Possible transmittance of A. actinomycetemcomitans from a dog to a child with rapidly destructive periodontitis

The Oral Microbiota

The oral microbiota represents an important part of the human microbiota, and includes several hundred to several thousand diverse species. It is a normal part of the oral cavity and has an important function to protect against colonization of extrinsic bacteria which could affect systemic health. On the other hand, the most common oral diseases caries, gingivitis and periodontitis are based on microorganisms. While (medical) research focused on the planktonic phase of bacteria over the last 100 years, it is nowadays generally known, that oral microorganisms are organised as biofilms. On any non-shedding surfaces of the oral cavity dental plaque starts to form, which meets all criteria for a microbial biofilm and is subject to the so-called succession. When the sensitive ecosystem turns out of balance - either by overload or weak immune system - it becomes a challenge for local or systemic health. Therefore, the most common strategy and the golden standard for the prevention of caries, gingivitis and periodontitis is the mechanical removal of this biofilms from teeth, restorations or dental prosthesis by regular toothbrushing.

Combined Therapy in a Patient With Papillon-Lefèvre Syndrome: A 13-Year Follow-Up

BACKGROUND

Papillon-Lefèvre syndrome (PLS) is an autosomal recessive disease characterized by hyperkeratosis of the palms and soles combined with premature loss of the primary and permanent dentition. Several treatment regimens have been recommended in the literature; however, a definitive treatment protocol has not been established. This case report evaluates the success of combined therapy in managing a patient with PLS.

METHODS

A 6-year-old girl diagnosed with PLS presented with aggressive periodontal destruction of her primary and permanent dentitions. After extraction of periodontally affected teeth, the edentate region was rehabilitated with different temporary dentures until her skeletal growth was complete. At the same time, her orthodontic treatment was performed. The early loss of her incisors resulted in inadequate alveolar bone height and width for esthetic-advanced prosthetic rehabilitation. Alveolar bone augmentation was performed, and 6 months later, two intraosseous dental implants were placed into the central incisor zone.

RESULTS

After 13 years of treatment and follow-up, the patient had periodontally healthy permanent dentition. She had practiced meticulous oral hygiene, and the orthodontic treatment was successful and without incident. Alveolar ridge augmentation and placement of an intraosseous implant with guided bone regeneration were performed successfully.

CONCLUSIONS

This case report demonstrates that individually developed treatment protocols can provide long-term dental/periodontal success in patients with PLS. A multidisciplinary approach with advanced periodontal surgery, orthodontic and prosthetic treatment, and implant therapy may be an appropriate treatment modality for dental rehabilitation in patients with PLS.

The effects of toothpastes on the residual microbial contamination of toothbrushes

BACKGROUND

Contaminated toothbrushes have been shown to harbor and transmit viruses and bacteria. The authors conducted a study to evaluate the effect of a triclosan-containing toothpaste on the residual anaerobic microbial contamination of toothbrushes.

METHODS

Twenty patients who had Type III or Type IV periodontitis participated in this study. One side of each of their mouths served as a control (no toothpaste). The teeth on the other side were brushed with a regular toothpaste or a triclosan-containing toothpaste. After the toothbrushes were allowed to dry in air for four hours, the authors placed the toothbrush heads in solution, dislodged the microbes from the brushes by vortexing and plated them in culture dishes. The authors anerobically incubated the culture dishes and determined the presence or absence of Prevotella species or Ps; Porphyromonas gingivalis, or Pg; and Actinobacillus actinomycetemcomitans, or Aa.

RESULTS

The authors detected Aa and Pg on the control toothbrushes more frequently than they did Ps. This variation in isolation frequency was statistically significant by chi 2 analysis (P < .001). The authors compared the isolation frequency of the three test organisms between the control and regular-toothpaste groups, between the control and triclosan-containing--toothpaste groups, and between the triclosan-containing--toothpaste and regular-toothpaste groups. They found no significant intergroup differences in the isolation frequencies after using chi 2 analysis.

CONCLUSIONS

Toothpaste use reduced the residual microbial contamination for two of three test organisms, but the lower isolation frequencies were not statistically significant. Further study in this area is indicated.

CLINICAL IMPLICATIONS

Dental professionals should advise patients who have systemic, localized or oral inflammatory diseases to disinfect or frequently replace their toothbrushes.

Clonal infection with Actinobacillus actinomycetemcomitans following periodontal therapy

Mechanical debridement results in a shift of the bacterial composition in the periodontal pocket on the species level. It is unknown, however, whether a clonal change within a species could lead to the emergence of strains with different levels of virulence. Therefore, in the present study, the genetic variability of Actinobacillus actinomycetemcomitans was assessed and strains identified which were associated with periodontal disease progression following periodontal therapy, i.e., refractory periodontitis. Twenty adult patients with untreated periodontitis and subgingival colonization of A. actinomycetemcomitans were randomly assigned to receive full-mouth scaling alone or scaling with an adjunctive antimicrobial therapy. Both groups received supportive periodontal therapy at 3, 6, 9, 12, 18, and 24 months. Subgingival plaque samples were taken at every visit; venous blood was obtained at 24 months only. A. actinomycetemcomitans isolates were typed by the RAPD method, and antibody reactivity against outer membrane proteins was assessed by immunoblot analysis. Eleven distinct RAPD patterns were found in 18 patients completing the study. All patients harbored only one A. actinomycetemcomitans genotype, and within each patient this genotype persisted throughout the 24-month observation period. No differences in the expression of antibody reactivity against outer membrane proteins were found between strains isolated at baseline and at 24 months. Three genotypes were associated with reduced survival rates of teeth without probing attachment loss of 2 mm or more. The results indicated that (i) most patients harbored only one A. actinomycetemcomitans genotype; (ii) the genotype persisted following therapy; and (iii) only some genotypes were associated with refractory periodontitis.

The distribution and transmission of Actinobacillus actinomycetemcomitans in families with localized juvenile periodontitis

The prevalence and distribution of A. actinomycetemcomitans in families where at least one family member (proband) suffered from localized juvenile periodontitis was investigated. 25 probands with localized juvenile periodontitis (LJP) and their 78 close family members were screened for the presence of A. actinomycetemcomitans. Among these 25 families, 10 contained at least one additional family member colonized with oral A. actinomycetemcomitans. Genomic DNA from subgingival A. actinomycetemcomitans strains from each of the probands and their family members were amplified and characterized by the polymerase chain reaction (PCR) using a single primer known to distinguish A. actinomycetemcomitans strains. The PCR products from each strain were separated by electrophoresis on a 1% submarine agarose gel containing ethidium bromide and visualized by UV light transillumination. The studies showed that 41.2% of the parents and 58% of the siblings in this LJP-based population harbored the bacterium. Comparison of the PCR generated amplitypes showed that there was a wide distribution of amplitypes among the probands and immediate relatives. No clear transmission paths were observed in this specific population.

Loss of deciduous teeth and germs of permanent incisors in a 4-year-old child. An atypic prepubertal periodontitis? A clinical, microbiological, immunological and ultrastructural study

A 4-year-old child was referred, in April 1988, to Rennes Dental School (France) for deciduous tooth mobility with premature loss of 4 deciduous teeth and germs of 2 permanent incisors. Microbiological examinations by culture revealed the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Immunofluorescence of plaque samples revealed the presence of Porphyromonas gingivalis that had not been isolated by culture. Neutrophil functions were within normal ranges. Transmission electron microscopy of gingiva showed a disorganised epithelium. The connective tissue was infiltrated by inflammatory cells. The basement membranes were normal, but the connective tissue-epithelium interface was mainly composed of short rete pegs. Scanning electron microscopy of extracted deciduous teeth revealed lack of cementum, lacunae in the cementum and lack of fibrillar insertion on the middle part of the root. Skin lesions, mainly situated on face, were observed. Treatment was by extraction of mobile deciduous teeth combined with 3-week courses of metronidazole. Clinical and microbiological follow-up was continued over a 7-year period. No periodontal lesions have been detected since eruption of the permanent teeth. The present subgingival and lingual microflora (December 1995) is composed of bacteria associated with periodontal health. However, the future appearance of a hitherto undetected systemic disease is still possible.

Bacterial transmission in periodontal diseases: a critical review

This review paper addresses intra- and extra-familial transfer of bacteria associated with periodontal diseases. Recent advances in molecular biology provide sensitive methods to differentiate organisms within the same species, thereby facilitating tracking routes of their transmission. Evidence for the passing of microorganisms between parents and children is particularly strong. In this regard, molecular genetic techniques have demonstrated that if a child is colonized by a potentially pathogenic species, then one of the parents will usually harbor genotypically identical bacteria. The data also indicate that transfer of bacteria between spouses occur, but it appears to happen infrequently. Saliva appears to be a major vector for bacterial transmission. However, the transfer of organisms does not necessarily result in colonization or infection of the host. Furthermore, individuals who harbor putative pathogens frequently do not manifest any signs of periodontal disease. This is attributed to host defenses, bacterial antagonism, and possibly lack of pathogenicity of infecting organisms. It is concluded, based upon current evidence, that periodontal pathogens are communicable; however, they are not readily transmissible.

Natural distribution of oral Actinobacillus actinomycetemcomitans in young men with minimal periodontal disease

A total of 1005 subgingival and extracrevicular samples from 201 male recruits, 18-25 yr old, were selectively cultivated for Actinobacillus actinomycetemcomitans. The organism was isolated in 55 subjects (27%); 9.5% of pooled subgingival plaque samples from first molars, 14% cheek mucosa, 20% dorsum of tongue and 20% saliva samples were culture-positive. In order to divide the study population into distinct clinical categories, cluster analysis was performed, based on previous caries experience, probing pocket depth categories, bleeding scores, visible plaque and calculus. Two clusters (n = 86 and n = 92, respectively) were identified with no or minimal periodontal disease (mean +/- standard deviation % of periodontal probing depth 1-2 mm 78.7 +/- 10.4% and 57.4 +/- 12.6%, respectively; virtually no periodontal probing/depth in excess of 4 mm) and a relatively low DMF-S (22 +/- 13). A third cluster (n = 22) had, in contrast, a high DMF-S (47.7 +/- 17.2) and a relatively high % of periodontal pockets of > or = 5 mm (5.9 +/- 5.2%). Prevalence of A. actinomycetemcomitans in this cluster was 41%, while the organism was found in 23% and 27% in the minimally diseased populations (p < 0.15). Whereas no heterogeneity of associations between subgingival and extracrevicular occurrence of the organism could be ascertained in different clusters, the organism was significantly more often identified in extracrevicular material, especially dorsum of tongue samples, compared with subgingival plaque (McNemar's chi2 = 12.45, p < 0.001). Multiple linear regression analysis revealed the number of A. actinomycetemcomitans positive samples as well as the % of sites bleeding on probing being positively associated with the % of sites with a probing pocket depth of > or = 5 mm (R2 = 0.345, p < 0.0001). The present large-scale investigation points to the wide distribution of this putative periodontopathogen in young individuals with minimal periodontal disease.

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 periodontal probing depth (PPD) of 1 or 2 mm, only 1.6 +/- 2.9% deep sites of > or = 5 mm were detected. More than 1000 subgingival and extracrevicular samples were selectively cultivated for A. actinomycetemcomitans. The organism was isolated in 55 subjects (27%). 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.

Occurrence of Actinobacillus actinomycetemcomitans and anti-leukotoxin antibodies in some members of an extended family affected by Papillon-Lefèvre syndrome

Eighteen (18) members of an extended family in which numerous individuals have Papillon-Lefèvre syndrome (PLS) were examined. In all, 6 affected members and 12 non-affected members were included. All patients underwent a clinical examination which, in the dentate persons, included plaque index, bleeding on probing, probing depth, and periodontal attachment loss and a set of full mouth periapical x-rays. Subgingival bacterial samples were also collected from 2 teeth in the dentate patients for cultures and identification of Actinobacillus actinomycetemcomitans. Serum samples were collected from all participants and assayed for antileukotoxin antibodies. The results indicate that there is a high prevalence of leukotoxic strains of A. actinomycetemcomitans in persons suffering from PLS, as well as in unaffected family members. The ubiquitous presence of A. actinomycetemcomitans in the family units suggests a close association between A. actinomycetemcomitans and the periodontal disease associated with the syndrome; it also suggests that A. actinomycetemcomitans by itself is not sufficient for the expression of periodontal disease and that other factors, some of which must be genetic, are necessary for lesion development.

Critical issues in periodontal research

The purpose of this paper is to highlight briefly the major achievements and the remaining critical issues in the areas of epidemiology, microbiology, pathogenesis, diagnosis, and therapy. Periodontitis affects a relatively small proportion of study populations in the United States and other countries. Prevalence may be decreasing, but that remains to be seen. The identity and characteristics of susceptible individuals and groups are not known, and risk indicators for severe disease are only beginning to be identified. A very large number of different microbial species has been implicated in the etiology. It seems unlikely that all of these are essential participants. Essential participants need to be identified and better characterized. Whether putative pathogens are members of the commensal flora or exogenous species that must be transmitted is unclear. The relationship between the presence of a pathogenic flora and disease status is obscure. Pathogenic bacterial species are essential, but insufficient to cause disease. A susceptible host and local environmental factors--for example, elevated iron concentration--may be necessary for disease to occur. Many clonal types may not be virulent, and numbers greater than certain threshold levels appear to be necessary. The pathways by which bone and connective tissues of the periodontium are destroyed are sufficiently understood to permit development of therapies aimed at their modification. Examples are the use of vaccines, topical application of anti-inflammatory drugs, and use of chemically modified tetracyclines.

Localized prepubertal periodontitis in a 5-year-old child: investigations and clinical observations over a 3-year period

A 5-year-old boy presented with persistent generalized gingival inflammation. Clinical and radiographic examination supplemented by immunological and microbiological investigation led to a diagnosis of localized prepubertal periodontitis. The child was subsequently monitored for 3 years and despite treatment there was continued bone loss related to his primary teeth. This case highlights the need for liaison between specialists in paediatric dentistry, periodontology, immunology and microbiology in order to diagnose prepubertal periodontitis and to establish a rational basis for treatment to prevent progression to juvenile periodontitis.

The distribution and transmission of Actinobacillus actinomycetemcomitans in families with established adult periodontitis

The prevalence and genotype distribution of Actinobacillus actinomycetemcomitans strains in families where at least one adult family member (proband) suffered from periodontal disease was investigated to better understand how this periodontal organism is acquired or transmitted. Fifteen probands with severe (established) periodontal disease (EPD) and their 46 immediate family members were sampled for A. actinomycetemcomitans. Among the 15 families, 10 contained at least one additional family member colonized with oral A. actinomycetemcomitans. Genomic DNA from 3 subgingival A. actinomycetemcomitans strains from each of the 10 probands and their 17 family members were amplified and characterized by the polymerase chain reaction (PCR) using a single arbitrary primer known to distinguish A. actinomycetemcomitans strains. The PCR products from each strain were separated by electrophoresis on a 1% submarine agarose gel containing ethidium bromide and visualized by UV light transillumination. The amplification products migrated to form readily distinguishable bands and, since the banding patterns were characteristic of strains of A. actinomycetemcomitans, these patterns were called "amplitypes." The culture studies showed that 51% of all patients suffering from EPD carried oral A. actinomycetemcomitans. Moreover, 50% of their spouses and 30% of their children harbored the bacterium. Comparison of the PCR-generated amplitypes showed that 26 out of 27 individuals had strains exhibiting a single amplitype of A. actinomycetemcomitans, the 27th being colonized by 2 different amplitypes. They also showed that in 6 out of 7 families, the husband and wife did not harbor the same A. actinomycetemcomitans amplitype. Furthermore, most often children carried an an amplitype identical to one of the parents.(ABSTRACT TRUNCATED AT 250 WORDS)

Differentiation of strains of Actinobacillus actinomycetemcomitans by arbitrarily primed polymerase chain reaction

The present study describes a method for amplifying DNA in Actinobacillus actinomycetemcomitans by using short, synthetic oligonucleotides of random sequence as primers in the polymerase chain reaction. Genomic DNA from each of 20 human isolates of A. actinomycetemcomitans was successfully amplified in a thermal cycler with a single synthetic primer (GGGTAACGCC) and reproducibly produced 14 different DNA amplification profiles (amplitypes). A. actinomycetemcomitans isolates from the same subject revealed the same amplitype. The arbitrarily primed polymerase chain reaction appears to be useful in characterizing human isolates of A. actinomycetemcomitans for studies of epidemiology and bacterial transmission.

An investigation into the use of restriction endonuclease analysis for the study of transmission of Actinomyces

DNA fingerprints of 28 reference strains of Actinomyces, comprising representatives of different species and serotypes, and 19 isolates recovered from 16 periodontal patients was performed. The aim was to determine the potential of the method for detecting strain differences in terms of discriminatory power and to evaluate its usefulness in the typing of Actinomyces strains for eco-epidemiological studies. Among the 17 restriction endonucleases tested, Bst EII, Pvu II and Sma I proved to be the most suitable for the genus Actinomyces restriction digest analysis. Visual comparisons of Bst EII, Pvu II and Sma I digest patterns of chromosomal DNA revealed clear differences within species but also within serotypes of Actinomyces that are otherwise identical. The method offers the qualities for use as an epidemiological tool for identifying sources and tracing routes of transmission of Actinomyces: stability, reproducibility, ease of preparation and interpretation and enough sensitivity for detection of differences between morphologically and serologically similar strains of Actinomyces.

Randomly amplified polymorphic DNA analysis confirms the biotyping scheme of Porphyromonas gingivalis

The application of the arbitrarily primed PCR (AP-PCR) procedure to generate randomly amplified polymorphic DNA (RAPD) fingerprints for the study of the taxon Porphyromonas gingivalis was investigated. Nine human strains and seven animal strains of P. gingivalis as well as eighteen strains other than P. gingivalis were analysed. Four nanomer primers of random sequence were evaluated for their ability to distinguish genetic diversity. Three primers generated RAPD fingerprints that allowed the sixteen strains to be differentiated; two of the primers yielded species-specific markers, and two of the primers permitted biotype distinction. Cluster analysis of the RAPD fingerprints revealed two major phenetic groups that matched the human and animal biotypes. Our results indicate that AP-PCR (i) can generate strain-specific fingerprints, (ii) confirms genetic heterogeneity and the biotype grouping of the P. gingivalis taxon, and (iii) enables identification of potential genetic markers at the species, biotype and subtype levels and is thus a promising tool for bacterial systematics. Our results also underline the potential of AP-PCR for epidemiological studies of periodontal pathogens.

Hybridization patterns of Actinobacillus actinomycetemcomitans serotypes a-e detected with an rRNA gene probe

This study reports a genetic characterization of Actinobacillus actinomycetemcomitans strains in relation to serotypes by using rRNA gene restriction patterns. Eighty-eight clinical strains were isolated from 20 unrelated subjects at one or several occasions. The strains were serotyped by using serotype-specific rabbit antisera against serotypes a, b, c, d or e. Three subjects harbored 2 A. actinomycetemcomitans serotypes, 15 subjects 1 serotype and 2 subjects untypable strains. Chromosomal DNA was digested with restriction endonuclease ClaI, BamHI, BglI or HindIII and hybridized to the rrnB ribosomal RNA operon of the Escherichia coli chromosome. Isolates belonging to the same serotype were genetically identical in the same individual but nonidentical if they belonged to different serotypes. Isolates of the same or different serotypes were genetically nonidentical in different individuals. The banding patterns of A. actinomycetemcomitans isolates recovered from the same individuals during several years always remained identical. The hybridization method using pKK3535 as a probe seemed suitable as an epidemiological tool for comparing the clonal identity of A. actinomycetemcomitans strains.

Review of chemosystematics: multivariate approaches to oral bacteria and yeasts

There are several problems related to the classification and identification of bacterial and yeast species assigned to the genera Actinobacillus, Haemophilus, Pasteurella, Bacteroides, Prevotella, Porphyromonas, Campylobacter, Wolinella, Treponema, Candida, Torulopsis, and Saccharomyces, most of which belong to the resident oral microflora. The present review was written to demonstrate how multivariate analyses of data on cellular fatty acids, sugars, enzyme activities, and lysis kinetics during ethylenediaminetetraacetic acid (EDTA) and EDTA plus lysozyme treatment can be used to distinguish closely related species of these bacterial and yeast genera. With the exception of the Actinobacillus-Haemophilus-Pasteurella group, fatty acids were more discriminating than sugars. Enzymes from whole cells and outer membrane vesicles also contributed to taxonomic distinction. Apparently, chemosystematics, involving multivariate analyses, is a useful adjunct in oral microbial taxonomy.

Entrance of Actinobacillus actinomycetemcomitans into HEp-2 cells in vitro

A strain of actinobacillus actinomycetemcomitans, freshly isolated from a juvenile periodontitis patient, and the FDC Y4 laboratory strain of Aa were tested for their capacity to adhere to and enter the epithelial cell line HEp-2 cells in vitro. Immunofluorescence microscopy as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that both strains adhered to the outer surface of the HEp-2 cells. In the TEM studies, the specimens were also treated with Aa specific antibodies and gold labeled protein A. These examinations showed that only the freshly isolated strain of Aa was found within the HEp-2 cells. The intracellular Aa were found to be viable, and in one case one of them was seen to undergo division. It is concluded that freshly isolated Aa has the ability to enter epithelial HEp-2 cells in vitro, and it is tentatively suggested that this may play a role in the pathogenesis of periodontal disease.

Strain identification of Actinobacillus actinomycetemcomitans using the polymerase chain reaction

A molecular assay that distinguishes among strains of the periodontal pathogen Actinobacillus actinomycetemcomitans was developed by identifying DNA restriction site polymorphisms in the highly variable transcribed spacer region between the 16S and 23S ribosomal genes. The polymerase chain reaction (PCR) was used to amplify this region from genomic DNA using primers within conserved regions of the 16S and 23S genes. This amplified region was digested using a series of restriction enzymes and electrophoresed. Examination of restriction fragment length polymorphisms obtained by separate digestion with RsaI and NciI allowed the 7 strains examined to be divided into 4 genetic groups. This assay provides a more precise and reproducible method of strain identification than whole genomic methods and should be useful as a method for studying the epidemiology of A. actinomycetemcomitans strains in human subjects. The genetic variability detected supplies strong evidence that direct sequence analysis of the region could provide extremely precise and potentially definitive identification of strains.

Microbiological testing in the diagnosis of periodontal disease

The oral microbiota plays a primary role in the initiation and progression of the most common forms of periodontal disease. Because of the multiplicity of factors that control the establishment and long-term evolution of the oral microbiota, a great deal of heterogeneity exists in the composition of the periodontal microbiota among individual subjects. Despite these individual differences and the complex interactions between bacteria and the host and among bacteria, an association has been demonstrated between certain species and various forms of periodontal disease. However, the predictive value of either positive or negative tests for selected bacterial species has not proved to be high enough for routine use in clinical practice. Nevertheless, bacteriological tests have been of value in the management of patients with juvenile periodontitis and refractory forms of periodontal disease. The increasing availability of diagnostic laboratory services and diagnostic kits for office use will make it easier for the practitioner to select appropriate antimicrobial treatments and monitor patients undergoing antimicrobial therapy.

The use of genomic DNA fingerprinting in studies of the epidemiology of bacteria in periodontitis

Recent studies of microbial epidemiology emphasizing the genetic organization and distribution of organisms associated with orofacial infections have led to new insights into the possible origins of pathogenicity. Studies into genetic heterogeneity, acquisition and transmission of these organisms have been markedly advanced by the utilization of the powerful technique of genomic DNA fingerprinting. Characteristic fingerprints for each bacterial isolate can be produced by cleavage of high molecular weight genomic DNA by restriction endonucleases. It is assumed that each DNA fingerprint represents a clonal type. In this report, we review and analyze studies of the epidemiology of bacteria associated with orofacial infections with an emphasis on periodontal disease. Studies of nontypable (NT) Haemophilus influenzae associated with recurrent otitis media illustrate the utility of this technique. DNA fingerprinting clearly demonstrates genetic heterogeneity of NT H. influenzae isolates, and clonality of infection of any individual. Furthermore, DNA fingerprinting has shown that the same clonal type is seen in siblings concurrently suffering from otitis media, suggesting horizontal transmission within the family. Studies of mutans Streptococci also show extensive genetic heterogeneity and show vertical transmission of a predominant clonal type only from mother to infant, but not from father to infant. Studies of Actinobacillus actinomycetemcomitans show considerable genetic heterogeneity among monkey isolates. Thus far, three clonal types have been reported with DNA fingerprinting among isolates from periodontal patients, but additional genetic heterogeneity can be found using specific DNA fragments as probes in hybridization experiments. Intrafamilial transmission of A. actinomycetemcomitans has been demonstrated. Porphyromonas (Bacteroides) gingivalis shows extensive genetic heterogeneity and case reports suggest clonal infection of any one individual. In contrast, results with DNA fingerprinting of Eikenella corrodens, Fusobacterium nucleatum, and Bacteroides intermedius show that individuals may be infected with 2 or more clonal types. These studies point to the great potential of DNA fingerprinting for investigating the epidemiology of putative orofacial pathogens. Such studies with periodontal microorganisms will likely reveal steps in the acquisition, intraoral and person-to-person transmission, which then could possibly be inhibited or interfered with to prevent periodontal disease or its recurrence.

Dental bacterial plaques. Nature and role in periodontal disease

Antony van Leeuwenhoek first described oral bacteria. However, not until almost 200 years later was the famous Koch postulate introduced. Since then, research has extensively been performed regarding the development and microbiology of dental plaques. In spite of the complexity of the developing flora of supragingival plaque, culture studies have shown a remarkably orderly succession of organisms. Lately, the concept of microbial specificity in the etiology of periodontal diseases has been widely suggested, i.e., that different forms of periodontal disease are associated with qualitatively distinct dental plaques. Cross-sectional and longitudinal studies of the predominant cultivable microflora reveal that only a small number of the over 300 species found in human subgingival plaques are associated with periodontal disease. Among the commonly mentioned are: Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Bacteroides intermedius, Capnocytophaga sp., Eikenella corrodens, Fusobacterium nucleatum, and Wolinella recta, as well as certain gram-positive bacteria such as Eubacterium species. Anti-infective therapy for many systemic infections equals the use of antimicrobial drugs. However, for localized infections like periodontal diseases, treatment may consist of a combination of mechanical wound debridement and the application of an antimicrobial agent. The general effectiveness of mechanical anti-infective therapy and successful oral hygiene in the management of periodontal disease is well established in the literature and has met the test of success in clinical practice for most cases of periodontitis in adults. The definition of periodontal pathogens as either opportunistic pathogens, or as exogenous pathogens carries with it significant implications.(ABSTRACT TRUNCATED AT 250 WORDS)

New views on periodontal microbiota in special patient categories

The microorganisms in periodontitis of special patient categories have been only partially elucidated. The periodontitis microbiota of HIV-infected individuals, cancer patients on myelosuppressive therapy, and persons with other medical disorders includes common suspected periodontal pathogens as well as enteric rods, pseudomonads, staphylococci and yeasts. Failing implants also may be associated with classical periodontal pathogens as well as primarily nonoral potential pathogens. Refractory periodontitis in systemically healthy adults can show a great variety of oral and nonoral organisms. The frequent occurrence of unusual periodontal organisms in special patient categories may be due to a weakened host response and/or usage of various chemotherapeutic regimens. The unusual organisms may contribute to progressive periodontitis and in leukemia patients may even give rise to life-threatening systemic manifestations. The primary therapeutic goal in special periodontitis patients is control of pathogens and amid the wide range of pathogenic microfloras, an effective treatment strategy should include a comprehensive microbiological analysis, especially if systemic antimicrobial therapy is contemplated.

Microflora and bacterial DNA restriction enzyme analysis in young adults with periodontitis

As a result of an epidemiological survey on the periodontal status of young adults, a school was found with a relatively high number of subjects showing loss of attachment (18 out of 87). In 10 of these subjects the microflora of one pocket and of the dorsum of the tongue was investigated with special reference to black-pigmented species and Actinobacillus actinomycetemcomitans. Prevotella intermedia was the most prevalent species, being found in 9 patients. A. actinomycetemcomitans was isolated from 3 subjects and Porphyromonas gingivalis from 2 subjects. To determine whether cross-infection had occurred, the P. intermedia, P. gingivalis, and A. actinomycetemcomitans isolates were examined by restriction endonuclease analysis of the DNA after digesting with one or a combination of the endonucleases Pst I, Bam HI, and Hind III. Evaluation of the restriction endonuclease typing method showed it to be sensitive and useful for the typing of P. intermedia, P. gingivalis, and A. actinomycetemcomitans. Using this restriction endonuclease typing method, all isolates of A. actinomycetemcomitans, P. gingivalis, and P. intermedia obtained from single individuals showed different digest patterns. We conclude that in the present study bacterial cross-infection did not occur among subjects in this school.

Intrafamilial transmission of Actinobacillus actinomycetemcomitans

Cross-sectional studies have shown that Actinobacillus actinomycetemcomitans is a frequent member of the oral flora in children with primary teeth. The purpose of the present study was to obtain information of the transmission of A. actinomycetemcomitans. Three types of families were studied for the prevalence and serotype distribution of A. actinomycetemcomitans. First, families whose periodontally healthy child member harbored A. actinomycetemcomitans; second, families of periodontally healthy children who did not harbor A. actinomycetemcomitans; third, families whose adult member harbored A. actinomycetemcomitans and had been referred to treatment for severe periodontitis. As a whole the study included 23 families. All the family members were invited for the examination. The final study population consisted of 38 children and 32 adults. The results showed that when a child was positive for A. actinomycetemcomitans, either the mother or the father was also positive with one exception, whereas when the adult member harbored A. actinomycetemcomitans, the children were infected in only 2 of the 9 families. Using immunodiffusion technique it was found that the child always harbored the same serotype of A. actinomycetemcomitans as the parent. In conclusion, the results suggest the intrafamilial transmittance of A. actinomycetemcomitans.

Outer membrane proteins of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus studied by SDS-PAGE and immunoblotting

This investigation characterized and compared outer membrane proteins (OMP) of the closely related Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus by means of SDS-PAGE patterns and reactions on immunoblots with rabbit antiserum against A. actinomycetemcomitans FDC Y4. Reactions with serum from a patient with Papillon Lefévre syndrome (PLS), from whom periodontal wild strains of A. actinomycetemcomitans had been isolated, were also studied. OMP were purified with selective solubilization from lyophilized cells of 10 wild and 4 reference strains of A. actinomycetemcomitans and 4 reference strains of H. aphrophilus. OMP profiles from wild and reference strains of A. actinomycetemcomitans were similar while those from A. actinomycetemcomitans and H. aphrophilus differed. The most prominent difference was absence of a heat modifiable protein in H. aphrophilus strains. Immunoblotting revealed strong common antigens in most strains, including a heat modifiable protein with mol wt 34 kDa, as well as a 29 kDa and a 16.5 kDa protein. Treatment with pronase and sodium periodate confirmed the protein nature of the major OMP antigens.

Molecular genetic analysis of Actinobacillus actinomycetemcomitans epidemiology

Research over the past decade has identified many of the microorganisms involved in the etiology of human periodontitis such as Actinobacillus actinomycetemcomitans. Efforts are now directed toward defining these species' role in the pathogenic process. Since microbial colonization of host tissues is a key first step in developing a bacterial infection, determining the source of the periodontal pathogens and their route of transmission is likely to be crucial in formulating preventive strategies. Recently, a technique from molecular biology, restriction endonuclease analysis, has been used to track bacterial infections. In the present study, this method was used to investigate the epidemiology of A. actinomycetemcomitans infection. One hundred twenty-four human subgingival plaque isolates of A. actinomycetemcomitans were examined including bacterial strains from the United States, Korea, and Norway as well as 15 strains from cynomolgus (Macaca fascicularis) and spider monkeys (Macaca iris) and 4 reference strains. The genomic DNA from each strain was purified, digested with each of 16 restriction endonucleases, and the DNA digests were resolved by electrophoresis. The resulting patterns of DNA fragments were compared and also correlated with the A. actinomycetemcomitans serotype determined using serotype-specific antisera in immunofluorescence. Human isolates of A. actinomycetemcomitans even from disparate geographic sources showed little diversity by restriction endonuclease analysis. Three major restriction patterns were found. Restriction pattern I was common to all 20 of the serotype a isolates, restriction pattern II was associated with 58% of the 73 serotype b isolates examined, while restriction pattern III was associated with the remaining serotype b strains and with all 15 of the serotype c strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic approach to the study of epidemiology and pathogenesis of Actinobacillus actinomycetemcomitans in localized juvenile periodontitis

Actinobacillus actinomycetemcomitans isolates from periodontal pockets were examined for restriction fragment-length polymorphism using a characterized 4.7-kb DNA probe. A total of 6 patterns of RFLP was found in 133 isolates originating from 12 subjects. No relatedness was found between RFLP types and serotypes. Different periodontal sites within the same subject and different individuals within the same family sometimes showed only one type of A. actinomycetemcomitans RFLP. When members among the same family showed 2 RFLP types, children were always infected with the A. actinomycetemcomitans strains found in at least one of the parents. These findings support the concept of familial spread of A. actinomycetemcomitans. A. actinomycetemcomitans RFLP type B, corresponding to reference strain JP2, seems to be particularly virulent, as indicated from the presence of RFLP type B in 3 subjects who converted from a healthy periodontal state to localized juvenile periodontitis. RFLP type B was not detected in any of the 21 A. actinomycetemcomitans-infected patients with adult periodontitis. The RFLP method seems to be useful in determining the epidemiology and possibly the potential virulence of periodontal strains of A. actinomycetemcomitans.

Plasmids in Actinobacillus actinomycetemcomitans strains isolated from periodontal lesions of patients with rapidly destructive periodontitis

Several strains of Actinobacillus actinomycetemcomitans newly isolated from periodontal lesions of patients with rapidly destructive periodontitis were all shown to possess identical plasmid profiles consisting of 4 plasmids. The largest plasmid, 20 MegaDalton (MDa), was also found in reference strains. Two different methods were used for isolation of the plasmids; the large 20 MDa plasmid (pHRP1) was found using the Kado and Liu method only. The 3 small plasmids of 7.0, 5.2 and 4.0 MDa (pHRP2, pHRP3, pHRP4), respectively, were seen using the Birnboim and Doly method. These plasmids are so far to be regarded as cryptic; no phenotypical characters have been linked to their presence. The large 20 MDa plasmid was found in all strains examined, and may be a genotypical marker for the A. actinomycetemcomitans species.

Actinobacillus actinomycetemcomitans contamination of toothbrushes from patients harbouring the organism

The main ecological niche of Actinobacillus actinomycetemcomitans (A.a.) seems to be the periodontal pocket, but it can also be isolated from supragingival plaque, buccal and tongue mucosa, or saliva. We examined toothbrushes from 21 patients, all identified as harbouring moderate to large numbers of A.a. in subgingival plaque, for contamination with this organism. 29% of the toothbrushes presented by our patients yielded detectable numbers of A.a. Immediately after toothbrushing this figure rose to 62%, but dropped to 50% after 1 h. Numbers of isolated A.a. on toothbrushes were weakly correlated with the degree of periodontal destruction, and significantly more numbers of A.a. on toothbrushes could be detected if the organism was found on mucous membranes or in saliva. There was no association with gingival inflammation, supragingival plaque nor mean numbers of isolated subgingival A.a.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

Dental research continued to grow during 1988. Unfortunately the quality does not always parallel the quantity of publications. This report obviously does not encompass all of the literature but focuses on studies that are related to trends and to matters that are considered controversial. Likewise the particular interests of the members of the American Academy of Restorative Dentistry were taken into consideration. The subjects covered include periodontics, preventive dentistry, bulp biology, craniomandibular disorders, ceramics, color in restorative dentistry, and dental materials.

Treatment of rapidly destructive periodontitis in Papillon-Lefèvre syndrome. Laboratory and clinical observations

This paper reports the successful treatment of the periodontal component of the Papillon-Lefèvre syndrome in 2 siblings. Treatment consisted of extractions of periodontally-involved teeth under antibiotic therapy. The exogenous source of the suspected pathogenic A. actinomycetemcomitans in this family, identified as a pet dog, was also treated with antibiotics. Assessments of monocyte function and levels of serum antibodies against A. actinomycetemcomitans were performed prior to an immediately after treatment. Microbiological screening of subgingival dental plaque of the PLS patients as well as the rest of the household members, including the dog, was performed every month during the study period. Remission of the rapidly destructive periodontitis, as well as an earlier-described monocyte dysfunction in these two PLS patients occurred concomitantly with the eradication of A. actinomycetemcomitans from the family. 15 months after this treatment, the children still had no signs of periodontitis or of A. actinomycetemcomitans infection. The legitimacy with which PLS is defined as a disease entity is discussed and questioned.

The origin of periodontal infections

Periodontal diseases are recognized as bacterial infections, and some forms are associated with specific organisms, such as Actinobacillus actinomycetemcomitans in juvenile periodontitis, and Bacteroides gingivalis and others in adult periodontitis. The source of the periodontal organisms, whether they are part of the indigenous or resident flora and overgrow to become opportunistic oral pathogens, or whether they are exogenous oral pathogens, is important to determine. The chain of periodontal infection, microbial agent(s) and their transmission, and host response are reviewed with respect to the role of A. actinomycetemcomitans in localized juvenile periodontitis and B. gingivalis in adult periodontitis. The present data lead us to hypothesize that some periodontal organisms may be exogenous pathogens.

Prevention of periodontal diseases may be influenced by the knowledge of whether various forms are caused by opportunistic organisms or exogenous pathogens. If exogenous pathogens are responsible, prevention can be directed to intercepting transmission, thereby preventing colonization. On the other hand, if the organisms are opportunistic pathogens, prevention might be directed at interfering with initial acquisition of the flora earlier in life, as well as suppressing them to low levels consistent with health. For those exogenous periodontal infections, attempts at eradication and prevention of re-infection are likely to be effective. If the organisms are part of the indigenous flora, there is little hope of complete elimination of the organism.

Criteria for distinguishing exogenous periodontal pathogens from opportunistic periodontal pathogens include the prediction that exogenous pathogens would be transient members of the oral flora associated with periodontal disease, likely to be comprised of one or a few clonal types, and intrinsically virulent. In contrast, opportunistic periodontal pathogens would likely be members of the indigenous flora and would overgrow. They would likely be comprised of many clonal types, and have an intrinsically low level of virulence.