Selective recovery of oral Capnocytophaga spp. with sheep blood agar containing bacitracin and polymyxin B

Antimicrobial susceptibility pattern of oral gram negative anaerobes from Indian subjects

OBJECTIVES

There is paucity of information on the antimicrobial susceptibility pattern of oral anaerobic bacteria. In this study, an attempt has been made to evaluate the antimicrobial susceptibility/resistance trend of oral Gram negative bacteria from Indian subjects.

METHODS

Minimum inhibitory concentrations (MIC) of 304 isolates against twelve different antibiotics were determined using gradient diffusion MIC strips. The organisms were isolated and identified based on phenotypic characteristics and included Porphyromonas gingivalis, Prevotella species, Tannerella forsythia, Fusobacterium nucleatum, Aggregatibacter actinomycetemcoitans, Eickenella corrodens and Capnocytophaga species. For each antimicrobial agent, MIC₅₀ and MIC₉₀ were calculated and expressed.

RESULTS

Resistance to azithromycin, clindamycin, and amoxicillin was observed in most of the anaerobic bacterial species studied. High degree of susceptibility was observed to amoxillin-clavulanic acid, doxycycline and moxifloxacin. A single strain of P. melaninogenica was resistant to moxifloxacin. The susceptibility pattern varied with cephalosporins among species. Ceftriaxone showed highest and cefazolin least efficacy among cephalosporins. All anaerobic bacteria tested were susceptible to metronidazole. Strains of T. forsythia were more resistant to several antibiotics than other anaerobic bacteria. All three species of capnophilic bacteria displayed high degree of resistance to metronidazole and significant resistance to amoxicillin, azithromycin, clindamycin, cefazolin and cefuroxime.

CONCLUSIONS

Amoxicillin-clavulanic acid, doxycycline, moxifloxacin and metronidazole appeared to be the most effective drugs against gram negative anaerobic bacteria. However, the MIC₅₀ and MIC₉₀ values against metronidazole were on the higher side of the normal indicating a potential for developing resistance.

Antibiotic content of selective culture media for isolation of Capnocytophaga species from oral polymicrobial samples

In oral microbiome, because of the abundance of commensal competitive flora, selective media with antibiotics are necessary for the recovery of fastidious Capnocytophaga species. The performances of six culture media (blood agar, chocolate blood agar, VCAT medium, CAPE medium, bacitracin chocolate blood agar and VK medium) were compared with literature data concerning five other media (FAA, LB, TSBV, CapR and TBBP media). To understand variable growth on selective media, the MICs of each antimicrobial agent contained in this different media (colistin, kanamycin, trimethoprim, trimethoprim-sulfamethoxazole, vancomycin, aztreonam and bacitracin) were determined for all Capnocytophaga species. Overall, VCAT medium (Columbia, 10% cooked horse blood, polyvitaminic supplement, 3·75 mg l(-1) of colistin, 1·5 mg l(-1) of trimethoprim, 1 mg l(-1) of vancomycin and 0·5 mg l(-1) of amphotericin B, Oxoid, France) was the more efficient selective medium, with regard to the detection of Capnocytophaga species from oral samples (P < 0·001) and the elimination of commensal clinical species (P < 0·001). The demonstrated superiority of VCAT medium, related to its antibiotic content, made its use indispensable for the optimal isolation of Capnocytophaga species from polymicrobial samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

Isolation of Capnocytophaga species is important for the proper diagnosis and treatment of the systemic infections they cause and for epidemiological studies of periodontal flora. We showed that in pure culture, a simple blood agar allowed the growth of all Capnocytophaga species. Nonetheless, in oral samples, because of the abundance of commensal competitive flora, selective media with antibiotics are necessary for the recovery of Capnocytophaga species. The demonstrated superiority of VCAT medium made its use essential for the optimal detection of this bacterial genus. This work showed that extreme caution should be exercised when reporting the isolation of Capnocytophaga species from oral polymicrobial samples, because the culture medium is a determining factor.

Influence of previous antimicrobial therapy on oral carriage of beta-lactamase producing Capnocytophaga isolates

AIM

In order to assess the prevalence of beta-lactamase producing oral bacteria in childhood, the influence of different parameters on the oral carriage of Capnocytophaga was studied in a specific population of children with cancer. The examined parameters included clinical observation of oropharyngeal mucosa, type of malignant disease and intake of chemotherapy and antimicrobial treatment.

METHODS

The gingival and mucosal status of the patients was recorded before each sampling procedure. Samples were collected by oropharyngeal swabbing in children with leukaemia or other oncological diseases for isolation of Capnocytophaga strains.

RESULTS

Capnocytophaga strains were more often isolated in samples from children with oncological diseases (71%) other than leukaemia (57%). Concomitant chemotherapy had no influence on oral Capnocytophaga carriage. A significant decrease of the prevalence of Capnocytophaga strains isolated was observed in children who received antimicrobial treatment within 8 days before the sampling procedure (15.5% vs. 28%). But, the incidence of beta-lactamase-producing strains was not linked to previous antimicrobial treatments.

CONCLUSION

Oral carriage of Capnocytophaga strains can be linked to haematological disease and previous antibiotherapy, but results did not confirm that beta-lactamase treatments exert a selective pressure. Other factors might be involved in emerging for oral beta-lactamase-producing Capnocytophaga strains.

Capnocytophaga in the dental plaque of immunocompromised children with cancer

OBJECTIVES

(i) To compare the prevalence and levels of Capnocytophaga, a known systemic pathogen in immunocompromised patients, in the dental plaque of healthy children and children with cancer, and (ii) to determine the susceptibility of strains isolated from cancer patients to a range of antibiotics.

PATIENTS AND METHODS

Thirty-one children with cancer undergoing a first course of immunosuppressive chemotherapy and 30 healthy control children were included in the study. Samples were collected on days 0, 7, 14, and 21 of the cure (and equivalent dates in controls). Susceptibility to antibiotics was tested using an agar dilution method and galleries with predefined concentrations of selected antibiotics.

RESULTS

There was a significant drop in the total anaerobic cultivable flora on day 14 and in the prevalence of Capnocytophaga on days 14 and 21 in the children with cancer. The proportion of Capnocytophaga in the anaerobic flora, however, was high in certain cancer patients. Beta-lactam/beta-lactamase inhibitor combinations, imipenem, clindamycin, and tetracycline were the most effective against Capnocytophaga.

CONCLUSION

This study showed that Capnocytophaga decreased in prevalence and proportion in the dental plaque of cancer patients during chemotherapy but became predominant in some cases. It is recommended that imipenem or beta-lactam/beta-lactamase inhibitor combinations be used to treat Capnocytophaga bacteraemia.

Prevalence of oropharyngeal beta-lactamase-producing Capnocytophaga spp. in pediatric oncology patients over a ten-year period

Background

The aim of this study was to evaluate the prevalence of beta-lactamase-producing Capnocytophaga isolates in young children hospitalized in the Pediatric Oncology Department of Hôpital Sud (Rennes, France) over a ten-year period (1993–2002).

Methods

In neutropenic children, a periodic survey of the oral cavity allows a predictive evaluation of the risk of systemic infections by Capnocytophaga spp. In 449 children with cancer, 3,053 samples were collected by oral swabbing and plated on TBBP agar. The susceptibility of Capnocytophaga isolates to five beta-lactams was determined.

Results

A total of 440 strains of Capnocytophaga spp. were isolated, 309 (70%) of which were beta-lactamase producers. The beta-lactamase-producing strains were all resistant to cefazolin, 86% to amoxicillin, and 63% to ceftazidime. The proportion of strains resistant to third-generation cephalosporins remained high throughout the ten-year study, while susceptibility to imipenem and amoxicillin combined with clavulanic acid was always conserved.

Conclusion

These results highlight the risk of antibiotic failure in Capnocytophaga infections and the importance of monitoring immunosuppressed patients and testing for antibiotic susceptibility and beta-lactamase production.

Microbiological diagnostic testing in the treatment of periodontal diseases

A variety of microbiological diagnostic tests are available for clinicians to use for evaluation of patients with periodontal disease. Each one has its own unique set of advantages and disadvantages, and probably the most useful information for the clinician can be obtained using a combination of the various analytic methods. The tests appear to have their greatest utility when used on patients with chronic or aggressive periodontitis who do not respond favorable to conventional mechanical therapy. The major limitation of all microbiological tests is that the information obtained is relevant to the site sampled, and may not be representative of the microflora of the entire dentition. However, since it is often only specific sites that do not respond to initial therapy, knowing the constituents of the microflora that populate these sites is clinically relevant.

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea

A beta-lactamase gene (cfxA3, 966 bp) was isolated from a beta-lactam-resistant Capnocytophaga ochracea clinical isolate and amplified using primers from the cfxA gene of Bacteroides vulgatus. The MICs of third-generation cephalosporins were much higher than those of the transconjugant Escherichia coli strain. The deduced protein sequence, by comparison with CfxA2 of Prevotella intermedia, had a Y239D substitution and possessed the characteristics of a class A, group 2e beta-lactamase.

Capnocytophaga granulosa and Capnocytophaga haemolytica: novel species in subgingival plaque

BACKGROUND

The oral cavity accommodates one of the most diverse microfloras in the human body. Knowledge of this microflora, and of the periodontal microflora in particular, proves crucial towards an understanding of the bacterial-host interactions which lead to the development of infectious inflammatory periodontal diseases. Capnocytophaga species have been implicated as putative periodontal pathogens. To date, only 3 members of this genus (C. gingivalis, C. ochracea and C. sputigena) have been isolated from subgingival plaque.

AIM

This communication reports the isolation of 2 recently-speciated strains, namely C. granulosa and C. haemolytica, from subgingival plaque collected from adult periodontitis patients.

MATERIAL AND METHODS

Subgingival plaque was collected from 29 patients with chronic adult periodontitis. Plaque samples were inoculated onto fastidious anaerobe agar and incubated anaerobically for 5 days. Routine identification of clinical isolates was performed by 16S rRNA PCR-RFLP analysis, using Cfo I as restriction enzyme and corroborated by 16S rRNA gene sequencing.

RESULTS

16 of 29 patients (55%) tested positive for either C. granulosa and or C. haemolytica. A total of 70 isolates (63 C. granulosa and 7 C. haemolytica) were cultivated from subgingival plaque. 15 (51%) patients tested positive for C. granulosa, and 3 (10%) patients tested positive for C. haemolytica.

CONCLUSION

This is the 1st report which recounts the presence of C. granulosa and C. haemolytica in subgingival plaque. Further research is required to establish the relative proportions of these species subgingivally in health and disease.

In vitro susceptibilities of Capnocytophaga isolates to beta-lactam antibiotics and beta-lactamase inhibitors

The susceptibilities of 43 pharyngeal isolates of Capnocytophaga to beta-lactam antibiotics, alone or in combination with beta-lactamase inhibitors, were tested by an agar dilution method. The 34 beta-lactamase-positive strains were highly resistant to beta-lactams, but the intrinsic activities of clavulanate, tazobactam, and sulbactam against Capnocytophaga, even beta-lactamase producers, indicates that these beta-lactamase inhibitors could be used for empirical treatment of neutropenic patients with oral sources of infection.

The taxonomy, ecology and cultivation of bacterial genera belonging to the family Flavobacteriaceae

The group known as the 'flavobacteria' has previously been regarded as synonymous with the genus Flavobacterium. Today, however, flavobacteria refers to the family Flavobacteriaceae comprising 10 genera. This review deals with the rapid changes in the taxonomy of these bacteria, especially over the last decade. It also briefly reviews the ecology of the genera in this family and describes the media that have been utilized in the general and selective cultivation of these organisms.

The effect of chemotherapy on the supragingival plaque of pediatric cancer patients

The anaerobic cultivable flora of the dental plaque was investigated in 16 cancer children at days 0, 7, 14 and 21 of a first cure of chemotherapy. Results were compared with those obtained in 16 healthy children. Diseased children showed more quantitative variations of the flora than the controls, especially during the first week of chemotherapy. Whatever the day of sampling, the flora of the diseased children was significantly less complex than that of the controls. Viridans streptococci, Capnocytophaga, and to a lesser extent staphylococci, appeared to be the most strongly affected in diseased children. This could be explained by different mechanisms, uncontrolled recolonization of the dental plaque, selection of multidrug-resistant strains or nosocomial acquisition. These results indicate that variations in quantity, complexity and quality of the oral flora occur during chemotherapy, leading to a major imbalance of the ecosystem.

Subgingival distribution of periodontopathic bacteria in adult periodontitis and their susceptibility to minocycline-HCl

The purpose of this study was to investigate the distribution of several periodontopathic bacteria in adult periodontitis, their in vitro susceptibility to minocycline-HCl, and whether the efficacy of the drug changes with a decrease in bacterial susceptibility. Twenty-one patients (43 to 75 years old) with 62 periodontal lesions from pockets > or =4 mm participated in the study. After subgingival sampling, an ointment containing 2% minocycline-HCl was applied locally to the selected pockets once a week for 4 weeks. The lesions were clinically examined after 1 and 4 weeks of administration. The distribution of the subgingival microorganisms included Capnocytophaga sputigena (37.1%), Prevotella intermedia (22.6%), Porphyromonas gingivalis (22.6%), Fusobacterium nucleatum (20.1%), Actinobacillus actinomycetemcomitans (9.7%), and Eikenella corrodens (4.8%). The distribution was complex, with 76.8% of the sites containing 1 to 3 bacterial spieces. The minimum inhibitory concentration (MIC) of minocycline-HCl for each organism showed that most were inhibited by a minocycline-HCl concentration equal to or less than the MIC for reference strains. However, some clinical strains of Prevotella intermedia seemed to exihibit low susceptibility to minocycline-HCl. There were no significant differences among sites with strains exhibiting low or normal susceptibility to minocycline-HCl. The concentration of the drug applied to deep periodontal pockets inhibited the growth of most of the microorganisms investigated in this study.

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.

Microbial ecology of Actinobacillus actinomycetemcomitans, Eikenella corrodens and Capnocytophaga spp. in adult periodontitis

Information on intraoral distribution of putative periodontal pathogens might be essential for controlling different forms of periodontal disease. Colonization may be either promoted or impeded by other bacteria competing in the subgingival ecosystem. In recent investigations microbial associations between dental organisms have been determined in a multitude of subgingival plaque samples within multiple patients and described by odds ratios, in most circumstances without taking into account the correlated structure of the observations within a single individual. The present investigation had 3 major objectives: (i) to describe the intraoral distribution of some facultatively anaerobic, Gram-negative rods, i.e. Actinobacillus actinomycetemcomitans, Eikenella corrodens-like organisms and Capnocytophaga spp., in a multitude of subgingival and extracrevicular samples of 10 adult subjects with A. actinomycetemcomitans-associated periodontitis; (ii) to analyse possible inconsistencies of microbial associations between these periodontal organisms; and (iii) to determine factors increasing the likelihood of isolating these bacteria in a given subgingival site by employing Generalized Estimation Equation (GEE) methods. Clinical examinations were carried out at 6 sites of every tooth present. In each subject, 13 extracrevicular (2 cheek mucosa, 3 tongue, 4 gingival, 2 tonsillar samples, 1 palatinal, 1 saliva sample) and between 22 and 44 subgingival samples from deepest sites of every tooth present (n = 296) were selectively cultivated for A. actinomycetemcomitans, E. corrodens and Capnocytophaga spp. In extracrevicular material, A. actinomycetemcomitans, Capnocytophaga spp. and E. corrodens were isolated in 9, 10 and 6 patients, and from 65, 82 and 15% samples, respectively. The organisms were recovered from 51, 62 and 27% subgingival plaque samples, respectively. Heterogeneity tests did not reveal significant inconsistencies of microbial associations between bacteria in subgingival plaque. Mantel-Haenszel's odds ratios ranged between 2.0 for A. actinomycetemcomitans and Capnocytophaga spp. and 18.7 for Capnocytophaga spp. and E. corrodens. An exchangeable working dependence structure was employed in the GEE approach. The odds of isolating A. actinomycetemcomitans was increased by factor 3.7 in 4-6 mm deep pockets, and 9.5 in > or = 7 mm deep pockets. The odds of presence of E. corrodens was increased by factor 10.8 in the case of presence of Capnocytophaga spp. and 2.1 in the case of presence of A. actinomycetemcomitans. Capnocytophaga spp. were associated with bleeding on probing and molar sites. Presence of E. corrodens was associated with clinical attachment loss but not periodontal probing depth. Results of the present study indicated an association of A. actinomycetemcomitans with periodontal pathology. Whereas this organism and Capnocytophagae were widely distributed in extracrevicular ecosystems of the mouth, E. corrodens only occasionally appeared in saliva or on mucous membranes of the oral cavity. In general, GEE methods seem to allow to determine factors associated with the presence of periodontal organisms in a multivariate approach and considering the correlated structure of the data.

Antimicrobial susceptibility tests on anaerobic oral mixed cultures in periodontal diseases

The ecosystem of the dental plaque in periodontal diseases is very complex: the study of such micro-organisms, which are mostly strict anaerobes, requires the use of specific techniques under conditions of strict anaerobiosis. The aim of the present study was to design a rapid method to evaluate the activity of antimicrobials on mixed bacterial plaque of subjects with periodontal diseases. The study was carried out using a computerised instrument generally used for simultaneous diagnostic tests with aerobic bacteria. Operative and methodological modifications were made to obtain conditions of strict anaerobiosis and the balanced growth of all the microbial forms present in the mixed cultures of the plaque. Penicillins and cephalosporins were active on all the samples, whereas colistin, gentamicin, kanamycin and nalidixic acid showed no activity. Clindamycin, tetracycline, erythromycin and penicillin G were effective only against some samples. The activity of the antimicrobials towards isolated strains was analogous to that towards the corresponding mixed culture.

Principles of evaluation of the diagnostic value of subgingival bacteria

This paper describes steps in the process of evaluating subgingival bacteria assays for the diagnosis of periodontal disease. The first step examines the infectious etiology of periodontal disease in pointing to specific oral bacteria as periodontal pathogens. Second is characterization of the laboratory test to detect and quantitate these pathogens as to sensitivity, specificity, and positive and negative predictive value. Third is the role of the laboratory test in the diagnosis of the different forms of periodontal disease which is related to the current clinical rather than microbiological definition of these diseases. The fourth and most important step is an analysis of the significance of subgingival bacterial tests in clinical decision-making.

Microbial alterations in supragingival dental plaque in response to a triclosan-containing dentifrice

A total of 325 subjects were entered into a double-blind, stratified 2-treatment clinical study that examined the effects of a dentifrice containing 0.3% triclosan, 2% Gantrez copolymer and 0.243% sodium fluoride on supragingival dental plaque and gingivitis. A subset of 159 subjects including 72 men and 87 women participated in the microbiological component of this study, which was designed to detect shifts in supragingival bacterial species in response to triclosan. Subjects were divided into two groups: one performed normal oral hygiene with the triclosan/copolymer dentifrice and a control group used a placebo dentifrice without triclosan. At baseline, 3 and 6 months during treatment and at 6, 12, 18 and 24 weeks post-treatment, supragingival dental plaque was collected from the buccal and lingual surfaces of the 4 first molar teeth and assayed for: 1) bacterial morphotypes by phase-contrast microscopy; 2) select bacterial groups and bacterial species by culture; and 3) target periodontal pathogens including Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis and Prevotella intermedia by immunofluorescence microscopy. There were few statistically significant differences between treatment groups in any of the 90 microbiological parameters measured at the 7 different time points. The control group demonstrated significantly higher levels of cultivable Neisseria and higher proportions at the 3-month treatment period of P. gingivalis-infected subjects and mean cells. After 6 months of treatment, the triclosan group demonstrated higher levels of fusiforms. Analysis of triclosan resistance data failed to detect a shift towards increased proportions of bacteria resistant to triclosan, and both treatment groups demonstrated triclosan-resistant strains, predominantly Veillonella dispar. This study confirms the microbiological safety of triclosan-containing dentifrices and suggests that continued use can be associated with beneficial alterations in the bacterial composition of supragingival dental plaque.

Occurrence of certain bacterial species and morphotypes in juvenile periodontitis in Chile

The occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, Fusobacterium nucleatum, Campylobacter rectus, Capnocytophaga species, and certain bacterial morphotypes was determined in 18 affected and 18 unaffected sites in 10 localized juvenile periodontitis (LJP) patients, and in 10 affected and 10 unaffected sites in 5 generalized juvenile periodontitis (GJP) patients. The subgingival proportion of the 7 bacterial species was determined by selective and nonselective culturing. The results showed that when considering the pure prevalence of bacteria ( > 0%) there were significant differences (P < 0.05) in the subgingival plaque microflora of the affected sites versus those of the unaffected sites for P. gingivalis, A. actinomycetemcomitans, P. intermedia, E. corrodens, C. rectus, and F. nucleatum in LJP, and for P. gingivalis, P. intermedia, and F. nucleatum in GJP. The mean proportions of cocci, motile rods and spirochetes were also significantly different (P < 0.05) in affected sites compared to unaffected sites. Capnocytophaga sp, F. nucleatum, P. intermedia, and E. corrodens were found in more than 75% of affected sites in LJP. When taking the approach that an organism, to be associated with periodontal disease, has to be detected above a certain minimum threshold, the results indicated that bacteria most frequently associated with LJP and GJP in Chile are P. gingivalis (66% of LJP and 80% of GJP affected sites), and A. actinomycetemcomitans (44% of LJP and 50% in GJP affected sites). Different bacterial species may be judged to be important in the disease process depending upon whether a pure bacterial prevalence, or a prevalence above a certain detection level, is considered.

Microbiological features of gingivitis in pubertal children

The subgingival microflora of 42 pubertal children (aged 12-15 years) and 18 young adults (aged 21-25 years) was investigated by anaerobic culture and phase contrast microscopy. Motile rods, spirochetes and Prevotella intermedia were elevated proportionately in pubertal children with gingivitis (median GI > or = 1); however, no statistically significant differences in enumerated organisms on selective media were observed between pubertal children and young adults. These organisms were positively correlated with the index of bleeding on probing and the gingival index of pubertal children. Pubertal children were divided into 3 distinct subject clusters according to the similarity of subgingival microbial features, and the subjects who were then selected for the gingivitis group were distributed into clusters 1 and 2. The proportions of motile rods, P. intermedia and Eikenella corrodens were significantly higher in cluster 2 than in cluster 1. These results suggest that these 2 species and motile rods which differentiated features of clusters, are useful for screening of high-risk subjects for worsening of inflammation.

Evaluation of the antimicrobial effects of sodium benzoate and dichlorobenzyl alcohol against dental plaque microorganisms. An in vitro study

Evaluation of antimicrobial agents is based on in vivo and in vitro studies. The minimum inhibitory concentrations (MICs) of sodium benzoate and dichlorobenzyl alcohol to 115 strains of plaque microorganisms were determined by a broth-dilution method. Sodium benzoate did not inhibit growth of any gram-positive cocci (MIC > 106,590 microM). MICs for Porphyromonas gingivalis and two strains of Treponema socranskii were 26,650 microM. The MIC of dichlorobenzyl alcohol to the reference strain of Actinobacillus actinomycetemcomitans was 723 microM and to P. gingivalis, two strains of T. socranskii, and Candida albicans 1,446 microM. MICs for other organisms were 2,892 to 5,784 microM. Saliva samples from 10 volunteers, collected at various times after toothbrushing with a dentifrice containing 10% sodium benzoate and 0.3% dichlorobenzyl alcohol, were analyzed gas-chromatographically. Immediately after toothbrushing mean levels of sodium benzoate and dichlorobenzyl alcohol were 372,626 microM and 7,529 microM, respectively. After 5 min mean levels were 38,700 microM and 734 microM. In conclusion, the concentrations of both antimicrobials dropped rapidly during the first 30 min, but for 5-10 min they were high enough to inhibit growth of potential periodontal pathogens.

The effects of a 0.3% triclosan-containing dentifrice on the microbial composition of supragingival plaque

144 subjects completed a 6-month, double-blind study which examined the effects of a 0.3% triclosan/2% copolymer/0.243% sodium fluoride dentifrice on the microflora of supragingival dental plaque. The subjects were randomly assigned to use, in an oral hygiene program, either the triclosan/copolymer/fluoride test dentifrice or a control dentifrice. The latter had the same formulation as the test dentifrice except it did not contain triclosan. Supragingival plaque was collected from the buccal and lingual surfaces of 4 teeth at baseline, 3 months, and 6 months, and microbiologically examined by darkfield microscopy, gram stain morphology, immunofluorescence, and selective and non-selective media. Antimicrobial susceptibilities were determined by agar dilution and whole plaque susceptibility methodologies on plaque samples from 136 subjects at each of the above sample periods and at 6-week intervals for an additional 6 months post-therapy. Both dentifrices resulted in highly statistically significant reductions in the total cultivable flora obtained at both the 3 and 6-month samples relative to baseline as well as at 6 months relative to the 3-month sample. The relative decrease in total anaerobic counts and in strict anaerobes, while not statistically significant, was more pronounced at both the 3- and 6-month sample periods in subjects receiving the triclosan dentifrice than for the controls. Neither dentifrice resulted in detrimental shifts in the microbial composition of the normal flora nor led to the emergence of periodontal or opportunistic pathogens.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical, bacteriological, and immunological examinations and the treatment process of two Papillon-Lefèvre syndrome patients

Papillon-Lefèvre Syndrome (PLS) is a rare disease associated with the early onset of periodontal breakdown in deciduous and permanent dentition. The etiology of the destruction has not been completely clarified. Two female patients (ages 4 and 7 years) with severe destruction of the periodontal structures were examined. Except for palmar and plantar hyperkeratosis, dermatologic examination revealed no other medical disorders. On immunological analysis, measurement of serum antibody titers to 7 periodontopathic bacteria including Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans was performed by enzyme-linked immunosorbent assay (ELISA). Further immunoblot analysis of A. actinomycetemcomitans and microbial culture of samples collected from deep periodontal pockets and mouthrinse solution were performed. The serum of the two patients showed high IgG titer against A. actinomycetemcomitans. Immunoblot results of the two patients against sonicated extract of A. actinomycetemcomitans Y4 strain exhibited a similar pattern. The band pattern differed from that observed in other forms of early onset periodontitis patients or periodontally healthy subjects. Moreover, A. actinomycetemcomitans colonies were cultured in high percentages from the pocket samples. Antibiotic therapy was instituted in addition to conventional periodontal therapy. In the younger patient, all deciduous teeth were extracted as part of the treatment and A. actinomycetemcomitans was no longer detected. All four permanent first molars and 8 permanent incisors subsequently erupted with healthy periodontium. However, the older patient did not improve after periodontal and antibiotic (minocycline and erythromycin) treatments and A. actinomycetemcomitans was consistently detected. Ofloxacin medication finally eliminated A. actinomycetemcomitans from the periodontal pockets. This antibiotic was also associated with reduced gingival inflammation and probing depth.(ABSTRACT TRUNCATED AT 250 WORDS)

Longitudinal monitoring for disease progression of localized juvenile periodontitis

The present study was performed to investigate the factors associated with disease progression in localized juvenile periodontitis (LJP) patients by longitudinal monitoring of microbiological changes. Following a 9-month period, 9 LJP patients were divided into 2 groups based upon attachment loss, progressing and non-progressing. Both groups received scaling, root planing, and modified Widman flaps. Clinical and microbiological data were obtained at baseline, following the observation period, and at 6 and 12 months post-treatment. At 6 and 12 months post-treatment significantly more cocci were persistent in the non-progressing group than in the progressing group. Actinobacillus actinomycetemcomitans was also more frequently isolated in the progressing group than in the non-progressing group initially and following the 9-month observation period. Also after treatment, A. actinomycetemcomitans recolonized earlier in the progressing group than in the non-progressing group. These studies suggest that A. actinomycetemcomitans may play a role in disease progression in LJP; however, they do not eliminate the possibility that other organisms may also play a role, since A. actinomycetemcomitans was not detected in all of the patients in whom disease progressed.

Periodontal bone loss in mice induced by different periodontopathic organisms

Periodontal bone loss in mice orally inoculated with Peptostreptococcus anaerobius, Pept. magnus and Actinobacillus actinomycetemcomitans was compared to that in sham-inoculated mice. Six-to-8-week-old BALB/c mice were inoculated with 1 x 10(5), 1 x 10(7) or 1 x 10(9) colony-forming units (c.f.u.) of bacteria in 50 microliters of medium. Ten mice received each concentration of bacteria and 10 sham-inoculated mice acted as controls. Five mice from each of the groups were killed 6 weeks after inoculation and the remaining five mice at 12 weeks. Right hemimandibles were defleshed, stained and bone loss was measured using an image analyser. All the organisms tested were associated with bone loss. Animals that had received Pept. anaerobius and Pept. magnus had up to 18% more bone loss than those sham inoculated. In contrast, mice inoculated with A. actinomycetemcomitans had up to 38% more bone loss than the sham-inoculated animals, this amount of loss occurring at the lowest inoculation of 1 x 10(5) c.f.u. These data demonstrate a differential ability of micro-organisms to cause periodontal bone loss in mice.

Microbiology of healthy and diseased periodontal sites in poorly controlled insulin dependent diabetics

A group of poorly-controlled insulin dependent diabetes mellitus (IDDM) patients were examined in a cross-sectional design for total microbial levels, microbial incidence, and the percent levels of selected periodontal microorganisms. These organisms were selected on the basis of prior reports that associated them with either periodontal disease or health. One periodontally-healthy and one periodontally-diseased site were examined in each IDDM patient. Increased levels of the periodontal pathogens Prevotella intermedia, P. melaninogenica spp., Bacteroides gracilis, Eikenella corrodens, Fusobacterium nucleatum and Campylobacter rectus (formerly Wolinella recta) were found at the periodontal diseased sites. Increased prevalence of the organisms P. intermedia, P. melaninogenica spp., and C. rectus were found at the diseased sites. A significantly higher percentage of P. intermedia was found at the sites exhibiting deep pockets and attachment loss.

Microbial patterns in pooled subgingival plaque samples from young adults with advanced marginal periodontitis

Different bacterial profiles of subgingival plaque have been described for different clinical categories of marginal periodontitis. In the present investigation the subgingival microflora was studied in young adults with advanced marginal periodontitis. From 12 patients pooled subgingival plaque samples from 5 advanced stages of diseased sites were examined by direct differential phase-contrast microscopy and by cultivation on enriched and selective media. The proportions of the following genera and species were calculated: black-pigmented Bacteroides sp., B. gingivalis, Fusobacterium nucleatum, Veillonella sp., Actinobacillus actinomycetemcomitans, Capnocytophaga sp., Eikenella corrodens, Campylobacter sp., and Candida sp. Spirochete identification was carried out ultrastructurally. Calculated percent minimum similarity levels between the individuals revealed that each patient harbored its characteristic cultivable subgingival microflora different from the other individuals. The spirochetes seemed to constitute the subgingival bacterial group with the smallest variation as certain morphotypes were dominating in almost all individuals.

Improved metabolic control, clinical periodontal status and subgingival microbiology in insulin-dependent diabetes mellitus. A prospective study

The effect of improved metabolic control on the clinical periodontal condition and the subgingival microflora of diseased and healthy periodontal pockets in 6 ambulatory insulin-dependent diabetes mellitus (IDDM) patients was prospectively studied. Duplicate measurements with a time-interval of 3 days were made every 4 moths for assessment of the metabolic status, the clinical periodontal condition and the subgingival microflora. During the study, patients maintained personal oral hygiene measures as they usually did before the study. Neither supplementary dental prophylaxis nor oral hygiene measures were applied during the investigation. Long-term metabolic control (HbAlc) improved significantly with intensive conventional insulin treatment. Gingival redness decreased significantly whereas gingival swelling showed a not significant trend to decrease. It is suggested that microvascular changes associated with improved metabolic control in diabetes mellitus may mediate the observed change in gingival redness. No effect could be demonstrated for probing pocket depth, probing attachment level, bleeding on probing and the plaque index. Statistical analysis of the effect of improved metabolic control on the subgingival microflora revealed that only the % of streptococci increased significantly in diseased periodontal pockets. In general, no significant changes were found in either healthy or diseased pockets with regard to the bacterial flora associated with periodontal disease. The results of the present study indicate that improved metabolic control in IDDM patients may have no potential impetus for an improved clinical periodontal condition nor on the subgingival bacterial flora. It is concluded that the periodontal condition in IDDM patients may only ameliorate when local oral hygiene measures are applied.

The incidence of periodontopathic microorganisms in young children

Thirty-six children in 4 cohorts of 0-1 week, 1-6 months, 1-2 years and 2-2 1/2 years of age were examined for the presence of black-pigmented Bacteroides species and some other bacteria suspected of being involved in the subsequent development of periodontal destruction. None of the sought-after bacteria were detected in the first week of life. Bacteroides intermedius and Bacteroides melaninogenicus were detected as early as 1 month after birth. Both of these bacteria were detected in 16-37% of children in the different cohorts. Bacteroides denticola was detected in one child. Other black-pigmented species including Bacteroides gingivalis and Bacteroides loescheii were not detected. Eikenella corrodens was detected in 62% of children under 6 months. Capnocytophaga spp. were detected in 12% and Fusobacterium nucleatum in 25% of children in this age group. With increasing age there was a trend towards an increase in the number of children with F. nucleatum but other bacteria were detected in similar numbers of children throughout the 3 older cohorts. Actinobacillus actinomycetemcomitans was not detected at any age.

Actinobacillus actinomycetemcomitans serotypes and leukotoxicity in Korean localized juvenile periodontitis

Actinobacillus actinomycetemcomitans is though to play an important role in the pathogenesis of localized juvenile periodontitis (LJP). Preliminary data suggested that the serotype distribution of A. actinomycetemcomitans in Korea and the United States differ. This study evaluated A. actinomycetemcomitans prevalence, serotype distribution, and leukotoxicity in Korean LJP patients by culture, enzyme-linked immunosorbent assay, indirect immunofluorescence, and lactate dehydrogenase release from polymorphonuclear leukocytes exposed to A. actinomycetemcomitans. A. actinomycetemcomitans occurred in 75% of LJP lesions and 6% of normal sites with approximately equal distribution of serotype a, b, and c. Single serotypes were isolated from nine patients while three patients harbored two serotypes either in the same or different disease sites. A. actinomycetemcomitans leukotoxicity occurred in 22% isolates with a 69% prevalence. Individual sites harbored both leukotoxic and non-leukotoxic strains with no serotype association. The distribution of serotypes and leukotoxic strains of A. actinomycetemcomitans in Korean LJP patients differed from those reported in the United States. This suggests that serotype b may not be more important in the pathogenesis of LJP.

Periodontal condition and microbiology of healthy and diseased periodontal pockets in type 1 diabetes mellitus patients

On the basis of glycosylated hemoglobin (HbA1c) values, 22 type 1 (insulin-dependent) diabetic adults were grouped into patients with near normal (HbA1c less than or equal to 7.7%) and poor (HbA1c greater than or equal to 9.9%) metabolic control. A total of 44 subgingival sites were examined for Actinobacillus actinomycetemcomitans, black-pigmented Bacteroides species and Capnocytophaga species. No significant difference could be demonstrated between patients in the 2 test groups with regard to periodontal condition. Neither age of diabetic patients nor duration of diabetes mellitus influenced the periodontal parameters. In both test groups, pocket depth of 4 mm or more (greater than or equal to 4 mm) was found to be significantly associated with increased swelling, bleeding after probing and amount of marginal plaque. Proportionally high %s of cultivable A. actinomycetemcomitans (mean 4.3%; range 2.8-5.8%), Bacteroides gingivalis (33.2% and 34.6%) and Bacteroides intermedius (mean 4.2%; range 0.001-13.5%) were isolated from diseased periodontal pockets. In diabetic patients with poor metabolic control, B. intermedius was isolated from diseased periodontal pockets with a mean % of 7.2%, range 0.3-12.5%. Independent of the degree of metabolic control, low %s of Capnocytophaga species were isolated from diseased and healthy periodontal pockets, mean 0.9% (range 0.003-3.9%) and mean 1.4% (range 0.04-4.9%), respectively. It was concluded from this study that metabolic control seems to have no direct effect on the periodontium. Furthermore, the rôle of Capnocytophaga species in the pathogenesis of infectious periodontal disease in type 1 diabetic patients seems to be overestimated.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro susceptibility of 96 Capnocytophaga strains, including a beta-lactamase producer, to new beta-lactam antibiotics and six quinolones

The in vitro activities of new beta-lactam antibiotics and new quinolones were studied against 96 Capnocytophaga strains, including a beta-lactamase-producing strain which was resistant to ampicillin, amoxicillin, carbenicillin, cephalothin, and cefamandole. All strains were susceptible to the combination of amoxicillin and clavulanic acid, ureidopenicillins, cefoxitin, broad-spectrum cephalosporins, and imipenem. Cephalothin and cefamandole did not show good activity against most strains. All Capnocytophaga spp. were uniformly susceptible to the five new quinolones tested.

Prevalence and microbiology of localized prepubertal periodontitis

Loss of crestal alveolar bone at primary teeth was ascertained radiographically in a dental school clinical population of 2264 children. 19 patients (0.84%) demonstrated distinct periodontal bone destruction around one or more primary teeth; in only 2 of these patients had periodontal disease been identified in previous clinical examinations. A microbiological study of 35 subgingival samples from 9 available patients revealed a high prevalence of black-pigmented Bacteroides spp., mainly Bacteroides intermedius. Actinobacillus actinomycetemcomitans and Capnocytophaga spp. were predominant organisms in some samples. The present data indicate that localized prepubertal periodontitis is more common than previously realized and is associated with bacteria generally regarded as major periodontal pathogens.

In vitro susceptibility of Capnocytophaga species to 29 antimicrobial agents

A hemoglobin-supplemented medium composed of Columbia agar base supplemented with 1% hemoglobin and 1% Polyvitex was used to investigate the in vitro activity of 29 antimicrobial agents against Capnocytophaga species. Clindamycin was the most active agent, with all strains being inhibited by 0.06 microgram/ml or less. Amoxicillin-clavulanic acid and imipenem were the most active among the beta-lactam antibiotics (MIC for 90% of strains tested [MIC90], 0.50 microgram/ml); other very active drugs were BMY 28142, cefpirome, cefotaxime, ceftazidime, and ceftriaxone (MIC90, 0.06 to 0.50 micrograms/ml), although at least one strain showed resistance to each of these antibiotics (MIC, greater than or equal to 16 micrograms/ml). Ciprofloxacin was the most active among the quinolones, with all strains being inhibited by 0.50 microgram/ml. The MICs of the other four drugs ranged from 0.12 to 4 micrograms/ml. Ampicillin, penicillin G, ticarcillin, aztreonam, and temocillin were moderately active (MIC90, 1 to 8 micrograms/ml; MIC range, less than or equal to 0.03 to greater than 128 micrograms/ml). All strains were uniformly resistant to the aminoglycosides, polymyxin B, vancomycin, trimethoprim, and amphotericin B. Three strains produced beta-lactamase. No significant difference was found between the susceptibility of strains isolated from various sources or patients.

Potential role of microorganisms isolated from periodontal lesions in the pathogenesis of inflammatory bowel disease

A total of 20 patients with inflammatory bowel disease (IBD) (Crohn's disease, ulcerative colitis) were evaluated with regard to the role of infectious agents and host response. Patients were selected based upon oral manifestations of their disease, 10 with periodontal disease and 10 without. Microbiologic studies of the periodontal flora of IBD-affected patients revealed a unique microflora composed predominantly of small, motile, gram-negative rods, which were most consistent with the genus Wolinella. Further studies of the host response of these patients revealed a serum-mediated defect in neutrophil chemotaxis in all 10 patients with periodontal disease. Neutrophil phagocytosis was normal. In vitro studies of neutrophil function in response to Wolinella extracts and culture supernatants revealed inhibition of neutrophil chemotaxis in a dose-response fashion. The organism was chemokinetic for neutrophils but not chemotactic. The data suggest that unusual microorganisms colonizing the oral cavity of IBD patients potentially play a role in the pathogenesis of the disease as infectious agents or modifiers of the host response or both.

The presence of bacteria in the oral epithelium in periodontal disease. II. Immunohistochemical identification of bacteria

Serial histological sections of gingiva obtained from each of six advanced adult periodontitis, two localized juvenile periodontitis and two periodontally healthy patients were used for specific identification of bacteria within the oral epithelium and adjacent connective tissue. Healthy gingival biopsies served as controls. Sections from patients and control biopsies were Gram-stained and also screened with antibacterial sera associated with the peroxidase immunocytochemical technique for specific bacterial identification. The "Pop-off" electron microscopic technique was also used to further demonstrate the bacterial nature of peroxidase-stained material. In addition, the possible correlation between bacteria and areas of possible reduced keratinization was investigated. The results showed that sections of orthokeratinized healthy gingiva did not contain bacteria. Gram-stained sections from diseased sites contained large numbers of bacteria in the oral epithelium and adjacent connective tissue. Bacteroides gingivalis and to a lesser extent Capnocytophaga gingivalis were found in periodontitis, and Actinobacillus actinomycetemcomitans was found in juvenile periodontitis when the immunoperoxidase technique was used. The bacterial nature of peroxidase-stained material was confirmed by the "pop-off" technique. In the disease biopsies, bacterial presence was correlated with areas of reduced amounts of keratin suggesting that the oral epithelium may be a portal of entry for bacteria into gingival tissues.

Isolation of Capnocytophaga species with a new selective medium

A selective medium (CAP) composed of a GC agar base supplemented with 1% hemoglobin, 1% Polyvitex, and an antibiotic mixture of polymyxin B (15 U/ml), vancomycin (5 micrograms/ml), trimethoprim (2.5 micrograms/ml), and amphotericin B (2.5 micrograms/ml) was compared with another selective medium (TBBP) and two nonselective media--a blood agar and a chocolate agar--to isolate Capnocytophaga species from 725 clinical specimens. These included sputa (467 specimens), throat swabs (116 specimens), oral ulcerations (35 specimens), and periodontal pockets (107 specimens). The recovery rate of Capnocytophaga species was significantly higher with the CAP medium (96%) than with the selective TBBP medium (52.2%), the nonselective blood agar (6.2%), and the chocolate agar (4.6%). Growth of the normal flora was best inhibited on CAP medium. Colony size and yellow-brown pigment formation were maximally expressed on chocolate agar and CAP medium, but gliding motility was mostly absent. We conclude that the CAP medium is an excellent medium for the recovery of Capnocytophaga species from contaminated clinical specimens.

Lysozyme-mediated aggregation and lysis of the periodontal microorganism Capnocytophaga gingivalis 2010

The ability of lysozyme to aggregate and lyse the gram-negative capnophilic periodontal microorganism Capnocytophaga gingivalis 2010 was monitored optically at 540 nm. Both hen egg white and chromatographically purified human lysozymes had significant but similar aggregation potentials for both logarithmic- and stationary-phase bacteria. In general, an increase in enzyme concentration resulted in a graded increase in both the initial and maximum changes in turbidity which occurred during the reaction period. The greatest change in turbidity occurred within the initial minutes of interaction of lysozyme and the cells, and the extent of aggregation paralleled a rapid depletion of lysozyme by the suspensions during the first minute of its incubation with the bacteria. Interestingly, the muramidase inhibitors N-acetyl-D-glucosamine and histamine did not block aggregation, whereas maleylation of lysozyme completely inhibited its aggregating ability. Demaleylation, however, restored aggregation activity comparable to the native enzyme, indicating that maleylated lysozyme retained its integrity and that aggregation was primarily dependent on charge. The addition of up to physiological concentrations of NaHCO3 and NaCl to cell aggregates resulted in varying degrees of deaggregation and lysis. Surprisingly, ultrastructural analysis of lysozyme-treated cells revealed morphological changes with or without the addition of salt. Damage appeared to occur at the blunted polar end of the cells where there was a large spherical outpouching bordered by a damaged cell envelope. Damaged cells uniformly contained dense granular cytoplasmic debris. In effect, the cationic enzyme lysed C. gingivalis 2010, which was not apparent in the spectrophotometric assay. The paradoxical finding that during bacterial aggregation there was lysis may be of significance to the further elucidation of lysozyme's antibacterial role in the gingival sulcus.

Capnocytophaga ochracea infection: two cases and a review of the published work

Bacteria of the genus Capnocytophaga are recently recognised pathogens which may cause oral disease and subsequent septicaemia in the immunocompromised host. We present two cases of infection caused by Capnocytophaga ochracea; a soft tissue infection in an immunologically normal patient and an episode of septicaemia in a child with leukaemia. The microbiology, pathogenicity, and antimicrobial susceptibility of the genus capnocytophaga are reviewed.

Bacteriological study of periodontal lesions in two sisters with juvenile periodontitis and their mother

A total of five bacteriological samples from the periodontal pockets of two sisters with localized juvenile periodontitis and their mother with advanced periodontitis was studied. Gram-negative anaerobic rods were predominant in the samples. Bacteroides intermedius and Bacteroides loescheii were the most predominant species. The antigenicity and bacteriocinogenicity of these isolates were quite similar. Serum immunoglobulin G antibody levels of the subjects to gram-negative periodontopathic bacteria were measured by using the micro-enzyme-linked immunosorbent assay. The levels of antibodies to saccharolytic black-pigmented Bacteroides species were significantly higher than the levels in healthy young females.

Suppression of the periodontopathic microflora in localized juvenile periodontitis by systemic tetracycline

Since recent studies have implicated Actinobacillus actinomycetemcomitans in the etiology of localized juvenile periodontitis, this investigation determined the effectiveness of subgingival debridement, topical Betadine Solution, and systemic tetracycline in suppressing subgingival A. actinomycetemcomitans and other microorganisms. A total of 20 deep periodontal pockets and 10 normal periodontal sites of 6 localized juvenile periodontitis patients was included in the study. Each patient was treated in 3 stages over a period of 22 weeks, and the result of treatment was monitored for an additional 38 weeks. The first stage of treatment included plaque control, as well as thorough scaling and root planing, composed of at least 6 h of debridement. No concomitant periodontal surgery was performed. In the second stage, Betadine saturated cotton gauze was inserted into the periodontal pockets for 10 min. Stage 3 involved systemic tetracycline therapy (1 g/day) for 14 days. The subgingival microflora was determined at frequent intervals by selective culturing of A. actinomycetemcomitans and Capnocytophaga and by direct microscopic examination. The clinical effect was assessed by measuring changes in probing periodontal attachment level, probing periodontal pocket depth, radiographic alveolar bone mass, and other relevant clinical parameters. Scaling and root planing reduced the total subgingival bacterial counts and the proportions of certain Gram-negative bacteria, but no periodontal pocket became free of A. actinomycetemcomitans. Betadine application had little or no effect on the subgingival microflora. In contrast, tetracycline administered via the systemic route suppressed A. actinomycetemcomitans, Capnocytophaga, and spirochetes to low or undetectable levels in all test periodontal pockets. A. actinomycetemcomitans reappeared in 9 of the deep periodontal pockets after the administration of tetracycline. Most of these 9 pockets became free of detectable A. actinomycetemcomitans during the second week of tetracycline administration, whereas pockets which yielded no A. actinomycetemcomitans after tetracycline therapy became free of the organisms during the first week of tetracycline treatment. This data suggests that systemic tetracycline therapy of localized juvenile periodontitis should, as a practical rule, be continued for 3 weeks. Periodontal destruction continued in 4 deep pockets which all showed high posttetracycline A. actinomycetemcomitans counts. All 6 pockets which demonstrated a marked gain in periodontal attachment yielded no cultivable A. actinomycetemcomitans. No association was found between periodontal disease status and subgingival Capnocytophaga, spirochetes or motile rods. The present study indicates that A. actinomycetemcomitans is an important etiologic agent in localized juvenile periodontitis.(ABSTRACT TRUNCATED AT 400 WORDS)