Immune labeling of certain strains of Actinomyces naeslundii and Actinomyces viscosus by fluorescence and electron microscopy

Relationship of Actinobacillus actinomycetemcomitans serotypes to periodontal condition: prevalence and proportions in subgingival plaque

No study available has utilized the new classification scheme (the consensus report of the American Academy of Periodontology 1999) to determine the prevalence of Actinobacillus actinomycetemcomitans in different periodontal conditions. The purpose of this study was to investigate prevalence and proportions of A. actinomycetemcomitans serotypes in subgingival plaque samples from a young Taiwanese population with aggressive periodontitis, chronic periodontitis and no periodontal disease. A total of 221 subgingival plaque samples from 171 diseased subjects (70 had aggressive periodontitis, and 101 had chronic periodontitis) (mean age 25.0 +/- 8.2 yr) and 50 periodontally healthy subjects (mean age 18.4 +/- 9.5 yr) were screened for A. actinomycetemcomitans. Serotypes of A. actinomycetemcomitans were determined by an indirect immunofluorescence assay using serotype-specific polyclonal antisera to A. actinomycetemcomitans strains ATCC 29523 (serotype a), ATCC 43728 (serotype b) and ATCC 33384 (serotype c). Prevalence (% of positive samples) of A. actinomycetemcomitans was 84.3% in aggressive periodontitis, 60.4% in chronic periodontitis, and 64.0% in periodontally healthy subjects. Proportions of A. actinomycetemcomitans (mean percentage per total bacteria) in periodontally healthy subjects were significantly lower than in aggressive periodontitis subjects. The proportion of serotype b in subjects with aggressive periodontitis and subjects with chronic periodontitis were significantly greater than that in periodontally healthy subjects. The proportion of serotype c in periodontally healthy subjects was much higher than that in chronic periodontitis subjects. The results of this study suggest that prevalence and proportions of A. actinomycetemcomitans are significantly greater in patients with aggressive periodontitis than in those with chronic periodontitis. Serotype b is the predominant serotype of A. actinomycetemcomitans in patients with diseased periodontal conditions. Serotype c is a more common serotype detected in periodontally healthy subjects.

Occurrence of Porphyromonas gingivalis and Tannerella forsythensis in periodontally diseased and healthy subjects

BACKGROUND

The purpose of this study was to compare the prevalence and level of Porphyromonas gingivalis (P. gingivalis) and Tannerella forsythensis (T. forsythensis) in subgingival plaque samples from both healthy individuals and periodontal patients in different age groups.

METHODS

A total of 498 subgingival plaque samples were studied. These samples were collected from 407 individuals diagnosed with periodontal disease (210 adult periodontitis [AP], 78 rapidly progressive periodontitis [RPP], and 119 refractory periodontitis [Ref-P] cases) and 91 healthy (H) subjects. P. gingivalis and T. forsythensis were detected by indirect immunofluorescent assay using species-specific polyclonal antisera to P. gingivalis strain (FDC 381) and T. forsythensis strain (FDC 335). The prevalence of P. gingivalis and T. forsythensis was compared by chi-square analysis. Differences in P. gingivalis and T. forsythensis levels among various periodontal status and age groups was determined by one-way analysis of variance and Fisher's multiple comparison tests. The association between the presence of P. gingivalis or T. forsythensis in different periodontal status and age groups was measured using odds ratios.

RESULTS

P. gingivalis was found in 85.7% (P < 0.0001) and T. forsythensis in 60.7% (P = 0.0002) of diseased subjects compared to 23.1% and 39.6%, respectively, in healthy subjects. P. gingivalis, but not T. forsythensis, was detected more frequently in any diseased group than in the H group in every age group (P<0.0001). No significant difference was found in the prevalence of P. gingivalis and T. forsythensis among age groups, except T. forsythensis was more prevalent in the age group of 40 to 59 years than in the age group < 20 years (chi2 = 3.93, P = 0.047) in the H group. The mean level of P. gingivalis and T. forsythensis was significantly higher in diseased groups than in the H group (P < 0.0001). The odds ratio for P. gingivalis in the AP group (25.0) was greater than any other group for P. gingivalis or T. forsythensis compared to the H group.

CONCLUSIONS

These data suggested that P. gingivalis is closely associated with the pathogenesis of periodontitis and that it may not be a normal inhabitant of periodontally healthy subjects. T. forsythensis is also important in the pathogenesis of periodontal disease; however, whether it causes periodontal disease or is a secondary invader of periodontal lesions remains to be determined.

Relationship ofActinobacillus actinomycetemcomitansSerotype b to Aggressive Periodontitis: Frequency in Pure Cultured Isolates

BACKGROUND

To our knowledge, the association of the five serotypes of Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) to the new diagnostic classification scheme defined by the American Academy of Periodontology in 1999 has not yet been described. The goal of this study was to characterize the frequencies of the five serotypes of A. actinomycetemcomitans in A. actinomycetemcomitans isolates from various forms of periodontitis using both old and new diagnostic classifications and to determine the relationships between serotype and age and clinical diagnosis.

METHODS

A total of 345 A. actinomycetemcomitans isolates from 115 A. actinomycetemcomitans culture-positive subjects (mean age 38.0 +/- 18.3 years, 59% female) were collected. Based on the new classifications, 33 subjects had aggressive periodontitis and 82 chronic periodontitis. According to old classifications, there were six prepubertal periodontitis (PPP), 12 localized juvenile periodontitis (LJP), 15 post-localized juvenile periodontitis (PLJP), 28 refractory periodontitis (Ref-P), and 54 adult periodontitis (AP) cases. Serotypes of A. actinomycetemcomitans were determined by an indirect immunofluorescence assay using serotype-specific polyclonal antisera to A. actinomycetemcomitans strains ATCC 29523, ATCC 43728, ATCC 33384, IDH 781 and IDH 1705 (serotype a, b, c, d, and e, respectively). Proportions of serotype b were examined between different diagnostic and age groups with a Z-test for proportions.

RESULTS

Most subjects (n = 100, 86.96%) were infected with a single serotype (22 serotype a, 44 serotype b, 30 serotype c, 1 serotype d, and 3 serotype e). There were 11 subjects (9.57%) with two serotypes and two subjects (1.74%) with 3 serotypes. Two individuals had isolates lacking any detectable serotype antigen. Serotype b was the predominant serotype in children under 18 years of age and young adults between 19 to 35 years, although serotype b status was not significantly associated with age. Serotypes d and e were not found in patients under 35 years old. In 62 adult patients, one subject had serotype d and three had serotype e. Serotype b was the most common serotype in aggressive periodontitis (60.61%). The proportion of cases with serotype b was significantly higher in aggressive periodontitis compared to chronic periodontitis (P = 0.031). Other serotypes were not significantly associated with new diagnostic categories. Serotypes d and e were not detected in aggressive periodontitis.

CONCLUSION

The results of this study show that proportions of serotype b of A. actinomycetemcomitans are significantly greater in culture-positive patients with aggressive periodontitis than those with chronic periodontitis.

Cell surface structures of Actinomyces israelii

Actinomyces israelii is the most common cause of human actinomycosis, a chronic granulomatous infection. Periapical actinomycosis involving A. israelii has been identified as an important cause of failure of conventional endodontic treatment. Structures on the bacterial cell surface have been implicated in the pathogenicity of Actinomyces. In this study the ultrastructure of A. israelii was investigated by electron microscopy. Negatively stained preparations revealed the presence of hairlike fimbriae protruding through a thick surface coat on some species, whilst thin sectioning disclosed a Gram-positive cell wall surrounded by a fuzzy outer coat. These structures may be important for the pathogenicity of A. israelii.

Wolinella recta in adult gingivitis and periodontitis

Wolinella recta has been associated with adult periodontitis, but its role in the disease remains uncertain. This report clarifies the distribution of W. recta in periodontally healthy and diseased subjects, and treated patients with recurrent disease. A specific polyclonal rabbit antiserum against W. recta strain 372 was used for indirect immunofluorescence localization of W. recta in dental plaque from untreated and treated patients. Supragingival plaque was collected from 15 periodontally healthy individuals (H), 10 adults with mild gingivitis (G1), 8 with severe gingivitis (G2) and 15 with periodontitis (AP). Subgingival samples from 23 diseased sites (G2 and AP) were examined as well. There was a significant difference (p = 0.000) between the proportions of W. recta in subgingival (4.4%) vs. supragingival (0.3%) plaque samples from AP. A significant difference (p = 0.000) in W. recta proportions was also detected between subgingival plaque samples of AP (4.4%) vs. G2 (1.2%). No significant difference in the mean % of W. recta was found between supragingival plaque of AP (0.3%) and G2 (0%), and samples of G1 (0.01%) and H (0.1%). In a separate study, 85 adults previously treated for moderate to severe adult periodontitis were monitored over a 12-month period for evidence of disease recurrence. Recurrent disease was detected at 32 sites in 18 subjects. Of these, 20 sites in 13 subjects were positive for W. recta. With subjects as the experimental unit, a significant increase in the proportions of W. recta was found at sites with recurrent disease (3.12%) as compared to stable, paired control sites (0.24%), but only when sites with breakdown and positive for W. recta were compared with their controls. These results indicate that W. recta is associated with some, but not all sites with advanced adult periodontitis. The association of W. recta with gingivitis was not statistically significant.

Distribution of Actinobacillus actinomycetemcomitans serotypes in periodontal health and disease

A total of 177 Actinobacillus actinomycetemcomitans isolates from 136 periodontally healthy or diseased subjects were serotyped by indirect immunofluorescence and/or immunodiffusion assays. Serotype-specific rabbit antisera against A. actinomycetemcomitans serotypes a, b and c were used. All 3 serotypes were commonly found in the study subjects. Serotype b was dominant in subjects with periodontal disease and serotype c was the most common serotype in the healthy subjects. In the immunofluorescence assay, when 85 isolates were cultured anaerobically and fixed in acetone, or cultured aerobically in 10% CO2 and heat-fixed, 60 isolates revealed the same serotypes. The remaining 25 isolates reacted with 2 of the serotype-determining reagents. In the immunodiffusion assay, 22 of these 25 isolates reacted with one antiserum only. These results suggest differences in the distribution of A. actinomycetemcomitans serotypes between periodontal health and disease and point to possible variation in serotype determination due to bacterial growth and preparation procedures.

Distribution of antigenic determinants between Actinomyces viscosus and Actinomyces naeslundii

A total of 18 monoclonal antibodies was raised against whole cells of Actinomyces viscosus and Actinomyces naeslundii. The monoclonal antibodies were used to determine the cross-reacting patterns among 26 strains of these species. Eleven different antigenic determinants were found. The specificity profiles of the antibodies indicated that the antigenic determinants of A. viscosus and A. naeslundii were arranged in a complicated mosaic. Extensive cross-reactions occurred between A. viscosus strains and strains of "typical" and "atypical" A. naeslundii. However, cross-reactions were rare between the two groups of A. naeslundii. A. viscosus appears to occupy a "middle position" between the two A. naeslundii groups. In addition to their value in seroclassification, some of the monoclonal antibodies were found to be useful in the identification of these species. One monoclonal antibody appeared to be selective for the "typical" A. naeslundii group. A. viscosus and "atypical" A. naeslundii-specific antibodies were also found, though they did not label every strain in their respective clusters. A. viscosus detection might be improved if mixtures of monoclonal antibodies were used.

Immunoelectron microscopic study of Actinomyces colony in odontogenic periapical infection

A periapical Actinomyces colony was studied by immunoelectron microscopy with a specific antiserum against Actinomyces israelii. Positive as well as some negative micro-organisms were seen within the colony. Reacting antigens were localized in the cytoplasm and the cell wall of the bacteria, which suggests that more than one antigen is involved in the reactions with the present antiserum. The ultrastructural results confirmed the applicability of the peroxidase method with Actinomyces antiserum in paraffin sections for diagnostic purposes.

Comparative histopathology of lesions produced by Actinomyces israelii, Actinomyces naeslundii, and Actinomyces viscosus in mice

The histopathologic features of experimental actinomycotic lesions produced in mice by Actinomyces israelii, Actinomyces naeslundii, and Actinomyces viscosus were examined. In lesions caused by A israelii the outer edge of the bacterial granule exhibited an eosinophilic fringe with no evidence of penetration of polymorphonuclear leukocytes (PMNs) into the bacterial granule. Chronic lesions after 6 weeks contained lobulated advancing fronts as well as areas of resolution showing heavy penetration by phagocytic cells. The number of macrophages and plasma cells in these lesions increased with time. In contrast, lesions caused by A viscosus and A naeslundii showed cellular evidence of resolution during the early stages of the infection (3-6 weeks). The bacterial core was readily penetrated and fragmented by PMNs in early A viscosus lesions. In lesions caused by A naeslundii there was less penetration of the central core by PMNs, and the bacterial granule tended to retain its structural integrity. Elongated crystals of hyaloid material appeared in lesions caused by all species. These protein-rich bodies appeared to be associated with resolving areas of the lesions. The observed contrast in the histopathologic appearance of actinomycotic lesions caused by A israelii, A naeslundii, and A viscosus is suggestive of important differences in the immune response of the host to infections caused by these three species.

Chemical and immunological comparison of surface fibrils of strains representing six taxonomic groups of Actinomyces viscosus and Actinomyces naeslundii

Human isolates of Actinomyces viscosus and Actinomyces naeslundii have been divided into six clusters in a numerical taxonomy study. Surface fibrils of strains representing these clusters were isolated and purified. Chemical analyses revealed that the major component of all fibrils was protein and that although differences in percentages of specific amino acid residues were found, the relative proportions of basic, acidic, polar uncharged, and nonpolar amino acids were rather similar among clusters. All of the fibrils except those from strain B236 (cluster 2) either failed to migrate or penetrated only slightly into gels during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, even after boiling, reduction, or alkylation. Immunological studies by electron microscopic examination of fibril-antibody immunocomplexes, whole bacterial cell agglutination, inhibition of hemagglutination, and immunofluorescence by using antifibril antisera and antibodies demonstrated that strains of typical A. naeslundii (cluster 5) have a specific fibril-associated antigen(s) distinct from those of strains of other clusters. Cross-reactions for atypical A. naeslundii (cluster 3) were few. The fibrils from A. viscosus clusters 1, 2, 4, and 6 demonstrated several cross-reactions. By absorbing antifibril antibodies with cross-reactive strains it was possible to obtain cluster-specific antibodies, as determined by whole cell agglutination, only for cluster 5. Absorbed antifibril antisera for both A. naeslundii clusters 3 and 5 were specific by indirect immunofluorescence, whereas anti-cluster 1 fibril antisera cross-reacted only with other A. viscosus cluster representatives. Purification of Actinomyces fibrils by methods used for appendages of other species yields preparations containing common antigens among taxonomic groups. However, absorbing antifibril antisera, gamma globulin, or both has promise for producing cluster-specific reagents useful in identification.

Transmission-scanning electron microscopic observations of selected Eikenella corrodens strains

The morphology of Eikenella corrodens 333/54-55 (ATCC 23834) and two human periodontal lesion isolates, strains 470 and 373, was examined by transmission and scanning electron microscopy. All strains exhibited a cell envelope characteristic of gram-negative bacteria. Staining with ruthenium red and alcian blue revealed a loosely organized fibrous slime layer associated with the outer surface of the outer membrane. Slime "stabilization" was achieved by incubation of cells with antisera prepared against whole cells of the Eikenella strains. The stabilized slime appeared as a thick, electron-opaque layer juxtaposed to the outer membrane. Negative staining and heavy metal shadow-casting revealed an interwoven network of fibrils approximately 4 nm in diameter. These fibrils appeared to represent subunits of a larger fibril. Scanning electron microscopy after antibody slime stabilization confirmed the presence and location of the slime layer.