, with a mean PI of 1.74 ± 0.37 and mean GI of 1.04 ± 0.26, showed a statistically significant difference only in the PI. Most of the children in both experimental and control groups presented a moderate PI degree (73.33% and 81.48%, respectively) and a high prevalence of mild gingivitis (53.33% and 70.37%, respectively). Analysis of the organisms showed that Prevotella nigrescens was detected in 16.67% of the experimental group and 11.11% of the control, whereas Porphyromonas gingivalis and Treponema denticola were not detected.

Conclusion

Children with clefts showed greater gingival inflammation, despite the same amount of plaque and prevalence of microorganisms.

Ubiquitination in Periodontal Disease: A Review

Periodontal disease (periodontitis) is a chronic inflammatory condition initiated by microbial infection that leads to gingival tissue destruction and alveolar bone resorption. The periodontal tissue's response to dental plaque is characterized by the accumulation of polymorphonuclear leukocytes, macrophages, and lymphocytes, all of which release inflammatory mediators and cytokines to orchestrate the immunopathogenesis of periodontal disease. Ubiquitination is achieved by a mechanism that involves a number of factors, including an ubiquitin-activating enzyme, ubiquitin-conjugating enzyme, and ubiquitin-protein ligase. Ubiquitination is a post-translational modification restricted to eukaryotes that are involved in essential host processes. The ubiquitin system has been implicated in the immune response, development, and programmed cell death. Increasing numbers of recent reports have provided evidence that many approaches are delivering promising reports for discovering the relationship between ubiquitination and periodontal disease. The scope of this review was to investigate recent progress in the discovery of ubiquitinated protein in diseased periodontium and to discuss the ubiquitination process in periodontal diseases.

A randomised clinical study to determine the effect of a toothpaste containing enzymes and proteins on plaque oral microbiome ecology

The numerous species that make up the oral microbiome are now understood to play a key role in establishment and maintenance of oral health. The ability to taxonomically identify community members at the species level is important to elucidating its diversity and association to health and disease. We report the overall ecological effects of using a toothpaste containing enzymes and proteins compared to a control toothpaste on the plaque microbiome. The results reported here demonstrate that a toothpaste containing enzymes and proteins can augment natural salivary defences to promote an overall community shift resulting in an increase in bacteria associated with gum health and a concomitant decrease in those associated with periodontal disease. Statistical analysis shows significant increases in 12 taxa associated with gum health including Neisseria spp. and a significant decrease in 10 taxa associated with periodontal disease including Treponema spp. The results demonstrate that a toothpaste containing enzymes and proteins can significantly shift the ecology of the oral microbiome (at species level) resulting in a community with a stronger association to health.

Mouthguards: does the indigenous microbiome play a role in maintaining oral health?

The existence of symbiotic relationships between bacteria and their hosts in various ecosystems have long been known to science. The human body also hosts vast numbers of bacteria in several habitats. Emerging evidence from the gastro-intestinal tract, genito-urinary tract and respiratory indicates that there are several health benefits to hosting a complex and diverse microbial community. Bacteria colonize the oral cavity within a few minutes after birth and form stable communities. Our knowledge of the oral microbiome has expanded exponentially with development of novel exploratory methods that allow us to examine diversity, structure, function, and topography without the need to cultivate the individual components of the biofilm. The purpose of this perspective, therefore, is to examine the strength of current evidence supporting a role for the oral microbiome in maintaining oral health. While several lines of evidence are emerging to suggest that indigenous oral microbiota may have a role in immune education and preventing pathogen expansion, much more work is needed to definitively establish whether oral bacteria do indeed contribute to sustaining oral health, and if so, the mechanisms underlying this role.

Age-dependent changes in Porphyromonas gingivalis and Prevotella species/phylotypes in healthy gingiva and inflamed/diseased sub-gingival sites

OBJECTIVES

Early colonisation of oral surfaces by periodontal pathogens presents a significant risk factor for subsequent development of destructive disease affecting tissues that support the dentition. The aims of the present study were to establish the age-dependent relationship between sub-gingival profiles of 22 Prevotella species/phylotypes in children, adolescents and adults from an isolated Aboriginal community and, further, to use this information to identify Prevotella species that could serve as microbial risk indicators.

MATERIALS AND METHODS

DNA isolated from sub-gingival plaque samples (three healthy sites and three inflamed/diseased sites) from adults, adolescents and children was screened for Porphyromonas gingivalis load and 22 Prevotella species/phylotypes by species-specific PCR.

RESULTS

A noticeable feature in adolescents was the marked increase in colonisation by P. gingivalis across all test sites. The mean number of Prevotella species/phylotypes colonising inflamed/diseased sub-gingival sites increased with age. Progressive partitioning of selected Prevotella species/phylotypes to healthy or inflamed/diseased sites was evident. Prevalence of Prevotella intermedia, Prevotella oral clone P4PB_24 and Prevotella oris increased significantly with age in diseased sites. Similarly, significant age-dependent increase in colonisation of healthy as well as inflamed/diseased sub-gingival sites was apparent for Prevotella oralis, Prevotella multiformis, Prevotella denticola, Prevotella strain P4P_53 and Prevotella oral clone BR014.

CONCLUSION

Early colonisation of children by P. gingivalis, P. intermedia and Prevotella oral clone P4PB_24 provides indication of risk for subsequent development of periodontal disease.

CLINICAL RELEVANCE

In the present study, the complexity of Prevotella species within gingival sites is explored as a basis for evaluating contribution of Prevotella species to disease.

Anti-inflammatory, Antioxidant and Antimicrobial Effects of Artemisinin Extracts from Artemisia annua L

The anti-inflammatory, antioxidant, and antimicrobial properties of artemisinin derived from water, methanol, ethanol, or acetone extracts of Artemisia annua L. were evaluated. All 4 artemisinin-containing extracts had anti-inflammatory effects. Of these, the acetone extract had the greatest inhibitory effect on lipopolysaccharide-induced nitric oxide (NO), prostaglandin E₂ (PGE₂), and proinflammatory cytokine (IL-1β , IL-6, and IL-10) production. Antioxidant activity evaluations revealed that the ethanol extract had the highest free radical scavenging activity, (91.0±3.2%), similar to α-tocopherol (99.9%). The extracts had antimicrobial activity against the periodontopathic microorganisms Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum subsp. animalis, Fusobacterium nucleatum subsp. polymorphum, and Prevotella intermedia. This study shows that Artemisia annua L. extracts contain anti-inflammatory, antioxidant, and antimicrobial substances and should be considered for use in pharmaceutical products for the treatment of dental diseases.

The identification of genes specific to Prevotella intermedia and Prevotella nigrescens using genomic subtractive hybridization

Prevotella intermedia and Prevotella nigrescens, which are often isolated from periodontal sites, were once considered two different genotypes of P. intermedia. Although the genomic sequence of P. intermedia was determined recently, little is known about the genetic differences between P. intermedia and P. nigrescens. The subtractive hybridization technique is a powerful method for generating a set of DNA fragments differing between two closely related bacterial strains or species. We used subtractive hybridization to identify the DNA regions specific to P. intermedia ATCC 25611 and P. nigrescens ATCC 25261. Using this method, four P. intermedia ATCC 25611-specific and three P. nigrescens ATCC 25261-specific regions were determined. From the species-specific regions, insertion sequence (IS) elements were isolated for P. intermedia. IS elements play an important role in the pathogenicity of bacteria. For the P. intermedia-specific regions, the genes adenine-specific DNA-methyltransferase and 8-amino-7-oxononanoate synthase were isolated. The P. nigrescens-specific region contained a Flavobacterium psychrophilum SprA homologue, a cell-surface protein involved in gliding motility, Prevotella melaninogenica ATCC 25845 glutathione peroxide, and Porphyromonas gingivalis ATCC 33277 leucyl-tRNA synthetase. The results demonstrate that the subtractive hybridization technique was useful for distinguishing between the two closely related species. Furthermore, this technique will contribute to our understanding of the virulence of these species.

The transmission of BANA-positive periodontal bacterial species from caregivers to children

BACKGROUND

The purpose of the authors' study was to use the N-benzoyl-DL-arginine-2-naphthy-lamide (BANA) test (BANAMet LLC, Ann Arbor, Mich.) to obtain information regarding the prevalence of an enzyme unique to certain periodontal pathogens in plaque samples of children, as well as the potential transmission of these pathogens from caregivers to children.

METHODS

The authors tested 218 subjects (3 to 10 years old) and 195 care-givers at four pediatric dentistry clinics in Taipei, Taiwan.

RESULTS

Forty-four percent of the children had at least one plaque sample that tested positive and/or weakly positive. Positive results were more frequent in the mixed dentition, as well as in children with gingivitis (P < .001). A logistic regression model showed that if the BANA test results for the care-giver were positive, the odds of the child's also having positive test results were 55 times greater (P < .001; confidence interval [CI] = 14 to 224) than those for a child whose caregiver had negative BANA test results. Other predictors were the presence of a mixed dentition (P < .001; odds ratio [OR] = 11; CI = 3.5 to 33.5) and the children's papillary bleeding scores (P < .001, OR = 3.1, CI = 2.0 to 4.7).

CONCLUSION

The BANA test results were positive for almost one-half of the children. A positive reaction was associated with gingivitis, a mixed dentition, a BANA-positive caregiver or a caregiver with a history of periodontal disease in the family.

CLINICAL IMPLICATIONS

The authors propose an anaerobic periodontal infection risk model in which children with a mixed dentition who have gingivitis and a caregiver with a history of periodontal disease would undergo the BANA test.

Distribution of 10 periodontal bacteria in saliva samples from Japanese children and their mothers

OBJECTIVE

We analyzed the distribution of 10 periodontal bacteria species (Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia, Prevotella nigrescens, Campylobacter rectus, Eikenella corrodens, Actinobacillus actinomycetemcomitans, Capnocytophaga ochracea, Capnocytophaga sputigena, and Treponema denticola) in children, and then compared their distribution in those children and their mothers, with special attention given to three of the species known as the red complex (P. gingivalis, T. forsythensis, and T. denticola) whose presence has been shown to be associated with conditions related to periodontal diseases.

METHODS

One hundred thirteen pairs of children and their mothers were randomly selected from patients treated at the Pedodontic Clinic of Osaka University Dental Hospital. Saliva samples were taken at the second visit prior to receiving professional tooth brushing instruction. Genomic DNA was extracted from each saliva sample, followed by a polymerase chain reaction assay with species-specific sets of primers.

RESULTS

A. actinomycetemcomitans was the most frequently detected species in the mothers, followed by C. sputigena, P. gingivalis, and T. forsythensis, while C. sputigena had the highest detection rate, followed by A. actinomycetemcomitans and T. denticola in the children. The detection rate of the red complex species in children whose mothers possessed the same species was significantly higher than in those whose mothers did not possess them.

CONCLUSIONS

Our results indicate a correlation between the presence of periodontal bacteria in children and their mothers, while the presence of red complex bacteria in children was highly associated with that in their mothers.

Use of the genomic subtractive hybridization technique to develop a real-time PCR assay for quantitative detection of Prevotella spp. in oral biofilm samples

Genomic subtractive hybridization was used to design Prevotella nigrescens-specific primers and TaqMan probes. Based on this technique, a TaqMan real-time PCR assay was developed for quantifying four oral black-pigmented Prevotella species. The combination of real-time PCR and genomic subtractive hybridization is useful for preparing species-specific primer-probe sets for closely related species.

Effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise ultrasonic debridement

BACKGROUND

The aim of this randomized controlled clinical trial was to determine the effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise therapy.

MATERIAL AND METHODS

Thirty-six subjects with chronic periodontitis, were randomly allocated to three groups--quadrant-wise ultrasonic debridement, single-visit full-mouth ultrasonic debridement with povidone iodine and single-visit full-mouth ultrasonic debridement with water. Whole-mouth plaque, bleeding on probing (BOP), pocket depth and attachment level were recorded before treatment and 1, 3 and 6 months post-treatment. Plaque and saliva samples were collected for microbiological analysis.

RESULTS

After treatment, all groups showed significant improvement in clinical parameters. Full-mouth treatments resulted in similar improvements in full-mouth mean plaque percentage, probing pocket depth and probing attachment level as conventional therapy. When data were analysed based on pocket depth and tooth type, there was no difference between groups in probing depth reduction or attachment gains. The full-mouth groups demonstrated greater reduction in BOP% and number of pockets > or =5 mm and the total treatment time was significantly shorter. The detection frequencies of periodontal pathogens in plaque and saliva showed slight changes with no difference between groups.

CONCLUSION

Single-visit full-mouth mechanical debridement may have limited additional benefits over quadrant-wise therapy in the treatment of periodontitis, but can be completed in a shorter time.

Intra-familial distribution of nine putative periodontopathogens in dental plaque samples analyzed by PCR

It is of great importance to understand the distribution of periodontopathogens within family members when considering the risk of periodontitis in children. The purpose of this study was to investigate the distribution of periodontopathogens among family members. We used the polymerase chain reaction method to test 4,8, and 7 probands with healthy gingiva, gingivitis, and periodontitis, respectively, and their 60 immediate family members. Plaque samples were collected from all erupted teeth sites using a sterile toothbrush. In 161 of the 165 positive cases, if a child harbored one of the periodontopathogens then at least one of the parents was also positive for the same bacterium. The prevalence of parent-child co-infection was 42.9% for Actinobacillus actinomycetemcomitans, 21.4% for Porphyromonas gingivalis, 29.2% for Treponema denticola, 59.5% for Tannerella forsythensis (Bacteroides forsythus) and 16.7% for Prevotella intermedia. Our results indicate that parents could be an important source of periodontopathogens for the colonization that occurs in their children.

Similarity of the oral microbiota of pre-school children with that of their caregivers in a population-based study

This study evaluated the similarity between the oral microbiota of young children and that of their adult caregivers. Oral samples from children (174 dentate and 18 pre-dentate) aged 6-36 months and their caregivers in Saipan were assayed using a DNA probe assay. Many species including Streptococcus mutans, Streptococcus sobrinus, Actinomyces species, Campylobacter rectus, Fusobacterium nucleatum, Prevotella intermedia, and Porphyromonas gingivalis were detected in dentate and pre-dentate children, whereas Bacteroides forsythus was detected only in dentate children. A higher percentage of children were positive for the detection of an individual species if the caregiver was also positive. There were significant relative risks of species detection between dentate children and their caregivers. By logistic regression, there were significant positive associations between species detection in caregiver and in child, but not between species detection and child age or maternal education level. In conclusion, dental pathogens were detected in young, including pre-dentate, children. The microbial profiles of children were strongly associated with the microbiota of their caregivers.

Periodontopathogens in the saliva and subgingival dental plaque of a group of mothers

The aim of this study was to assess the periodontal condition and the presence of putative periodontal pathogens in 30 Brazilian mothers, aging 21-40 years (28.4 4.49 years), and in their children, aging 5-6 years, since mothers can be a source of pathogens and, thus, influence their children's bacteriological and clinical condition. Besides assessing the plaque index (PI), gingival index (GI) and pocket probing depth (PD), the survey analyzed four subgingival dental plaque samples from mothers and children, as well as a sample of stimulated saliva from mothers. Those samples were analyzed by means of the slot immunoblot (SIB) technique, in order to determine the presence of Actinobacillus actinomycetemcomitans (Aa), Prevotella nigrescens (Pn), Porphyromonas gingivalis (Pg) and Treponema denticola (Td). The mean values and standard deviations of the evaluated clinical variables for mothers and children were, respectively: 1.86 0.67 and 1.64 0.68 for PI, and 1.24 0.67 and 0.82 0.37, for GI. Only for mothers, the total PD was 1.81 0.69 mm, and the PD of four sites was 4.03 1.40 mm. The Wilcoxon test revealed significant difference (p < 0.05) between mothers and their children only as to GI. The most prevalent bacteria in mothers were, in decreasing order: Aa, Pn, Pg and Td. The children presented patterns of oral hygiene and bacterial profiles similar to those of their mothers, in spite of the fact that most of them did not present enough subgingival plaque for testing. The comparison between mothers' subgingival dental plaque and saliva samples revealed statistically significant differences (p < 0.05) for all bacteria, with greater positivity and scores in the saliva, which demonstrates that it is an indicator of oral colonization and can work as a vehicle for the transmission of periodontopathogens from mothers to their children.

The effect of shared genetic and environmental factors on periodontal disease parameters in untreated adult siblings in Guatemala

BACKGROUND

Increasing evidence supports the role of genetic factors in susceptibility to infectious diseases, including chronic periodontitis. The role of genetic factors in phenotypic expression can be estimated from the degree of resemblance between relatives, as compared with that of unrelated members of a population. Heritability is an estimate of the proportion of total phenotypic variation of a quantitative trait, which is attributable to genetic factors, and is based on the variance within versus between family members. The aim of this study was to determine whether there is a familial basis for periodontal disease status in an untreated population in Guatemala using heritability estimates as a measure of familial clustering of disease.

METHODS

One-hundred and thirteen adult subjects (including both siblings and spouse pairs), age range 35 to 60 years, participated in this study. Full-mouth periodontal examinations were performed and heritability estimates were calculated for mean plaque score, mean gingival index (GI), probing depth (PD), and clinical attachment level (CAL). Intraclass correlation coefficients (ICCs) were calculated using the same parameters for spouses to determine whether a common family environment in adulthood plays a role in disease expression.

RESULTS

Only in the case of mean plaque score and mean recession score were heritability estimates significantly above zero at alpha = 0.05. For spouse pairs, mean GI score, mean PD, and percentage of sites of PD > or = 5 mm showed a statistically significant ICC.

CONCLUSIONS

These results lead us to reject the hypothesis that there is substantial heritability for periodontal disease expression in this population. This may be due to an underlying lack of genetic variation within this sample or may indicate that, compared with the role of environmental factors, the genetic contribution to periodontal disease phenotypes is relatively minor.

Direct quantitative differentiation between Prevotella intermedia and Prevotella nigrescens in clinical specimens

This paper describes a quantitative fluorescent in situ hybridization (FISH) assay for the differential identification of Prevotella intermedia and Prevotella nigrescens in clinical samples, and compares its performance with less discriminatory culture and quantitative immunofluorescence (IF) assays. Fluorescence-labelled oligonucleotide probes directed to specific 16S rRNA sequences of P. intermedia, P. nigrescens, Prevotella pallens and Prevotella denticola were hybridized under stringent conditions with cultured reference strains or plaque samples from deep periodontal pockets. Probe specificity was defined with strains from multiple oral Prevotella species. The lower detection level of the assays was approximately 3x10(3) target cells per ml of plaque-sample suspension. P. intermedia, P. nigrescens, P. pallens and P. denticola were detected in plaques with prevalences of 69, 67, 0 and 28%, respectively. On average, 3.9 x 10(6) P. intermedia, 3.1 x 10(6) P. nigrescens and 5.6 x 10(5) P. denticola cells were counted per positive sample. All three species were found almost exclusively in dense mixed aggregates. Quantitative FISH data agreed satisfactorily with corresponding IF data (r=0.711). Both FISH and IF enumerations of the sum of P. intermedia and P. nigrescens markedly exceeded the c.f.u. counts of black-pigmented colonies in Porphyromonas gingivalis-free cultured subgingival plaques. The results demonstrate the validity of this new assay. Unlike established IF, culture, PCR or checkerboard DNA hybridization assays, this FISH assay differentiates quantitatively between P. intermedia and P. nigrescens, provides visual accuracy control, and offers insights into the spatial distribution of the target cells within a clinical sample.

Distribution of the tetracycline resistance determinant tetQ gene in oral isolates of black-pigmented anaerobes in Japan

We investigated the distribution of tetracycline resistance determinant tetQ in oral black-pigmented anaerobes using a polymerase chain reaction (PCR) METHOD: A total of 185 healthy subjects were divided into 3 groups based on subject age: young (6 to 10 years, n=58), middle (11 to 40 years, n=96), and elder (exactly 70 years, n=31). The prevalence of black-pigmented anaerobes in the gingival sulcus among these groups was 29.3%, 28.2%, and 64.5%, respectively. The prevalence of Prevotella nigrescens among these groups was 22.4%, 15.6%, and 32.3%, respectively, whereas the prevalence of Prevotella intermedia was 1.7%, 4.2%, and 35.5%, respectively. Porphyromonas gingivalis was found only in the elder group (16.1%). The prevalence of the tetQ gene in the black-pigmented anaerobes-positive subjects was almost the same among the 3 groups (approximately 30%). The tetQ gene was found in 27.5% (46 of 167) of P. nigrescens isolates, whereas it was found in only 6.4% (3 of 47) of P. intermedia isolates and in none of the 19 P. gingivalis isolates. Restriction endonuclease digestion patterns of the PCR products revealed 83.6% of 49 tetQ-positive isolates were of subtype A2H2 (AluI type 2, HpaII type 2).

Occurrence of Prevotella intermedia and Prevotella nigrescens in relation to gingivitis and gingival health

AIM

The occurrence of Prevotella intermedia (Pi) and Prevotella nigrescens (Pn) in relation to natural gingivitis, gingival health and 14-day experimental gingivitis was investigated in 25 non-dental students.

MATERIALS AND METHODS

Samples were taken from the dorsum of the tongue, the tonsils (or tonsillar area), and the supra- and subgingival plaque.

RESULTS

The microbiological results show that 73% of the samples were positive for the bacterial species presumed to be Pi and/or Pn. In natural gingivitis, gingival health and in experimental gingivitis 25, 23 and 25 subjects were found to be positive for Pi and/or Pn, respectively. The results of the 889 isolates that were successfully purified and differentiated, show that almost all subjects were colonized with Pn whereas approximately half of the study population harboured Pi. These 2 species were isolated from both dental plaque and mucosal sites and were found to colonize the oral cavity simultaneously.

CONCLUSION

In natural gingivitis, at the start and after 14 days of experimental gingivitis, Pn was the predominant micro-organism.

Genotypic heterogeneity of Streptococcus oralis and distinct aciduric subpopulations in human dental plaque

The genotypic heterogeneity of Streptococcus oralis isolated from the oral cavity was investigated using repetitive extragenic palindromic PCR. Unrelated subjects harbored unique genotypes, with numerous genotypes being isolated from an individual. S. oralis is the predominant aciduric bacterium isolated from noncarious tooth sites. Genotypic comparison of the aciduric populations isolated at pH 5.2 with those isolated from mitis-salivarius agar (MSA) (pH 7.0) indicated that the aciduric populations were genotypically distinct in the majority of subjects (chi(2) = 13.09; P = 0.0031). Neither the aciduric nor the MSA-isolated strains were stable, with no strains isolated at baseline being isolated 4 or 12 weeks later in the majority of subjects. The basis of this instability is unknown but is similar to that reported for Streptococcus mitis. Examination of S. oralis strains isolated from cohabiting couples demonstrated that in three of five couples, genotypically identical strains were isolated from both partners and this was confirmed by using Salmonella enteritidis repetitive element PCR and enterobacterial PCR typing. These data provide further evidence of the physiological and genotypic heterogeneity of non-mutans streptococci. The demonstration of distinct aciduric populations of S. oralis implies that the role of these and other non-mutans streptococci in the caries process requires reevaluation.

Genetic heterogeneity in Prevotella intermedia, Prevotella nigrescens, Prevotella corporis and related species isolated from oral and nonoral sites

Prevotella intermedia (43 isolates), Prevotella nigrescens (55) and Prevotella corporis (8) from oral and nonoral sites were distinguished by species-specific DNA fragments, after hybridization of DNA fragments with ribosomal RNA (ribotyping). Eight strains previously identified as P. intermedia did not have these specific fragments. P. nigrescens, P. intermedia and P. corporis formed separate clusters in dendrograms constructed using clustering with an unweighted pair group method with arithmetic averages of similarity values derived from ribotype patterns, with 10 subclusters in P. intermedia isolates and 26 in P. nigrescens. Nine groups of P. intermedia isolates and 6 of P. nigrescens shared identical patterns. Specific ribotypes or species were not associated with particular diseases when all isolates were analyzed. However, results from organisms isolated by one laboratory using consistent clinical reporting indicated that P. intermedia was associated with more severe forms of periodontitis and P. nigrescens with mild to moderate disease.

Development of oral bacterial flora in young children

The intimate relationship with bacteria is a fundamental factor in the health status of an individual. After birth infants are exposed to continuous person-to-person and environmental contacts with microbes, and the development of the indigenous microflora begins on the surfaces of the human body. In a developing ecosystem microbial colonization may easily occur because of the still inadequate host response. Adhesion is the initial event in the colonization of bacteria. In the mouth, only mucosal surfaces are available during the first months of life. After teeth emerge, the number of attachment sites and potential niches increases significantly. Bacteria adhere not only to oral surfaces but also to each other, forming multigeneric communities where specific partner relationships influence their composition and stability. Viridans streptococci and a strictly anaerobic species, Fusobacterium nucleatum, are of interest in this context. The oral colonization pattern differs between individuals already in infancy; variable bacterial load in saliva of attendants and other close contacts and the frequency of this bacterial exposure may partly account for individual differences. In addition, the exposure of an infant to antibiotics affects the quality of colonizing bacteria. This article presents an overview of the age-related acquisition of oral bacteria and the role of the indigenous oral microflora in health and disease.

Intrafamilial Transmission of Black-pigmented, Putative Periodontal Pathogens

Porphyromonas gingivalis and Prevotella intermedia are black-pigmented, putative periodontopathogenic bacteria considered to cause some forms of periodontal disease. Porphyromonas gingivalis and P. intermedia can be transmitted between humans and produce periodontal disease in susceptible hosts. In this article, studies using molecular typing methods for determining the transmission of black-pigmented, putative periodontopathogens between family members are reviewed. As individuals living close to each other are more prone to transmit bacteria, the studies on transmission of periodontopathogens have been performed on family members. It has been shown that black-pigmented bacteria are not only transferred between spouses but also between parents and child. Since only a limited number of studies have been done, longitudinal and controlled studies should be carried out to elucidate further the transmittance potential of these bacteria.

Oral colonization by anaerobic bacteria during childhood: role in health and disease

Anaerobes constitute a significant part of bacterial communities in human mouths. Their ability to colonize and survive in the environment, where remarkable changes occur during early childhood, is fundamental for oral homeostasis. However, relatively little is known of the time of colonization and succession of anaerobic species in the oral cavity. This article presents an up-to-date review on the development of the oral anaerobic microflora in respect to age, and in addition, considers some aspects of the role of oral anaerobes in health and disease.

Incidence of Prevotella intermedia and Prevotella nigrescens carriage among family members with subclinical periodontal disease

We established a typing system for Prevotella intermedia and Prevotella nigrescens using the combination of PCR ribotyping and arbitrarily primed PCR (AP-PCR) fingerprinting and applied this system to the study of intrafamilial incidence of these species in the oral cavity. PCR ribotyping followed by subtyping by AP-PCR fingerprinting was applied to each type strain of P. intermedia and P. nigrescens and 54 isolates (32 isolates of P. intermedia and 24 isolates of P. nigrescens) from extraoral infections, resulting in an excellent discriminatory power (discrimination index, 0.99) for both species. A total of 18 subjects from six families, with the subjects from each family comprising the mother, the father, and a child who had subclinical early-stage to moderate adult periodontitis or simple gingivitis and who carried P. intermedia or P. nigrescens, or both, were enrolled in the study of intrafamilial carriage. When 20 colonies per specimen of subgingival plaque, if available, were picked from primary culture, 115 P. intermedia and 178 P. nigrescens isolates were recovered from the 18 subjects. Among the subjects studied, family members shared the same subtype strain(s) but non-family members did not. Multiple subtypes were found in 8 (57%) of the 14 P. nigrescens-positive subjects but in only 3 (27%) of the 11 P. intermedia-positive subjects; the difference was, however, not statistically significant (P = 0.14). These results suggest that the combination of PCR ribotyping and AP-PCR fingerprinting is well suited for the epidemiological study of P. intermedia and P. nigrescens and that each family seems to carry a distinct subtype(s) of these species.

Clonal diversity of Actinobacillus actinomycetemcomitans isolates from young adults with minimal periodontal disease

Actinobacillus actinomycetemcomitans is a major periodontal pathogen which is associated with both early-onset periodontitis and adult cases refractory to conventional periodontal therapy, although the organism has also been shown to be widely distributed among dentate healthy individuals. The observed disease status may be associated with a variation in virulence of different strains or clones. The aim of the present study was to analyse genotype distribution as assessed by an arbitrarily primed polymerase chain reaction (AP-PCR) among 51 isolates of A. actinomycetemcomitans recovered from more than 200 young adult recruits with no or minor periodontal disease. In addition, isolates from 25 periodontitis patients as well as reference strains were genotyped. Primers amplifying (i) a specific sequence in the ltxA region, (ii) a specific 16S rRNA sequence and (iii) sequences in the leukotoxin promoter region were used to verify species identity of the strains. Three random oligonucleotide primers were employed to analyse genomic polymorphisms of the organism by means of PCR. A total of 19 genotypes could be distinguished, which were grouped by cluster analysis into 5 major clusters based on genetic similarity and a complete linkage sort. Whereas 3 clusters assembled A. actinomycetemcomitans genotypes isolated from both healthy subjects and periodontitis patients, one cluster containing 4 different genotypes exclusively comprised isolates from healthy or gingivitis subjects. Another cluster with 2 genotypes consisted of strains originating from periodontitis patients (p < 0.05). One strain characterized by a specific 530 bp deletion in the promoter region of the leukotoxin region was identified in a Ghanese patient with localized juvenile periodontitis. It was concluded that there is considerable clonal diversity of A. actinomycetemcomitans strains isolated from healthy or periodontally diseased subjects, and that genetically closely related groups might be associated with health or disease.

Flow cytometry to monitor phagocytosis and oxidative burst of anaerobic periodontopathogenic bacteria by human polymorphonuclear leukocytes

The reduced susceptibility to phagocytosis found among some periodontopathogenic anaerobes may account for the differences between invasive and non-invasive strains. We applied flow cytometry as a powerful tool to analyze and quantify phagocytosis using standardized cultures of oral anaerobes (Porphyromonas gingivalis, Prevotella intermedia, P. nigrescens, Capnocytophaga gingivalis, C. ochracea, C. sputigena, Fusobacterium nucleatum and Peptostreptococcus micros) and heparinized whole blood. Bacteria were labeled by a fluorescein-methylester and their esterase activity, resulting in green fluorescence. Ingested bacteria could be detected easily and quantified by a shift towards green fluorescence in the PMNL population involved and a concomitant decrease in the bacterial population. Furthermore, the oxidative burst of PMNLs was detected in parallel assays using the dye DHR123 which becomes fluorescent upon oxidation during the oxidative burst process. We found a great diversity in phagocytosis susceptibility determined by estimating the portion of phagocytosing PMNLs, ranging from 10.6% (strain W83) to > 99.4% (e.g. ATCC 33277T) in P. gingivalis and from 15.9% (strain MH5) to > 95% (ATCC 33563T) in P. nigrescens. In contrast, almost all P. intermedia strains as well as the representatives of the other anaerobic, putative periodontopathic species tested showed no or only moderate resistance in the phagocytosis assay. Comparison of clinical data of patients and the extent of phagocytosis resistance of the corresponding P. gingivalis strains suggests that this virulence factor may contribute to the clinical outcome.