Presence of Aggregatibacter actinomycetemcomitans in young individuals: a 16-year clinical and microbiological follow-up study.

AIM: To look for clinical signs of periodontal disease in young adults who exhibited radiographic bone loss and detectable numbers of Aggregatibacter actinomycetemcomitans in their primary dentition. MATERIAL AND METHODS: Periodontal status and radiographic bone loss were examined in each of the subjects 16 years after the baseline observations. Techniques for anaerobic and selective culture, and checkerboard, were used to detect periodontitis-associated bacterial species. The isolated A. actinomycetemcomitans strains were characterized by polymerase chain reaction. RESULTS: Signs of localized attachment loss were found in three out of the 13 examined subjects. A. actinomycetemcomitans was recovered from six of these subjects and two of these samples were from sites with deepened probing depths and attachment loss. Among the isolated A. actinomycetemcomitans strains, serotypes a-c and e, but not d or f, were found. None of the isolated strains belonged to the highly leucotoxic JP2 clone, and one strain lacked genes for the cytolethal distending toxin. CONCLUSIONS: This study indicates that the presence of A. actinomycetemcomitans and early bone loss in the primary dentition does not necessarily predispose the individual to periodontal attachment loss in the permanent dentition.

Tracking of plasma antibodies against Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis during 15 years.

BACKGROUND: Plasma antibody measurements of antibody levels to periodontal pathogens may be used to support diagnosis, disease activity, classification, and prognosis of periodontitis. OBJECTIVE: The aim of this study was to investigate the long-term stability of plasma antibody levels against Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. DESIGN: Plasma immunoglobulin G (IgG) antibody levels against the pathogens were analyzed annually during 15 years from 21 voluntary subjects, whose periodontal status was not known at the point of selection. The total number of plasma samples was 315. In connection of the last sampling, the clinical and radiographic periodontal status was examined. Pooled bacterial samples from periodontal pockets, as well as salivary samples were collected for A. actinomycetemcomitans and P. gingivalis detection, and antibody determinations, respectively. According to the clinical status, six subjects had periodontitis, whereas 15 did not. RESULTS: Plasma IgG-class antibody levels to periodontal pathogens remained extremely stable during the 15-year period and no significant (p>0.05) intra-individual variations were observed. Retrospectively, the average plasma IgG antibody levels against A. actinomycetemcomitans and P. gingivalis were 1.6-2.3 (p<0.05) and 1.4-1.7 (p<0.05) fold higher in the subjects with periodontitis than those without, respectively, during the whole 15-year tracking. As expected, at the time of the periodontal examination the plasma and salivary IgG antibody levels were associated both with periodontitis and bacterium-positivity. CONCLUSIONS: Plasma IgG levels against A. actinomycetemcomitans and P. gingivalis are extremely stable during 15 years both in subjects with and without periodontitis.

Pro-atherogenic properties of lipopolysaccharide from the periodontal pathogen Actinobacillus actinomycetemcomitans.

An association between cardiovascular and periodontal disease may be due to lipopolysaccharide (LPS)-promoted release of inflammatory mediators, adverse alterations of the lipoprotein profile, and an imbalance in cholesterol homeostasis. Since periodontopathogenic potential differs between serotypes of a major periodontal pathogen, Actinobacillus actinomycetemcomitans, we studied the pro-atherogenic properties of LPS preparations from serotypes b and d strains on macrophages (RAW 264.7). A. actinomycetemcomitans LPS preparations induced a time-dependent release of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). LPS induced foam cell formation and cholesteryl ester accumulation from native low density lipoprotein in the following order: A. actinomycetemcomitans strains JP2 (serotype b) > Y4 (serotype b) > IDH781 (serotype d). mRNA expression levels of scavenger receptor class B, type-I, and ATP-binding cassette transporter-1, receptors mediating cholesterol efflux from macrophages, were decreased by LPS preparations. The results suggest that the pro-atherogenic potential of A. actinomycetemcomitans LPS may depend on the infecting strain and correlate with the periodontopathogenic potential of the pathogen.

Characteristics of periodontal microflora in acute myocardial infarction.

BACKGROUND: Periodontitis has been linked to increased risk of cardiovascular diseases. Systemic reactions associated with cardiovascular events may depend on characteristics of the subgingival microflora in periodontitis. Our objectives were to compare the numbers of cultivable bacteria, composition of subgingival microflora and clonal distribution of Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) in two groups of patients with generalized chronic periodontitis (GCP), one with an acute myocardial infarction (AMI-GCP) and the other one without AMI (non-AMI-GCP). METHODS: In all, 150 dentate individuals were screened for suitability to this study. Subgingival bacterial samples were collected from 11 AMI-GCP and 11 non-AMI-GCP patients who had been selected using strict inclusion criteria in an attempt to exclude confounding factors and to increase comparability of periodontal conditions by matching for periodontal probing depths and attachment levels. Culture methods were used to determine the total viable counts and occurrence and proportions of six periodontal bacterial species and yeasts. Polymerase chain reaction (PCR) technique was used to detect A. actinomycetemcomitans and Porphyromonas gingivalis (P. gingivalis). Intraspecies characterization of A. actinomycetemcomitans included serotyping and genotyping. RESULTS: The mean proportions of P. gingivalis (P = 0.05) and Tannerella forsythensis (T. forsythensis) (P = 0.01) were significantly lower, but the numbers of Micromonas micros (M. micros) and A. actinomycetemcomitans were up to nine times higher and the mean total number of cultivable bacteria per sample higher (P <0.01) in AMI-GCP than in non-AMI-GCP. CONCLUSION: The findings that no target subgingival species were overrepresented but the total bacterial number was higher in AMI-GCP than non-AMI-GCP patients may provide support to the hypothesis that elevated numbers of bacteria in close vicinity to sterile parenteral area present a risk for systemic health.

Actinobacillus actinomycetemcomitans serotype d-specific antigen contains the O antigen of lipopolysaccharide.

Actinobacillus actinomycetemcomitans is a gram-negative, facultatively anaerobic bacterium which is associated especially with aggressive forms of periodontitis. Contradictory results on the localization of the A. actinomycetemcomitans serotype-specific antigen have been reported. The aim of the present study was to characterize the A. actinomycetemcomitans serotype d-specific antigen. The antigen was isolated by affinity chromatography. The affinity column was prepared from immunoglobulin G isolated from rabbit antiserum raised against A. actinomycetemcomitans serotype d. The isolated antigen was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and silver staining, all of which revealed a ladder-like structure typical for the O antigen of lipopolysaccharide (LPS). In a displacement enzyme-linked immunosorbent assay (ELISA), the isolated antigen displaced in a concentration-dependent manner the binding of the polyclonal rabbit antiserum raised against A. actinomycetemcomitans serotype d to the competing whole-cell serotype d antigen. The isolated antigen contained LPS, and an equal concentration of LPS isolated from A. actinomycetemcomitans serotype d gave a similar displacement curve in the ELISA. In order to test the immunogenic properties of the isolated antigen, it was used to immunize a rabbit. The antiserum raised against the isolated antigen displayed specificity in Western blotting and ELISA similar to that of antibody raised against LPS isolated from A. actinomycetemcomitans serotype d. In conclusion, our results show that the A. actinomycetemcomitans serotype d-specific antigen contains the O-antigenic structure of LPS.

Subgingival microflora in Turkish patients with periodontitis.

BACKGROUND: No information exists on periodontitis-associated subgingival microbiota from Turkey. We determined the occurrence, interspecies relationships, and clonal characteristics for a group of periodontal bacteria in a Turkish study population. METHODS: Subgingival microbial samples were obtained from patients with localized (LAgP, N = 18) or generalized (GAgP, N = 17) types of aggressive periodontitis, generalized chronic periodontitis (GCP, N = 14), and non-periodontitis subjects (N = 20). Culture methods were used to recover 6 periodontal bacterial species and yeasts, and a polymerase chain reaction technique was used to detect Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Intraspecies characterization of A. actinomycetemcomitans was carried out by serotyping and genotyping. RESULTS: All species, except for Micromonas micros (formerly Peptostreptococcus micros) occurred more frequently (P < 0.05) in periodontitis than non-periodontitis subjects. Detection frequencies for Tannerella forsythensis (formerly Bacteroides forsythus) and Campylobacter rectus differed among the periodontitis subgroups; the lowest frequency occurred in LAgP. The mean proportions of A. actinomycetemcomitans, P. gingivalis, and C. rectus were higher (P < 0.008) in GAgP than in non-periodontitis subjects. Significant positive associations were seen between 7 of the 22 possible combinations (P < 0.05). A. actinomycetemcomitans serotype c (34%) and non-serotypeable isolates (34%) were the most common antigenic types among the 305 strains analyzed. Eleven arbitrarily primed (AP)-PCR genotypes were distinguished among 273 isolates from 29 subjects. Yeasts were found in 23% of the 69 subjects. CONCLUSIONS: The results on the Turkish study population were generally in line with earlier reports on the occurrence and interspecies relationships of certain bacteria in periodontitis. However, A. actinomycetemcomitans was not overrepresented in LAgP, and the serotype distribution resembled that reported from the East. The high frequency of non-serotypeable isolates suggests local characteristics of the species.

Actinobacillus actinomycetemcomitans proportion of subgingival bacterial flora in relation to its clonal type.

We investigated whether certain Actinobacillus actinomycetemcomitans clones occur in elevated proportions in subgingival flora, and if the proportions relate to other bacteria in the samples. A total of 121 A. actinomycetemcomitans strains from 121 patients with periodontitis were serotyped and 60 strains were also genotyped. The 121 strains were divided into three groups and the 60 strains into two groups according proportion of A. actinomycetemcomitans. The samples from the 60 patients with genotyped strains were cultured for five other species. Among the 121 strains, serotype b occurred significantly more frequently in the high- (n = 14, proportions > 5%, mean = 18.09, SD = 20.07%) than low- (n = 49, proportions < or = 0.1%), mean = 0.04, SD = 0.03%) or intermediate-proportion groups (n = 58, proportions > 0.5%, mean = 1.31, SD = 1.24%). Genotype 3 occurred significantly more frequently in samples with low A. actinomycetemcomitans proportions (n = 28, < or = 0.1%, mean = 0.04, SD = 0.03%) than in those with high proportions (n = 32, > 0.1%, mean = 5.70, SD = 14.60%). No differences were seen in the detection frequencies or proportions of the five bacterial species between the samples with low or high A. actinomycetemcomitans proportions. The results indicate that certain clonotypes of A. actinomycetemcomitans may preferentially occur as low proportions, suggesting their controlled growth. Conversely, some serotype b clones may have a competitive advantage in subgingival flora.