Subgingival Dental Plaque Samples Research Articles

Detection And Quantification Of Treponema Denticola In Subgingival Plaque Of Humans By Polymerase Chain Reaction

Introduction: Inflammation of the supporting tissues which is also known as periodontitis contributes to the major etiological factor for tooth loss. Consortium of pathogenic bacteria with elevated levels lead to onset and progression of periodontal disease. Gram negative bacteria, primarily severe anaerobes, are responsible for most of it. Aims and Objectives: The present study aimed to assess the presence of Treponema denticola in periodontal disease in different subgingival plaque samples collected from the oral cavity of 30 patients diagnosed with chronic periodontitis. The plaque samples were compared with similar plaque samples of 15 healthy patients. Method: Subgingival dental plaque samples from shallow and deep crevices were examined for the presence of bacterial DNA using the PCR method, which enables the simultaneous identification of multiple bacterial genomes. Results: PCR results show amplification and quantification of T. denticola in 10 out of 15 patients in group-1, 9 out of 15 patients in group-2, and 4 out of 15 patients in group-3. The statistical analyses of the results show that they are statistically significant. Conclusion: According to the aforementioned study, PCR microorganism identification is sensitive and specific. For early infection diagnosis and subsequently for the prevention and treatment of periodontal disease, a rapid and accurate assessment of periodonto-pathogens is crucial. Bangladesh Journal of Medical Science Vol.22 (Special Issue) 2023 p.93-99

Paraclostridium dentum, a novel species with pathogenic features isolated from human dental plaque sample

A strictly anaerobic bacterial strain designated as SKVG24 was isolated from subgingival dental plaque samples of patients suffering from periodontitis. Cells were stained Gram-positive, rod shaped with endospore. The strain showed negative reaction to catalase and oxidase enzymes, but positive for gelatinase activity. Optimal growth was observed at 37 °C temperature and 7.0 pH. The 16S rRNA gene sequence BLAST analysis assigned strain SKVG24 to the genus Paraclostridium as it displayed 99.93% identity with P. benzoelyticum JC272T followed by P. bifermentans ATCC 638T (99.79%). However, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) of the whole genome sequence showed <97% and <70% identity, respectively, with type strains of all closely related species. The G + C content of the DNA was 28.7 mol%. Total lipids profile showed presence of glycolipids as major lipids. Pathogenic features like hemolysis, gelatin hydrolysis and production of volatile sulfur compounds exhibited by strain SKVG24T were analogous to those observed in the established oral pathogenic strains. Further, whole genome sequence analysis confirmed the presence of genes encoding virulence factors and provided genomic insights on adaptation of the strain in oral environment. Based on the phenotypic and genetic differences with phylogenetic relatives, strain SKVG24T is proposed to represent a new species of the genus Paraclostridium with potential pathogenic ability, for which the name Paraclostridium dentum sp. nov., is suggested. The proposed type strain is SKVG24T (MTCC 12836T; = JCM 32760T).

Early and accurate detection of bacterial isolates from dental plaque in subjects with primary, mixed, and permanent dentition by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry technique.

Background:Bacterial colonization of dentition in different age groups can impact prognosis in different dental diseases. Latest diagnostic technique such as matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF) is increasingly being used for accurate identification of bacteria. This study was undertaken to evaluate the MALDI-TOF MS technique to identify bacterial pathogens from dental plaques in subjects with primary, mixed, and permanent dentition.Materials and Methods:The study included 150 subjects of different age groups and were divided into three groups - Group A: Subjects with primary dentition (n = 50), Group B: Subjects with mixed dentition (n = 50), and Group C: Subjects with permanent dentition (n = 50). Subgingival dental plaque samples were collected from buccal and lingual surfaces of premolar and molar teeth. Clinical parameters such as gingival index were recorded. Samples were cultured in routine aerobic and anaerobic medium. Bacterial growths were assessed by semiquantitative methods. Bacterial isolates were confirmed by MALDI-TOF MS technique.Results:MALDI-TOF MS detected all the culture-grown bacteria. In primary dentition group, purple and yellow complex bacteria predominated. Streptococcus spp. was the predominant bacteria (51%) followed by Escherichia coli (19%) and Veillonella spp. (19%). In mixed dentition and permanent group also, Streptococcus spp. was predominant (46%) followed by Veillonella spp. (24%) and E. coli(19%). However, in both groups, orange complex bacteria (bridge complex) such as Prevotella nigrescens and red complex bacteria (Porphyromonas gingivalis, 3%) were seen. For majority of bacteria, the load increased with age.Conclusions:The bacterial isolates showed a distinct age-specific colonization. The use of advanced technique such as MALDI-TOF MS is helpful in the detection of periodontal pathogens, and the effective oral health programs can be implemented to minimize the risk of periodontal diseases.

Detection of Virus Herpes Simplex Type 1 in Patients with Chronic Periodontal Disease.

BACKGROUND:Periodontal disease is an inflammatory-destructive condition of the supporting tissues of the teeth. Microorganisms found in the dental plaque were considered to be the primary local etiologic factor responsible for the periodontal destruction. It is also evident that herpes simplex viruses may have an impact in the etiopathogenesis of periodontal disease.AIM:This study has been made with the aim to analyse the prevalence of herpes simplex virus type 1 (HSV-1) in the dental plaque (supra- and subgingival) of patients with the chronic periodontal disease.MATERIAL AND METHODS:The study comprised a total of 89 patients with chronic periodontal disease divided into two groups (patients with moderate and severe periodontitis). Supragingival dental plaque samples were taken with sterile cotton (supragingival), and subgingival dental plaque samples were taken with paper absorbents. Samples were subjected to extraction of DNA and further analysis with multiplex PCR for the presence of herpes viral DNA.RESULTS:HSV-1 virus was detected In 24.7% of all patients included in the study. HSV-1 was detected in 22.2% of patients with the moderate stage of the disease, of which in all (100%) in the supragingival plaque samples and only 16.7% in subgingival plaque samples. In two patients HSV-1 was concomitantly detected in supra and subgingival plaque samples. In patients with advanced stage of the disease, the HSV-1 virus was detected in 28.6% patients. In two of the patients, HSV-1 was concomitantly detected in supra and subgingival plaque samples. Statistically, a significant difference was found in HSV-1 positive patients with a moderate stage of disease, between the presence of the virus in subgingival (100%) and subgingival (16.7%) dental plaque samples, p < 0.05.CONCLUSION:Herpes simplex viruses type 1 are present in supragingival and subgingival dental plaque.

Porphyromonas gingivalis and the pathogenesis of rheumatoid arthritis: analysis of various compartments including the synovial tissue

IntroductionWe evaluated the presence of Porphyromonas gingivalis (Pg) DNA in the synovial tissue through synovial biopsy and in other compartments of rheumatoid arthritis (RA) patients in comparison with patients affected by other arthritides. Possible links with clinical, immunologic and genetic features were assessed.MethodsPeripheral blood (PB), sub-gingival dental plaque, synovial fluid (SF) and synovial tissue samples were collected from 69 patients with active knee arthritis (32 with RA and 37 with other arthritides, of which 14 had undifferentiated peripheral inflammatory arthritis - UPIA). Demographic, clinical, laboratory and immunological data were recorded. The presence of Pg DNA was evaluated through PCR. The HLA-DR haplotype was assessed for 45 patients with RA and UPIA.ResultsNo differences arose in the positivity for Pg DNA in the sub-gingival plaque, PB and SF samples between RA and the cohort of other arthritides. Full PB samples showed a higher positivity for Pg DNA than plasma samples (11.8% vs. 1.5%, P = 0.04). Patients with RA showed a higher positivity for Pg DNA in the synovial tissue compared to controls (33.3% vs. 5.9%, P <0.01). UPIA and RA patients carrying the HLA DRB1*04 allele showed a higher positivity for Pg DNA in the synovial tissue compared to patients negative for the allele (57.1% vs. 16.7%, P = 0.04). RA patients positive for Pg DNA in the sub-gingival plaque had a lower disease duration and a higher peripheral blood leucocyte and neutrophil count. The presence of Pg DNA did not influence disease activity, disease disability or positivity for autoantibodies.ConclusionsThe presence of Pg DNA in the synovial tissue of RA patients suggests a pathogenic role of the bacterium. The higher positivity of Pg DNA in full peripheral blood and synovial tissue samples compared to plasma and synovial fluid suggests a possible intracellular localization of Pg, in particular in patients positive for HLA-DR4.

Prevalence of Aggregatibacter actinomycetemcomitans in Sudanese patients with aggressive periodontitis: a case-control study

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.

Oral cavity is not a reservoir for Helicobacter pylori in infected patients with functional dyspepsia

Helicobacter pylori infection is very prevalent in Brazil, infecting almost 65% of the population. The aim of this study was to evaluate the presence of this bacterium in the oral cavity of patients with functional dyspepsia (epigastric pain syndrome), establish the main sites of infection in the mouth, and assess the frequency of cagA and vacA genotypes of oral H. pylori. All 43 outpatients with epigastric pain syndrome, who entered the study, were submitted to upper gastrointestinal endoscopy to rule out organic diseases. Helicobacter pylori infection in the stomach was confirmed by a rapid urease test and urea breath tests. Samples of saliva, the tongue dorsum and supragingival dental plaque were collected from the oral cavity of each subject and subgingival dental plaque samples were collected from the patients with periodontitis; H. pylori infection was verified by polymerase chain reaction using primers that amplify the DNA sequence of a species-specific antigen present in all H. pylori strains; primers that amplify a region of urease gene, and primers for cagA and vacA (m1, m2, s1a, s1b, s2) genotyping. Thirty patients harbored H. pylori in the stomach, but it was not possible to detect H. pylori in any oral samples using P1/P2 and Urease A/B. The genotype cagA was also negative in all samples and vacA genotype could not be characterized (s-m-). The oral cavity may not be a reservoir for H. pylori in patients with epigastric pain syndrome, the bacterium being detected exclusively in the stomach.

Effects of fixed orthodontic appliances on subgingival microflora

Fixed orthodontic appliances cause plaque accumulation around bands and brackets. Since the microbiological composition of dental plaque is closely connected to periodontal tissue health, the aim of this study was to determine the effects of fixed orthodontic appliances on subgingival microflora and periodontal status. This prospective study was carried out on 32 adolescents scheduled for fixed orthodontic treatment. Subgingival dental plaque samples and periodontal records (pocket probing depth and clinical attachment level) were obtained in four recording times: before bonding of fixed appliances (T0), 1 (T1), 3 (T2) and 6 (T3) months after the beginning of orthodontic therapy, in order to detect the changes in periodontopathic anaerobe microbial flora and its effects on periodontal status. The values of pocket probing depth, total number of microorganisms and number of patients with positive findings of Prevotella intermedia and other periodontopathic anaerobes increased from T0 to the maximum obtained in T2 recording time. Both clinical and microbiological values decreased 6 months after the beginning of orthodontic therapy. The therapy with fixed appliances may transitionally increase the growth of periodontopathogenic bacteria and consequently result in gingival inflammatory response but without destructive effect on deep periodontal tissues.

Clinical and microbiological effects of fixed orthodontic appliances on periodontal tissues in adolescents

To determine the effects of fixed orthodontic appliances on periodontal health and microbiological composition of subgingival dental plaque. This prospective longitudinal self-controlled study was conducted on 32 adolescents (13 males, 19 females), who were scheduled for fixed orthodontic treatment between 2002 and 2005. Dental plaque accumulation, gingival inflammation and pocket probing depth were measured at the mesio-vestibular angle of the examined group of teeth followed by collection of subgingival dental plaque samples in the same points. These periodontal indices and microbiological parameters were determined prior to the placement of fixed appliances and 1, 3 and 6 months after the beginning of orthodontic treatment. All values of both clinical and microbiological parameters started to increase after the placement of fixed appliances. Maximum values were reached 3 months after fixed appliance placement followed by their decrease in the last registration period of 6 months after the placement of fixed appliances. Treatment with fixed appliances in adolescents may transitionally increase the values of all periodontal indices and stimulate the growth of periodontopathogenic bacteria, but without destructive effects on deep periodontal tissues.

Clinical and microbiological evaluations of mandibular lateral incisor with radicular-gingival groove

We present a case of radicular-gingival groove identified in the mandibular left lateral incisor. A female visited our clinic at the age of 11Y5M complaining of repeated gingival inflammation. An intraoral examination found severe gingival swelling in the affected region, while clinical examinations revealed a groove from the cingulum to the apex of the mandibular left lateral incisor. A gingivectomy and professional brushing instruction were performed, with follow-up examinations given periodically. After a long interval, the patient returned at the age of 18Y4M and reported that gingival inflammation had repeatedly occurred. Subgingival dental plaque samples were collected from the affected area as well as areas around 3 normal teeth with a periodontal healthy condition, along with a saliva sample. Using bacterial DNA extracted from each sample, detection of 10 putative periodontopathic bacterial species was done by PCR, which identified Tannerella forsythensis , Campylobacter rectus , Eikenella corrodens , Actinobacillus actinomycetemcomitans , and Capnocytophaga sputigena in the sample from the affected region. Further, broad-range PCR targeting 16S rRNA with direct sequencing of the samples showed a variety of bacterial species, including Neisseria , Corynebacterium , and Fusobacterium . Streptococcus species occurred at a high rate in the plaque samples from the control teeth, whereas there were none in the affected region. Our findings indicate that the bacterial profile in the area of a radicular-gingival groove may be different from other periodontal healthy sites, which might be related to the occurrence of repeated inflammation in the groove area.

Relationship Between Transmission of Porphyromonas gingivalis and fimA Type in Spouses

Porphyromonas gingivalis is one of the major microbial pathogens associated with chronic periodontitis. To eradicate such pathogens by periodontal therapy, it is essential to clarify the source of infection. Recent findings suggest that the genotype of the fimbriae is one of the important factors in infection by P. gingivalis. The objectives of the present study were to investigate the transmission of P. gingivalis between spouses and to determine the relationship between P. gingivalis fimA type and colonization. A total of 14 couples were selected to investigate the transmission of P. gingivalis and its association with the fimA types. To examine the distribution of fimA type in the general population, 32 subgingival plaque samples from 47 patients with periodontitis were also tested. The transmission of P. gingivalis strains was determined by using pulsed field gel electrophoresis (PFGE). P. gingivalis strains isolated from the couples and subgingival dental plaque samples were studied for fimA classification. The PFGE patterns of P. gingivalis strains from matched husbands and wives were identical for six of the 14 couples. In five of these six couples (83.3%), P. gingivalis strains harboring the type II fimA gene were present. The proportion of type II fimA in the strains isolated from couples with probable intrafamilial transmission was significantly higher than that in patients with periodontitis or in the group of samples isolated from one member of a couple. This study suggests that fimA type II, even though widely distributed in patients with periodontitis, may be an important factor in the transmission of P. gingivalis between spouses.

Periodontopathogens in the saliva and subgingival dental plaque of a group of mothers.

The aim of this study was to assess the periodontal condition and the presence of putative periodontal pathogens in 30 Brazilian mothers, aging 21-40 years (28.4 4.49 years), and in their children, aging 5-6 years, since mothers can be a source of pathogens and, thus, influence their children's bacteriological and clinical condition. Besides assessing the plaque index (PI), gingival index (GI) and pocket probing depth (PD), the survey analyzed four subgingival dental plaque samples from mothers and children, as well as a sample of stimulated saliva from mothers. Those samples were analyzed by means of the slot immunoblot (SIB) technique, in order to determine the presence of Actinobacillus actinomycetemcomitans (Aa), Prevotella nigrescens (Pn), Porphyromonas gingivalis (Pg) and Treponema denticola (Td). The mean values and standard deviations of the evaluated clinical variables for mothers and children were, respectively: 1.86 0.67 and 1.64 0.68 for PI, and 1.24 0.67 and 0.82 0.37, for GI. Only for mothers, the total PD was 1.81 0.69 mm, and the PD of four sites was 4.03 1.40 mm. The Wilcoxon test revealed significant difference (p < 0.05) between mothers and their children only as to GI. The most prevalent bacteria in mothers were, in decreasing order: Aa, Pn, Pg and Td. The children presented patterns of oral hygiene and bacterial profiles similar to those of their mothers, in spite of the fact that most of them did not present enough subgingival plaque for testing. The comparison between mothers' subgingival dental plaque and saliva samples revealed statistically significant differences (p < 0.05) for all bacteria, with greater positivity and scores in the saliva, which demonstrates that it is an indicator of oral colonization and can work as a vehicle for the transmission of periodontopathogens from mothers to their children.

The distribution and interrelationship of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and BANA scores among older adults.

In a random sample of subgingival dental plaque samples from 375 blacks and 300 whites aged 65 and older, immunofluorescence assays for 3 target pathogens including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia, and BANA enzyme analysis were carried out. Blacks had significantly greater proportions of P. gingivalis and P. intermedia in their subgingival plaque and had significantly higher BANA scores. These assay results were investigated for concordance with each other and with 2 cariogenic salivary bacteria, Streptococcus mutans and lactobacilli. In general for both races, the periodontal pathogens were more likely to occur in combination with each other than with either S. mutans or lactobacilli. P. gingivalis and P. intermedia were more frequently associated with each other than with A. actinomycetemcomitans. There was a significant negative concordance between BANA and A. actinomycetemcomitans in whites and a significant positive concordance between BANA and P. intermedia in blacks.

Studies of the Subgingival Microflora in Patients With Acquired Immunodeficiency Syndrome

Two unique forms of periodontal disease, HIV-gingivitis and HIV-periodontitis, have been described in patients with Acquired Immunodeficiency Syndrome (AIDS). In order to determine the bacterial species associated with periodontitis in AIDS patients, the predominant cultivable microflora was examined in 21 subgingival plaque samples from 11 AIDS patients with periodontitis. The presence of putative periodontal pathogens including Actinobacillus actinomycetemcomitans, Bacteroides intermedius, Porphyromonas gingivalis (formerly B. gingivalis), and Wolinella recta was examined by immunofluorescence in 128 subgingival dental plaque samples from 50 AIDS patients including 32 patients with periodontitis. Of 666 bacterial strains isolated from the 21 subgingival plaque samples, Streptococcus sanguis II was the most frequently recovered species comprising 18.5% of the total number of isolates followed by Lactobacillus acidophilus (12.2%), Porphyromonas gingivalis (12%), Fusobacterium nucleatum (11.4%), Staphylococcus epidermidis (8.7%), Actinomyces naeslundii (7.5%), and Actinomyces viscosus (4.7%). Fusobacterium nucleatum was the most prevalent species and was found in 76% of the sites and 91% of the patients. Enteric species including Enterococcus avium and Enterococcus faecalis, Clostridium clostridiiforme and Clostridium difficle as well as Klebsiella pneumoniae also were recovered. Immunofluorescence assays detected similar carriage rates of A. actinomycetemcomitans, B. intermedius, and P. gingivalis in both gingivitis patients and periodontitis patients, while four times more periodontitis patients demonstrated W. recta. Subgingival yeast was a frequent finding in these AIDS patients, present in 62% of the subjects and 55% of the sites. This study indicates that subgingival plaque in AIDS patients with periodontitis can harbor high proportions of the same periodontal pathogens as are associated with periodontitis in non-HIV infected subjects as well as high proportions of opportunistic pathogens.

Isolation and Identification from Subgingival Dental Plaque Samples of Bacteria with Low Susceptibility to Chlorhexidine and Phenoxyethanol

Subgingival plaque samples from 19 patients with chronic periodontitis were exposed to various concentrations of phenoxyethanol, chlorhexidine and a mixture of both. Organisms surviving at concentrations lower than the minimum inhibitory concentrations of the antimicrobial agents were isolated and identified: these were designated the 'mostresistant organisms'. In the case of the plaque samples exposed to phenoxyethanol, most (78 per cent) of the isolates were streptococci; Gram-negative obligate anaerobes were recovered from only one of the samples. From the samples exposed to chlorhexidine, streptococci were again the most frequently encountered organisms, comprising 48 per cent of the 27 isolates. However, Gram-negative obligate anaerobes accounted for a high proportion (33 per cent) of the isolates. The organisms recovered from the samples exposed to a combination of phenoxyethanol and chlorhexidine were similar to those found in samples exposed to phenoxyethanol alone. Hence, streptococci accounted for 82 per cent of the isolates and no Gram-negative obligate anaerobes were recovered. These results imply that the use of chlorhexidine alone as an adjunct to the mechanical treatment of chronic periodontitis may permit the survival of organisms implicated in the aetiology of chronic periodontitis. In contrast, the use of phenoxyethanol alone, or in combination with chlorhexidine, would in general permit the survival of only those organisms compatible with gingival health. Keywords: Subgingival plaque; Chlorhexidine; Phenoxyethanol; Bacteria; Susceptibility.

Isolation and Identification from Subgingival Dental Plaque Samples of Bacteria with Low Susceptibility to Chlorhexidine and Phenoxyethanol

Isolation and Identification from Subgingival Dental Plaque Samples of Bacteria with Low Susceptibility to Chlorhexidine and Phenoxyethanol

Coaggregation properties of human oral Veillonella spp.: relationship to colonization site and oral ecology.

The primary habitats of oral veillonellae are the tongue, dental plaque, and the buccal mucosa. Isolates were obtained from each habitat and tested for coaggregation with a battery of other oral bacterial strains. All 59 tongue isolates tested for coaggregation were Veillonella atypica or Veillonella dispar. All but one of them coaggregated with strains of Streptococcus salivarius, a predominant inhabitant of the tongue surface but not subgingival dental plaque. These tongue isolates were unable to coaggregate with most normal members of the subgingival flora such as Actinomyces viscosus, Actinomyces naeslundii, Actinomyces israelii, and Streptococcus sanguis. In contrast, 24 of 29 Veillonella isolates, of which 20 were Veillonella parvula from subgingival dental plaque samples, coaggregated strongly with the three species of Actinomyces, S. sanguis, and other bacteria usually present in subgingival plaque, but they did not coaggregate with S. salivarius. The majority of isolates from the buccal mucosa (42 of 55) has coaggregation properties like those from the tongue. These results indicate that the three human oral Veillonella species are distributed on oral surfaces that are also occupied by their coaggregation partners and thus provide strong evidence that coaggregation plays a critical role in the bacterial ecology of the oral cavity.

Enumeration of cultivable black-pigmented Bacteroides species in human subgingival dental plaque and fecal samples.

The distribution of black‐pigmented Bacteroides species among 468 isolates from human subgingival dental plaque and feces from 20 adults selected from periodontally healthy, gingivitis and periodontitis groups is reported. Bacteroides intermedius was detected in all dental plaque samples. Bacteroides gingivalis, Bacteroides melaninogenicus and Bacteroides loescheii were isolated from 8, 3 and 2 dental plaques, respectively. Bacteroides denticola and Bacteroides levii were each detected in one dental plaque. Only 3 fecal samples contained black‐pigmented Bacteroides, identified as Bacteroides carporis, with a frequency ranging from 0.001 to 0.06% of total colonies on non‐selective blood agar plates.

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

This study was designed to detect a possible exogenous source of oral A. actinomycetemcomitans in a family where the 2 children suffered from Papillon‐Lefévre syndrome (PLS). Every month for 1 yr subgingival dental plaque samples were obtained from the 2 children, their parents, grandparents and their pet dog. Dental plaque samples were also obtained from a 12‐yr‐old boy whose family had owned a dog from the same litter as the PLS family. Dispersed and diluted plaque samples were cultured anaerobically on Slots medium and A. actinomycetemcomitans was identified by standard criteria. The various A. actinomycetemcomitans wild strains were mass cultivated and their total genomes compared after DNA restriction endonuclease mapping in 2 different electrophoretic gels, using ECO RI, HIND III and BAM HI. Only the plaque samples from 1 of the PLS children, the pet dog and the 12‐yr‐old boy produced A. actinomycetemcomitans. The restriction endonucleases could not distinguish between the A. actinomycetemcomitans wild strains from the PLS child and those from the family dog or the 12‐yr‐old boy. However, the methods could readily differentiate between both reference strains and wild strains, indicating that transfer of A. actinomycetemcomitans from dog to the PLS child had taken place.

Eubacterium yurii subsp. yurii sp. nov. and Eubacterium yurii subsp. margaretiae subsp. nov.: Test Tube Brush Bacteria from Subgingival Dental Plaque

Eighteen strains of anaerobic gram-positive rods exhibiting an unusual three-dimensional cellular arrangement resembling test tube brushes (TTB) were recovered from subgingival dental plaque samples of randomly selected periodontitis patients. The isolates were obtained from subgingival sites exhibiting bone loss of ≥20% and pocket depth of ≥4 mm. Based upon biochemical profiles, these organisms belong to the family Propionibacteriaceae and are somewhat similar biochemically to some species of Eubacterium, notably Eubacterium saburreum. Relatedness between TTB bacteria and E. saburreum was assessed by deoxyribonucleic acid base composition and deoxyribonucleic acid renaturation rates. Moles percent guanine plus cytosine were 32 and 33, respectively. Hybridization studies showed 32% relatedness between E. saburreum and TTB bacteria, indicating that they are related but distinct species. We therefore propose a new species, Eubacterium yurii. Strains of this species characteristically form three-dimensional brushlike aggregates mediated by an amorphous, extracellular material. E. yurii is divided into two subspecies that exhibit 53% homology: E. yurii subsp. yurii, which is phosphatase positive, and E. yurii subsp. margaretiae, which is phosphatase negative.