Subgingival microflora and periodontal disease

Bactericidal action of bicarbonate ion on selected periodontal pathogenic microorganisms

Organisms representative of soil, skin and fecal flora and of supragingival and subgingival flora were tested for inhibition of growth and killing by various salts (NaHCO3, NaCl, MgSO4). The antimicrobial activities of KHCO3, NaF, sodium lauryl sulfate (SLS) and chloramine T were also compared with that of NaHCO3, and the rate at which NaHCO3 exerts its bactericidal effect was studied. Suspected periodontal pathogens were more susceptible to salts than were control non-oral bacteria. Supragingival plaque organisms showed intermediate susceptibility. Periodontal pathogens were more susceptible to NaHCO3 than to NaCl; NaHCO3 and KHCO3 showed similar activity against all strains tested. Accordingly, the antibacterial activity of NaHCO3 is not simply an osmotic effect and is due to the bicarbonate ion. NaF, SLS and chloramine T had greater antimicrobial activity than NaHCO3. Supragingival bacteria required at least 6-hour exposure to 1.0 M NaHCO3 to produce 99% lethality (decrease colony-forming units by 2 log10), whereas selected periodontal pathogens were killed more rapidly (30-120 minutes). The higher the concentration of bicarbonate, the faster the lethality. Morphologic examination by transmission electron microscopy of organisms exposed to bactericidal salt concentrations revealed marked fibrillar condensations within the cytoplasm and shrinkage of the cytoplasm from the outer membrane. For NaHCO3 to be clinically effective, a high concentration must be introduced into the periodontal pocket and maintained there long enough to kill periodontal pathogens. Furthermore, NaHCO3 must be reapplied often enough to prevent recolonization by these pathogens. An advantage of NaHCO3 over NaF, SLS and other antimicrobial agents is its safety, availability and low cost.

Pathogenic synergy: mixed infections in the oral cavity

In almost all infections in the oral cavity, mixed populations of bacteria are present. However, recent evidence points to a certain specificity in these infections: Streptococcus mutans is related to caries and black-pigmented Bacteroides species are suspected pathogens in periodontal disease. Periodontal diseases, endodontic infections and submucous abscesses in the oral cavity are probably mixed infections in which anaerobic bacteria together with facultatives or other anaerobes are present. In experimental mixed anaerobic infections black-pigmented Bacteroides strains have been shown to play a key role. Little is known about the pathogenic synergy between the bacteria involved in mixed infections. Important mechanisms could be nutritional interrelationships and interactions with the host defense. Within the group of black-pigmented Bacteroides B. gingivalis seems to be the most virulent species. These bacteria possess a great number of virulence factors, which might be important in the pathogenesis of oral infections.

Pulmonary actinomycosis of periodontal origin

A case of pulmonary actinomycosis of periodontal origin is presented. Microbiologic testing including culture and typing of multiple systemic and oral lesions revealed the presence of Actinomyces naeslundii and A viscosus in all sites. In addition, biopsies demonstrating branching filamentous forms and "sulfur granules" were found in exudates from the lungs, submandibular region and left quadrants of the oral cavity. Seeding of tooth-associated materials containing Actinomyces sp into the pulmonary field may have resulted in this case of pulmonary actinomycosis. Therapy of the pulmonary and periodontal infections was completed and the patient is maintaining satisfactory health 18 months later.

Inflammatory cells and their subsets in lesions of juvenile periodontitis. A family study

The inflammatory cells in the gingival biopsy samples from a total of 9 patients with juvenile periodontitis (JP) and from 10 of their family members (JPrelat) belonging to 5 different families were subjected to phenotypic characterization. Plasma cells and their immunoglobulins were stained with immunoperoxidase kits for IgA, IgG, and IgM. B, T, and MPS (cells of the mononuclear phagocyte system) cells were demonstrated by the alpha-naphthyl acetate esterase (ANAE) technique in cryostat sections. The subsets (T helper/inducer and T suppressor/cytotoxic cells) of T cells were detected with monoclonal antibodies OKT4 and OKT8, respectively, using indirect immunofluorescence. Similar studies were completed for 19 age- and sex-matched periodontally healthy subjects. IgG plasma cells for outnumbered the IgA and IgM cells in all three series and were most pronounced in JPrelat series. Most of the inflammatory cells were ANAE-negative (B cells) in all series (78-87%). The highest proportions of T and MPS cells were found in the JP series (10% for both). A statistically significantly higher ratio for TH/Ts (OKT4+/OKT8+) was found in both the JP and JPrelat series as compared with that of the healthy controls. The findings suggest that imbalance (either inherited or acquired) in the immune regulation may play role in the development of JP.

Oxygen tension (pO2) in untreated human periodontal pockets

The purpose of this study was to assess the oxygen tension in untreated human periodontal pockets and test the hypothesis that the subgingival environmental is anaerobic in nature. Twenty-six patients with advanced chronic inflammatory periodontal disease participated. A total of 111 untreated pockets, 5 to 10 mm in depth, were selected for the pO2 measurements. Pocket depths, Plaque-Index and Gingival-Index were recorded. The pO2 at the base of the 111 pockets ranged from 5 to 27 mm Hg, with an average of 13.3 mm Hg (1.8% O2). Mean pocket depth was 6.9 mm. Moderately deep pockets (5-6 mm) had a mean pO2 of 15.0 mm Hg, whereas deep pockets (7-10 mm) showed a significantly lower pO2 of 11.6 mm Hg. No correlation was found between the pO2 and the Plaque-Index. Higher Gingival-Index scores tended to be associated with higher pO2 values. The pO2 in untreated periodontal pockets was low. However, it does not represent a completely anaerobic environment. Deep pockets contained less oxygen than moderately deep sites.

Sustained release device containing metronidazole for periodontal use

The purpose of this study was to develop a sustained release device containing metronidazole for insertion within periodontal pockets and to examine the release kinetics in vitro and in vivo. Cast films of ethyl cellulose with or without polyethylene glycol, containing metronidazole, were prepared and exhibited sustained release. Release rate of metronidazole from the film was measured by means of a UV spectrophotometer, and kinetics of release in vitro was found to conform to Higuchi's diffusional model. The microbiological results proved that embedding metronidazole in ethyl cellulose film does not inhibit the biological activity. The release kinetics in vivo correlated with in vitro results, exhibiting a sustained release of metronidazole over a period of three days from 30% metronidazole with polyethylene glycol or 40% metronidazole in ethyl cellulose chloroform cast. This study demonstrates that, by embedding metronidazole in ethyl cellulose, it is possible to obtain sustained release of the drug within the periodontal pocket for three days.

Simple bacteriological methods to assess changes in subgingival microflora produced by metronidazole-containing acrylic strips placed into periodontal pockets

Dark field microscopy is perhaps the simplest microbiological technique to monitor the effects of treatment methods on bacterial plaque. However, the method provides qualitative rather than true quantitative data. This study attempts to measure changes in flora by a number of methods following the placement of 40% metronidazole acrylic strips into periodontal pockets. 10 patients with periodontal pockets greater than 6 mm which bled on probing had acrylic strips placed for 2 to 3 days. Prior to insertion and after removal, subgingival plaque samples were collected into 1 ml of saline and processed as follows. (a) Dark field microscopy for qualitative shifts. (b) Gram stain for differential counts. (c) Counting chamber for total counts. (d) Serial dilution and culture for total cultivable counts. After treatment the significant changes were as follows. (a) % increase in cocci and decreases in other forms, particularly motile organisms. (b) Gram-positive cocci increased and Gram-negative bacilli decreased. (c) Total counts obtained by the sampling method decreased greater than 80%. (d) Total cultivable counts decreased greater than 75%. (e) The efficiency of culturing appeared low and the potential problems of sampling to quantification were identified. The consistency of the changes produced suggested that using simple bacteriological techniques it was possible to show marked changes in the numbers and types of organism present in subgingival plaque following the use of local antimicrobial therapy.

Automated immunofluorescent speciation of oral bacteria using flow cytometry

Mixtures containing two bacterial species were analyzed using flow cytometric techniques. Light scattering characteristics of Streptococcus mutans and Actinomyces viscosus show unique profiles for pure cultures. However, the light scatter analysis of a mixture containing these two species demonstrates overlapping near the origin. Thus, light scatter analysis was not sufficient to speciate bacteria with different morphologies. Labeling of samples with species-specific immunofluorescent antibodies permitted speciation of mixtures. As the percentage of the bacterium to which the antibody is directed increased in a two-component mixture, fluorescent flow cytometric analysis showed a corresponding increase in the percentage of cells displaying fluorescent labeling. These methods could permit the rapid identification of bacteria from oral sites without culturing.

Comparison of the immediate effects on the sub-gingival microflora of acrylic strips containing 40% chlorhexidine, metronidazole or tetracycline

In the management of chronic periodontitis, there has been a renewed interest in the local delivery of antimicrobial drugs into periodontal pockets. This study assessed the effects of the acrylic strip delivery system containing chlorhexidine, metronidazole or tetracycline on subgingival microflora assessed by dark field microscopy. Strips containing 40% chlorhexidine, metronidazole or tetracycline were placed for 2 to 3 days into pockets greater than 6 mm which bled on probing. Plaque samples were obtained before and after treatment and counts of morphological and motile groups of organisms were made by dark field microscopy. Prior to treatment, the dark field microscopic counts were similar to those previously reported for diseased sites with motile bacteria, in particular spirochaetes, present in high numbers. Following treatment, all 3 antimicrobial drugs produced a significant increase in the proportion of cocci and significant decreases in all other types of organisms. Motile organisms, in particular, were markedly reduced and spirochaetes could not be recovered from some sites treated with metronidazole and tetracycline. Metronidazole was significantly more effective than tetracycline or chlorhexidine on spirochaetes. The results indicate that acrylic strips may be useful in the management of chronic periodontitis as an adjunct to routine mechanical methods.

Surface markers of human gingival fibroblasts in vitro. Characterization and modulation by enzymes and bacterial products

Surface markers of human gingival fibroblasts in vitro were investigated using monoclonal and heterologous antisera against a range of cell surface antigens, together with rosetting techniques to characterize surface receptors for IgG and C3. WI-38 fibroblasts and human peripheral blood monocytes were used as control cells. Human gingival fibroblasts exhibited complement receptors and beta2-microglobulin, as did WI-38 cells. Ten per cent of the human gingival fibroblasts were positive for HLA-DR antigens and additionally exhibited a granulocyte antigen not apparent on WI-38 cells. Monolayers of the gingival fibroblasts were further exposed for short periods to varying concentrations of enzymes (trypsin, collagenase and neuraminidase), bacterial extracts (lipopolysaccharide and lipoteichoic acid) and crude supra- and subgingival plaque sonicates. Surface-marker analysis was then carried out. The most noticeable effects were obtained with Vibrio cholerae neuraminidase which enhanced C3 receptor and surface antigen expression, and supragingival plaque sonicate which depressed the expression of HLA-DR and granulocyte antigens while not affecting beta2-microglobulin expression. Trypsin reduced antigen expression to a degree, but its effects were mainly on cell adherence.

The rests of Malassez and chronic marginal periodontitis

The structure of the rests of Malassez and the relationship which they bear to the junctional epithelium in the marginal region of pigs' molars was investigated. A 3-dimensional picture of the marginal rests and their relationship to the junctional epithelium was built up by means of standardized photomicrographs made from serial sections. In teeth involved in chronic marginal inflammation, the rests in this region appeared to form a continuous network and we confirmed the original suggestion of Grant & Bernick that, at frequent intervals, the junctional epithelium"... seemed to be continuous with the epithelial rests in the upper third of the root...". If the anatomical relationship of the rests in man resembles that seen in the pig and they form a continuous network communicating at intervals with the junctional epithelium, this relationship must inevitably lead to speculation about the effects of any potential for reactive proliferative equivalent to that which is frequently seen in the apical region. It is possible that the rests might be acting as the "thin end of the wedge", augmenting and facilitating apical migration of the junctional epithelium during the pathogenesis of the periodontal pocket.

Serological identification of oral Bacteroides spp. by enzyme-linked immunosorbent assay

A rapid method for identifying black-pigmented oral Bacteroides spp. is described. Species-specific rabbit antisera to Bacteroides gingivalis, B. intermedius, and B. melaninogenicus were used in an enzyme-linked immunosorbent assay to identify clinical isolates of black-pigmented Bacteroides spp. from humans. The results showed excellent agreement with biochemical identification of B. gingivalis and B. intermedius. Only 36% of the B. melaninogenicus isolates were identified with the enzyme-linked immunosorbent assay, suggesting that this group of black-pigmented Bacteroides spp. is made up of more than one serotype. The serological enzyme-linked immunosorbent assay should enable rapid identification of black-pigmented Bacteroides spp. isolated from sites of oral diseases and may also be used to identify the presence of these organisms in complex bacterial mixtures from oral sites.

Clinical, microbiological and immunological studies of a family with a high prevalence of early-onset periodontitis

Extensive clinical, laboratory and microbiological studies were performed on members of a family with an unusually high prevalence of early-onset severe periodontitis. Clinical observations included intraoral photographs and assessment of inflammation, plaque, probing depths and bone loss. Pocket bacteria were sampled, cultivated and identified. Immunological studies included assessment in vitro of neutrophil (PMN) and monocyte (MN) chemotaxis, assessment of PMN phagocytosis and other functions using the iodination assay, measurement of serum opsonic and chemoattractant activities and determination of levels of serum antibodies specific to various putative periodontal pathogens. The proband, a 19-year-old white woman, had rapidly progressive periodontitis (RP). Of her six siblings available for study, all had juvenile periodontitis (JP), and both parents had been edentulous since early adulthood. Early edentulism and recurrent infections, especially otitis media, were prevalent in the forebearers, especially on the maternal side. Two married sisters of the proband had young male children with recurrent infections. Abnormalities in leukocyte chemotaxis were found in the proband, in two of her siblings and in both parents. The pocket flora was predominantly Gram-negative, anaerobic rods with a high prevalence of Bacteroides species, and serum antibodies specific to Bacteroides species were detected in the sera of five of the seven patients studied. Actinobacillus actinomycetemcomitans was not found in any of the pockets studied, nor were antibodies specific to any of the three known serotypes of this bacterium detected in the serum of any of the patients. There was a relatively good correlation between the bacterial species isolated from the periodontal pockets and the antibodies found in the serum. PMN iodination and serum opsonic activity were normal in all of the patients. Thus not all JP patients have detectable Actinobacillus species in their periodontal pockets, nor do all have antibody detectable with the techniques we used specific to these bacteria in their serum. In contrast, JP patients may have Bacteroides species in their periodontal pockets and antibody specific to Bacteroides species in their serum. Although abnormal leukocyte chemotaxis is generally common in RP and JP patients, in this family the correlation between this defect and the presence of these diseases was poor.

Colonization of the subgingival area by Bacteroides gingivalis

The initial event in colonization of the subgingival area by B. gingivalis is its attachment to host cells and Gram-positive bacteria in pre-formed plaque. The level of B. gingivalis is partly governed by products of other plaque bacteria, especially by sanguicin. Once B. gingivalis resides in its nidus and starts to proliferate, expulsion of pre-existing residents may occur, especially of attached Gram-positive bacteria, through the inhibitory action of the B. gingivalis product, hematin. The bacteriocin produced by black-pigmented Bacteroides also seems to play an important role in their establishment. Melaninogenicus possessed strong inhibitory activity against Actinomyces species. This was not completely confirmed with fresh isolates of B. gingivalis from advanced periodontitis patients. Various factors other than inhibitory substances produced by B. gingivalis and related bacteria can also affect the colonization of this species. Since the crevice area is influenced by gingival fluid, the nature of specific antibody and the other affecting components should be considered collectively with the interaction between new predominant colonizers and other pre-existing residents.

Degradation in vivo of the C3 protein of guinea-pig complement by a pathogenic strain of Bacteroides gingivalis

The pathogenicity of five black-pigmented strains of Bacteroides was tested in subcutaneously implanted Teflon cages in guinea pigs. The tissue reaction around the cages was registered and the contents of the fluid of the cages were analyzed. Two strains of B. intermedius produced a localized abscess around the cages, while one strain (381) of B. gingivalis and an asaccharolytic strain (BN11a-f) different from B. gingivalis did not induce any signs of abscess formation. One strain (W83) of B. gingivalis caused extensive purulent breakdown of the tissues. When the inoculum of strain W83 contained more than 10(9) cells, the animals were killed. Strain W83 was the only strain that increased in number in the cage. The fluid of cages inoculated with strain W83 was also remarkably different from the fluid of cages inoculated with the other strains. The fluid had a high proteolytic activity. No C3 protein of complement and only traces of immunoglobulins could be detected in the fluid. Both strain W83 and strain 381 had a high proteolytic activity against whole guinea-pig serum and when bacteria of these two strains were incubated with guinea-pig serum for 24 h, almost all serum proteins, including the C3 protein, were degraded. These two strains might thus have similar capacity in perturbing the host defence when inoculated into the tissue cages. The actual difference in pathogenicity between the strains might be explained by a recent finding that the pathogenic strain W83, but not strain 381, requires complement in activating polymorphonuclear leukocytes. The degradation of the C3 protein by the pathogenic strain W83 of B. gingivalis thus may be the crucial event in its perturbation of the host defence. A degradation of the C3 protein by strain 381 would be of no help in eluding the host defence, since this strain activates polymorphonuclear leukocytes in the absence of complement.

Characterization of a trypsin-like protease from the bacterium Bacteroides gingivalis isolated from human dental plaque

A trypsin-like, membrane-bound protease from Bacteroides gingivalis was solubilized by Triton X-100 and partially purified by a combination of DEAE-Sepharose and aminophenylmercuric Sepharose chromatography, by taking advantage of the thiol group on the enzyme. The purified enzyme hydrolysed the synthetic substrates benzoyl-L-arginine-p-nitroanilide (L-BAPA), benzoyl-D,L-arginine-beta-naphthylamide (BANA) and tosyl-L-arginine methyl ester, as well as bovine serum albumin and ovalbumin, but not tosyl-L-lysine methyl ester. The enzyme activity was enhanced by SH-reagents and was inhibited to different degrees by SH-inhibitors, chelators and microbial low-molecular-weight inhibitors such as leupeptin, antipain and chymostatin. These microbial inhibitors could be of practical use as ligands for affinity chromatography for further purification. The possible involvement of the protease in periodontal diseases is also discussed.

Effect of metronidazole on chronic periodontal disease in subjects using a topically applied chlorhexidine gel

A double blind between subject comparison of the effect of metronidazole and placebo tablets was completed over 22 weeks in 45 subjects with chronic periodontal disease ranging in severity from moderate (PI = 2.0-3.9) to high (PI = 4.0-6.0). All subjects used a topically applied chlorhexidine gel for the first 10 weeks. Throughout the trial plaque, bleeding and calculus were assessed on the buccal, lingual, mesial and distal surfaces of teeth 16, 21, 24, 36, 41 and 44 and their supporting tissues. The pocket depths on the same 4 aspects of all teeth present were measured. The regime employed consisted of oral hygiene instruction (OHI) at the initial visit followed by scaling and further OHI at visits 1 and 2 weeks later. After the third visit 16 X 200 mg metronidazole or placebo tablets were issued with instructions to take 1 that evening and 3 per day at 5-h intervals for the next 5 days. 4 weeks later, scaling and OHI were carried out and the course of test or placebo tablets was repeated. The subjects returned for further scaling and OHI 4 weeks later and the chlorhexidine gel was withdrawn. Final assessments were made 12 weeks later. The results showed that metronidazole had no effect on plaque levels and gingival bleeding beyond the effect of OHI, scaling and chlorhexidine gel. On the other hand, significantly greater reductions in pocket depths were achieved with the use of metronidazole. A surprising and interesting finding was that these reductions were apparent only in the subjects with severe periodontal disease (PI = 4.0-6.0).

Purification and characterization of mucopolysaccharidase from an oral strain of Bacteroides sp

A mucopolysaccharidase in the cell extract of an oral strain of Bacteroides sp. was purified to homogeneity by ammonium sulfate precipitation, DEAE-cellulose column chromatography, gel filtration on Sephadex G-200, and isoelectric focusing. Specific activity increased 110-fold and recovery was 2%. The molecular weight was determined to be 89,000 by gel filtration, and the isoelectric point was 7.0. The optimum pH for the activity was 6.5. The enzyme was inactivated by heating at 60 degrees C for 5 min. The purified mucopolysaccharidase degraded hyaluronic acid more rapidly than chondroitin and chondroitin sulfate A and C. However, it had no activity against chondroitin sulfate B, heparin, and heparan sulfate. Since unsaturated disaccharides were derived from the enzyme substrate, this enzyme was considered to be a mucopolysaccharide lyase.

Actinobacillus actinomycetemcomitans in human periodontal disease. Prevalence in patient groups and distribution of biotypes and serotypes within families

Actinobacillus actinomycetemcomitans is a Gram-negative oral bacterium which has been implicated in the etiology of localized juvenile periodontitis. In this study, 403 subjects from four study groups were examined for A actinomycetemcomitans in subgingival dental plaque. Samples pooled from at least six periodontal sites were included from each subject. A actinomycetemcomitans was detected in 28 of 29 localized juvenile periodontitis patients but in only 15% of the other subjects including 28 of 134 adult periodontitis patients, 24 of 142 periodontally healthy subjects and 5 of 98 insulin dependent juvenile diabetics with varying degrees of gingivitis. A actinomycetemcomitans isolates from members of five families with localized juvenile periodontitis patients were biotyped on the basis of variable fermentation of dextrin, maltose, mannitol and xylose and serotyped by indirect immunofluorescence using serotype specific rabbit antisera. Individuals within a family all harbored A actinomycetemcomitans of the same biotype and serotype. However, even in families with individuals heavily infected with A actinomycetemcomitans, some family members did not appear to be infected with the organism. The apparent poor transmissibility of A actinomycetemcomitans between individuals may, in part, explain the overall low prevalence of localized juvenile periodontitis and the familial pattern of the disease. The high prevalence of A actinomycetemcomitans in the subgingival plaque of localized juvenile periodontitis patients, compared to the much lower prevalence in other patient groups, supports the hypothesis that A actinomycetemcomitans is an etiologic agent in this periodontal disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of long-term tetracycline therapy on human periodontal disease

The present investigation was performed to study the effect of long-term, low dosage tetracycline therapy on advanced periodontal disease in humans. 14 volunteers participated in the trial. Each of the participants had at least 4 pairs of diseased sites around contralateral premolars and incisors with deep pockets and advanced bone loss. The trial extended over a 50-week period and was designed as a double-blind split-mouth study. A Baseline examination included assessments of oral hygiene, gingival conditions, probing depth, attachment level and analysis of the composition of the subgingival microbiota in samples obtained from 8 selected diseased sites. All participants received oral hygiene instruction. In each patient 2 quadrants of the mouth, chosen at random, were treated by scaling and root planing. The 2 remaining quadrants were left unscaled. Following the Baseline examination the patients were randomly distributed into 2 groups of 7 members each. In one of the groups the patients received tetracycline on a daily basis during a 50-week period. The participants of the control group received placebo. Reexaminations were performed 2, 10, 20, 30 and 50 weeks after the Baseline examination. The findings demonstrated that in patients with advanced periodontal disease long-term tetracycline therapy in the absence of scaling resulted in the establishment of a subgingival microbiota almost devoid of motile bacteria and in markedly reduced signs of gingivitis, probing depth and attachment loss. In fact, the alterations observed as a result of tetracycline administration to patients with excellent self-performed plaque control were similar to those obtained by conventional scaling and root planing in the control group.

Antigenic heterogeneity of Bacteroides intermedius as recognized by monoclonal antibodies

Four hybrid cell lines secreting monoclonal antibodies against antigens of Bacteroides intermedius were generated by fusing murine NSI cells with splenocytes from a rat immunized with B. intermedius strain OMZ248. An enzyme-linked immunosorbent assay was used to analyze the distribution of the recognized antigens on 39 strains from various Bacteroides species and on 5 strains from other genera. Only Bacteroides species B. intermedius, B. loescheii, B. melaninogenicus, and B. corporis were found to express at least one of the recognized antigens. Strains of the two asaccharolytic black-pigmenting Bacteroides species were negative. Among the strains capable of binding to one or more of the monoclonal antibodies, five groups with different reactivity patterns could be distinguished. Two of the monoclonal antibodies were specific for B. intermedius. The B. intermedius strains were metabolically almost identical, expressed at least three of the recognized antigens, and fell into three distinct antibody reactivity groups, suggesting a tentative separation of this species into three new serogroups. Oral and nonoral isolates of B. intermedius were, however, not distinguished by the monoclonal antibodies. One monoclonal antibody was directed against an antigen strongly expressed on all saccharolytic black-pigmenting Bacteroides strains tested so far, thus confirming the previously noted antigenic relationship between the species which had emerged from the former B. melaninogenicus subsp. intermedius and B. melaninogenicus subsp. melaninogenicus groups.

Relationship between oxygen tension and subgingival bacterial flora in untreated human periodontal pockets

The predominance of anaerobic bacteria in subgingival plaque samples suggests that the pocket environment is anaerobic. In the present investigation, a small oxygen tension (pO2) electrode was inserted into the base of the pocket and the pO2 was recorded. In addition, the plaque in these pockets was examined culturally and microscopically. The oxygen tension at the bottom of 36 pockets (5 to 10 mm in depth) ranged from 5 to 27 mmHg (1 mmHg congruent to 133.3 Pa) with a mean value of 13.3 mmHg. Moderate pockets (5 and 6 mm) exhibited a mean pO2 of 15.7 mmHg, which was significantly higher than the 12.0 mmHg found in the deeper pockets. The deep pockets had higher percentages of spirochetes and Bacteroides intermedius, whereas the moderate pockets had elevated proportions of Actinomyces naeslundii and Streptococcus mutans. The sites with oxygen tensions equal to or less than 15 mmHg had significantly higher percentages of spirochetes, whereas the microaerophilic Capnocytophaga species were found in pockets with a pO2 greater than 15 mmHg. The presence of bleeding in the pocket was associated with higher proportions of B. intermedius, Capnocytophaga sp., and A. naeslundii. These pO2 readings of periodontal pockets indicated that there is a spectrum of pO2 values which seem to define, in a general way, the microbiological composition of the pocket.

Bacteriology of dental abscesses of endodontic origin

Aspirates have been cultured from 10 dental abscesses of endodontic origin, all of which had penetrated beyond the bony alveolus to produce fluctuant swelling. Sampling was by syringe aspiration. Strict anaerobic techniques, including the use of an anaerobic chamber, were used for serial dilution and plating. Randomly selected colonies (100) from each culture were purified, characterized, and identified. Seventy percent of the bacterial isolates were either strict anaerobes or microaerophilic. One abscess yielded a pure culture of a viridans streptococcus, Streptococcus milleri. Streptococcus intermedius dominated the flora in a second abscess. The common oral streptococcus, Streptococcus sanguis, constituted only 2% of the isolates from one additional infection. Fusobacterium nucleatum, Bacteroides melaninogenicus, other Bacteroides including B. oralis and B. ruminicola, anaerobic diphtheroids, Peptostreptococcus micros, and Staphylococcus epidermis were other predominant isolates.

Characterization of black-pigmented Bacteroides strains isolated from animals

The aims of the study were: the isolation of strains of black-pigmented Bacteroides from the gingival sulcus of different animals, their biochemical and immunological characterization and comparison of their properties for classification within the genus. A total of 104 strains, isolated from cats, dogs, racoons and a jaguar, were characterized on the basis of fermentation of carbohydrates, metabolic end products, haemagglutination studies, enzymatic activities, catalase production and indirect immunofluorescence. No differences were observed between the strains regardless of their animal origin. The strains did not ferment carbohydrates, produce phenylacetic acid, show an array of enzyme activities or agglutinate sheep red blood cells. They were catalase-positive and so differed from the human oral strains of Bact. gingivalis. Immunofluorescence microscopy revealed that the animal strains shared at least one major antigen with Bact. gingivalis but none with Bact. asaccharolyticus. Apart from their catalase activity, the animal strains isolated were similar to those of human Bact. gingivalis strains.

Human immune responses to oral microorganisms. II. Serum antibody responses to antigens from Actinobacillus actinomycetemcomitans and the correlation with localized juvenile periodontitis

Human serum antibody responses to antigens from a suspected oral pathogen, Actinobacillus actinomycetemcomitans (Aa), were studied. IgG and IgM isotype antibodies to four antigen preparations, sonicate antigen (SA), leukotoxin (LT), group carbohydrate (LG), and lipopolysaccharide (LPS), were determined using an ELISA. An ELISA inhibition technique was developed to show that human serum antibodies reacting with the LT, LG, or LPS materials were binding to different antigenic moieties in each preparation. Cross-sectional studies of serum IgG antibodies showed that patients with localized juvenile periodontitis (LJP) had a greater frequency of occurrence and a higher level of antibodies to the SA (82%), LT (70%), and LG (62%) antigens compared to all other diseased (11-46%) or normal (4-13%) groups. Serum IgM antibodies to LPS were increased in LJP, generalized juvenile periodontitis, and adult periodontitis patients compared to all other groups. Therefore, while both IgG and IgM antibodies were found against various Aa antigens, the detection of IgG antibodies was most clearly associated with the specific disease classification of LJP. Blocking studies suggested that the human serum responses were specific for the Aa antigens and that the LT, LG, and LPS comprise major antigenic determinants on the organisms to which human serum antibody reacts.

Fusobacterium periodonticum, a new species from the human oral cavity

Isolates of Fusobacterium that differ from type strains of various fusobacterial species with respect to DNA sequence, cellular fatty acid composition, and biochemical activity, were obtained from periodontitis lesions in a patient with insulin-dependent diabetes mellitus. These isolates have the following distinguishing characteristics: 28% guanine + cytosine content; 40% or less DNA homology with type strains of representative fusobacterial species; cell size, 0.5 - 1 X 4 -100 microns; absence of motility; ability to ferment glucose, fructose, and galactose, but not 25 other carbohydrates; ability to produce indole; ability to hydrolyze hippurate but not esculin; sensitivity to bile; ability to produce little or no gas; ability to utilize threonine but not lactate. We propose that the organisms be classified as a distinct species of Fusobacterium to be named Fusobacterium periodonticum. The type strain of this new species has been deposited with the American Type Culture Collection under the designation ATCC 33693.

Minimal inhibitory concentrations of various antimicrobial agents for human oral anaerobic bacteria

The minimal inhibitory concentrations of a series of antimicrobial agents for human oral organisms were determined under anaerobic growth conditions by an agar dilution assay. With the exception of black-pigmented Bacteroides spp., minimal inhibitory concentrations for oral isolates were similar to those for non-oral isolates of organisms of the same or closely related species.

The periodontal microflora of juvenile diabetics. Culture, immunofluorescence, and serum antibody studies

These studies demonstrate a unique constellation of organisms populating the subgingival area in periodontitis lesions of patients with juvenile or insulin-dependent diabetes mellitus (IDDM). The cultivable microflora was predominated by Capnocytophaga and anaerobic vibrios in the patients studied. In some patients, Actinobacillus actinomycetemcomitans were also found. This distinguishes the subgingival flora of IDDM patients suffering from periodontitis from that of patients with localized juvenile periodontitis (LJP), and that of adult periodontitis patients. In LJP most patients harbor both A actinomycetemcomitans and Capnocytophaga subgingivally; and in periodontitis lesions from nondiabetic adults, black-pigmented Bacteroides such as B gingivalis or B melaninogenicus subspecies intermedius are often found. Antibiotic susceptibility patterns suggest that penicillin or tetracycline or its analogs such as minocycline may be effective against the predominant cultivable microflora in periodontal lesions of IDDM patients; however, individual patients may harbor flora with significant resistance to these antibiotics.

Phase contrast microscopy of microbial aggregates in the gingival sulcus of Macaca mulatta. Subgingival plaque bacteria in macaca mulatta

The objective of this study was to study the relationship of microbial aggregates in the subgingival crevice to changes in periodontal health in Macaca mulatta. The sample included 68 oral sites from 17 Rhesus monkeys of various ages. The periodontal health of each site was evaluated using Plaque and Gingival Indices and crevice depth measurement. The subgingival plaque samples were examined by phase contrast microscopy and recorded on 16 mm film. A Microbial Index was developed based on a qualitative estimate of the numbers of organisms, morphology of predominant organisms, and the presence or absence of motility. The Microbial Index was demonstrated to be simple in use and highly reproducible. The findings indicate that changes in the Microbial Index are consistent with tissue changes seen in the periodontal status in M. mulatta. From this preliminary study, the oral flora of adult M. mulatta appears to have sufficient similarities to human oral flora to be used as a microbial model for experimental periodontal disease research. Future studies to refine and confirm the validity of the Microbial Index are warranted. It may prove to be a useful tool to monitor the effect of various treatment modalities on the periodontal flora and to determine the presence or absence of active disease.

Antibiotic susceptibility testing of subgingival plaque samples

The in vitro inhibitory effect of several antimicrobial agents was determined against dispensed dental plaque samples taken from periodontally diseased sites as an aid in the selection of antibiotics for adjunctive use in periodontal therapy. 2 groups of patients were sampled. 1 group of 10 patients with severely advanced disease had received periodontal treatment which included the frequent adjunctive use of an antibiotic. The second group consisted of 15 individuals with less severe periodontal disease; only 4 individuals had been previously treated with antibiotics for their periodontal disease. Bacterial samples of subgingival plaque were taken from each patient and tested against a battery of antibiotics to determine which agent was the most effective in suppressing bacterial growth. Each antibiotic was incorporated into Trypticase-soy blood agar at a concentration equivalent to that achieved in either gingival fluid or blood following recommended oral dosages. The inhibitory effect was determined by comparing the number of bacterial recovered on the antibiotic-containing medium to the total number of bacteria recovered on the basal medium. Penicillins, with the exception of cloxacillin, were the most effective in inhibiting bacterial growth. Benzylpenicillin consistently inhibited the growth of 90% of the isolates recovered on media free of antibiotics while ampicillin and amoxicillin frequently inhibited 99% or more of the bacteria recovered. Tetracycline was generally inhibitory for at least 90% of the isolates if the patients had not been previously treated with this agent. However, resistance to this drug was common in samples taken from patients previously treated with tetracycline. Doxycycline, a tetracycline derivative, did not inhibit significantly more isolates than tetracycline. Clindamycin was inhibitory for 90% or more of the organisms in most of the samples; and, was usually effective in inhibiting isolates in samples which exhibited large numbers of isolates resistant to tetracycline. Erythromycin was relatively ineffective against the isolates recovered from samples from the severely diseased group but was inhibitory to isolates in some samples taken from the more moderately diseased group. Metronidazole, at the concentration tested, was largely ineffective against the isolates in bacterial samples from both groups. No single antimicrobial agent was found to be inhibitory for greater than 90% of the bacteria recovered from all of the subgingival plaque samples with the possible exception of some penicillins.

A rationale for the management of periodontal diseases: effects of tetracycline on subgingival bacteria

Microbiologic criteria obtained with phase-contrast microscopy were used in a short-term, double-blind study to measure the effects of systemic tetracycline HCl on subgingival bacterial populations in advanced periodontal pockets refractory to local therapy (repeated scaling, root planing, and the subgingival administration of chemotherapeutic agents [H2O2, NaHCO3, NaCl, MgSO4]). Twenty-one subjects, selected for study, had at least one of the following conditions present after local therapy: spirochetes, motile rods, or crevicular leukocytes greater than or equal to 125 per phase-contrast microscopic field. Tetracycline HCl (1 gm/day for 14 days) was randomly distributed to 11 subjects and a placebo to ten subjects, so that neither the subjects nor investigators were aware of the prescription contents. Evaluations after two weeks disclosed that tetracycline HCl significantly reduced elevated levels of spirochetes, motile rods, and crevicular leukocytes to low or undetectable levels, whereas levels in the placebo subjects remained generally unchanged. The results clearly demonstrate the value of tetracycline HCl as an adjunct to periodontal therapy in reducing remaining suspected periodontopathic bacterial populations in advanced lesions after local therapy of scaling, root planing, and topically applied chemotherapy.

A rationale for management of periodontal diseases: rapid identification of microbial 'therapeutic targets' with phase-contrast microscopy

Monitoring the composition of subgingival flora can provide clinicians with a supplement to periodontal diagnosis and therapy. Conventional bacteriologic culturing may be clinically impractical, but direct microscopy may not.

Periodontal status associated with chronic neutropenia

A case of chronic neutropenia in a 12-year-old boy is reported. The patient presented with severe gingival inflammation and alveolar bone loss. Immunologic analysis of the patient's serum revealed the presence of precipitating antibodies against antigenic components of Actinobacillus actinomycetemcomitans Y4 and 652. It was also found that the serum neutralized the leukotoxic activity of Actinobacillus actinomycetemcomitans Y4. The etiology and the pathogenesis of periodontal disease in neutropenic patients are discussed in view of these findings.

Plaque-host imbalance in severe periodontitis. A discussion based on two cases

One child and one adult with severe periodontitis were investigated for relevant systemic factors and predominant periodontal pocket bacteria. The child had a chronic neutropenia, the adult late yaws, a chronic iron deficiency and possibly rheumatoid arthritis. The predominant organisms in both pocket floras were gram-negative cocci showing occasional filament formation and resembling strains of Bacteroides asaccharolyticus and possibly Actinobacillus actinomycetemcomitans described by others. There were indications that the flora was determined by the host response rather than vice versa and that thorough systemic investigation may aid the efficient diagnosis and treatment of patients with severe periodontitis.

Haemolysis of human erythrocytes by the Fusobacterium nucleatum associated with periodontal disease

Fusobacterium nucleatum and Bacteroides gingivalis are associated with oral disease. They both attach to haemagglutinate and human erythrocytes. Experiments were performed to determine whether haemolysis would occur following attachment of strains of F. nucleatum and Bacteroides species including B. gingivalis. The F. nucleatum strains consistently displayed both haemagglutination and haemolytic activity. The B. gingivalis strains and other Bacteroides species displayed haemagglutination but no measurable haemolytic activity. Varying the concentration of the F. nucleatum whole cells in the standard haemolysis assay suggested a F. nucleatum-erythrocyte binding site interaction. The haemolytic moiety was observed in various cell, cell wall and lipopolysaccharide extracts.

Blastogenic responses by lymphocytes from periodontally healthy populations induced by periodontitis-associated bacteria

Studies of blastogenic responsiveness induced in peripheral blood lymphocytes (PBL) from periodontally healthy subjects by periodontal bacteria have conflicted. This study was undertaken to examine the blastogenic response of periodontally healthy subjects under experimental conditions which provide improved control of laboratory variables. By using cryopreserved PBL the responses of all subjects in an experiment were determined on the same day under identical conditions. The periodontally healthy populations consisted of subjects of the same age range and sex matched to three distinct groups of periodontally diseased subjects (i.e., juvenile (JP), severe (SP), and moderate (MP) periodontitis). The bacterial stimulants tested were chosen on the basis of known association with and isolation from persons fitting the disease classifications. If PBL response differences between periodontally healthy and diseased subjects exist they should be most obvious in response to predominant organisms associated with the disease states. PBL cultures were harvested after a 4 hour pulse with 3H-thymidine on days 4 and 6 of culture. Three separate experiments were conducted comparing one healthy group and one diseased group. In all three experiments subjects in the healthy group responded as frequently as did those in the diseased group, the dose-response distribution was indistinguishable, and the magnitude of the responses was not substantially different between groups. These results suggest nonspecific activation as the major determinant in the blastogenic response, rather than specific sensitization occurring during initiation or progression of periodontitis.

Regulatory effect of monocytes on T cell proliferative responses to oral microbial antigens

Mononuclear cell preparations isolated by Ficoll-Hypaque centrifugation from human peripheral blood were found to vary considerably in the number of monocytes they contained (mean, 20.3%; range, 13 to 33%). The regulatory role of monocytes in T cell proliferative responses to sonic extracts of a panel of oral microorganisms was therefore investigated. T cells were fractionated by anti-immunoglobulin chromatography and depleted of monocytes by treatment with a monoclonal anti-human Ia-like (DR locus antigen) antibody and complement. Purified populations of monocytes were obtained by extensive adherence procedures. The resultant cell populations were greater than 95% pure, as judged by indirect immunofluorescence on a fluorescence-activated cell sorter. Monocyte-depleted T cells failed to respond by proliferation to the nonoral antigen tetanus toxoid, as well as to any oral microorganism, but retained responsiveness to phytohemagglutinin. Readdition of monocytes in final concentrations of from 5 to 15% resulted in the restoration of maximal T cell proliferation. Monocytes in greater numbers suppressed T cell responses to all sonic extracts tested.