Clinical and microbiological changes associated with the use of combined antimicrobial therapies to treat "refractory" periodontitis

Anne Haffajee: An inspirational role model

This article honors Dr. Anne Haffajee's career, her highest research standards, scholarly integrity, and inspirational mentorship. Anne-as she liked to be called-was one of the most productive clinical scientists of her time. Gifted with the unique combination of knowledge in the fields of clinical research, oral ecology, data analysis, and computer programing, her work triggered unprecedented advances in the diagnosis, progression, and treatment of periodontitis. Anne's pivotal clinical trials elucidated the effects of non-surgical and surgical periodontal therapies. In addition to her scholarly achievements, Anne played an important role in mentoring young scientists, many of whom have developed independent leadership careers in periodontal research. She always found time to help her mentees, and ultimately became a warm-hearted friend to many of them, including myself. Anne was consistently devoted to contributing to the future of clinical investigation, and more specifically concerned about the lack of interest by (1) funding agencies in supporting such studies and by (2) the new generation of investigators in pursuing a career in the area. She passed away prematurely, in 2013, at the age of 65. Undoubtedly, her work and legacy assured the continuity of high-standard clinical studies in periodontics and the survival of a whole generation of clinical researchers.

Resolving the Contradictory Functions of Lysine Decarboxylase and Butyrate in Periodontal and Intestinal Diseases

Periodontal disease is a common, bacterially mediated health problem worldwide. Mastication (chewing) repeatedly traumatizes the gingiva and periodontium, causing traces of inflammatory exudate, gingival crevicular fluid (GCF), to appear in crevices between the teeth and gingiva. Inadequate tooth cleaning causes a dentally adherent microbial biofilm composed of commensal salivary bacteria to appear around these crevices where many bacteria grow better on GCF than in saliva. We reported that lysine decarboxylase (Ldc) from Eikenella corrodens depletes the GCF of lysine by converting it to cadaverine and carbon dioxide. Lysine is an amino acid essential for the integrity and continuous renewal of dentally attached epithelium acting as a barrier to microbial products. Unless removed regularly by oral hygiene, bacterial products invade the lysine-deprived dental attachment where they stimulate inflammation that enhances GCF exudation. Cadaverine increases and supports the development of a butyrate-producing microbiome that utilizes the increased GCF substrates to slowly destroy the periodontium (dysbiosis). A long-standing paradox is that acid-induced Ldc and butyrate production support a commensal (probiotic) microbiome in the intestine. Here, we describe how the different physiologies of the respective tissues explain how the different Ldc and butyrate functions impact the progression and control of these two chronic diseases.

Adjunctive effect of locally delivered antimicrobials in periodontitis therapy: A systematic review and meta-analysis

AIM

To answer the following PICOS question: in adult patients with periodontitis, which is the efficacy of adjunctive locally delivered antimicrobials, in comparison with subgingival debridement alone or plus a placebo, in terms of probing pocket depth (PPD) reduction, in randomized clinical trials with at least 6 months of follow-up.

MATERIAL AND METHODS

A systematic search was conducted: 59 papers, reporting 50 different studies, were included. Data on clinical outcome variables changes were pooled and analysed using weighted mean differences (WMDs) and 95% confidence intervals (CI), and prediction intervals (PI), in case of significant heterogeneity.

RESULTS

Statistically significant differences were observed, in 6- to 9-month studies, for PPD (WMD = 0.365, 95% CI [0.262; 0.468], PI [-0.29; 1.01]) and clinical attachment level (CAL) (WMD = 0.263, 95% CI [0.123; 0.403], PI [-0.43; 0.96]). For long-term studies, significant differences were observed for PPD (WMD = 0.190, 95% CI [0.059; 0.321]), but not for CAL. For adverse events, no differences were observed. Results were affected by study design (split-mouth versus parallel studies) and assessment (full- or partial-mouth), as well as by the formulation tested.

CONCLUSIONS

The use adjunctive locally delivered antimicrobials in periodontitis therapy results in statistically significant benefits in clinical outcomes, without relevant side effects.

In Vitro Anti-Biofilm and Antibacterial Properties of Streptococcus downii sp. nov

The aim of this study was to evaluate the potential anti-biofilm and antibacterial activities of Streptococcus downii sp. nov. To test anti-biofilm properties, Streptococcus mutans, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans were grown in a biofilm model in the presence or not of S. downii sp. nov. for up to 120 h. For the potential antibacterial activity, 24 h-biofilms were exposed to S. downii sp. nov for 24 and 48 h. Biofilms structures and bacterial viability were studied by microscopy, and the effect in bacterial load by quantitative polymerase chain reaction. A generalized linear model was constructed, and results were considered as statistically significant at p < 0.05. The presence of S. downii sp. nov. during biofilm development did not affect the structure of the community, but an anti-biofilm effect against S. mutans was observed (p < 0.001, after 96 and 120 h). For antibacterial activity, after 24 h of exposure to S. downii sp. nov., counts of S. mutans (p = 0.019) and A. actinomycetemcomitans (p = 0.020) were significantly reduced in well-structured biofilms. Although moderate, anti-biofilm and antibacterial activities of S. downii sp. nov. against oral bacteria, including some periodontal pathogens, were demonstrated in an in vitro biofilm model.

Adjunctive local treatments for patients with residual pockets during supportive periodontal care: A systematic review and network meta-analysis

AIM

This systematic review and network meta-analysis aimed to evaluate the efficacy of adjunctive locally delivered antimicrobials, compared to subgingival instrumentation alone or plus a placebo, on changes in probing pocket depth (PPD) and clinical attachment level (CAL), in patients with residual pockets during supportive periodontal care.

MATERIALS AND METHODS

Literature search was performed with electronic databases and by hand until 31 May 2020. Primary outcome was the changes in PPD. The treatment effects between groups were estimated with weighted mean differences (WMD) with 95% confidence intervals (CI) and prediction intervals (PI) by using random-effects network meta-analysis.

RESULTS

Twenty-two studies were included. Significantly greater PPD reduction was achieved in chlorhexidine chip group (WMD: 0.65 mm, 95% CI: 0.21-1.10) and tetracycline fibre group (WMD: 0.64 mm, 95% CI: 0.20-1.08) over 6-month follow-up. Other adjunctive antimicrobial agents achieved non-significant improvements compared to scaling and root planing alone. All differences between adjunctive therapies were statistically non-significant. Similar findings were observed for CAL gain.

CONCLUSION

Adjunctive local antimicrobial agents achieved small additional PPD reduction and CAL gain in residual pockets for a follow-up of up to 6 months. Tetracycline fibre and chlorhexidine chip achieved better results than other antimicrobials.

Induction of M2 Macrophages Prevents Bone Loss in Murine Periodontitis Models

Periodontitis is characterized by the progressive destruction of tooth-supporting alveolar bone, which is mainly caused by chronic inflammation in response to persistent bacterial insult. It has recently become clear that the pathogenesis of periodontitis is associated with a high ratio of proinflammatory M1 (classically activated) macrophages to anti-inflammatory M2 (alternatively activated). To decrease the inflammatory activity, we locally delivered the C-C motif chemokine ligand 2 (CCL2) using controlled-release microparticles (MPs). CCL2 is known to promote chemotaxis of M0 or M2 phenotype macrophages to the inflamed site and induce M2 phenotype polarization locally. Our in vitro data showed that CCL2 increased the number of M2 phenotype macrophages, decreased TNF-α secretion, and enhanced chemotaxis of RAW264.7 cells toward CCL2 MPs. Moreover, we induced periodontal disease in 2 animal models through inoculation of Porphyromonas gingivalis and ligature around the murine molar. Micro-computed tomography analysis showed significant reduction of alveolar bone loss in the CCL2 MP treatment group when compared with a blank MP group and a no-treatment periodontitis group in both models. Immunohistologic analysis showed a significant increase in the M2 phenotype subset and a decrease in the M1 phenotype subset in the CCL2 MP group of the P. gingivalis-induced model. Also, in both models, tartrate-resistant acidic phosphatase staining showed significantly fewer numbers of osteoclasts in the CCL2 MP group in alveolar bone area. Moreover, quantitative polymerase chain reaction results showed a significant increase in IL-1RA (interleukin 1 receptor antagonist) mRNA expression and a decrease in RANKL (receptor activator of nuclear factor kappa-Β ligand) mRNA expression in the CCL2 MP group in the ligature model. In summary, manipulation of endogenous M2 phenotype macrophages with CCL2 MPs decreased the M1 phenotype:M2 phenotype ratio and prevented alveolar bone loss in mouse periodontitis models. The delivery of CCL2 MPs provides a novel approach to treat periodontal disease.

Ecological Therapeutic Opportunities for Oral Diseases

The three main oral diseases of humans, that is, caries, periodontal diseases, and oral candidiasis, are associated with microbiome shifts initiated by changes in the oral environment and/or decreased effectiveness of mucosal immune surveillance. In this review, we discuss the role that microbial-based therapies may have in the control of these conditions. Most investigations on the use of microorganisms for management of oral disease have been conducted with probiotic strains with some positive but very discrete clinical outcomes. Other strategies such as whole oral microbiome transplantation or modification of community function by enrichment with health-promoting indigenous oral strains may offer more promise, but research in this field is still in its infancy. Any microbial-based therapeutics for oral conditions, however, are likely to be only one component within a holistic preventive strategy that should also aim at modification of the environmental influences responsible for the initiation and perpetuation of microbiome shifts associated with oral dysbiosis.

Low Biofilm Lysine Content in Refractory Chronic Periodontitis

BACKGROUND

Chronic periodontitis is controlled without antibiotics by scaling and root planing (SRP) to remove dental biofilm. It has been previously reported that the epithelial barrier to bacterial proinflammatory products is impaired when biofilm lysine falls below the minimal content of normal blood plasma. Aims were to examine whether being refractory and requiring antibiotics to supplement SRP were associated with low biofilm lysine contents.

METHODS

Sixteen patients with periodontitis and six periodontally healthy volunteers (HVs) (respective mean ages: 57 ± 6 and 36 ± 8 years) were examined. Patients with periodontitis received SRP and surgery, and HVs received prophylaxis. At quarterly maintenance or prophylaxis visits during the subsequent year, therapeutic response was good (GR, n = 9) or poor (PR, n = 7; including five cigarette smokers). Biofilm cadaverine, lysine, and other amino acid (AA) contents were determined by liquid chromatography. Cadaverine mole fraction of lysine plus cadaverine (CF) indicated biofilm lysine decarboxylase activity.

RESULTS

Biofilm lysine was 0.19 ± 0.10 and 0.20 ± 0.09 μmol/mg in GRs and HVs, but 0.07 ± 0.03 μmol/mg in PRs (Kruskal-Wallis: P <0.01). All AAs were depleted in biofilm from smokers, but only lysine was depleted in biofilm from non-smokers. CF was inversely associated with clinical attachment level (CAL) at baseline before therapy in all patients (R² = 0.28, P <0.01) and with CAL change after therapy in GR (R² = 0.49, P <0.05). Lysine and cadaverine contents discriminated PRs from GRs and HVs (Wilks' λ = 0.499, P <0.012).

CONCLUSIONS

Refractory responses requiring antibiotic therapy result from smoking and/or microbial infections that starve the biofilm and epithelial attachment of lysine. Biofilm CF is associated with periodontitis severity pretherapy and extent of therapeutic response post-therapy.

The use of systemic antibiotics in the treatment of refractory periodontitis: A systematic review

BACKGROUND

The goal in treating refractory periodontitis (RP) is to arrest or slow disease progression, which usually has included the use of systemic antibiotics adjunct to conventional mechanical debridement. The aim of this systematic review was to evaluate the evidence that the association of systemic antibiotics with conventional mechanical debridement increases the efficacy of periodontal therapy in the treatment of RP.

TYPES OF STUDIES REVIEWED

The authors searched for studies in PubMed MEDLINE, Cochrane Central Register of Controlled Trials, Thomson Reuters Web of Science, Scopus, Latin American and Caribbean Center on Health Sciences Information, and Scientific Electronic Library Online electronic databases by using selected key words from the earliest records up through October 31, 2014. Only clinical intervention studies in which investigators compared the treatment of participants with RP with either mechanical debridement alone or associated with systemic antibiotics were eligible for selection. Two authors independently assessed the risk of bias of each selected study.

RESULTS

The authors identified 13 articles and included 6 of them. Investigators in all studies reported greater reductions in probing depth or in loss of clinical attachment level after adjunct systemic antibiotic therapy when compared with mechanical debridement alone. Antibiotics tested included metronidazole, clindamycin, tetracycline hydrochloride, amoxicillin, and amoxicillin and potassium clavulanate. Five studies presented a high risk of bias, and 1 study presented an unclear risk.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The overall quality of the evidence does not allow the conclusion that adjunct systemic antibiotics are of additional benefit to conventional mechanical debridement alone.

Antibiotic susceptibility of periodontal Streptococcus constellatus and Streptococcus intermedius clinical isolates

BACKGROUND

Streptococcus constellatus and Streptococcus intermedius in subgingival dental plaque biofilms may contribute to forms of periodontitis that resist treatment with conventional mechanical root debridement/surgical procedures and may additionally participate in some extraoral infections. Because systemic antibiotics are often used in these clinical situations, and little is known of the antibiotic susceptibility of subgingival isolates of these two bacterial species, this study determined the in vitro susceptibility to six antibiotics of fresh S. constellatus and S. intermedius clinical isolates from human periodontitis lesions.

METHODS

A total of 33 S. constellatus and 17 S. intermedius subgingival strains, each recovered from separate patients with severe chronic periodontitis (n = 50) before treatment, were subjected to antibiotic gradient strip susceptibility testing with amoxicillin, azithromycin, clindamycin, ciprofloxacin, and doxycycline on blood-supplemented Mueller-Hinton agar and to the inhibitory effects of metronidazole at 16 mg/L in an enriched Brucella blood agar dilution assay. Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing interpretative standards were used to assess the results.

RESULTS

Clindamycin was the most active antibiotic against S. constellatus (minimum inhibitory concentration at 90% [MIC90] 0.25 mg/L), and amoxicillin was most active against S. intermedius (MIC90 0.125 mg/L). A total of 30% of the S. constellatus and S. intermedius clinical isolates were resistant in vitro to doxycycline, 98% were only intermediate in susceptibility to ciprofloxacin, and 90% were resistant to metronidazole at 16 mg/L.

CONCLUSION

Subgingival S. constellatus and S. intermedius exhibited variable antibiotic susceptibility profiles, potentially complicating empirical selection of periodontitis antibiotic therapy in patients who are species positive.

Clinical and microbiological evaluation of one-stage full-mouth disinfection: a short-term study

INTRODUCTION: Patients seem to adhere better to short-term periodontal treatment schemes. Besides, time-reduced treatments are more cost-effective. However, the degree of benefits related to this type of treatment still requires additional investigations. AIM: The present short-term study evaluated clinical and microbiological outcomes, from baseline to 3-months, of chronic periodontitis subjects treated by the one-stage full-mouth disinfection protocol. MATERIAL AND METHOD: Sixteen chronic periodontitis subjects (mean-age 49.87 ± 8.22) who met inclusion/exclusion criteria were included. A calibrated examiner measured whole-mouth plaque and gingival indices, periodontal pocket depth and clinical attachment level at baseline and at 3-months. Subgingival samples were also collected from the 5 most diseased periodontal sites to determine total bacterial load and levels of P. gingivalis and S. oralis by real time qPCR. Periodontal treatment consisted of full-mouth manual debridement plus wide intraoral use of chlorhexidine in gel and solution. Additionally, after debridement, individuals rinsed 0.12% chlorhexidine at home twice a day for the following 2 months. Data monitored were compared by paired Student-t test (p<0.05). RESULT: Statistical analysis revealed that, in general, one-stage full-mouth disinfection treatment provided significant clinical and microbiological improvements at 3-months. Total bacterial load showed one of the most pronounced reductions from baseline to 3-months (p=0.0001). Also, subgingival levels P. gingivalis and S. oralis reduced overtime. CONCLUSION: After a short period of monitoring, chronic periodontitis subjects showed clinical and microbial improvements following one-stage full-mouth disinfection treatment.

Microbial sampling process can change results of microbiological analysis in periodontitis diagnosis. A minireview

This minireview aims to verify the supposition that the microbial sampling process can change results of microbiological analysis in periodontitis diagnosis. The literature search via Pubmed yielded 52 appropriate articles for analysis. Of which 38% (20/52) described that the sampling sites were isolated from saliva, whereas 62% (32/52) did not. Also, 29% (15/52) declared that the microbial sampling was performed before probing pocket depth (PPD), whereas 71% (37/52) did not. Comparison of the results of microbiological analysis in these studies showed that the bacteria most frequently detected in periodontal pockets was variable. Therefore, a sampling process that includes both the microbial sample being taken before PPD and saliva isolation of the sampling sites is needed to ensure the accuracy of microbiological analysis in periodontitis diagnosis.

Impact of periodontal therapy on the subgingival microbiota of severe periodontitis: comparison between good responders and individuals with refractory periodontitis using the human oral microbe identification microarray

BACKGROUND

This study compares the changes to the subgingival microbiota of individuals with "refractory" periodontitis (RP) or treatable periodontitis (good responders [GR]) before and after periodontal therapy by using the Human Oral Microbe Identification Microarray (HOMIM) analysis.

METHODS

Individuals with chronic periodontitis were classified as RP (n = 17) based on mean attachment loss (AL) and/or >3 sites with AL ≥2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GR (n = 30) based on mean attachment gain and no sites with AL ≥2.5 mm after treatment. Subgingival plaque samples were taken at baseline and 15 months after treatment and analyzed for the presence of 300 species by HOMIM analysis. Significant differences in taxa before and post-therapy were sought using the Wilcoxon test.

RESULTS

The majority of species evaluated decreased in prevalence in both groups after treatment; however, only a small subset of organisms was significantly affected. Species that increased or persisted in high frequency in RP but were significantly reduced in GR included Bacteroidetes sp., Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella spp., Tannerella forsythia, Dialister spp., Selenomonas spp., Catonella morbi, Eubacterium spp., Filifactor alocis, Parvimonas micra, Peptostreptococcus sp. OT113, Fusobacterium sp. OT203, Pseudoramibacter alactolyticus, Streptococcus intermedius or Streptococcus constellatus, and Shuttlesworthia satelles. In contrast, Capnocytophaga sputigena, Cardiobacterium hominis, Gemella haemolysans, Haemophilus parainfluenzae, Kingella oralis, Lautropia mirabilis, Neisseria elongata, Rothia dentocariosa, Streptococcus australis, and Veillonella spp. were more associated with therapeutic success.

CONCLUSION

Persistence of putative and novel periodontal pathogens, as well as low prevalence of beneficial species was associated with chronic refractory periodontitis.

Porphyromonas gingivalis: a clonal pathogen?: Diversities in housekeeping genes and the major fimbriae gene

The introduction of multilocus sequence typing (MLST) in infectious disease research has allowed standardized typing of bacterial clones. Through multiple markers around the genome, it is possible to determine the sequence type (ST) of bacterial isolates to establish the population structure of a species. For the periodontal pathogen, Porphyromonas gingivalis, the MLST scheme has been established at www.pubmlst.org/pgingivalis, and data from the database indicate a high degree of genetic diversity and a weakly clonal population structure comparable with Neisseria menigitidis. The major fimbriae (FimA) have been held responsible for the adhesive properties of P. gingivalis and represent an important virulence factor. The fimA genotyping method (PCR based) indicate that fimA genotype II, IV and Ib are associated with diseased sites in periodontitis and tissue specimens from cardiovascular disease. fimA genotyping of the isolates in the MLST database supports the association of genotypes II and IV with periodontitis. As a result of multiple positive PCR reactions in the fimA genotyping, sequencing of the fimA gene revealed only minor nucleotide variation between isolates of the same and different genotypes, suggesting that the method should be redesigned or re-evaluated. Results from several investigations indicate a higher intraindividual heterogeneity of P. gingivalis than found earlier. Detection of multiple STs from one site in several patients with "refractory" periodontitis, showed allelic variation in two housekeeping genes indicating recombination between different clones within the periodontal pocket.

Early microbial succession in redeveloping dental biofilms in periodontal health and disease

BACKGROUND AND OBJECTIVE

The development of dental biofilms after professional plaque removal is very rapid. However, it is not clear whether most bacterial species return at similar rates in periodontally healthy and periodontitis subjects or if there are differences in bacterial recolonization between supragingival and subgingival biofilms in periodontal health and disease.

MATERIAL AND METHODS

Supragingival and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects immediately after professional cleaning. Samples were taken again from seven teeth in randomly selected quadrants after 1, 2, 4 and 7 d of no oral hygiene and analyzed using checkerboard DNA-DNA hybridization. The percentage of DNA probe counts were averaged within subjects at each time-point. Ecological succession was determined using a modified moving-window analysis.

RESULTS

Succession in supragingival biofilms from subjects with periodontitis and from healthy individuals was similar. At 1 d, Streptococcus mitis and Neisseria mucosa showed increased proportions, followed by Capnocytophaga gingivalis, Eikenella corrodens, Veillonella parvula and Streptococcus oralis at 1-4 d. At 4-7 d, Campylobacter rectus, Campylobacter showae, Prevotella melaninogenica and Prevotella nigrescens became elevated. Subgingival plaque redevelopment was slower and very different from supragingival plaque redevelopment. Increased proportions were first observed for S. mitis, followed by V. parvula and C. gingivalis and, at 7 d, by Capnocytophaga sputigena and P. nigrescens. No significant increase in the proportions of periodontal pathogens was observed in any of the clinical groups or locations.

CONCLUSION

There is a defined order in bacterial species succession in early supragingival and subgingival biofilm redevelopment after professional cleaning.

Comparisons of subgingival microbial profiles of refractory periodontitis, severe periodontitis, and periodontal health using the human oral microbe identification microarray

BACKGROUND

This study compared the subgingival microbiota of subjects with refractory periodontitis (RP) to those in subjects with treatable periodontitis (GRs = good responders) or periodontal health (PH) using the Human Oral Microbe Identification Microarray (HOMIM).

METHODS

At baseline, subgingival plaque samples were taken from 47 subjects with periodontitis and 20 individuals with PH and analyzed for the presence of 300 species by HOMIM. The subjects with periodontitis were classified as having RP (n = 17) based on mean attachment loss (AL) and/or more than three sites with AL >or=2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GRs (n = 30) based on mean attachment gain and no sites with AL >or=2.5 mm after treatment. Significant differences in taxa among the groups were sought using the Kruskal-Wallis and chi(2) tests.

RESULTS

More species were detected in patients with disease (GR or RP) than in those without disease (PH). Subjects with RP were distinguished from GRs or those with PH by a significantly higher frequency of putative periodontal pathogens, such as Parvimonas micra (previously Peptostreptococcus micros or Micromonas micros), Campylobacter gracilis, Eubacterium nodatum, Selenomonas noxia, Tannerella forsythia (previously T. forsythensis), Porphyromonas gingivalis, Prevotella spp., Treponema spp., and Eikenella corrodens, as well as unusual species (Pseudoramibacter alactolyticus, TM7 spp. oral taxon [OT] 346/356, Bacteroidetes sp. OT 272/274, Solobacterium moorei, Desulfobulbus sp. OT 041, Brevundimonas diminuta, Sphaerocytophaga sp. OT 337, Shuttleworthia satelles, Filifactor alocis, Dialister invisus/pneumosintes, Granulicatella adiacens, Mogibacterium timidum, Veillonella atypica, Mycoplasma salivarium, Synergistes sp. cluster II, and Acidaminococcaceae [G-1] sp. OT 132/150/155/148/135) (P <0.05). Species that were more prevalent in subjects with PH than in patients with periodontitis included Actinomyces sp. OT 170, Actinomyces spp. cluster I, Capnocytophaga sputigena, Cardiobacterium hominis, Haemophilus parainfluenzae, Lautropia mirabilis, Propionibacterium propionicum, Rothia dentocariosa/mucilaginosa, and Streptococcus sanguinis (P <0.05).

CONCLUSION

As determined by HOMIM, patients with RP presented a distinct microbial profile compared to patients in the GR and PH groups.

Application of the checkerboard immunoblotting technique to the quantification of host biomarkers in gingival crevicular fluid

BACKGROUND

The aim of this study was to describe the development and validation of the checkerboard immunoblotting (CBIB) technique for the high-throughput quantification of multiple inflammatory mediators in gingival crevicular fluid (GCF) samples.

METHODS

Monoclonal antibodies were used to bind GCF interleukin (IL)-1beta and -8 and matrix metalloproteinase (MMP)-8 to the surface of membranes. Biotinylated antibodies were used to detect bound antigens in a checkerboard format. Signals were developed using chemiluminescence, captured on film, and quantified using software for array analysis. The assay was tested for potential cross-reactions among the three pairs of antibodies. Eleven CBIBs were processed to determine the analytical sensitivity of the assay. Forty GCF samples were analyzed using CBIB and enzyme-linked immunosorbent assay (ELISA) in parallel, and the significance of the correlations among the results was tested using the Pearson correlation coefficient. Nine hundred thirty-one GCF samples were collected from 20 periodontally healthy subjects and 20 periodontitis subjects and analyzed using CBIB to test the assay's sensitivity and dynamic ranges using clinical samples.

RESULTS

The CBIB was capable of distinguishing among the three analytes. The sensitivity and dynamic ranges of the assay were suitable for the detection of the three targets in the majority of GCF samples. There were highly statistically significant (P <0.0001) positive correlations between CBIB and ELISA data for all three biomarkers. The periodontitis subjects had statistically significantly higher mean levels of IL-1beta and -8 compared to healthy subjects.

CONCLUSION

The CBIB technique is a sensitive and specific assay for the high-throughput quantification of MMP-8 and IL-8 and -1beta in GCF.

Periodontitis in pregnancy: clinical and serum antibody observations from a baboon model of ligature-induced disease

BACKGROUND

Chronic oral infections that elicit host responses leading to periodontal disease are linked with various sequelae of systemic diseases. This report provides seminal information on the clinical and adaptive immunologic characteristics of a baboon model of ligature-induced periodontitis during pregnancy.

METHODS

Female Papio anubis were evaluated for periodontal health at baseline. Ligatures were tied around selected teeth to initiate oral inflammation and periodontitis. Then the animals were bred. At midpregnancy ( approximately 90 days), a clinical evaluation was performed, and additional ligatures were tied on teeth in the contralateral quadrants to maintain progressing periodontitis throughout pregnancy. A final clinical evaluation was done for all experimental teeth after delivery, and ligatures were removed. Serum was collected at all sampling intervals for the determination of antibody levels to a group of 20 oral bacteria. Unligated animals served as controls.

RESULTS

At baseline, 16% of animals exhibited minimal plaque and gingival inflammation without periodontal disease. The remaining baboons demonstrated varying levels of inflammation/bleeding, and approximately 20% of the population had periodontal pocketing (>3 mm). Ligated animals expressed increased levels of inflammation and increased probing depths and clinical attachment loss (AL) and could be stratified into multiple subsets postligation based upon changes in clinical parameters at midpregnancy and at delivery. Baboons were categorized into disease susceptibility groups (periodontal disease susceptibility 1 through 4) that described the extent/severity of induced disease during pregnancy. Control animals showed minimal periodontal changes during gestation. Significant differences in serum antibody to multiple oral bacteria were found in animals presenting with periodontitis at baseline and during the 6 months of ligature-induced disease. A significant correlation to antibody to P. gingivalis, which was sustained throughout ligation and pregnancy, was observed with disease presentation.

CONCLUSIONS

The clinical presentation at baseline, reflecting the natural history of oral disease in these animals, suggests individual variation that is reflected in the characteristics of the adaptive immune responses to oral bacteria. The variability in the response to ligation with resulting periodontal disease provides a model to document prospectively the relationship between oral and systemic health outcomes.

Genetic diversity of Porphyromonas gingivalis isolates recovered from single "refractory" periodontitis sites

Multilocus sequence typing and fimA genotyping were performed on Porphyromonas gingivalis isolates from 15 subjects with "refractory" periodontitis. Several sequence types were detected for most individual pockets. The variation indicated recombination at the recA and pepO genes. The prevalence of fimA genotypes II and IV confirmed their association with periodontitis.

Effects of Full-Mouth Scaling and Root Planing in Conjunction With Systemically Administered Azithromycin

BACKGROUND

One-stage full-mouth disinfection (FMD), in which full-mouth scaling and root planing (SRP) is performed with adjunctive use of chlorhexidine, was introduced in 1995. There have been several reports on the effectiveness of this treatment protocol. However, FMD was reported to induce pyrexia frequently. We examined the effects of full-mouth SRP in conjunction with azithromycin administered orally before SRP to control the number of bacteria. The purpose of this study was to compare the effects of full-mouth SRP using azithromycin with conventional SRP.

METHODS

Thirty-four subjects (17 in the test group and 17 in the control group) with severe chronic periodontitis were selected. The subjects of the test group had azithromycin 3 days before full-mouth SRP. Clinical parameters (probing depth [PD], gingival index [GI], bleeding on probing [BOP], and gingival crevicular fluid [GCF]), total number of bacteria, and number of black pigment-producing rods (BPRs) were evaluated at baseline and 5, 13, and 25 weeks after baseline.

RESULTS

All clinical parameters improved in the test group more than in the control group. In the bacteriologic examination, the total number of bacteria did not change during the examination. In the test group, BPRs were not detected until 13 weeks. However, BPRs were detected in the control group by 13 weeks.

CONCLUSION

It was shown that full-mouth SRP using systemically administered azithromycin was a clinically and bacteriologically useful basic periodontal treatment for severe chronic periodontitis.

The gene expression profile in refractory periodontitis patients

BACKGROUND

There are no specific bacterial profiles or diagnostic tests capable of identifying refractory periodontitis patients before a treatment regimen is initiated. Therefore, in this high-risk cohort of patients who do not respond appropriately, host factors that might be partly under genetic control may play a crucial role in their susceptibility. Specifically, we tested the hypothesis that patients with refractory periodontitis have multiple upregulated and/or downregulated genes that might be important in influencing clinical risk.

METHODS

Oral subepithelial connective tissues were harvested aseptically from seven refractory periodontitis and seven periodontally well-maintained patients. An RNA isolation kit was used to isolate total RNA from tissue samples that had been stabilized in the RNA stabilizing reagent. The isolated total RNA was then subjected to gene expression profiling using the microarray to measure gene expression levels. The retrieved data were analyzed with a computer program for the differential analysis of gene expression microarray experiments. In addition, real-time polymerase chain reaction (PCR) analysis was performed on selected samples to confirm the microarray data's gene expression patterns.

RESULTS

A total of 68 upregulated and six downregulated genes were identified that were differentially expressed at least two-fold out of 22,283 genes we analyzed. The selected model provided a 93% intrinsic validation along with a 93% extrinsic validation. To validate the microarray data, five upregulated genes (lactotransferrin [LTF], matrix metalloproteinase-1 [MMP-1], MMP-3, interferon induced-15 [IFI-15], and Homo sapiens hypothetical protein MGC5566) and two downregulated genes (keratin 2A [KRT2A] and desmocollin-1 [DSC-1]) were randomly selected for further analysis by real-time PCR. The relative RNA expression level of these genes measured by real-time PCR was similar to those measured by microarrays.

CONCLUSION

The combined use of microarray technology with the computer program for the differential analysis of gene expression microarray experiments provided a set of candidate genes that may serve as novel therapeutic intervention points and improved diagnostic and screening procedures for high-risk individuals.

Rifaximin, a Peculiar Rifamycin Derivative: Established and Potential Clinical Use Outside the Gastrointestinal Tract

Rifaximin is a poorly absorbed semisynthetic rifamycin derivative with a broad spectrum of antibacterial activity including Gram-positive and Gram-negative bacteria, both aerobes and anaerobes. Although originally developed for the treatment of infectious diarrhea, the appreciation of the pathogenic role of gut bacteria in several organic and functional gastrointestinal diseases has increasingly broadened its clinical use. The availability of a topical formulation (a cream containing 5% of the drug) and the lack of transcutaneous absorption pointed out in both animal and human studies has allowed its topical use in skin infections. Furthermore, since the spectrum of antibacterial action of rifaximin includes many organisms (e.g. Bacteroides bivius-disiens, Gardnerella vaginalis, Haemophilus ducreyi) causing genital infections, including Trichomonas vaginalis and Chlamydia trachomatis, its local application in the treatment of bacterial vaginosis (BV) has been attempted. Finally, since periodontal disease, caused by plaque (an aggregate of various bacteria), can be considered a 'local' infection, intrapocket rifaximin was tried in the treatment of periodontal infections. While the efficacy in pyogenic infections of the skin has been confirmed by several investigations, which showed an improvement of both subjective and objective parameters significantly better than that of the reference drug (i.e. chlortetracycline or oxytetracycline), the usefulness of rifaximin in BV and periodontal disease needs to be further studied in well-designed clinical trials.