Identical clonal types of Porphyromonas gingivalis or Prevotella nigrescens recovered from infected root canals and subgingival plaque

Bacterial diversity in primary infected root canals of a Chinese cohort: analysis of 16 S rDNA sequencing

PURPOSE

To characterize the bacterial community in the primarily infected root canals.

METHODS

A total of 13 samples were collected from the primarily infected root canals. 16 S rDNA sequencing was performed to define bacterial community. Taxonomic annotation, bacterial hierarchical structures, community richness and diversity, and inter-subject variability of the bacterial community in the root canal samples were analyzed. Gender, age, and duration of the toothache-specific bacterial community associated with the patient groups were analyzed.

RESULTS

A total of 359 Species were annotated and identified in the whole study cohort. The Alpha diversity analysis showed that the species diversity and detection rate of the 13 samples were high, which reflected the authenticity of sequencing results. The Beta diversity analysis was used to compare the degree of difference between different root canal samples. The 13 samples were divided into two groups according to the results, group A was samples I1-I12, and group B was samples I13. The bacterial species of group A samples were analyzed with the clinical characteristics of patients, and it was found that gender, and duration specific differences in bacterial species, and there was no significant difference in species types among different ages of patients.

CONCLUSION

There were a wide diversity and inter-subject variability in the bacterial community in the primary infected root canals. While Porphyromonas gingivalis was the most abundant species, Fusobacterium nucleatum was the most variable species in the bacterial community of the root canal. The bacterial community at different taxonomic levels varied from sample to sample, despite consistent disease diagnoses. There was gender, duration-specific differences in the bacterial species in the primary infected root canals.

Comparison of cluster analysis of Porphyromonas gingivalis by arbitrarily primed-polymerase chain reaction between healthy and chronic periodontitis subjects

Introduction

Periodontitis is a chronic destructive inflammatory disease of the oral cavity. The main causative agent is presence of biofilm formed due to different micro-organisms. Among different micro- organisms "red complex" bacteria is known to be the main causative agent in progression of periodontitis. Porphyromonas gingivalis out of the red the complex organism plays a major role in progression of periodontitis. P. gingivalisis present in both in healthy and diseased individuals. The difference in the strains will determine the virulence factor of the organism and also progression of disease. Only few studies have been done showing variation in strains present between healthy and diseased.

Aims

To check the difference in heterogeneity of P. gingivalis in chronic periodontitis and healthy individuals through Arbitrarily Primed-PCR (AP-PCR).

Materials and Methods

A total of 400 subjects (200 each of chronic periodontitisandhealthy individuals) were included. Sub-gingival plaque was collected in the Reduced transport fluid (RTF) medium and processed at the institutional central research laboratory. Presence of P. gingivalis was, confirmed by culture andphenotypical analysis. Further confirmed cases were processed for PCR after DNA extraction using 16S rRNA. Positive cases of P. gingivalis were subjected for AP-PCR for clonal analysis using the specific 272 primer.

Results

In 152(76%) and 98(49%) were confirmed for P. gingivalis in chronic periodontitis and healthy individual respectively by PCR. AP-PCR analysis showed 6 clusters with similarity index in CP and 3 clusters with similarity index in Healthy individuals.

Conclusion

The present study showed difference in clusters between chronic periodontitis and healthy individual'sthussuggestive variantin genetic heterogeneity of P. gingivalis strain between healthy and chronic periodontitis. AP- PCR appears to be a promising tool for clonal analysis of P. gingivalis.

Detection and clonal analysis of anaerobic bacteria associated to endodontic-periodontal lesions

BACKGROUND

Microbial agents in root canal systems can induce periodontal inflammation. The aims of this study are to detect anaerobic microorganisms in endodontic-periodontal lesions, determine the genetic diversity among them, and assess the simultaneous colonization of the pulp and periodontal microenvironments by a single clone.

METHODS

Twenty-seven teeth of patients with endodontic-periodontal lesions were selected. Samples were spread on an agar-blood medium, the detection of each species was performed using a polymerase chain reaction, and the determination of the simultaneous presence of the same species in the microenvironments by one or more clones was determined using arbitrarily primed PCR.

RESULTS

Prevotella intermedia (Pi) was the most prevalent species of the colonies in periodontal pockets, whereas Porphyromonas gingivalis (Pg) and Pi were the more prevalent in root canals. Isolates of Pi and Pg were simultaneously identified in root canals and periodontal pockets. Eighteen percent of teeth exhibited the simultaneous colonization by Pg, Tannerella forsythia (previously T. forsythensis), and Porphyromonas endodontalis in the pulp and periodontal microenvironments. The presence of these species was noted even in niches from which no colonies were isolated. Seventeen different genotypes were found in periodontal and pulp sites, with the majority of sites colonized by one or two different genotypes. A high degree of genotype similarity was found for samples of Pg isolated from only one site as well as for those isolated from both microenvironments.

CONCLUSION

Different clones of Pi and Pg with a high intraspecific genotype similarity were found to colonize the same anatomic sites in endodontic-periodontal infections.

Prevalence and clonal analysis of Porphyromonas gingivalis in primary endodontic infections

This study investigated the prevalence of Porphyromonas gingivalis in 62 teeth with primary endodontic infections by using a species-specific 16S rRNA gene-based nested polymerase chain reaction assay. P. gingivalis isolates recovered from 2 infected root canals were also analyzed for clonal diversity by using arbitrarily primed PCR. Overall, P. gingivalis was found in 48% of the samples. This species was specifically detected in 36% of canals of teeth with chronic apical periodontitis, in 46% of the cases of acute apical periodontitis, and in 67% of acute apical abscesses. P. gingivalis was significantly more frequent in abscess aspirates than in canals of teeth with chronic apical periodontitis (P < .05). Typing of colonies retrieved from 2 infected canals revealed 2 clones per individual. These findings confirmed that P. gingivalis can be an important endodontic pathogen, mostly associated with acute abscesses, and demonstrated that different clonal types of this species can colonize the root canal in the same individual.

Increase in probing depth is correlated with a higher number of Prevotella intermedia genotypes

BACKGROUND

The aims of this study were to determine the genotypic diversity of Prevotella intermedia in subgingival plaque samples by using two techniques, arbitrarily primed polymerase chain reaction (AP-PCR) and heteroduplex analysis, and to assess the relationship of this diversity with increase in probing depth.

METHODS

The subgingival plaque samples were obtained from 12 patients using paper points inserted into periodontal pockets (diseased sites) and healthy gingival sulci (healthy sites) of the same subjects. After isolation and identification, AP-PCR was performed for genotypic characterization of P. intermedia (80 isolates). The clinical samples with a positive result for P. intermedia were amplified by 16S rRNA-based PCR method, and the amplicons were subjected to heteroduplex analysis.

RESULTS

The agreement between the two methods was very high; the AP-PCR and heteroduplex analysis showed that subjects harbored between one and five distinct genotypes of P. intermedia, with a positive association between numbers of genotypes by AP-PCR (P = 0.0042) or heteroduplex (P = 0.0099) and increase in probing depth. No matching of P. intermedia genotypes was observed between healthy and diseased sites of the same individual. Interindividual analyses demonstrated absence of identical clones and indicated a high level of genetic diversity in the species.

CONCLUSION

A clear relationship was observed between a higher number of genotypes and increase in probing depth; these results suggest that environmental challenges in the periodontal pockets may modulate the microbiota by selecting genotypes best able to exploit the environment.

Identification of Cultivable Microorganisms from Primary Endodontic Infections with Exposed and Unexposed Pulp Space

This study was aimed at comparing the cultivable microorganisms in canals with periapical radiolucencies with exposed and unexposed pulp space. Microbiological samples were taken and analyzed from 45 canals with exposed pulp space, and 43 canals with unexposed pulp space. The canal contents were analyzed by aerobic/anaerobic culture, and conventional identification techniques. There were 211 isolates of bacteria belonging to 28 genera and 55 species recovered from exposed canals. In the unexposed group, 185 isolates of bacteria were recovered, of which 54 species of 28 genera were identified. Among the four most common genera, Prevotella was significantly more common in the exposed group (51/211 in the exposed group versus 30/185 in the unexposed group) (p = 0.049), while there were no differences in prevalence of Actinomyces, Peptostreptococcus, and Campylobacter between two groups of canals. In addition, Fusobacterium nucleatum and Propionibacterium acne were significantly more common in the unexposed canals (p = 0.047 and p = 0.0051, respectively). Similarity in bacterial species in these two groups suggests that pulp space exposure may not be a significant factor in determining the type of bacteria present in infected canals.

Isolation and properties of a tripeptidyl peptidase from a periodontal pathogen Prevotella nigrescens

Prolyltripeptidyl amino peptidase activity was found in a crude extract of Prevotella nigrescens and this enzyme was purified by procedures including concentration with ammonium sulfate, ion exchange chromatography, gel filtration, and isoelectric focusing. This peptidase hydrolyzed Ala-Ala-Pro-p-nitroanilide as well as Ala-Phe-Pro-p-nitroanilide. Furthermore, several p-nitroanilide derivatives of dipeptides with a proline residue in the second position from the amino-terminal end (Xaa-Pro) were also cleaved detectably. The molecular mass of this tripeptidase was calculated as 56 kDa and its isoelectric point was 5.8. The enzyme was inactivated completely by heating at 60 degrees C for 5 min and inhibited significantly by specific serine enzyme inhibitors.

PCR-based identification of bacteria associated with endodontic infections

PCR primers that target the bacterial 16S rRNA genes (or the tuf gene for the genus Enterococcus) were used to identify 10 putative bacterial pathogens in root canals with necrotic pulp. In addition, the associations of these microorganisms with symptoms and a history of diabetes mellitus were investigated. Microbial samples from the root canals of 24 teeth with necrotic pulp were included in the study. PCR with universal bacterial primers identified bacterial DNA in 22 specimens; the remaining 2 specimens were from intact teeth that had been traumatized 6 months prior to treatment. PCR with specific primers showed that preoperative symptoms were significantly associated with the presence of Streptococcus spp. (P < 0.001 by chi-square analysis). There was also a nonsignificant trend for symptoms to be associated with Fusobacterium nucleatum and Porphyromonas gingivalis (odds ratio, >2) and for diabetes mellitus to be associated with P. gingivalis and Porphyromonas endodontalis (odds ratio, >2). Cloning and sequencing of the universal PCR product in one specimen revealed the presence of an organism related to the genus Olsenella, which has not previously been described in endodontic infections.