leukotoxin and Aggressive-Periodontitis

Aggregatibacter (Actinobacillus) actimycetemcomitans (Aa) is a gram-negative bacterium that colonizes the human oral cavity and is causative agent for localized aggressive (juvenile) periodontitis (AgP). In the middle of 1990s, a specific JP2 clone of belonging to the cluster of serotype b strains of Aa with highly leukotoxicity (leukotoxin, LtxA) able to kill human immune cells was isolated. JP2 clone of Aa was strongly associated with in particularly in rapidly progressing forms of aggressive periodontitis. The JP2 clone of Aa is transmitted through close contacts. Therefore, AgP patients need intense monitoring of their periodontal status as the risk for developing severely progressing periodontitis lesions are relatively high. Furthermore, timely periodontal treatment, including periodontal surgery supplemented by the use of antibiotics, is warranted. More importantly, periodontal attachment loss should be prevented by early detection of the JP2 clone of Aa by microbial diagnosis testing and/or preventive means.

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Caspase 1; Cell Death; Clone Cells; Exotoxins; Gene Expression Regulation; History, 20th Century; Host-Pathogen Interactions; Humans; Interleukin-18; Interleukin-1beta; Leukocytes, Mononuclear; Lymphocyte Function-Associated Antigen-1; Mouth; Pasteurellaceae Infections; Protein Binding; Signal Transduction

Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a Gram-negative, facultative anaerobic bacillus that causes periodontal diseases such as localized aggressive periodontitis (LAP) and. consequently. bone resorption. The potential virulence factors of this organism are powerful leukotoxin, lipopolysaccharide (LPS), cell surface-associated materials, enzymes, and less well-defined virulence factors that will modulate the activity of the host defenses. This organism can induce bone resorption by various virulence factors in periodontal disease. In this review article, we reviewed the pathogenic roles of A. actinomycetemcomitans in periodontal disease and the mechanism which can induce bone resorption. Findings from several studies indicate that the interaction between virulence factors and the host immune system's response often progress bone resorption in periodontal disease. In this organism, GroEL, DnaK, HtpG, LTX, CDT, LPS, and cell surface-associated materials produce cytokines when exposed to the immune system. The produced cytokines are the main cause of tissue destruction and bone resorption in A. actinomycetemcomitans inflammation in periodontal disease.

Topics: Adaptive Immunity; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Proteins; Bacterial Toxins; Biofilms; Bone Resorption; Cytokines; Exotoxins; Host-Pathogen Interactions; Immune System; Immunity, Innate; Lipopolysaccharides; Pasteurellaceae Infections; Virulence Factors

Periodontitis is an infection-induced inflammatory disease that causes loss of the tooth supporting tissues. Much focus has been put on comparison of the microbial biofilm in the healthy periodontium with the diseased one. The information arising from such studies is limited due to difficulties to compare the microbial composition in these two completely different ecological niches. A few longitudinal studies have contributed with information that makes it possible to predict which individuals who might have an increased risk of developing aggressive forms of periodontitis, and the predictors are either microbial or/and host-derived factors. The most conspicuous condition that is associated with disease risk is the presence of Aggregatibacter actinomycetemcomitans at the individual level. This Gram-negative bacterium has a great genetic variation with a number of virulence factors. In this review we focus in particular on the leukotoxin that, based on resent knowledge, might be one of the most important virulence factors of A. actinomycetemcomitans.

Topics: Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bone Resorption; Exotoxins; Female; Genetic Variation; Humans; Interleukin-1beta; Virulence Factors

Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium that colonizes the human oral cavity and is the causative agent for localized aggressive periodontitis (LAP), an aggressive form of periodontal disease that occurs in adolescents. A. actinomycetemcomitans secretes a protein toxin, leukotoxin (LtxA), which helps the bacterium evade the host immune response during infection. LtxA is a membrane-active toxin that specifically targets white blood cells (WBCs). In this review, we discuss recent developments in this field, including the identification and characterization of genes and proteins involved in secretion, regulation of LtxA, biosynthesis, newly described activities of LtxA, and how LtxA may be used as a therapy for the treatment of diseases.

Topics: Actinobacillus Infections; Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Cytotoxins; Exotoxins; Humans; Immunosuppressive Agents; Leukocytes

Actinobacillus actinomycetemcomitans is a facultative anaerobe implicated in a variety of periodontal diseases. Its presence is most closely associated with localized juvenile periodontitis (LIP), although the exact role of the organism in this and other periodontal diseases is not entirely clear. While A. actinomycetemcomitans produces several different putative virulence factors, the most widely studied is the leukotoxin. The leukotoxin selectively kills polymorphonuclear leukocytes and macrophages in vitro, constituting the host's first line of defense. Interestingly, even though all strains of A. actinomycetemcomitans have the genes encoding the leukotoxin, there is variability in leukotoxin expression. Differences in the structure of the promoter region of the leukotoxin gene operon were shown to correlate directly with levels of leukotoxin production. Highly leukotoxic forms appear to exhibit increased pathogenic potential, as evidenced by recent studies that have shown a significant association between the prevalence of such strains and the occurrence of LIP in several different populations. This represents the first demonstration of an association between a particular subset of a pathogenic species and a specific periodontal disease. Early identification of A. actinomycetemcomitans by microbial and genetic assays to evaluate leukotoxicity may enhance the efficacy of preventive and/or therapeutic techniques. Future investigations should continue to evaluate pathogenic variations of additional virulence factors expressed in vivo, not only of A. actinomycetemcomitans, but also of other periodontal bacteria and infectious disease pathogens.

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Animals; Cytotoxins; Exotoxins; Humans; Pleuropneumonia; Swine; Virulence

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 epith

Topics: Actinobacillus; Actinobacillus Infections; Adult; Aggressive Periodontitis; Anti-Bacterial Agents; Bacteriological Techniques; Collagen; Endocarditis, Bacterial; Exotoxins; Humans; Infections; Periodontal Diseases; Serotyping

Aggregatibacter actinomycetemcomitans strains of serotype b and with a deletion of 530 bp in the promoter region of the leukotoxin gene (JP2 clone) are known to be associated with severe periodontitis. Our study was aimed to detect virulence genes of A. actinomycetemcomitans strains obtained from patients living in four German cities with different proportions of immigrants.. Samples were obtained from severe periodontitis patients in Frankfurt, Hamburg, Leipzig, and Jena. Those being tested positive for A. actinomycetemcomitans were analyzed for serotypes, deletion in the promoter region of the leukotoxin gene, presence of cytolethal distending toxin encoding genes (cdtA, cdtB, and cdtC) and fibril gene1(flp-1).. From all 99 A. actinomycetemcomitans-positive samples, the JP2 clone was found in two immigrants in Frankfurt. Seventy strains were tested positive for the cdtA, 52 for cdtB, and 92 for cdtC and flp-1 genes. Twenty-five strains belonged to serotype a, 22 to serotype b, 21 to serotype c, 31 to the others or could not be serotyped, respectively. The distribution of the serotypes differed between the cities. Further, differences regarding the serotypes were also significant between natives and immigrants.. The JP2 clone is not spread within the Caucasian inhabitants in German cities. The serotypes distribution seems to be influenced by the numbers of immigrants in the cities.. Patients originated from North Africa should be especially screened for the presence of the deletion in the ltx promoter region.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Proteins; Bacterial Toxins; Base Pairing; Base Sequence; Black People; Child; Chronic Periodontitis; Emigrants and Immigrants; Exotoxins; Female; Fimbriae, Bacterial; Germany; Humans; Male; Middle Aged; Promoter Regions, Genetic; Protein Subunits; Sequence Deletion; Serotyping; Virulence Factors; White People; Young Adult

To investigate the presence of A. actinomycetemcomitans, including the highly virulent JP2 clone, in young adult patients with aggressive periodontitis, and associate the findings with the two forms of the disease.. Seventy Moroccan subjects with aggressive periodontitis, aged less than 35 years, were recruited. Among these, 41 had LAgP and 29 had GAgP. Plaque samples were collected from periodontal pockets and examined using a PCR that detects the presence of A. actinomycetemcomitans and which differentiates between JP2 and non-JP2 genotypes of the bacterium.. total of 58 (83%) from the 70 AgP patients were positive for A. actinomycetemcomitans, among whom 77% were positives for the JP2 clone. The JP2 clone was detected in 34 (83%) of the LAgP patients compared to 20 (69%) of the GAgP patients (p = 0.17). Fourteen (20%) of the patients harbored non-JP2 genotypes of A. actinomycetemcomitans, although most of these patients (10/14) also harbored the JP2 clone.. The presence of the JP2 clone of A. actinomycetemcomitans is strongly associated with both LAgP and GAgP in young adults in Morocco. This implies that treatment of AgP in this population should include microbiological screening and aim at eradication of the bacterium when present.

Topics: Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Chi-Square Distribution; Child; Dental Plaque; Exotoxins; Female; Genotype; Humans; Male; Morocco; Periodontal Pocket; Promoter Regions, Genetic; Virulence; Young Adult

Limited data are reported concerning the presence of A. actinomycetemcomitans and attachment loss (AL) in sub-Saharan countries. The authors investigate the carrier frequency of JP2 and non-JP2 genotypes of A. actinomycetemcomitans and the presence of AL in Ghanaian adolescents and evaluate socioeconomic conditions and oral hygiene practices.. Five hundred individuals (mean ± SD age: 13.2 ± 1.5 years) in public and private schools were interviewed about demographic characteristics and oral hygiene practices and were given a full-mouth periodontal examination. Subgingival plaque samples were obtained from periodontal sites around permanent first molars and incisors. The carrier status of A. actinomycetemcomitans at the individual level was determined based on results obtained by cultivation and polymerase chain reaction.. The findings of this study show a relatively high carrier rate of JP2 and non-JP2 genotypes of Aggregatibacter actinomycetemcomitans in the Ghanaian adolescent population and the presence of this bacterium is associated with the occurrence of AL. The overall carrier rate of A. actinomycetemcomitans was 54.4%, and the highly leukotoxic JP2 genotype was detected in 8.8% of the study population. A total of 107 (21.4%) individuals had ≥ 1 tooth with AL ≥ 3 mm. The majority of the individuals carrying A. actinomycetemcomitans (80.1%) (P <0.001) and of the periodontally diseased individuals (91.6%) (P <0.001) were found in public schools.. A. actinomycetemcomitans and AL were frequently found in Ghanaian adolescents. The school type was the strongest predictor of both presence of A. actinomycetemcomitans and AL.

Topics: Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Carrier State; Child; Confidence Intervals; Cross-Sectional Studies; Dental Plaque; Exotoxins; Female; Genotype; Ghana; Humans; Logistic Models; Male; Oral Hygiene; Periodontal Attachment Loss; Private Sector; Public Sector; Schools; Sequence Deletion; Social Class; Surveys and Questionnaires; Young Adult

Cross-sectional and longitudinal studies identify the JP2 clone of Aggregatibacter actinomycetemcomitans as an aetiological agent of aggressive periodontitis (AgP) in adolescents of northwest African descent. To gain information on why a significant part of Moroccan adolescents show clinical signs of periodontal disease in the absence of this pathogen we performed comprehensive mapping of the subgingival microbiota of eight young Moroccans, four of whom were diagnosed with clinical signs of AgP. The analysis was carried out by sequencing and phylogenetic analysis of a total of 2717 cloned polymerase chain reaction amplicons of the phylogenetically informative 16S ribosomal RNA gene. The analyses revealed a total of 173 bacterial taxa of which 39% were previously undetected. The JP2 clone constituted a minor proportion of the complex subgingival microbiota in patients with active disease. Rather than identifying alternative aetiologies to AgP, the recorded infection history of the subjects combined with remarkably high concentrations of antibodies against the A. actinomycetemcomitans leukotoxin suggest that disease activity was terminated in some patients with AgP as a result of elimination of the JP2 clone. This study provides information on the microbial context of the JP2 clone activity in a JP2-susceptible population and suggests that such individuals may develop immunity to AgP.

Topics: Actinobacillus Infections; Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Antibodies, Bacterial; Bacterial Toxins; Case-Control Studies; Clone Cells; Disease Susceptibility; Exotoxins; Gingival Hemorrhage; Humans; Immunosuppressive Agents; Morocco; Nucleic Acid Amplification Techniques; Periodontal Attachment Loss; Periodontal Pocket; Polymerase Chain Reaction; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Young Adult

Aggregatibacter actinomycetemcomitans is considered a possible etiological agent for aggressive periodontitis. The aim of this study was to determine the prevalence of the JP2 clone and non-JP2 genotypes of A. actinomycetemcomitans in the subgingival plaque of patients with aggressive periodontitis and controls among Sudanese high-school students.. In a previous study we examined a large representative sample of students attending high schools in Khartoum, Sudan. In this population, 17 patients with aggressive periodontitis and 17 controls (14-19 years of age) consented to participate in the present study. The subjects underwent a clinical periodontal examination, and subgingival dental plaque samples were collected using paper points. The presence of the A. actinomycetemcomitans JP2 clone and non-JP2 genotypes were assessed using loop-mediated isothermal amplification (LAMP) and the PCR.. The JP2 clone of A. actinomycetemcomitans was not detected in the subgingival plaque of either the cases or the controls. Non-JP2 types of A. actinomycetemcomitans were detected in the subgingival plaque of 12 (70.6%) patients with aggressive periodontitis and from only one (5.9%) control subject, showing a significantly higher frequency of detection in cases than in controls (p = 0.0001). The odds ratio for the detection of A. actinomycetemcomitans in the subgingival plaque of the patients with aggressive periodontitis was 38.4 (95% confidence interval: 4.0-373.0; p = 0.002). The PCR and LAMP methods showed identical results pertaining to the identification of non-JP2 types of A. actinomycetemcomitans.. The JP2 clone of A. actinomycetemcomitans was not detected in the subgingival plaque of high school subjects in Sudan. The detection of non-JP2 types of A. actinomycetemcomitans may be a useful marker of increased risk for development of aggressive periodontitis in young subjects.

Topics: Actinobacillus Infections; Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Case-Control Studies; Clone Cells; Dental Plaque; DNA, Bacterial; Exotoxins; Female; Genotype; Humans; Male; Nucleic Acid Amplification Techniques; Polymerase Chain Reaction; RNA, Bacterial; RNA, Ribosomal, 16S; Sudan; Young Adult

Although certain serotypes of Aggregatibacter actinomycetemcomitans are associated more with aggressive periodontitis than are other serotypes, the correlation between distinct lineages and virulence traits in this species is poorly understood. This study aimed to evaluate the polymorphism of genes encoding putative virulence factors of clinical isolates, and to correlate these findings with A. actinomycetemcomitans serotypes, genotypes and periodontal status of the hosts.. Twenty-six clinical isolates from diverse geographic populations with different periodontal conditions were evaluated. Genotyping was performed using pulse-field gel electrophoresis. Polymorphisms in the genes encoding leukotoxin, Aae, ApaH and determinants for serotype-specific O polysaccharide were investigated.. The isolates were classified into serotypes a-f, and exhibited three apaH genotypes, five aae alleles and 25 macrorestriction profiles. Two serotype b isolates (7.7%), obtained from Brazilian patients with aggressive periodontitis, were associated with the highly leukotoxic genotype; these isolates showed identical fingerprint patterns and aae and apaH genotypes. Serotype c, obtained from various periodontal conditions, was the most prevalent among Brazilian isolates, and isolates were distributed in two aae alleles, but formed a genetically distinct group based on apaH analysis. Cluster analysis showed a close relationship between fingerprinting genotypes and serotypes/apaH genotypes, but not with aae genotypes.. Apart from the deletion in the ltx promoter region, no disease-associated markers were identified. Non-JP2-like strains recovered from individuals with periodontal disease exhibited considerable genetic variation regarding aae/apaH genotypes, serotypes and XhoI DNA fingerprints.

Topics: Actinobacillus Infections; Adhesins, Bacterial; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Alleles; Bacterial Outer Membrane Proteins; Bacterial Toxins; Base Pairing; Chronic Periodontitis; Deoxyribonucleases, Type II Site-Specific; DNA Fingerprinting; Exotoxins; Genetic Variation; Genotype; Humans; O Antigens; Periodontal Index; Periodontal Pocket; Periodontitis; Periodontium; Polymorphism, Genetic; Promoter Regions, Genetic; Serotyping; Virulence Factors

This study was designed to investigate the utility of two "new" definitions for assessment of bone loss in a rodent model of periodontitis.. Eighteen rats were divided into three groups. Group 1 was infected by Aggregatibacter actinomycetemcomitans (Aa), group 2 was infected with an Aa leukotoxin knock-out, and group 3 received no Aa (controls). Microbial sampling and antibody titres were determined. Initially, two examiners measured the distance from the cemento-enamel-junction to alveolar bone crest using the three following methods; (1) total area of bone loss by radiograph, (2) linear bone loss by radiograph, (3) a direct visual measurement (DVM) of horizontal bone loss. Two "new" definitions were adopted; (1) any site in infected animals showing bone loss >2 standard deviations above the mean seen at that site in control animals was recorded as bone loss, (2) any animal with two or more sites in any quadrant affected by bone loss was considered as diseased.. Using the "new" definitions both evaluators independently found that infected animals had significantly more disease than controls (DVM system; p<0.05).. The DVM method provides a simple, cost effective, and reproducible method for studying periodontal disease in rodents.

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Alveolar Bone Loss; Animals; Antibodies, Bacterial; Diagnosis, Oral; Disease Models, Animal; Exotoxins; Male; Mutagenesis; Photography, Dental; Radiography; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Virulence Factors

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.. 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.. 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.. 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.

Topics: Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Alveolar Bone Loss; Bacterial Toxins; Bacteroides; Clone Cells; Colony Count, Microbial; Cytotoxins; Dental Calculus; Dental Plaque; DNA, Bacterial; Exotoxins; Female; Follow-Up Studies; Genotype; Humans; Male; Nucleic Acid Hybridization; Peptostreptococcus; Periodontal Attachment Loss; Periodontal Pocket; Porphyromonas gingivalis; Prevotella intermedia; Prevotella nigrescens; Serotyping; Young Adult

Very little is known of the diversity and expression of virulence factors of serotypes of Aggregatibacter actinomycetemcomitans. Toxic activity on Chinese hamster ovary (CHO) cells and cdt and ltx genotyping were evaluated in A. actinomycetemcomitans serotypes.. Forty-one A. actinomycetemcomitans isolates were analysed for CHO cell growth inhibition. Genotyping was performed by polymerase chain reactions specific to the ltx promoter region, serotype-specific and cdt region and by sequencing of cdtB.. cdtABC was detected in 40 strains. Analysis of the cdtA upstream region revealed 10 cdt genotypes. Toxicity to CHO cells was detected for 92.7% of the isolates; however, no correlation between the toxic activity and the cdt genotype was detected. Serotype c was more prevalent among Brazilian samples (68.0%). Four serotype b isolates from subjects with aggressive periodontitis were associated with high leukotoxin production and exhibited moderate to strong toxic activity in CHO cells, but were classified in different cdt genotypes. High levels of toxicity in CHO cells were not associated with a particular serotype; 57.1% of serotype a isolates presented low toxicity to CHO cells whereas the highly toxic strains belonged to serotypes b and c. Sequencing of cdtB revealed a single nucleotide polymorphism of amino acid 281 but this was not related to the toxic activity in CHO cells.. Differences in prevalence of the low and highly cytotoxic strains among serotypes reinforce the hypothesis that serotype b and c isolates of A. actinomycetemcomitans are more virulent than serotype a strains.

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Animals; Bacterial Toxins; CHO Cells; Cricetinae; Cricetulus; Cytotoxins; Exotoxins; Genetic Variation; Humans; Polymorphism, Single Nucleotide; Serotyping; Species Specificity; Virulence

The identification of Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) serotypes may add some important information to the understanding of the pathogenetic background of severe periodontal infections. This study compared serotypes of A. actinomycetemcomitans in two groups of periodontal patients with different ethnic backgrounds.. A total of 194 patients (96 Germans and 98 Koreans) with aggressive or severe chronic periodontitis participated in the study. Microbiologic analysis of pooled samples from subgingival plaque was performed by using a real-time polymerase chain reaction (PCR) test for A. actinomycetemcomitans. In patients who tested positive for A. actinomycetemcomitans, serotypes (a through f) were determined by nucleic acid-based methods.. The prevalence of patients who tested positive for A. actinomycetemcomitans with the real-time PCR was comparable in both groups (Germans: 27.0%; Koreans: 22.2%). In German patients, the serotypes detected most frequently were b (33.3%), c (25.0%), and a (20.8%), whereas in Korean patients, the serotype distribution was different, with serotypes c (61.9%) and d (19.0%) accounting for >80% of the complete serotype spectrum.. Even if the percentage of patients who tested positive for A. actinomycetemcomitans was identical in patients with generalized aggressive and severe chronic periodontitis and different ethnic backgrounds, the distribution of A. actinomycetemcomitans serotypes may exhibit marked differences.

Topics: Actinobacillus Infections; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Asian People; Bacterial Toxins; Chronic Periodontitis; Dental Plaque; Dental Plaque Index; Ethnicity; Exotoxins; Female; Germany; Gingival Hemorrhage; Humans; Korea; Male; Middle Aged; Operon; Periodontal Attachment Loss; Periodontal Index; Periodontal Pocket; Polymerase Chain Reaction; Promoter Regions, Genetic; Serotyping; White People

The highly leukotoxic JP2 clone of Actinobacillus actinomycetemcomitans is strongly associated with periodontitis in adolescents. Availability of the DNA sequence of the complete genome of A. actinomycetemcomitans strain HK1651, a representative strain of the JP2 clone (http://www.genome.ou.edu/act.html), has provided new possibilities in basic research regarding the understanding of the pathogenesis of A. actinomycetemcomitans in periodontitis. This case report describes the periodontal treatment of the original source of A. actinomycetemcomitans HK1651, a 16-year-old Ghanaian adolescent girl with aggressive periodontitis. The bacterial examination involved polymerase chain reaction analysis for presence of JP2 and non-JP2 types of A. actinomycetemcomitans. The treatment, including periodontal surgery supplemented by antibiotics, arrested the progression of periodontitis for more than 10 years. Initially, infection by A. actinomycetemcomitans, including the JP2 clone, was detected at various locations in the oral cavity and was not limited to the periodontal pockets. Post-therapy, the JP2 clone of A. actinomycetemcomitans disappeared, while the non-JP2 types of A. actinomycetemcomitans remained a part of the oral microflora.

Topics: Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Alveolar Bone Loss; Exotoxins; Female; Humans; Immunosuppressive Agents; Mandibular Diseases; Maxillary Diseases; Periodontal Pocket; Radiography

The highly leukotoxic JP2 clone of Actinobacillus actinomycetemcomitans is strongly associated with aggressive periodontitis in adolescents of African descent. DNA fingerprinting using the frequently cutting restriction enzyme MspI and multilocus sequence typing (MLST) showed that five strains of this clone were genetically virtually identical, although ribotyping of the six rrn genes and EcoRI RFLP analysis of the seven IS150-like elements revealed differences. PCR analyses demonstrated that these multi-copy sequences are subject to intragenomic homologous recombination, resulting in translocations or large inversions. The genome rearrangements were reflected in differences among 25 strains representing the JP2 clone in DNA fingerprinting using the rare-cutting restriction enzyme XhoI and resolved by PFGE. XhoI DNA fingerprinting provides a tool for studying local epidemiology, including transmission of this particularly pathogenic clone of A. actinomycetemcomitans.

Topics: Actinobacillus Infections; Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Clone Cells; Deoxyribonucleases, Type II Site-Specific; DNA Fingerprinting; Electrophoresis, Gel, Pulsed-Field; Exotoxins; Genome, Bacterial; Humans; Polymorphism, Restriction Fragment Length; Recombination, Genetic; Ribotyping

The JP2 clone of Actinobacillus actinomycetemcomitans is associated with early-onset periodontitis in certain ethnic populations of African origin. Here, we describe and evaluate a set of primers for PCR to assay for the presence of A. actinomycetemcomitans and to discriminate between JP2-like strains and other genotypes in subgingival plaque samples.

Topics: Actinobacillus Infections; Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Dental Plaque; DNA Primers; Exotoxins; Gingiva; Humans; Polymerase Chain Reaction; Sensitivity and Specificity

A clone of Actinobacillus actinomycetemcomitans (JP2) with increased leukotoxin production and characterized by a 530-bp deletion in the leukotoxin gene operon is endemically present in Morocco and strongly associated with the presence of early onset periodontitis (EOP).. To compare patterns of attachment loss among EOP-patients with or without JP2-type of A. actinomycetemcomitans in dental plaque.. Among 45 Moroccan adolescents with EOP (i.e. one or more teeth with attachment loss >/= 3 mm) 39 had cultivable plaque samples. Fifteen (38.5%) were culture-positive for A. actinomycetemcomitans of the JP2-type as determined by PCR, and 24 (61.5%) were not (mean age 16.5 years in both groups).. EOP-patients culture-positive for A. actinomycetemcomitans of the JP2-type had significantly more teeth with attachment loss (mean 5.1, median 4.0) than EOP-patients not culture-positive for A. actinomycetemcomitans of the JP2-type (mean 2.8 teeth, median 1.0) (p = 0.02), and higher attachment loss (mean 4.3 mm vs. 3.4 mm; median 4.0 mm vs. 3.0 mm) (p = 0.01). No major differences could be detected between the two groups in the pattern of affected teeth in the dentition.. The study demonstrates increased periodontal destruction among EOP-patients culture-positive for A. actinomycetemcomitans of the JP2-type compared with EOP-patients without the JP2-clone.

Topics: Actinobacillus Infections; Adolescent; Adult; Age Factors; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Base Pairing; Clone Cells; Cross-Sectional Studies; Dental Plaque; Exotoxins; Gene Deletion; Humans; Morocco; Periodontal Attachment Loss; Polymerase Chain Reaction; Statistics, Nonparametric

The phylogeny of 20 Actinobacillus actinomycetemcomitans strains isolated from patients with localized juvenile periodontitis (LJP) was investigated by using partial sequence analysis of 16S rRNA genes, arbitrarily primed PCR (AP-PCR), and four additional PCR assays that amplified polymorphic regions in the leukotoxin (lkt), cytolethal distending toxin (cdt), major fimbrial subunit (flp-1), and serotype-specific O polysaccharide gene clusters. Our analysis also included four strains isolated from healthy subjects and nine reference strains. We found that A. actinomycetemcomitans strains comprised three major phylogenetic lineages. One lineage consisted of serotype b strains, a second lineage consisted of serotype c strains, and a third lineage consisted of serotype a, d, e, and f strains. 16S rRNA sequences within each lineage were highly conserved (<1% base substitutions), whereas sequences between lineages were exceptionally divergent (1.9 to 5.0% substitutions). Two strains exhibited 16S rRNA sequences that were even more distantly related to those of the three major lineages (2.7 to 6.7% substitutions), indicating that additional minor lineages or variants exist. The distribution of 16S rRNA sequences and lkt, cdt, flp-1, and AP-PCR genotypes was consistent with a clonal population structure, with little evidence of assortative recombination between strains of different serotypes. Strains from all three major lineages were recovered from LJP patients, suggesting that phylogenetically diverse strains of A. actinomycetemcomitans carry pathogenic potential.

Topics: Actinobacillus Infections; Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Proteins; Bacterial Toxins; Base Sequence; Child; DNA, Ribosomal; Exotoxins; Female; Genetic Variation; Humans; Male; Middle Aged; Molecular Sequence Data; Phylogeny; Polymerase Chain Reaction; Promoter Regions, Genetic; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Serotyping

A particular clone (JP2) of Actinobacillus actinomycetemcomitans with increased leukotoxin production has been isolated from individuals with early-onset periodontitis (EOP). The aim of this study was to determine the frequency of carriers of this clone and its association with EOP in Moroccan schoolchildren. Of 217 plaque samples, 131 (60.4%) were culture-positive for A. actinomycetemcomitans. A total of 19 of these isolates had a 530-bp deletion in the leukotoxin promoter region characteristic of the JP2 clone. A strong association between the presence of A. actinomycetemcomitans with the 530-bp deletion and EOP was found (adjusted OR = 29.4; 95% Cl = 8.3 - 104.4; p < 0.0005), while no association could be demonstrated between the presence of A. actinomycetemcomitans without the deletion and EOP (adjusted OR = 1.3; 95% CI = 0.5 -2.9; p = 0.750). The study demonstrates that the endemic presence, in a human population, of the highly leukotoxic JP2 clone may result in an unusually high prevalence of EOP.

Topics: Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Clone Cells; DNA Mutational Analysis; DNA, Bacterial; Exotoxins; Female; Humans; Male; Morocco; Polymerase Chain Reaction; Prevalence; Sequence Deletion; Serotyping; Virulence

Actinobacillus actinomycetemcomitans leukotoxin is thought to be an important virulence factor in the pathogenesis of localized juvenile and other forms of early-onset periodontitis. Some highly leukotoxic A. actinomycetemcomitans strains produce 10 to 20 times more leukotoxin than other minimally leukotoxic strains. The distribution, clonality, and intrafamilial transmission of highly leukotoxic A. actinomycetemcomitans were examined in order to determine the importance of leukotoxin in the pathogenesis of periodontitis.. The polymerase chain reaction (PCR) was used to differentiate highly leukotoxic from minimally leukotoxic strains in examining 1,023 fresh A. actinomycetemcomitans isolates and strains from our culture collection. These were obtained from 146 subjects including 71 with localized juvenile periodontitis (LJP), 4 with early-onset periodontitis, 11 with post-localized juvenile periodontitis, 41 with adult periodontitis, and 19 periodontally normal subjects. The arbitrarily primed polymerase chain reaction (AP-PCR) analysis of 30 oral isolates from each of 25 subjects was used to determine the intraoral distribution of A. actinomycetemcomitans clones. AP-PCR was also used to examine the transmission of A. actinomycetemcomitans in 30 members of 6 families. The clonality of 41 highly leukotoxic A. actinomycetemcomitans strains was evaluated by both AP-PCR and ribotyping.. Highly leukotoxic A. actinomycetemcomitans was found only in subjects with localized juvenile and early-onset periodontitis. Fifty-five percent of the LJP subjects harbored highly leukotoxic A. actinomycetemcomitans isolates. Seventy-three percent of the A. actinomycetemcomitans isolates in these subjects were highly leukotoxic. Highly leukotoxic A. actinomycetemcomitans infected younger subjects (mean age 13.95 years, range 5 to 28 years) than minimally leukotoxic (mean age 35.47 years, range 6 to 65 years). Most subjects were infected with only one A. actinomycetemcomitans genotype. However, PCR of whole dental plaques and subsequent analysis of up to 130 individual oral isolates suggested a possible shift in A. actinomycetemcomitans over time in that a few subjects harbored both highly leukotoxic and minimally leukotoxic strains. AP-PCR analysis was consistent with intrafamilial A. actinomycetemcomitans transmission. Ribotyping and AP-PCR analysis confirmed a previous report that highly leukotoxic A. actinomycetemcomitans consists of a single clonal type.. This study suggests that localized juvenile and other forms of Actinobacillus-associated periodontitis are primarily associated with the highly leukotoxic clone of A. actinomycetemcomitans.

Topics: Actinobacillus Infections; Adolescent; Adult; Age Factors; Aged; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Chi-Square Distribution; Child; Child, Preschool; Clone Cells; Cytotoxins; Dental Plaque; Exotoxins; Female; Humans; Male; Middle Aged; Periodontitis; Periodontium

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.

Topics: Actinobacillus Infections; Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Base Pairing; Clone Cells; Cytotoxins; Exotoxins; Gene Deletion; Genetic Linkage; Genotype; Gingivitis; Humans; Male; Periodontitis; Periodontium; Polymerase Chain Reaction; Polymorphism, Genetic; Promoter Regions, Genetic; RNA, Ribosomal, 16S; Virulence

Actinobacillus actinomycetemcomitans is a major periodontal pathogen which is associated with early-onset and adult periodontitis. The organism has been shown to be widely distributed among dentate, healthy individuals as well. It has been demonstrated that A. actinomycetemcomitans shows great genetic diversity. An especially virulent clone of the organism (JP2-like) with a specific 530-base pair (bp) deletion in the promoter region of the leukotoxin gene has been isolated from localized juvenile periodontitis patients and related subjects of African and African-American origin. The aim of the present study was to examine the presence of this specific clone employing specific oligonucleotide primers in a polymerase chain reaction among 51 isolates of A. actinomycetemcomitans recovered from 201, 18- to 25-year-old recruits with no or minor periodontal disease. In addition, clinical isolates from 37 periodontitis patients were analyzed as well as reference strains ATCC 29524, NCTC 9710, Y4 and JP2. Primers amplifying a specific 285-bp amplification product in the ltxA region of the leukotoxin gene and a specific 547-bp amplification product of 16 S rRNA were used to genetically confirm identification of the organisms. Primers amplifying sequences in the leukotoxin promoter region were used to identify the deletion. Species specific primers definitively identified all A. actinomycetemcomitans isolates. No isolates from army recruits or the reference strains displayed the deletion in the leukotoxin promoter region. However, in the periodontitis group, a 24-year-old individual from Ghana with localized juvenile periodontitis was identified with an intraoral infection with highly toxic A. actinomycetemcomitans (JP2-like). Present results confirm previous observations of absence of a highly toxic clone of A. actinomycetemcomitans among periodontally healthy and diseased Caucasians as well as a possible presence in localized juvenile periodontitis in individuals of African origin.

Topics: Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Black People; Clone Cells; DNA, Bacterial; Exotoxins; Genes, Bacterial; Humans; Military Personnel; Periodontitis; Polymerase Chain Reaction; Promoter Regions, Genetic; Sequence Deletion; United States; Virulence; White People

The periodontal pathogen Actinobacillus actinomycetemcomitans produces a leukotoxin that is considered a primary virulence factor in localized juvenile periodontitis (LJP). Select strains of the bacterium contain a 530-bp deletion in the promoter region of the leukotoxin gene operon which results in enhanced transcription of the leukotoxin. DNA hybridization and polymerase chain reaction (PCR) were used to examine genetic variants of A. actinomycetemcomitans in 24 LJP-susceptible children from 21 families having a history of the disease and 34 control children from non-LJP families. A significant association was found between the detection of variants that had a deletion in the leukotoxin promoter region, indicative of a high level expression leukotoxin genotype, and conversion from a healthy periodontal status to disease. Subjects harboring A. actinomycetemcomitans of this genotype were more likely to convert to LJP than those subjects who had variants containing the full length leukotoxin promoter region (odds ratio = 22.5; 95% C.I., 2.84 < 206.66) [corrected]. These findings support the concept that highly virulent strains or clonal types of periodontal pathogens play a major role in the initiation of periodontal disease in susceptible hosts.

Topics: Adolescent; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Base Pairing; Child; Clone Cells; Cytotoxins; Disease Progression; Disease Susceptibility; DNA, Bacterial; Exotoxins; Female; Gene Deletion; Gene Expression Regulation, Bacterial; Genetic Variation; Genotype; Humans; Male; Nucleic Acid Hybridization; Odds Ratio; Operon; Polymerase Chain Reaction; Promoter Regions, Genetic; Transcription, Genetic; Virulence

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Black People; Child; Cytotoxins; DNA, Bacterial; Exotoxins; Gene Deletion; Genetic Variation; Humans; Mutation; Risk Factors; Virulence; White People

The epithelial cell invasiveness of Actinobacillus actinomycetemcomitans strains of different restriction fragment-length polymorphism (RFLP) groups associated with disease conversion and asymptomatic carrier status in localized juvenile periodontitis was examined. Twenty clinical isolates were studied for their ability to invade KB monolayers, using the quantitative gentamicin killing assay. Five isolates were found to be invasive, five were not invasive; and the other 10 did not invade better than an invasion negative control Haemophilus aphrophilus strain ATCC 19415. Using probe-specific DNA fingerprinting. 11 strains were assigned to RFLP group II (disease-associated); 4 to RFLP type XIII (carrier status associated); and the other to groups III, IV, V and VII. Eight isolates, all RFLP group II, were leukotoxin producers as determined by PCR amplification of the lkt promoter region. No correlation was found between invasiveness and RFLP group. Leukotoxin production was more associated with noninvasive than invasive strains.

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Carrier State; Epithelial Cells; Exotoxins; Humans; KB Cells; Polymorphism, Restriction Fragment Length; Virulence

The objective of this study was to determine whether a relationship exists between antibody reactive with the Actinobacillus actinomycetemcomitans leukotoxin and the severity of periodontal disease. Serum concentrations of antibody reactive with the leukotoxin were determined for 119 early-onset periodontitis patients and 59 non-periodontitis subjects using limiting dilution analysis on Western blots. Immunoglobulin G (IgG) antibody reactive with the A. actinomycetemcomitans leukotoxin ranged from undetectable to 29 micrograms/ml (mean = 3.13 +/- 0.97 micrograms/ml for the generalized early-onset periodontitis and 2.17 +/- 0.86 micrograms/ml for the localized juvenile periodontitis patients vs 0.32 +/- 0.24 ng/ml for 59 non-periodontitis controls), and the dominant subclass was IgG1. Analysis of the relationship between antibody reactive with A. actinomycetemcomitans sonicate, A. actinomycetemcomitans leukotoxin and attachment loss patterns indicates that seropositive generalized early-onset periodontitis patients had decreased attachment loss compared with patients lacking this antibody. The statistical relationship appeared to be stronger for the sonicate than the purified leukotoxin. These data suggest that antibody reactive with A. actinomycetemcomitans leukotoxin may be protective in early-onset periodontitis, but given that the sonicate appeared better than the leukotoxin alone, it is not likely that leukotoxin is the only antigen of importance to host defense.

Topics: Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Analysis of Variance; Animals; Antibodies, Bacterial; Antibodies, Monoclonal; Antibody Specificity; Antigens, Bacterial; Bacterial Toxins; Blotting, Western; Dental Plaque Index; Exotoxins; Female; Humans; Immunoglobulin G; Male; Mice; Periodontal Attachment Loss

Actinobacillus actinomycetemcomitans has been associated with different forms of periodontitis, particularly with localized juvenile periodontitis (LJP). The bacterium possesses several virulence factors which have been shown to interact with the host immune system. Among these factors, leukotoxin, surface antigens (serotype) and bacteriophages have been suggested directly or indirectly to influence the course of infection. However, few studies have been able to show associations between these factors and periodontal disease, alone or in combination. Thus, the purpose of the present study was to investigate possible correlations between periodontal disease status and selected virulence factors (serotype, presence of bacteriophages, and the presence of a 530 bp deletion in the promoter region of the leukotoxin gene). 36 subjects took part in the study. Serotype c was the most frequently found serotype among periodontally affected subjects, although serotypes a and b were also present. 27 out of 36 strains harbored bacteriophages, and there was strong evidence that some of the bacteriophages were different from the previously characterized phi Aa phage. A. actinomycetemcomitans containing the F-fragment phage were more frequently associated with periodontal disease. Five strains, all serotype b, 3 from LJP patients and 2 from healthy subjects, showed a 530-bp deletion in the promoter region of the leukotoxin gene.

Topics: Actinobacillus Infections; Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Antibodies, Bacterial; Antigens, Bacterial; Antigens, Surface; Bacterial Toxins; Bacteriophages; Base Composition; Child; Cytotoxins; Exotoxins; Gene Deletion; Humans; Immunoblotting; Lysogeny; Middle Aged; Nucleic Acid Hybridization; Periodontitis; Periodontium; Promoter Regions, Genetic; Serotyping; Virulence

Actinobacillus actinomycetemcomitans strains with enhanced levels of production of leukotoxin are characterized by a 530-bp deletion from the promoter region of the leukotoxin gene operon. Previous isolates with this deletion constituted a single clone belonging to serotype b, although they displayed minor differences among each other. We have analyzed the geographic dissemination of this clone by examining 326 A. actinomycetemcomitans isolates from healthy and periodontally diseased individuals as well as from patients with different types of extraoral infections originating from countries worldwide. A total of 38 isolates, all belonging to the same clone, showed the 530-bp deletion. Comparison of a 440-bp sequence from the promoter region of the leukotoxin gene operon from 10 of these strains revealed complete identity, which indicates that the deletion originates from a single mutational event. This particular clone was exclusively associated with localized juvenile periodontitis (LJP). In at least 12 of 28 families from which the clone was isolated, more than one family member had LJP. Notably, all the subjects carrying this clone had a genetic affiliation with the African population. These observations suggest that juvenile periodontitis in some adolescents with an African origin is associated with a disseminating clone of A. actinomycetemcomitans.

Topics: Actinobacillus Infections; Adolescent; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Base Sequence; Black People; Child; Cloning, Molecular; DNA Primers; DNA, Bacterial; Exotoxins; Genes, Bacterial; Hemolysis; Humans; Operon; Polymerase Chain Reaction; Racial Groups; Sequence Deletion; Virulence

The bacterium Actinobacillus actinomycetemcomitans has been implicated in the pathogenesis of juvenile periodontitis as the etiologic agent on the basis of several lines of circumstantial evidence. A matter of extensive debate is whether A. actinomycetemcomitans is an exogenous contagious pathogen or an opportunistic pathogen that resides in the normal oral microflora. Here we show evidence of a single clone of A. actinomycetemcomitans isolated from multiple patients with juvenile periodontitis in members of families of African origin living in geographically widespread areas. The clone is characterized by a 530-bp deletion in the leukotoxin gene operon, resulting in a significantly increased production of leukotoxin.

Topics: Adolescent; Adult; Africa; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Base Sequence; Child; Denmark; DNA Primers; DNA, Bacterial; Emigration and Immigration; Exotoxins; Genes, Bacterial; Humans; Operon; Sequence Deletion; Sweden

Genetic analysis of an Actinobacillus actinomycetemcomitans population consisting of 88 clinically well characterized Finnish isolates performed by multilocus enzyme electrophoresis confirmed that the five serotypes divide into two phylogenetic lineages, one comprising serotypes b and c and one comprising serotypes a, d, and e. There was no association between any subpopulation and the periodontal health status of the subject from whom the isolates originated, suggesting that the role of A. actinomycetemcomitans in periodontitis is largely opportunistic in the population examined. Southern blot analyses of genomic DNA digested with each of the restriction endonucleases MspI, RsaI, and TaqI revealed extremely limited genetic polymorphism of the structural leukotoxin gene, ltxA, and its associated promoter. All isolates hybridized to a 530-bp DNA fragment derived from the promoter region of the leukotoxin gene operon of a minimally leukotoxic A. actinomycetemcomitans strain. Deletion of the 530-bp sequence has been associated with significantly increased toxin production detected among isolates from patients with juvenile periodontitis in North America but was detected neither among the 88 isolates in the present collection analyzed nor among more than 60 strains in another population of northern European A. actinomycetemcomitans isolates analyzed previously.

Topics: Actinobacillus Infections; Adult; Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Alleles; Base Sequence; Child; Chromosome Mapping; DNA Primers; DNA, Bacterial; Enzymes; Europe; Exotoxins; Genes, Bacterial; Genetic Variation; Humans; Molecular Sequence Data; Periodontitis; Polymerase Chain Reaction; Polymorphism, Genetic; Promoter Regions, Genetic; Serotyping; Virulence

Actinobacillus actinomycetemcomitans has been strongly implicated in the etiology of localized juvenile periodontitis. Techniques used in the identification of this periodontal pathogen include cultural, biochemical, immunological and DNA hybridization analysis. In this study, we report the use of polymerase chain reaction (PCR) to amplify unique sequences of A. actinomycetemcomitans. Specific oligonucleotide primers LKT2 and LKT3 were designed to hybridize to the A. actinomycetemcomitans lktA gene, which encodes leukotoxin, a putative A. actinomycetemcomitans virulence factor. The LKT2 and LKT3 primers amplified lktA-specific sequences from all 12 A. actinomycetemcomitans strains tested. In another set of experiments, 13 other bacterial species, most of which are normal residents of the oral cavity, were tested with these primers. These PCR amplifications also contained 2 additional primers, RRN4 and RRN5, which served as positive controls; RRN4 and RRN5 were designed to amplify specific sequences of eubacterial 16S ribosomal DNA (rDNA). PCR amplifications of all bacterial species tested, including A. actinomycetemcomitans, yielded 16S rDNA-specific DNA fragments. Furthermore, each bacterial species tested, with the exception of A. actinomycetemcomitans, failed to amplify lktA sequences. The LKT and RRN primers were used in further PCR experiments to detect A. actinomycetemcomitans directly from gingival fluid samples. The results clearly demonstrate the simplicity, rapidity, specificity and accuracy of the LKT primers in the identification of A. actinomycetemcomitans.

Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Bacterial Toxins; Bacterial Typing Techniques; Base Sequence; DNA, Bacterial; DNA, Ribosomal; DNA, Single-Stranded; Exotoxins; Gingival Crevicular Fluid; Humans; Molecular Sequence Data; Polymerase Chain Reaction; RNA, Ribosomal, 16S

Strains of A. actinomycetemcomitans (A.a) from juvenile periodontitis patients (JP), adult periodontitis patients (AP), and 14-yr-old healthy children were tested for the correlation between leukotoxin activity and the number of outer membranous vesicles measured in electron micrographs. To determine the potential for connective tissue destruction following the interaction of polymorphonuclear leukocytes (PMN) with the bacteria, the lysosomal release of neutrophil elastase was assessed. The highest potential to kill leukocytes and to release lysosomal elastase from them was observed in the strains isolated from JP patients. No correlation existed between leukotoxic activity and the number of outer membranous vesicles per bacterium when the data from A.a. strains from all sources were combined. Furthermore, no significant differences were found between the numbers of outer membranous vesicles in the three groups tested. The only significant correlation between the number of vesicles and leukotoxicity was found in the A.a. strains derived from the mouths of healthy children.

Topics: Actinobacillus; Adolescent; Adult; Aggressive Periodontitis; Bacterial Toxins; Cell Membrane; Exotoxins; Humans; Microscopy, Electron; Middle Aged; Neutrophils; Pancreatic Elastase; Periodontal Diseases; Periodontitis

We have recently isolated several groups of bacteriophages infecting Actinobacillus actinomycetemcomitans from periodontal lesions in patients with rapidly destructive periodontitis. Bacteriophage infection of these bacteria in these patients was restricted to periodontal pockets showing radiographic evidence of recent bone loss and suggests an association between phage-infected A. actinomycetemcomitans and active periodontal disease. On the basis of the biological activity of bacteriophages we propose a working hypothesis to explain the mechanism by which a phage may increase bacterial virulence in periodontal disease.

Topics: Actinobacillus; Adolescent; Adult; Aged; Aggressive Periodontitis; Bacteriolysis; Bacteriophages; Child; Child, Preschool; Exotoxins; Humans; Middle Aged; Periodontitis; Periodontium; Virulence

Topics: Actinobacillus; Adolescent; Adult; Aggressive Periodontitis; Animals; Cell Survival; Dental Plaque; Exotoxins; Humans; Macaca fascicularis; Male; Microscopy, Electron; Mitogens; Monocytes; Neutrophils

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.

Topics: Actinobacillus; Actinobacillus Infections; Adolescent; Adult; Aggressive Periodontitis; Antibodies, Bacterial; Antigen-Antibody Reactions; Antigens, Bacterial; Binding Sites, Antibody; Binding, Competitive; Enzyme-Linked Immunosorbent Assay; Epitopes; Exotoxins; Humans; Middle Aged; Periodontal Diseases; Polysaccharides, Bacterial