Simultaneous isolation of Actinobacillus actinomycetemcomitans from subgingival and extracrevicular locations of the mouth

Abstract In the present study, a total of 619 subgingival and extracrevicular samples from 66 early-onset periodontitis, 42 adult periodontitis/gingivitis and 36 treated Actinobacillus actinomycetemcomitans-associated periodontitis patients were selectively cultivated for presence of A. actinomycetemcomitans. The organism was recovered from 68% cases with early-onset periodontitis, 24% cases with adult periodontitis/gingivitis and 50% of treated patients. Associations between recovery from pooled subgingival plaque and samples from extracrevicular locations as well as between different extracrevicular samples, were not heterogeneous with regard to different groups with the exception for cheek/saliva comparisons (odds ratios: early-onset periodontitis 825; adult periodontitis 8.1; treated patients 117; 0.05<p<0.1). For associations between recovery of A. actinomycetemcomitans from pooled subgingival plaque/extracrevicular samples, Mantel-Haenszel's odds ratios of between 12.2 and 21.6 were calculated (p<0.0001). The organism was isolated from 17 cheek mucosa samples of 18 patients identified as still harboring the organism after therapy. Present results point to the considerable value of cheek mucosa samples especially in treated patients to diagnose persistent A. actinomycetemcomitans colonization of the oral cavity.     

Immunodominant antigens of Actinobacillus actinomycetemcomitans serotype b in early-onset periodontitis patients

Previous work with Actinobacillus actinomycetemcomitans strain Y4 (serotype b) indicates that the immunodominant antigen in high-responding patients (top 10%, 80% of which were black) is the serotype-specific antigen. In this study we examined the immunodominant antigens of A. actinomycetemcomitans strain Y4 in both black and white patients having a range of antibody titers. We sought to test the hypothesis that the immunodominant antigen in these subjects was the same antigen found in high responders. Seropositive white early-onset periodontitis (EOP) patients were selected from 99 EOP patients. Black subjects were then selected with comparable antibody titers. Double immunodiffusion and competition assays were used to determine whether reactive antibodies were A. actinomycetemcomitans serotype b-specific or whether the response was to serotype a or c. The immunodominant antigens were then determined for the patients reacting specifically to A. actinomycetemcomitans Y4 using limiting dilution analysis on Western blots. The immunodominant antigen for the A. actinomycetemcomitans Y4-specific patients appeared to be the serotype-specific carbohydrate for most subjects (19/20 or 95%, including: 13/14 black and 6/6 white patients). In conclusion, the immunodominant antigen for A. actinomycetemcomitans Y4 was the serotype-specific carbohydrate regardless of antibody titer for both black and white specifically reactive patients.     

Localized juvenile periodontitis and Actinobacillus actinomycetemcomitans in a Brazilian population

Localized juvenile periodontitis (LJP) has been used as a model for studying periodontal disease, and its prevalence is considered to be higher in third-world countries (0.3–8%) than in industrialized countries (0.1%). Mostly, the disease has been associated with Actinobacillus actinomycetemcomitans ( A.a. ) but lack of association has also been reported. The aim of this study was to identify LJP patients in geographically different Brazilian populations and assess the presence of A.a. in their periodontal lesions. 7843 children, 12–19–years of age, from the cities of Rio de Janeiro, Votorantim and Belo Horizonte were screened, and LJP patients were identified by strict clinical and radiographical criteria. A final LJP prevalence of 0.3%, with a 99% confidence interval between 0.16%) to 0.47%, was found. The prevalence in the subpopulations varied between 0.1–1.1% in the different areas. Subgingival bacterial samples were obtained from the oral cavity of 25 patients and their family members. 80% of these patients, 39.5% of their family members, 35.3% of their parents, and 43.9% of all siblings were culture positive for A.a. All but one of the families had at least one member in addition to the patient who was culture positive for A.a. In 3 families, >1 member showed radiographic and clinical signs of LJP. 30% of non-LJP subjects coming from one of the areas with higher LJP prevalence harbored A.a. We conclude that LJP is highly associated with A.a. in this Brazilian population.     

Significance of serum antibody against surface antigens of Actinobacillus actinomycetemcomitans in patients with adult periodontitis

This study was undertaken to examine the prevalence of Actinobacillus actinomycetemcomitans , its serotype distribution and the serum immune responses against its surface antigens in 41 Japanese patients with adult periodontitis. The dominant A. actinomycetemcomitans serotype isolated was serotype c. Immunoblot analysis of 3 serotypes of A. actinomycetemcomitans -sonicated antigens and the patient sera revealed that the reactivities with serotype c were the most frequent and that heat-stable surface serotype-specific antigen appeared to be immunodominanl. Elevated serum immunoglobulin G titers to extracted lipopolysaccharide and fimbriae antigen of A. actinomycetemcomitans were noted for the patient sera by enzyme-linked immunosorbent assay. High serum immunoglobulin G tilers to the fimbriae antigen detected in patients without cultivable A. actinomycetemcomitans suggested Ihe possibilily that the clicked antibody to the antigen played a role in eliminating A. actinomycetemcomitans from the periodontal lesions.     

Black-pigmented Bacteroides species and Actinobacillus actinomycetemcomitans in subgingival plaque of adult Kenyans

A microbiological study was performed of the subgingival plaque on 2 sites in each of 20 adults originating from a rural area 40 km outside Nairobi, Kenya. The recovery rate of B. gingivalis was 70%, of B. intermedius 100% and of A. actinomycetemcomitans 40% of the subjects, and 50%, 90% and 28%, respectively, of the sites. The isolated strains exhibited similar biochemical characteristics and antibiotic susceptibility pattern as type strains of these species. The high recovery rate of these 3 bacterial species in adult Kenyans was a rather surprising finding, since pathological pocketing was found only sporadically. Furthermore, the results of 2 methodological approaches tested demonstrated that such microbiological studies can be carried out in countries with limited laboratory facilities.     

Characterization of serum antibody to Actinobacillus actinomycetemcomitans GroEL-like protein in periodontitis patients and healthy subjects

Recent evidence suggests that molecular mimicry between bacterial and human heat shock protein 60 (hsp60) is involved in various conditions of autoimmune and infectious diseases. Many periodontopathic bacteria have been reported to express GroEL-like protein that is homologous to human hsp60. In this study, the presence of antibodies to the hsp60 of Actinobacillus actinomycetemcomitans in the sera of periodontitis patients and periodontally healthy control subjects was evaluated by enzyme-linked immunosorbent assay using a recombinant A. actinomycetemcomitans GroEL as an antigen. Furthermore, their cross-reactivity with Escherichia coli GroEL and Mycobacterium bovis BCG hsp65 was examined. The mean values of antibody were 0.624 (range 0.088-1.113) and 0.728 (range 0.217-1.296) in control subjects and periodontitis patients, respectively. The antibody levels to A. actinomycetemcomitans after absorption with E. coli GroEL and M. bovis BCG clearly decreased in both control subjects and periodontitis patients. The remaining antibody levels to A. actinomycetemcomitans GroEL after absorption with M. bovis BCG hsp65 were higher than those with E. coli GroEL, indicating higher cross-reactivity with E. coli GroEL. These results suggest that not only periodontitis patients but also periodontally healthy subjects may be infected with A. actinomycetemcomitans but that the part of the antibody could be derived from the cross-reactivity with E. coli GroEL. Any relationship of the antibody to the disease, however, remains to be determined.     

Actinobacillus actinomycetemcomitans, Capnocytophaga and Porphyromonas gingivalis in subgingival plaque of adolescents with Down''s syndrome

Levels of Actinobacillus actinomycetemcomitans, Capnocytophaga and Porphyromonas gingivalis were determined in subgingival plaque samples from 37 adolescents with Down's syndrome and 37 healthy controls matched with respect to age and sex. Gingival inflammation, supra- and subgingival calculus, periodontal pockets ( > 4 mm) and alveolar bone loss were registered. Alveolar bone loss was more frequent in Down's syndrome subjects (32%) than in the controls (3%). A. actinomycetemcomitans was detected in the subgingival plaque in 35% of the Down's syndrome adolescents and in 5% of the controls. On site level, A. actinomycetemcomitans and Capnocytophaga were more frequent in the subgingival plaque samples of Down's syndrome children than in those of controls. Comparing Down's syndrome subjects positive or negative for A. actinomycetemcomitans and Capnocytophaga, no significant differences were found in terms of gingival inflammation, periodontal pockets ( > 4 mm) or number of sites with alveolar bone loss. The results indicate an altered microbial composition of the subgingival plaque of Down's syndrome subjects compared with healthy controls, with higher frequency of A. actinomycetemcomitans.     

Quantitative aspects of the subgingival distribution of Actinobacillus actinomycetemcomitans in a patient with localized juvenile periodontitis

Abstract The subgingival microflora in a patient with localized juvenile periodontitis was studied. Of the 97 sites investigated, 28 (29%) showed attachment loss. A correlation was found between the number of Actinobacillus actinomycetemcomitans cells and the clinical attachment level and probing pocket depth. Of the 97 test sites, 70 (73%) were positive for A. actinomycetemcomitans. Of the total number of A. actinomycetemcomitans cells isolated from this patient, more than 99% were found at sites with attachment loss, <1 % being present at sites without attachment loss. The mean percentage of A. actinomycetemcomitans was 21.2% at sites with attachment loss and 0.45% at sites without attachment loss. The distribution of Porphyromonas gingilis showed a symmetrical pattern, being present at the 1st molar and 2nd premolar sites in all quadrants and at the lower incisor sites. This species was absent at multiple sites showing overt attachment loss.     

Actinobacillus actinomycetemcomitans in human periodontal disease

Recent evidence implicates Actinobacillus actinomycetemcomitans in the etiology of localized juvenile periodontitis. This paper reviews the morphological, biochemical and serological charcteristics of A. actinomycetemcomitans, evidence incriminating it as a periodontopathogen, its importance in human nonoral infections, and virulence factors which may be involved in the pathogenesis of A. actinomycetemcomitans infections. A. actinomycetemcomitans is a non-motile, gram-negative, capnophilic, fermentative coccobacillus which closely resembles several Haemophilus species but which does not require X or V growth factors. The organism has been categorized into 10 biotypes based on the variable fermentation of dextrin, maltose, mannitol, and xylose and into 3 serotypes on the basis of heat stable, cell surface antigens. A. actinomycetemcomitans' primary human ecologic niche is the oral cavity. It is found in dental plaque, in periodontal pockets, and buccal mucosa in up to 36% of the normal population. The organism can apparently seed from these sites to cause severe infections throughout the human body such as brain abscesses and endocarditis. There is a large body of evidence which implicates A. actinomycetemcomitans as an important micro-organism in the etiology of localized juvenile periodontitis including: (1) an increased prevalence of the organism in almost all localized juvenile periodontitis patients and their families compared to other patient groups; (2) the observation that localized juvenile periodontitis patients exhibit elevated antibody levels to A. actinomycetemcomitans in serum, saliva and gingival crevicular fluid; (3) the finding that localized juvenile periodontitis can be successfully treated by eliminating A. actinomycetemcomitans from periodontal pockets; (4) histopathologic investigations showing that A. actinomycetemcomitans invades the gingival connective tissue in localized juvenile periodontitis lesions; (5) the demonstration of several pathogenic products from A. actinomycetemcomitans including factors which may: (a) facilitate its adherence to mucosal surfaces such as capsular polysaccharides; (b) inhibit host defense mechanisms including leukotoxin, a polymorphonuclear leukocyte chemotaxis inhibiting factor, and a lymphocyte suppressing factor (c) cause tissue destruction such as lipopolysaccharide endotoxin, a bone resorption-inducing toxin, acid and alkaline phosphatases, collagenase, a fibroblast inhibiting factor and an epitheliotoxin.(ABSTRACT TRUNCATED AT 400 WORDS)     

Actinobacillus actinomycetemcomitans recovery from extracrevicular locations of the mouth

Associations between recovery of Actinobacillus actinomycetemcomitans from samples of subgingival plaque, and samples of buccal mucosa, tongue and unstimulated saliva were studied in 107 subjects. Ten subjects had gingivitis, 18 localized juvenile periodontitis, 45 rapidly progressive periodontitis and 32 adult periodontitis. Two children suffered from prepubertal periodontitis. Heterogeneity tests for associations in different study populations yielded nonsignificant results. Mantel-Haenszel's common odds ratios were 52.9, 37.2 and 19.8 for respective associations between pooled subgingival samples, and cheek, saliva and tongue samples. Significant McNemar's chi-square of 5.88, 11.25 and 16.96 for respective associations pointed to secondary occurrence of A. actinomycetemcomitans in extra-crevicular samples. Multiple linear regression yielded a significant influence of the number of deep periodontal pockets of 7 mm or more and a negative influence of the diagnosis "adult periodontitis" on the log-transformed number of colony-forming units of A. actinomycetemcomitans in samples from cheek mucosa in patients infected with the organism. Extracrevicular occurrence of A. actinomycetemcomitans seems to reflect total subgingival numbers of the organism. Especially sampling check mucosa appears to be a promising tool in the diagnosis of a periodontal infection with A. actinomycetemcomitans .     

Characterization of serum antibody to Actinobacillus actinomycetemcomitans GroEL‐like protein in periodontitis patients and healthy subjects

Recent evidence suggests that molecular mimicry between bacterial and human heat shock protein 60 (hsp60) is involved in various conditions of autoimmune and infectious diseases. Many periodontopathic bacteria have been reported to express GroEL‐like protein that is homologous to human hsp60. In this study, the presence of antibodies to the hsp60 of Actinobacillus actinomycetemcomitans in the sera of periodontitis patients and periodontally healthy control subjects was evaluated by enzyme‐linked immunosorbent assay using a recombinant A. actinomycetemcomitans GroEL as an antigen. Furthermore, their cross‐reactivity with Escherichia coli GroEL and Mycobacterium bovis BCG hsp65 was examined. The mean values of antibody were 0.624 (range 0.088–1.113) and 0.728 (range 0.217–1.296) in control subjects and periodontitis patients, respectively. The antibody levels to A. actinomycetemcomitans after absorption with E. coli GroEL and M. bovis BCG clearly decreased in both control subjects and periodontitis patients. The remaining antibody levels to A. actinomycetemcomitans GroEL after absorption with M. bovis BCG hsp65 were higher than those with E. coli GroEL, indicating higher cross‐reactivity with E. coli GroEL. These results suggest that not only periodontitis patients but also periodontally healthy subjects may be infected with A. actinomycetemcomitans but that the part of the antibody could be derived from the cross‐reactivity with E. coli GroEL. Any relationship of the antibody to the disease, however, remains to be determined.     

Clinical significance of Actinobacillus actinomycetemcomitans in young individuals during orthodontic treatment

Abstract The aim of the present study was: (I) to assess longitudinally the occurrence of Actinobacillus actinomycetemcomitans (Aa) in young subjects wearing fixed orthodontic appliances compared to matched appliance-free controls: (2) to determine whether the presence of the micro-organism at baseline could influence the periodontal status assessed 3 years later. 70 subjects. 27 male and 43 female. aged between 12 and 20 years participated in the study: 35 subjects under orthodontic treatment with fixed appliances for at least 6 months, and 35 appliance-free individuals matched for age and gender. All subjects were free of clinically demonstrable loss of attachment. They all received oral hygiene instructions 2× during the 2 months preceding the first clinical and microbiological examination. No subgingival instrumentation was performed between baseline and the 3-year examination. Clinical parameters included gingival bleeding index (GBI). pocket probing depth (PPD) and measurements of attachment level (AL). Statistically significant differences were reported regarding frequency of detection of Aa between both groups at each examination. The %s of orthodontic subjects infected with Aa at the baseline and at the 3-year examination were 86% and 80%, respectively, while the corresponding figures for control subjects were 16.6% and 26.6%. The frequency distribution of %s of Aa in the total anaerobic subgingival flora among control subjects remained fairly stable, whereas the proportion of orthodontic subjects yielding Aa at a concentration 1.0% dropped significantly from 32% at baseline to 19% at the 3-year visit. Calculations of the relative risk for increasing GBI and PPD in both groups when Aa was present at baseline, revealed that the orthodontic subjects positive for Aa had a negligible relative risk of experiencing worse periodontal conditions compared to orthodontic patients where Aa was not detected at baseline. In contrast, control subjects initially infected with Aa presented with a risk for increased GBI 6.6×higher than that for subjects without Aa. In conclusion, the present study confirmed previous cross-sectional findings reporting that young individuals with an integer periodontium wearing fixed orthodontic appliances harbor Aa with a statistically significant greater frequency than appliance-free matched controls. However, although orthodontic patients exhibited more inflammation, their deteriorated clinical conditions could not be accounted for by the sole presence of Aa in their sulci. In contrast, appliance-free young subjects initially infected with Aa had a higher risk of experiencing more gingival inflammation than subjects without the bacterium during a 3-year observation period.     

Eradication of Actinobacillus actinomycetemcomitans from the oral cavity in adult periodontitis

Eradication of Actinobacillus actinomycetemcomitans from the oral cavity seems to be a prerequisite for successful therapeutic outcome in patients periodontally infected with the organism. In view of the limited number of subgingival samples obtained in recent studies one cannot conclude, however, whether eradication has actually been achieved. In the present study clinical and microbiological parameters were monitored in 10 adult patients with A. actinomycetemcomitans-associated periodontitis during successive non-surgical and adjunctive metronidazole plus amoxicillin (or ciprofloxacin) (AB) therapy. In every patient, 13 extracrevicular samples and subgingival samples from the deepest site of every tooth present were selectively cultivated for A. actinomycetemcomitans. The organism was isolated in 47 ± 29% subgingival and 64 ± 31% extracrevicular samples. Six weeks following subgingival scaling, A. actinomyceterncomitans was detected in 37 ± 30% subgingival and 55 ± 38% extracrevicular samples (n.s.). Three months after antibiotic therapy, the organism was recovered from only 1 patient. At baseline, 7.5 ± 4.2% sites had a probing pocket depth (PPD) ≥7 mm. This proportion dropped to 2.3 ± 2.4% after scaling (p<0.05) and to 0.3 ± 0.4% after AB (p<0.05). The proportion of sites with clinical attachment loss (CAL) ≥6 mm dropped from 23.3 ± 13.3% to 17.7 ± 13.4% (p<0.05) and to 16.8 ± 14.6%. Statistical analysis revealed that the organism was strongly related, at baseline, to PPD ≥7 mm (odds ratio 9.8, p<0.001). Six weeks after scaling, the organism was associated with CAL ≥6mm (odds ratio 1.8, p = 0.02). After scaling, high counts of A. actinomycetemcomitans in excess of 10⁴ CFU/ml significantly interfered with attachment gain of ≥2 mm (odds ratio 0.24, p = 0.001). Based on the present findings, eradication of A. actinomycetemcomitans seems to be possible with adjunctive antibiotic treatment. Elimination of the organism after scaling was only weakly associated with clinical improvement.     

Actinobacillus actinomycetemcomitans,Capnocytophaga and Porphyromonas gingivalis in subgingival plaque of adolescents with Down's syndrome

Levels of Actinobacillus actinomycetemcomitans, Capnocytophaga and Porphyromonas gingivalis were determined in subgingival plaque samples from 37 adolescents with Down's syndrome and 37 healthy controls matched with respect to age and sex. Gingival inflammation, supra- and subgingival calculus, periodontal pockets (>4 mm) and alveolar bone loss were registered. Alveolar bone loss was more frequent in Down's syndrome subjects (32%) than in the controls (3%). A. actinomycetemcomitans was detected in the subgingival plaque in 35% of the Down's syndrome adolescents and in 5% of the controls. On site level, A. actinomycetemcomitans and Capnocytophaga were more frequent in the subgingival plaque samples of Down's syndrome children than in those of controls. Comparing Down's syndrome subjects positive or negative for A. actinomycetemcomitans and Capnocytophaga, no significant differences were found in terms of gingival inflammation, periodontal pockets (>4 mm) or number of sites with alveolar bone loss. The results indicate an altered microbial composition of the subgingival plaque of Down's syndrome subjects compared with healthy controls, with higher frequency of A. actinomycetemcomitans.     

Supragingival and subgingival microbiota of adult patients with Down''s syndrome. Changes after periodontal treatment

In this longitudinal study, five adult Down's syndrome patients with periodontitis were placed on a frequent recall visit schedule (every 6 weeks) after treatment, in order to investigate: 1) the microbiological status, both supragingivally and subgingivally, and the changes that occurred after treatment and 2) the effect of frequent professional supragingival plaque control on the subgingival microbiota and clinical variables in these patients. The clinical variables recorded were probing pocket depth, probing attachment level, bleeding on probing and presence of plaque (full mouth, six surfaces per tooth). Microbiological examination was performed separately for supragingival and subgingival samples from the same site for 14 species, using whole genomic DNA probes and the "checkerboard" DNA-DNA hybridization technique. The findings indicate that, although a reduction of periodontal indices was noticed, plaque levels remained high (60%) even at the end of the experimental period. Periodontal pathogens including Porphyromonas gingivalis, Bacteroides forsythus and Actinobacillus actinomycetemcomitans were frequently detected both supragingivally and subgingivally (>30%). The presence of a species supragingivally and the presence at the same time points subgingivally were correlated. This finding suggested that supragingival plaque acts as a reservoir for reinfection of treated sites. A reduction of the percentages of detection of these species was noticed 1 month after an oral hygiene period as well as at 3 and 6 months after treatment. Inadequate oral hygiene as performed by these patients probably affected supragingival, and consequently subgingival, plaque composition.     

Postoperative bleeding tendency as a risk factor in Actinobacillus actinomycetemcomitans-associated periodontitis

Frequent bleeding on probing (BOP) has been considered a risk factor for recurrence of periodontitis. In the present study, 29 patients with Actinobacillus actinomycetemcomirans-associated periodontitis were enrolled in a carefully performed recall system. At 6 sites per tooth, periodontal probing depth (PPD), gingival index (GI), plaque index (PII) and BOP was assessed 6 weeks, 6 months, 1 and 2 years after comprehensive therapy. Professional toothcleaning and subgingival scaling at sites with PPD ≥ 5 mm and BOP was carried out every 2nd or 3rd month. Subgingival samples from 2 sites, a pooled subgingival sample, check mucosa, saliva and tongue samples were selectively cultivated for A. actinomycetemcomitans after 2 years. Following active therapy, 8 % sites had a PPD of ≥ 4 mm, whereas 21 % sites bled on probing. After 2 years, respective figures were 12 and 27 %. During maintenance, frequent BOP (≥3 times at 4 visits) had a predictive value of 0.133 to indicate an increase in PPD of ≥ 2 mm and a negative predictive value of 0.947. The predictive value of no bleeding to indicate a stable site was 0.972, the negative predictive value 0.078. There was evidence for heterogeneity of associations between increase in PPD of ≥ 2 mm and ≥ 3 times BOP among patients (X²₍₂₈₎ = 41.45, p < 0.05). Significant sources for the variation of weighted In-transformed estimates of individual odds ratios (range -0.83 to 6.21, median 1.52) were relative numbers of A. actinomycetemcomitans-positive samples 2 years after therapy, age, and mean % of PII 2 (R² =0.439, p<0.001). No association between increase in PPD and BOP was found in patients where A. actinomycetemcomitans was not recovered from any sample (X²_MH = 1.96), but A. actinomycetemcomitans-positive subjects still had inconsistent associations (X²_MH = 37.65. p < 0.01). Ignoring patient characteristics may be misleading in the search for risk factors for recurrence of the disease.     

Frequency and stability of mono-or poly-infection by Actinobacillus actinomycetemcomitans serotypes a, b, c, d or e

The aims of the study were to determine the prevalence of simultaneously multiple Actinobacillus actinomycetemcomitans serotypes in one individual, stability of infection by the same serotype and the occurrence of previously not described serotypes of A. actinomycetemcomitans. The serotypes of 515 clinical isolates of A. actinomycetemcomitans from 91 Finnish, Caucasian subjects, including 321 follow-up samples from 51 subjects, were determined with immunodiffusion assay. Most subjects (n = 86, 95%) were infected with one serotype only; 466 (91%) isolates from 80 subjects belonged to serotype a (25% of isolates/25 subjects), b (25% of isolates/27 subjects) or c (41% of isolates/30 subjects). Fifteen isolates from 4 subjects reacted with the antiserum raised against previously untypable clinical strain IDH 781 (serotype d) and 18 isolates from 5 subjects with the antiserum raised against strain IDH 1705 or IDH 3096 (serotype e). Sixteen (3%) isolates from 5 subjects remained untypable. The same infecting A. actinomycetemcomitans serotype(s) persisted for the 1-6 years of follow-up. In conclusion, the study indicates a rare simultaneous occurrence of multiple oral A. actinomycetemcomitans serotypes, the stability of infection by the same serotype(s) and the existence of serotypes of A. actinomycetemcomitans not previously described.     

Potential diagnostic value of sampling oral mucosal surfaces for Actinobacillus actinomycetemcomitans in young adults*

Actinobacillus actinomycetemcomitans has been implicated in the pathogenesis of several forms of early onset and refractory adult periodontitis. Early diagnosis of colonization of the oral cavity might be of importance in order to initiate preventive measures. The aim of the present study was to determine the potential diagnostic value of oral mucosal and salivary tests to identify, among healthy young men with no or minor periodontal disease, individuals colonized by A. actinomycetemcomitans. Two hundred and one male recruits. 18–25 yr of age, took part in the present study. Mean values of periodontal parameters suggested only minor periodontal disease. Of the sites, 64.8±17.6% (mean ± SD) had a periodonta) probing depth (PPD) of 1 or 2 mm. only 1.6±2.9% deep sites of 5 mm were detected. More than 1000 subgingival and extracrevicular samples were selectively cultivated for A. actinomycetemcomitans. The organism was isolated in 55 subjects (21%). The odds for presence of at least 1 deep site of 5 mm was increased by a factor 1.99 if A. actinomycetemcomitans could be recovered. In identifying subjects colonized by A. actinomycetemcomitans. diagnostic test parameters sensitivity and predictive value for a negative test were 74.5±5.9% and 91.1±2.3%', respectively, for both saliva and dorsum of tongue samples. In contrast, pooled subgingival plaque from mesial surfaces of 1st molars was only 34.5±6.4% sensitive: the negative predictive value was 80.2±3.0%. The results point to a high diagnostic value of oral mucosal and especially saliva samples to identify young adult individuals colonized by A. actinomycetemcomitans.     

Clonal diversity of Actinobacillus actinomycetemcomitans isolates from young adults with minimal periodontal disease

Actinobacillus actinomycetemcomitans is a major periodontal pathogen which is associated with both early-onset periodontitis and adult cases refractory to conventional periodontal therapy, although the organism has also been shown to be widely distributed among dentate healthy individuals. The observed disease status may be associated with a variation in virulence of different strains or clones. The aim of the present study was to analyse genotype distribution as assessed by an arbitrarily primed polymerase chain reaction (AP-PCR) among 51 isolates of A. actinomycetemcomitans recovered from more than 200 young adult recruits with no or minor periodontal disease. In addition, isolates from 25 periodontitis patients as well as reference strains were genotyped. Primers amplifying (i) a specific sequence in the ltxA region, (ii) a specific 16S rRNA sequence and (iii) sequences in the leukotoxin promoter region were used to verify species identity of the strains. Three random oligonucleotide primers were employed to analyse genomic polymorphisms of the organism by means of PCR. A total of 19 genotypes could be distinguished, which were grouped by cluster analysis into 5 major clusters based on genetic similarity and a complete linkage sort. Whereas 3 clusters assembled A. actinomycetemcomitans genotypes isolated from both healthy subjects and periodontitis patients, one cluster containing 4 different genotypes exclusively comprised isolates from healthy or gingivitis subjects. Another cluster with 2 genotypes consisted of strains originating from periodontitis patients (p < 0.05). One strain characterized by a specific 530 bp deletion in the promoter region of the leukotoxin region was identified in a Ghanese patient with localized juvenile periodontitis. It was concluded that there is considerable clonal diversity of A. actinomycetemcomitans strains isolated from healthy or periodontally diseased subjects, and that genetically closely related groups might be associated with health or disease.     

Likelihood of transmitting Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in families with periodontitis

This study examined the frequency of spouse-to-spouse and parent-child transmission of the periodontal pathogens Actinobacillus actinomycetemcomitans (124 subjects in 47 families) and Porphyromonas gingivalis (78 subjects in 31 families). The two test organisms were recovered from subgingival and tongue surface specimens using established microbiological techniques. Arbitrarily primed polymerase chain reaction (AP-PCR) was used to genetically characterize isolates of the test species. The probability of isolating identical AP-PCR types of A. actinomycetemcomitans and P. gingivalis in family members by chance was estimated from the AP-PCR genotype distribution of the two species among unrelated individuals. A probability of 5% or less for occurrence by chance alone suggests intra-familial transmission. With a bacterium-positive spouse, A. actinomycetemcomitans revealed inter-spousal transmission in 4/11 (36%) married couples and P. gingivalis in 2/10 (20%) married couples. Parent-child transmission of A. actinomycetemcomitans took place in 6/19 (32%) families. P. gingivalis was not transmitted from parent to child in any of the study families. The intra-familial transmission of A. actinomycetemcomitans and P. gingivalis may in part explain a familial pattern of periodontitis and may have important prophylactic and treatment implications.