Antibiotic susceptibility testing of subgingival plaque samples

Europe's contribution to the evaluation of the use of systemic antimicrobials in the treatment of periodontitis

This narrative review celebrates Europe's contribution to the current knowledge on systemically administered antimicrobials in periodontal treatment. Periodontitis is the most frequent chronic noncommunicable human disease. It is caused by dysbiotic bacterial biofilms and is commonly treated with subgingival instrumentation. However, some sites/patients do not respond adequately, and its limitations and shortcomings have been recognized. This has led to the development of alternative or adjunctive therapies. One is the use of antimicrobials to target bacteria in subgingival biofilms in the periodontal pocket, which can be targeted directly through the pocket entrance with a locally delivered antibiotic or systemically by oral, intravenous, or intramuscular methods. Since the early 20th century, several studies on systemic antibiotics have been undertaken and published, especially between 1990 and 2010. Europe's latest contribution to this topic is the first European Federation of Periodontology, S3-level Clinical Practice Guideline, which incorporates recommendations related to the use of adjuncts to treat stage I-III periodontitis. Understanding the etiopathogenesis of periodontal diseases, specifically periodontitis, has influenced the use of systemic periodontal antibiotic therapy. Randomized clinical trials and systematic reviews with meta-analyses have demonstrated the clinical advantages of adjunctive systemic antimicrobials. However, current recommendations are restrictive due to concerns about antibiotic misuse and the increase in microbial antibiotic resistance. European researchers have contributed to the use of systemic antimicrobials in the treatment of periodontitis through clinical trials and by providing rational guidelines. Nowadays, European researchers are exploring alternatives and directing clinical practice by providing evidence-based guidelines to limit the use of systemic antimicrobials.

Bacterial resistance to antiseptics used in dentistry: A systematic scoping review of randomized clinical trials

OBJECTIVES

To evaluate the prevalence and proportions of bacteria resistant to antiseptics used in dentistry.

METHODS

A review of randomized clinical trials (RCTs) was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for scoping reviews involving different databases. MeSH terms and keywords were provided to examine only RCTs with antiseptic-resistant results.

RESULTS

Five RCTs were included. These investigations analysed 442 patients. Concerning the prevalence and proportion of species resistant to antiseptics, it was found that the chlorhexidine group showed a statistically significant increase in Streptococcus mutans and Lactobacillus acidophilus counts indicating bacterial resistance (p < 0.001). Moreover, Veillonella species showed resistance to triclosan at the commencement and during the RCTs, and a slight increase in the proportion of resistant strains was observed. Porphyromonas gingivalis, Staphylococcus aureus, and Pseudomonas aeruginosa did not show resistance to cetylpyridinium chloride. Similarly, it was no observed resistance to medicinal herbal plant formulations.

CONCLUSIONS

Resistance of S. mutans and L. acidophilus to chlorhexidine was observed, this resistance increased during the follow-up period. Similarly, although in a slight proportion, an increase in the resistance of Veillonella spp. to triclosan during the study period was also described. No microorganisms resistance was observed to any of the other antiseptics studied.

Role of antibiotics in generalized aggressive periodontitis: A review of clinical trials in humans

BACKGROUND

It is well-recognized fact that periodontal diseases are caused by multifactorial etiologies, in which microorganisms play an important role. An essential component of therapy is to eliminate or manage these pathogens. This has been traditionally accomplished through mechanical means by scaling and root planning which is ineffective in some of the aggressive periodontal diseases. These aggressive diseases involve particular groups of microorganisms which are not eliminated by mechanical means; and they require anti-infective therapy, which includes local and systemic antimicrobials. This approach of therapy is of interest to periodontist due to the aforementioned shortcomings of conventional methods.

MATERIALS AND METHODS

A manual and electronic search was made for human studies up to March 2011 that presented clinical and microbiological data for the efficacy of a systemic antibiotics in generalized aggressive periodontitis along with scaling and root planning. A systematic approach was followed by two independent reviewers and included eligibility criteria for study inclusion, quality assessment, and determination of outcome measures, data extraction, data synthesis, and drawing of conclusion.

RESULTS

Only three randomized controlled human trials qualified, and they concluded that both scaling and root planing (SRP) mono-therapy and SRP with antibiotics proves beneficial in improving clinical and microbiological parameters in aggressive periodontitis. Better results were seen in SRP with antibiotic groups as compared with SRP alone.

CONCLUSION

Because of the insufficient quantity and heterogenecity of studies, no adequate evidence could be gathered to use the beneficial effects of these antibiotics along with SRP in aggressive periodontitis compared with SRP alone.

Subantimicrobial dose doxycycline effects on osteopenic bone loss: microbiologic results

BACKGROUND

Based on microbiologic concerns, the safety of a 24-month regimen of subantimicrobial dose doxycycline (SDD; 20 mg twice a day) was evaluated in postmenopausal osteopenic women with periodontitis in a double-blind, placebo-controlled, randomized clinical trial.

METHODS

Subgingival samples were collected from two sites (probing depth > or = 5 mm) in each of 128 subjects at baseline, with the same sites resampled at the conclusion of the 2-year period. The samples were enumerated on selective and non-selective media and on doxycycline (4 microg/ml) medium. Up to five different colonial morphologies were subcultured from the doxycycline medium, identified to species, and susceptibilities determined to doxycycline and five other antibiotics. Data were analyzed for microbial differences in total colony forming units (CFU), periodontal and opportunistic pathogens, and changes in species and in susceptibilities of isolates recovered on doxycycline medium.

RESULTS

There was no significant evidence that changes in total anaerobic counts over the treatment period (P = 0.96) differed between treatment groups. Likewise, periodontal pathogens, opportunistic pathogens, or normal flora did not differ descriptively between groups. Although there was a significant increase (P <0.001) in the total CFU recovered from the 4 microg/ml doxycycline plates at 24 months for SDD versus placebo, the percentage that was clinically resistant to doxycycline (minimal inhibitory concentration [MIC] > or = 16 microg/ml) decreased over the 24-month period in both groups and did not differ between the treatment groups (SDD: 79% to 76%; placebo: 83% to 70%; P = 0.2). There were no significant differences (P >0.28 for each) in the change in cross-resistance between the groups for doxycycline and the other five antibiotics.

CONCLUSIONS

No antimicrobial effect on the subgingival flora was detected following treatment with SDD for 24 months, relative to baseline or to placebo. The increase in initial resistance (at 4 microg/ml) did not translate into a significant increase in the percent resistant to doxycycline (MIC > or = 16 microg/ml) for patients in the SDD group.

An in vitro biofilm model of subgingival plaque

INTRODUCTION

Numerous biofilm models have been described for the study of bacteria associated with the supragingival plaque. However, there are fewer models available for the study of subgingival plaque. The purpose of this study was to develop and validate a model that closely mimicked the composition of the subgingival flora.

METHODS

The model was developed as follows: calcium hydroxyapatite disks were coated overnight with 10% sterile saliva, placed in flat-bottomed tissue culture plates containing trypticase-soy broth, directly inoculated with a small aliquot of dispersed subgingival plaque, incubated anaerobically, and transferred to fresh medium at 48-h intervals until climax (steady-state) biofilms were formed ( approximately 10 days).

RESULTS

The model, based on samples from eight periodontitis patients and eight healthy subjects, yielded a multi-species, heterogeneous biofilm, consisting of both gram-positive and gram-negative species, and comprising 15-20 cultivable species associated with the subgingival flora. The species present and their proportions were reflective of the initial cultivable subgingival flora. Comparisons of the initial plaque samples from healthy subjects and the mature biofilms showed 81% similarity in species and 70% similarity in the proportions present. Biofilms formed from samples obtained from periodontally diseased subjects were 69% similar in species and 57% similar in the proportions present.

CONCLUSIONS

The biofilm model described here closely reproduces the composition of the cultivable subgingival plaque both in the species present and in their relative proportions. Differences existed between biofilms grown from diseased and non-diseased sites with the former being characterized by the presence of periodontal pathogens at microbially significant levels.

Proportion of antibiotic resistance in subgingival plaque samples from Mexican subjects

AIM

To determine the proportion of bacteria resistant to amoxicillin and doxycycline in subgingival plaque samples from Mexican subjects.

MATERIALS AND METHODS

Two subgingival plaque samples were taken from 20 Mexican subjects. Samples were dispersed, diluted and plated on non-antibiotic agar plates and on plates containing 0.5, 1, 2, 4, 8 and 16 microg/ml of either amoxicillin or doxycycline. The proportion of resistant bacteria was calculated based on the total number of colony-forming units present in the non-antibiotic containing plates.

RESULTS

On average, 0.4-13.4% and 0.9-20.4% of the total cultivable subgingival microbiota was resistant to the concentrations tested of amoxicillin and doxycycline, respectively. The differences between antibiotics were statistically significant for the 0.5, 2 and 4 mug/ml concentrations (p < 0.05, Wilcoxon's test).

CONCLUSIONS

Our findings revealed that a relatively small proportion of the total cultivable subgingival microbiota from Mexican subjects was resistant to amoxicillin and doxycycline.

Effects of metronidazole plus amoxicillin as the only therapy on the microbiological and clinical parameters of untreated chronic periodontitis

AIM

To determine the effect of metronidazole plus amoxicillin (M+A) as the sole therapy, on the subgingival microbiota of chronic periodontitis.

MATERIAL AND METHODS

Twenty-two patients with untreated chronic periodontitis were randomly assigned to a group that received M+A for 7 days, or to a group receiving scaling and root planing (SRP) and two placebos. Clinical measurements including sites with plaque, bleeding on probing (BOP), probing depth (PD) and attachment level (AL) were made at baseline, 3, 6, 9 and 12 months. Subgingival plaque samples were taken from all teeth at baseline 3, 6, 9 and 12 months for the counts of 40 subgingival species using checkerboard DNA-DNA hybridization.

RESULTS

Mean PD was reduced from 2.80+/-0.45 at baseline to 1.95+/-0.05 at 12 months (P<0.001) and from 2.39+/-0.41 to 1.95+/-0.10 (P<0.001) in the M+A- and SRP-treated patients, respectively. Corresponding values for relative mean AL were 10.07+/-1.30-9.77+/-0.34 (P<0.001) and 9.94+/-0.28-9.77+/-0.26 (P<0.001). Percentage of sites exhibiting BOP were 40.6+/-18.3-14.0+/-1.4 (P<0.001), and 38.5+/-5.1-19.0+/-2.8 (P<0.001) in the M+A and SRP groups, respectively. Mean total DNA probe counts and counts of the majority of the 40 test species were significantly reduced over time in both groups, with no significant differences detected at any time point between groups. At 12 months many of the species were still present at significantly lowered levels compared with their baseline counts in both groups.

CONCLUSIONS

Changes in clinical and microbiological parameters were similar after receiving systemically administered M+A as the sole therapy or after receiving SRP only.

A laboratory model biofilm fermenter: design and initial trial on a single species biofilm

BACKGROUND

The minimum inhibitory concentration (MIC) does not provide information on the efficacy of antimicrobial agents against infections involving biofilms, which are many times more resistant than planktonic forms of bacteria. This report is on the design and initial trial of a device for growing standard biofilms and testing antimicrobial agents.

METHODS

We constructed a durable, autoclaveable laboratory model biofilm fermenter (LMBF) that holds hydroxyapatite discs 300 microm below a surface onto which an artificial saliva medium drips at a rate comparable to human salivary flow. Inoculated with Streptococcus sanguinis, the device formed biofilms that were swept with a Teflon wiper under aerobic conditions. Five-day-old biofilm-coated discs were aseptically removed and placed in 3 ml of sterile saline, 0.12% chlorhexidine gluconate, or 0.1% phosphate-buffered chlorine dioxide mouthwash for 1 minute. The discs and test agent were immediately diluted with saline to 10 ml, vortexed for 30 seconds, serially diluted, plated on blood agar, and incubated anaerobically 2 days. Bacterial counts were done, and the MIC of each mouthwash was determined.

RESULTS

In tests with sterile water and sterile medium, the device maintained a closed system. After inoculation with S. sanguinis, a steady state was reached at day 5. Chlorhexidine at stock concentration achieved about a 2 log10 reduction (P = 0.002), but never achieved complete killing. Chlorine dioxide had no significant effect. The MIC against planktonic S. sanguinis was 112.8 microg/ml for chlorhexidine and 9.0 microg/ml for chlorine dioxide.

CONCLUSIONS

The LMBF generates and maintains a single-species oral model biofilm to a steady state and enables in vitro tests of disinfectant mouthwashes in simulated clinical use. It should be usable for more advanced tests of multiple species biofilms.

Clindamycin and dentistry

Clindamycin is an antimicrobial agent that dentists use in the UK for infective endocarditis prophylaxis but rarely for other clinical situations that require antimicrobial intervention. This has been largely due to its association with acute pseudomembranous colitis. Up to date information on the efficacy and safety of this antimicrobial agent should be known before prescription.

Markers of periodontal infection and preterm birth

OBJECTIVE

This study was undertaken to explore the relationship between clinical, microbiologic, and serologic markers of periodontitis and preterm birth (PTB).

STUDY DESIGN

We compared women with a singleton gestation giving birth before the 37th week (cases, n = 83) with term delivery controls (n = 120). Periodontal examination and collection of dental plaque and blood samples were performed within 48 hours after delivery. Microbial levels and maternal immunoglobulin G titers to oral bacteria were analyzed. Multivariate regression models were fitted controlling for common covariates.

RESULTS

Cases showed greater mean attachment loss (1.7 vs 1.5 mm, P = .003) and higher prevalence of periodontitis (30.1% vs 17.5%, P = .027). No differences in microbial or serum antibody levels were detected between the groups. Logistic regression revealed that PTB was associated with attachment loss (adjusted odds ratio: 2.75, 95% CI: 1.01-7.54). Linear regression indicated a significant ( P = .04) association between attachment loss and low birth weight (LBW).

CONCLUSION

The data support the notion that periodontitis is independently associated with PTB and LBW.

Antibiotic resistance profile of the subgingival microbiota following systemic or local tetracycline therapy

BACKGROUND

Tetracyclines have been extensively used as adjunctives to conventional periodontal therapy. Emergence of resistant strains, however, has been reported. This study evaluated longitudinally the tetracycline resistance patterns of the subgingival microbiota of periodontitis subjects treated with systemic or local tetracycline therapy+scaling and root planing (SRP).

METHODS

Thirty chronic periodontitis patients were randomly assigned to three groups: SRP+500 mg of systemic tetracycline twice/day for 14 days; SRP alone and SRP+tetracycline fibers (Actsite) at four selected sites for 10 days. Subgingival plaque samples were obtained from four sites with probing pocket depths (PPD)> or =6 mm in each patient at baseline, 1 week, 3, 6 and 12 months post-therapy. Samples were dispersed and diluted in pre-reduced anaerobically sterilized Ringer's solution, plated on Trypticase Soy Agar (TSA)+5% blood with or without 4 microg/ml of tetracycline and incubated anaerobically for 10 days. The percentage of resistant microorganisms were determined and the isolates identified by DNA probes and the checkerboard method. Significance of differences among and within groups over time was sought using the Kruskal-Wallis and Friedman tests, respectively.

RESULTS

The percentage of resistant microorganisms increased significantly at 1 week in the tetracycline groups, but dropped to baseline levels over time. The SRP+Actsite group presented the lowest proportions of resistant species at 6 and 12 months. No significant changes were observed in the SRP group. The predominant tetracycline-resistant species included Streptococcus spp., Veillonela parvula, Peptostreptococcus micros, Prevotella intermedia, Gemella morbillorum and Actinobacillus actinomycetemcomitans (Aa). A high percentage of sites with resistant Aa, Porphyromonas gingivalis and Tanerella forsythensis was observed in all groups at baseline. However, T. forsythensis was not detected in any group and P. gingivalis was not present in the SRP+Actsite group at 1 year post-therapy. Aa was still frequently detected in all groups after therapy. However, the greatest reduction was observed in the SRP+Actsite group.

CONCLUSION

Local or systemically administered tetracycline results in transitory selection of subgingival species intrinsically resistant to this drug. Although the percentage of sites harboring periodontal pathogens resistant to tetracycline were quite elevated in this population, both therapies were effective in reducing their prevalence over time.

Position Paper: Diagnosis of Periodontal Diseases

At the present time, the diagnosis and classification of periodontal diseases are almost entirely based on traditional clinical assessments. Supplemental quantitative and qualitative assessments of the gingival crevicular fluid and subgingival microflora can potentially provide useful information about the patient's periodontal disease. In certain situations, these supplemental risk-assessment tests may be particularly valuable in establishing the endpoint of therapy prior to placing patients on a periodontal maintenance program. Although the clinical utility of none of these tests has been validated, their further development is warranted. A genetic test for susceptibility to periodontitis has become commercially available. How best to use this and future host-based tests in clinical practice remains to be determined. Probing depth and clinical attachment loss measurements obtained with periodontal probes are practical and valid methods for assessing periodontal status. Computer-linked, controlled-force electronic periodontal probes are commercially available and are currently in use by some practitioners. Many of the logistical problems associated with subtraction radiography are being overcome and this powerful diagnostic tool may soon come into widespread use. Future developments in this and other imaging techniques are likely to have a profound effect on our approach to the diagnosis of periodontal diseases.

Antibiotic resistance of subgingival species during and after antibiotic therapy

AIM

The purpose of the present investigation was to determine the percentage and identity of antibiotic-resistant species in subgingival plaque and saliva samples from chronic periodontitis patients treated by scaling and root planing followed by orally administered amoxicillin or metronidazole.

METHOD

In all, 20 chronic periodontitis patients were selected for study. After clinical and microbiological monitoring, subjects were randomly assigned to receive either orally administered amoxicillin at the dosage of 500 mg, 3 times daily for 14 days or orally administered metronidazole at the dosage of 250 mg, 3 times daily for 14 days. For the antibiotic resistance determinations, subgingival plaque samples were taken from six posterior teeth at baseline, and 90 days; and from two randomly selected teeth at 3, 7 and 14 days during and after antibiotic administration. Samples were plated on enriched blood agar plates with or without either 2 micro g/mL metronidazole or 2 micro g/mL amoxicillin. Colonies were counted at 7 days. Significant differences in percentage of resistant organisms over time were determined by the Quade test. Microbial growth was washed from antibiotic-containing media and the identity of species determined using checkerboard DNA-DNA hybridization. Data were compared with those obtained in a previous study from subjects receiving SRP only or SRP followed by 14 days of orally administered doxycycline. The level of doxycycline used to determine antibiotic resistance in that study was 4 micro g/mL.

RESULTS

The mean percentage of resistant isolates increased during antibiotic administration and returned to baseline levels by 90 days post therapy. The mean percentages (+/- SEM) of isolates resistant to 2 micro g/mL metronidazole were 53 +/- 9, 65 +/- 9, 79 +/- 4 and 69 +/- 7 at baseline, 3, 7 and 14 days during antibiotic administration, and 57 +/- 4, 64 +/- 5, 62 +/- 7 and 47 +/- 6 at 3, 7, 14 and 90 days after antibiotic administration. At the same time points, the percentage of resistant isolates to amoxicillin was 0.5 +/- 0.2, 22 +/- 12, 14 +/- 5 and 37 +/- 11 during, and 31 +/- 11, 8 +/- 3, 3 +/- 2 and 3 +/- 0.6 after, administration. Antibiotic-resistant isolates of resistant species detected during or after therapy were also detected prior to therapy. The most prevalent resistant species in the metronidazole-treated group were: A. naeslundii 1, S. constellatus, A. naeslundii 2, S. mitis, S. oralis, A. odontolyticus, S. sanguis, and in the amoxicillin-treated group: S. constellatus, P. nigrescens, E. saburreum, A. naeslundii 1, S. oralis, P. melaninogenica and P. intermedia.

CONCLUSIONS

Systemic antibiotic administration transiently increased the percentage of resistant subgingival species, but a major component of subgingival plaque remained sensitive to the agents during their administration. Antibiotic-resistant isolates of resistant species could be detected in samples both prior to and after therapy. However, % antibiotic-resistant isolates returned to baseline levels 90 days after antibiotic administration.

Change in subgingival microbial profiles in adult periodontitis subjects receiving either systemically-administered amoxicillin or metronidazole

AIM

The current investigation evaluated changes in levels and proportions of 40 bacterial species in subgingival plaque samples during, immediately after and up to 1 year after metronidazole or amoxicillin therapy combined with SRP.

METHOD

After baseline clinical and microbiological monitoring, 17 adult periodontitis subjects received full mouth SRP and 14 days systemic administration of either metronidazole (250 mg, TID, n=8) or amoxicillin (500 mg, TID, n=9). Clinical measurements including % of sites with plaque, gingival redness, bleeding on probing and suppuration, pocket depth (PD) and attachment level (AL) were made at baseline, 90, 180 and 360 days. Subgingival plaque samples were taken from the mesial surface of all teeth in each subject at baseline, 90, 180 and 360 days and from 2 randomly selected posterior teeth at 3, 7, and 14 days during and after antibiotic administration. Counts of 40 subgingival species were determined using checkerboard DNA-DNA hybridization. Significance of differences over time was determined using the Quade test and between groups using ANCOVA.

RESULTS

Mean PD was reduced from 3.22+/-0.12 at baseline to 2.81+/-0.16 (p<0.01) at 360 days and from 3.38+/-0.23 mm to 2.80+/-0.14 mm (p<0.01) in the amoxicillin and metronidazole treated subjects respectively. Corresponding values for mean AL were 3.21+/-0.30 to 2.76+/-0.32 (p<0.05) and 3.23+/-0.28 mm to 2.94+/-0.23 mm (p<0.01). Levels and proportions of Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola were markedly reduced during antibiotic administration and were lower than baseline levels at 360 days. Counts (x10(5), +/-SEM) of B. forsythus fell from baseline levels of 0.66+/-0.16 to 0.04+/-0.02, 0.13+/-0.04, 0.10+/-0.03 and 0.42+/-0.19 in the amoxicillin group at 14, 90, 180 and 360 days respectively (p<0.001). Corresponding values for metronidazole treated subjects were: 1.69+/-0.28 to 0.02+/-0.01, 0.20+/-0.08, 0.22+/-0.06 and 0.22+/-0.08 (p<0.001). Counts of Campylobacter species, Eubacterium nodatum, Fusobacterium nucleatum subspecies, F. periodonticum and Prevotella nigrescens were also detected at lower mean levels during and immediately after therapy, but gradually increased after withdrawal of the antibiotics. Members of the genera Actinomyces, Streptococcus and Capnocytophaga were minimally affected by metronidazole. However, amoxicillin decreased the counts and proportions of Actinomyces species during and after therapy.

CONCLUSIONS

The data suggest that metronidazole and amoxicillin are useful in rapidly lowering counts of putative periodontal pathogens, but must be accompanied by other procedures to bring about periodontal stability.

Repeated metronidazole and amoxicillin treatment of periodontitis. A follow-up study

BACKGROUND

The prevailing concept is that little or no clear benefit is derived from antibiotic therapy in chronic periodontitis. Studies to determine the effect of metronidazole plus amoxicillin (M+A) on adult periodontitis are questionable because standard design for clinical trials was usually not used. In addition, there is no information about the effect of M+A as the sole therapy for periodontitis.

METHODS

A randomized, triple-blind, controlled clinical trial was used to determine the effect of systemic administration of M+A, as the sole therapy, in progressive adult periodontitis. Forty-six subjects with moderate to advanced adult periodontitis who showed > or =2 mm attachment loss in at least 2 sites in the previous 2 months were entered in the study. Subjects were randomly distributed to a group who received 21 tablets of metronidazole 250 mg plus amoxicillin 500 mg, or to a group receiving a placebo (1 tablet every 8 hours for 1 week). Patients were examined every 2 months for 12 months. The M+A or placebo regimen was repeated at 4 and 8 months. No effort was made to change the oral habits of patients and they received no additional therapy. Differences between groups were assessed using the Mann-Whitney U test. The differences at every 2-month interval within each group were assessed using the ANOVA test.

RESULTS

Seven subjects abandoned the study; at 12 months the M+A group had 20 subjects and the placebo group 19. There were no significant differences in the clinical parameters at baseline between the 2 groups. After 2 months and thereafter, the M+A group showed significant clinical improvement while the placebo group showed a progressive deterioration of periodontal status. At 12 months compared to baseline, subjects of the M+A group showed: 1) a significant overall mean attachment gain of 0.43 mm (P = 0.005); 2) a significant decrease of active sites (P< or =0.03); 3) a significant increase of sites gaining attachment level (P< or =0.01); 4) a significant reduction of pocket depth (P< or =0.00006); and 5) a significant decrease in percentage of bleeding on probing sites (BOP) (P< or =0.0005). Significant differences between both groups at all 2-month evaluations were found in overall mean attachment level (P < or =0.000004), in percent of active sites (P< or =0.03), and in percent of BOP sites (P< or =0.02). Sites exhibiting > or =2 mm of attachment loss in 2 successive or alternate evaluations, and periodontal abscess were noticed only in the placebo group.

CONCLUSIONS

A 1-week course of systemic M+A every 4 months, as the only therapy, arrests the progression of adult periodontitis and significantly improves the clinical parameters of the disease.

Effects of metronidazole plus amoxicillin in progressive untreated adult periodontitis: results of a single 1-week course after 2 and 4 months

A randomized, double-blind, clinical study was done to assess the microbiological and clinical effects of metronidazole plus amoxicillin (M+A) as the only therapy in 46 patients with moderate to advanced progressive adult periodontitis. Patients were included in the study after at least 2 sites showed > or =2 mm clinical attachment loss. Bleeding on probing, probing depth, and clinical attachment level were measured using on automated probe. The percentage of surfaces with plaque was recorded at day 0, and at 2 and 4 months after therapy. No effort was made to change the oral hygiene habits of patients. Identification of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia was assessed utilizing DNA technology at day 0 and 2 months after therapy. Twenty-three patients received metronidazole 250 mg plus amoxicillin 500 mg, 3 times/day for a week and 23 a placebo. Two patients in the placebo group were dropped at 2 months because they had taken antibiotics for medical reasons. Statistical analyses of differences between groups was done using the Mann-Whitney test, and the differences within each group were tested with ANOVA. There were no significant changes in surfaces with plaque in either group after therapy. The percentage of bleeding sites decreased significantly from baseline to 2 and 4 months in the M+A group (P = 0.001), and increased in the placebo group. Differences in bleeding on probing between groups were significant at 2 (P = 0.018), and 4 months (P = 0.005). The mean attachment level values at 2 and 4 months post-therapy improved significantly in the M+A group compared to the placebo group (P = 0.001). Treatment with M+A resulted in a significant mean reduction in probing depth at 2 and 4 months compared to baseline values (P = 0.001). The M+A group showed a significant reduction of sites with high levels of Pg (P = 0.001) at 2 months compared with baseline values, and there was a significant reduction of sites with Pg and Pi in the M+A group compared with the placebo group. The results showed that a combined M+A treatment as the only therapy changes the proportion of some subgingival microorganisms and allows a significant improvement in clinical conditions.

Development of resistance to metronidazole and minocycline in vitro

By local delivery of antibiotics to periodontal pockets, very high initial concentrations are often quickly succeeded by subinhibitory concentrations, which may facilitate development of bacterial resistance. The purpose of the present study was to investigate possible development of resistance in suspected periodontal pathogens after exposure to subinhibitory concentrations of metronidazole and minocycline. The minimal inhibitory concentration (MIC) of 18 reference strains and 12 clinical isolates was determined by a broth dilution method. Subsequently, all strains with MIC < 8 micrograms/ml were exposed to serial passage on plates containing subinhibitory and gradually increasing concentrations of antibiotics, until growth was inhibited. Initially, most strains were inhibited at < or = 0.250 microgram/ml of minocycline and < or = 0.5 microgram/ml of metronidazole, though A. actinomycetemcomitans was resistant to metronidazole. After growth at subinhibitory concentrations, 8 strains survived 1-2 x and 11 stains survived 8-32 x their initial MIC of metronidazole, growing at up to 8 micrograms/ml. All A. actinomycetemcomitans survived 8-64 x their initial MIC of minocycline, growing at > or = 2 micrograms/ml, while all other strains were inhibited at < or = 0.250 microgram/ml, corresponding to a 1-8 x increase in their initial MIC. Thus, development of resistance was observed for periodontal bacteria growing at up to 64 x their initial MIC, but the final level of resistance was moderate.

Clinical evaluation of tetracycline HCl conditioning in the treatment of gingival recessions. A comparative study

Thirty Class I and Class II recessions in 30 patients were treated with a modified subepithelial connective tissue graft procedure. Fifteen recessions in the test group received a tetracycline hydrochloride (50 mg/ml) root treatment for 5 minutes (TTC-HCl group); the remaining 15 recessions composed the control group and received a citric acid root treatment for 3 minutes (CA group). Clinical assessments were taken at baseline and at 6 months. The differences between treatments were not statistically significant. In the central area of the recession, the mean percentage of root coverage was 81.7% corresponding to a mean percentage of 79.3% and 84.0% for the TTC-HCl and the CA group, respectively. In the test group, 6 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 57.8%. In the control group, 8 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 43.6%. The mean surface area of root exposure was reduced from 11.53 mm2 and 13.30 mm2 to 0.34 mm2 and 0.29 mm2 for the TTC-HCl group and the CA group, respectively. This reduction corresponds to a mean percentage of 97.4% root coverage for both groups. Within the limits of this study, the results indicate that tetracycline hydrochloride and citric acid root conditioning have comparable clinical effects in root coverage surgical therapy. The data also suggest that the measurement of the surface area of the recession is a more accurate criterion in the evaluation of the mean percentage of root coverage than a single central vertical linear measurement.

Treatment of periodontal disease based on microbiological diagnosis. Relation between microbiological and clinical parameters during 5 years

The purpose of this study was to assess the clinical effect of treatment aimed to suppress Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis below detection level and Prevotella intermedia below 5% of the cultivable periodontal pocket flora. Sixteen patients and a total of 111 periodontal pockets with probing depth > or = 6 mm were included in the study. Twelve patients and a total of 77 sites completed the 5-year study. The results demonstrated clinical improvement of probing depth and gain of clinical attachment level of 3.4 mm and 1.2 mm, respectively. Treatment to eliminate indicator bacteria continued for 3 years before the aim was fulfilled. In order to eliminate A. actinomycetemcomitans from a majority of the sites, a combination of surgery and generalized tetracycline treatment was performed. A recolonization or regrowth of the indicator bacteria exceeding detection levels took place in several sites. The presence of A. actinomycetemcomitans. P. gingivalis, and P. intermedia, alone or in combination, correlated with attachment level change on the individual level. No such correlation was obtained by using presence of plaque, bleeding on probing, or three other bacteria (Campylobacter rectus, Eikenella corrodens, and Fusobacterium nucleatum) not used as treatment goal markers.

Slow release of tetracycline hydrochloride from a cellulose membrane used in guided tissue regeneration

The objective of this study was to evaluate if the biologic membrane utilized for GTR can be impregnated by tetracycline hydrochloride and if the chemotherapeutic agent, once impregnated, can be released in minimal inhibitory concentrations for a period compatible with clinical application. Initially, an in vitro study was done with cellulose membranes cut in pieces measuring 9 cm2. A volume of 100 microliters containing a 72,000 micrograms/ml solution of tetracycline was dispensed onto each fragment, and dried for 70 minutes at 37 degrees C. Four pieces measuring 0.5 cm2 were cut from different points of the 9 cm2 membrane (presumably, containing 400 micrograms of tetracycline), placed in test tubes containing 4 ml of sterile deionized water, and agitated for 2 minutes. A standard curve was made from known concentrations of tetracycline and compared to 10 microliters of the test solutions obtained by the elution of the 0.5 cm2 fragments. The concentrations were determined through the bioassay technique in 3 duplicate experiments. The samples recovered from the membrane fragments had a mean of 101 micrograms/ml of tetracycline liberated, demonstrating that the membrane was impregnated homogeneously by the chemotherapeutic agent. In a second phase, an in vivo study was carried out to determine the length of time the drug was liberated from the membranes and at which concentrations, in the presence of an inflammatory process. Fourteen 0.5 cm2 fragments containing 400 micrograms of tetracycline were placed in 14 polypropylene chambers containing 200 microliters of thioglycolate medium. The chambers were implanted in the peritoneal cavities of 14 mice, one chamber per animal, and left in from 1 to 14 days. They were then removed and the concentrations of tetracycline determined from 20 microliters samples using a bioassay. The results showed that the antibiotic was released slowly from the 1st through the 12th day in decreasing concentrations that varied from 218 to 20.8 micrograms/ml. The impregnated cellulose membrane can probably be used in GTR acting as a membrane and as a slow-release device, liberating the chemotherapeutic agent in concentrations high enough to eliminate periodontopathic microorganisms.

Treatment of subjects with refractory periodontal disease

The aim of the present study was to evaluate the effect of non-surgical periodontal therapy with the adjunct of a selected antibiotic in subjects diagnosed with refractory periodontal disease. 21 subjects were selected for the study; all had a history of periodontal surgery, tetracycline therapy, and regular maintenance by a periodontist. When disease activity was detected, a bacterial sample was taken and a whole plaque susceptibility test was performed. Before the outcome of the susceptibility test the subjects were assigned to either antibiotic or placebo therapy. All subjects received scaling and rootplaning prior to antibiotic or placebo therapy. Based on the susceptibility test, subjects in the antibiotic group were treated either with Augmentin or clindamycin. The results demonstrated that in subjects with refractory periodontal disease there was no significant difference (N.S.) in the proportion of sites losing attachment before and after treatment (11.3% and 12.4%, respectively) over a 2-year post therapy observation period. However, the proportion of sites showing gain of attachment increased from 0.9% before therapy to 5.1% (p = 0.029) following selective antibiotic therapy when combined with scaling and rootplaning. The remainder of sites showed no change between pre- and post-therapy monitoring periods. The progression of attachment loss in the active sites could not be completely stopped over the entire 2-year period. After 12-15 months following therapy, there was a tendency towards new loss of attachment and an increase of pocket depth. However, all 4 subjects treated with placebo drug demonstrated continuous deterioration and had to be retreated. Although the proportion of sites losing attachment decreased from 5.1% to 2.3% (N.S.), the proportion of sites gaining attachment also decreased from 2.0% to 1.0% (N.S.). The results suggest that scaling and rootplaning together with selected antibiotic therapy repeated every 12-15 months may be beneficial for these subjects although it may not completely stop progressive attachment loss.

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)

Changes in the prevalence of subgingival enteric rods, staphylococci and yeasts after treatment with penicillin and erythromycin

The changes in the balance of microbial flora in the periodontium after antibiotic treatment were investigated in a blind study. The prevalence of gram-negative enteric rods, staphylococci and yeasts was followed before and during penicillin or erythromycin treatment of 72 periodontitis patients without periodontal cleaning. The prevalence of subgingival coagulase-positive staphylococci increased significantly following systemic penicillin therapy. After systemic erythromycin therapy, the prevalence of subgingival gram-negative enteric rods increased. Ten of 24 (42%) patients receiving systemic penicillin therapy developed clinical evidence of periodontal abscesses. In the absence of conventional mechanical cleaning, systemic administration of penicillin and erythromycin antibiotic to patients with pre-existing periodontitis may lead to periodontal superinfection with opportunistic organisms.

Antibiotic resistance of the subgingival microbiota following local tetracycline therapy

The antibiotic resistance of the subgingival microbiota was studied by 3 approaches. First, we assessed the ability of subgingival isolates taken following therapy to grow on media containing tetracycline (TC). Higher percentages of TC-resistant organisms appeared at TC fiber-treated periodontal sites and within the saliva 1 week after treatment as compared with pre-treatment levels. By 1 month, the percentage of TC-resistant organisms had returned to levels comparable to those seen before treatment. In the second approach, subgingival isolates taken following therapy were grown on media without antibiotics, and isolates were selected for Gram-stain and cell morphology determination. This study indicated that subgingival sites became colonized with gram-positive cocci in the same time period that an increase of TC-resistant isolates was observed in the first study. This may account for the transient increase in TC resistance, because many gram-positive cocci are intrinsically resistant to TC. In the third approach, the antibiotic resistance of subgingival gram-negative species was determined. The predominant cultivable microbiota of 9 sites from 3 subjects were isolated immediately before and 6 months after TC fiber treatment. Gram-negative rods were characterized and tested for sensitivity to TC (minimum inhibitory concentration [MIC] 1-128 micrograms/ml), penicillin at 80 micrograms/ml, and erythromycin at 8 micrograms/ml. None of the gram-negative rods were resistant to TC (MIC greater than or equal to 16 micrograms/ml), either before or after treatment. Before treatment 98% of the gram-negative rods were susceptible to TC at 1-2 micrograms/ml and after therapy 88% were susceptible.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical, microbiological and immunological characteristics of subjects with "refractory" periodontal disease

The aim of the present study was to analyze the relationship between attachment loss and clinical, microbiological, and immunological parameters in a group of 21 human subjects exhibiting poor response to previous periodontal therapy. All had been treated with periodontal surgery, tetracycline, and subsequent maintenance recalls to periodontists who, upon detection of disease progression, referred the subjects to our clinic. In our clinic, each subject received oral hygiene instruction and a thorough subgingival scaling and root planing utilizing as many appointments as necessary. Clinical indices, including gingival index, bleeding on probing, suppuration, plaque index, pocket depth, and duplicate measurements of attachment level from an acrylic stent, were collected at monthly intervals. Probing measurements were performed using the Florida Probe. When significant attachment loss (0.8-1.2 mm) was detected in at least 1 site, a bacterial sample was taken from that site and from a comparably deep, but non-progressing, control site. Microbial samples were enumerated by darkfield microscopy, on selective and non-selective media, and by predominant cultivable technique. Blood samples were also collected to determine antibody levels against potential pathogens. There was no difference in the amount of plaque present in sites gaining or losing attachment, but losing sites exhibited more bleeding and suppuration. 20 of the 21 subjects were tested; of these, 17 exhibited elevated serum antibody against one or more of the following microorganisms: Actinobacillus actinomycetemcomitans, Bacteroides, gingivalis, and Eikenella corrodens. However, few, if any, of the "classical" pathogens were detected in the plaque samples obtained at the time progressive disease was diagnosed. The only exception was Streptococcus intermedius, which occurred in slightly higher numbers in active sites.

The effect of clindamycin on the microbiota associated with refractory periodontitis

The purpose of this investigation was to determine the effect of clindamycin hydrochloride, as an adjunct to scaling, on the microbiota associated with refractory periodontitis and to elucidate the probable causative bacteria associated with the disease. Microbial samples were collected from a subset of 9 patients with severe adult periodontitis who had not responded to conventional treatment modalities including the use of tetracycline and other antibiotics. Microbial samples were collected from a relatively deep site determined to be actively losing attachment and a comparably deep, but quiescent, control site in each patient prior to clindamycin therapy. Samples continued to be collected from the same sites for up to 1 year post-therapy. The microbial flora of each sample were enumerated by darkfield microscopy and predominant cultivable methods. Prior to clindamycin therapy, both active and control sites consisted on average of approximately 50% spirochetes and motile rods and 40% Gram-negative anaerobic rods. Bacteroides intermedius and Porphyromonas gingivalis (formerly B. gingivalis) were elevated in the active, as compared to control, sites and accounted for approximately 20% of the cultured microbiota in the former. Following treatment with clindamycin, the Gram-negative components of the microbiota were either eliminated or severely suppressed. At 1 year post-therapy, spirochetes and motile rods together accounted for about 15% of the microscopic flora. Total Gram-negative anaerobic rods accounted for approximately 20%, and B. intermedius and P. gingivalis combined accounted for less than 2% of the cultured microbiota from historical active sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of clindamycin hydrochloride in refractory periodontitis: 24-month results

The purpose of this investigation was to evaluate the use of clindamycin hydrochloride in the treatment of adult refractory periodontitis. Thirty patients with a history of unsuccessful treatment with scaling, periodontal surgery, and the use of tetracyclines were entered into the study. Upon entry, the suspected refractory patients were scaled several times and then monitored for the presence of active disease by probing attachment level measurements performed in duplicate. Active disease was defined as a 3.0 mm or greater loss in attachment from the baseline examination or the occurrence of a periodontal abscess. When active disease was detected, patients were treated with scaling and clindamycin 150 mg qid for 7 days. Patients served as their own controls. Twenty four patients demonstrated further attachment loss following scaling alone and were treated with clindamycin hydrochloride. Scaling and clindamycin treatment decreased the incidence of active disease from an annual rate of 8.0% to 0.5% of sites per patient (P less than .001). The mean time required to detect the first active site increased from 4.9 +/- 3.7 months following scaling alone to 16.7 +/- 7.6 months following scaling and clindamycin (P less than 001). Active sites lost an average of 3.1 mm of probing attachment following scaling alone but "gained" back 2.0 mm at 6 months and 1.5 mm at 24 months post-antibiotic and scaling treatment. Bleeding on probing was significantly reduced (P less than .05) from 31.8% of sites pre-clindamycin treatment to 12.3% at 12 months and 17.9% of sites at 24 months post-clindamycin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of minocycline on subgingival plaque bacteria

The effects of minocycline on subgingival plaque samples from patients with chronic periodontitis were investigated in vitro. Minocycline concentrations as low as 1.0 microgram/ml inhibited 95.7% of the cultivable bacteria in the samples but 256 micrograms/ml was necessary to inhibit all of the cultivable bacteria in the samples. Although up to 99.9% of bacteria in the plaque samples were killed by a 6 h exposure to 8.0 micrograms/ml of minocycline, large numbers of viable bacteria remained. These results imply that adequate reductions in the numbers of viable subgingival plaque bacteria are unlikely to occur after exposure to minocycline at concentrations attainable in gingival crevicular fluid after systemic administration.

Effect of non-surgical periodontal therapy combined with adjunctive antibiotics in subjects with "refractory" periodontal disease. (I). Clinical results

The aim of the present study was to evaluate the clinical effect of non-surgical periodontal therapy with the adjunct of a selected antibiotic in subjects with refractory periodontitis. 10 subjects were selected for the study; all had a history of periodontal surgery, tetracycline therapy, and regular maintenance by a periodontist. Clinical registrations including gingival index, plaque index, presence of bleeding and suppuration, pocket depth, and duplicate measurements of attachment level were performed at baseline and at monthly intervals. When disease activity was detected based on the tolerance method, a bacterial sample was taken from the active site and its susceptibilities to a number of antibiotics were determined. For the selected 10 subjects, Augmentin was the antibiotic of choice. Each subject received 750 mg/day for 2 weeks, during which time a full-month scaling and root planing was performed under local anesthesia. Clinical re-evaluation was performed after 3, 6, 9 and 12 months. At the time disease activity was detected, the average loss of attachment at all active sites was 2.2 mm, and the increase in pocket depth 1.5 mm. At 3 months post-therapy, these sites had regained 2 mm of attachment which remained stable through the 12-month examination. Pocket depths decreased 2.5 mm over the first 6 months and then stabilized. The frequency of all sites that gained 1 mm or more of attachment increased by approximately 10% over the first 9 months following therapy. The frequency of all sites that decreased 1 mm or more in pocket depth increased approximately 15% over the same period.(ABSTRACT TRUNCATED AT 250 WORDS)

Unusually aggressive osteomyelitis of the jaws. A report of two cases

Two cases of unusually aggressive osteomyelitis of the jaws are reported. Both cases manifested severe, rapidly progressive lytic destruction of the maxilla in spite of the fact that patients were young, healthy adults with no local or systemic factors that would predispose them to severe infection in either case. Characteristic historical, clinical, radiographic, and histologic features are elaborated. Also, theoretical aspects of this disease entity are discussed in an effort to explain the unusually aggressive manner in which these cases presented.

The in vitro effects of chlorhexidine on subgingival plaque bacteria

The purpose of this study was to determine the susceptibility to chlorhexidine of a range of bacteria which may be isolated from subgingival plaque. In addition, the effect of chlorhexidine on the survival of bacteria in subgingival plaque samples from patients with chronic inflammatory periodontal disease was investigated. The minimum inhibitory concentration (MIC) of chlorhexidine for 52 strains of bacteria ranged from 8 to 500 micrograms/ml. The modal value of the MIC was found to be 62 micrograms/ml, 64% of the strains tested being inhibited at this concentration. A concentration of 250 micrograms/ml of chlorhexidine inhibited the growth of all bacteria in the 25 subgingival plaque samples investigated. The MIC of chlorhexidine for the samples ranged from 31 to 250 micrograms/ml, the modal value being 125 micrograms/ml.

Refractory chronic periodontitis: effect of oral tetracycline hydrochloride and root planning

Refractory chronic periodontitis of 16 patients was treated by root planing and adjunctive tetracycline hydrochloride therapy. The antibiotic was taken orally one hour before root planing and continued for six days at a dosage of 250 mg six hourly. The clinical data for each patient were recorded as the number of probing depths in each of the 1-3 mm, 4-6 mm and 7-10 mm ranges. The Multivariate Analysis of Variance (MANOVA) procedure for repeated measurements was used to analyse the data. The results demonstrated that the number of sites with probing depths of 4-6 mm and 7-10 mm associated with incisors, canines, premolars and molars decreased with a corresponding increase in the number of sites in the 1-3 mm range. Incisor and canine teeth showed a better response to treatment than premolars, which responded better than molars. The cases were followed for varying periods of time from six months to two years following antibiotic therapy. The probing depth reduction achieved following root planing and tetracycline hydrochloride therapy was maintained during this review period.

Clinical and microbiologic effects of local tetracycline irrigation on periodontitis

This investigation was conducted on seven individuals referred for treatment of moderate adult periodontitis. Twenty-eight sites with an average probing depth of 5.6 +/- 0.9 mm were evaluated. One tooth per jaw quadrant was randomly assigned to receive one of the following treatments: (I) no treatment, i.e., control; (II) saline irrigation; (III) tetracycline irrigation and (IV) scaling and root planing (SC/RP). A plaque control program was instituted one week prior to the experimental period and reinforced throughout the eight-week study. Irrigation was performed every 48 hours during the first two weeks of the experiment for Groups II and III, and the single treatment of SC/RP was carried out immediately following the baseline examination for Group IV. Clinical and microbiologic changes were monitored every two weeks using plaque and gingival indices, gingival fluid flow, probing depths, bleeding on probing and dark-field microscopic examination of the subgingival microbial flora. The tetracycline and SC/RP treatment modalities resulted in statistically significant clinical and microbiological improvements when compared with the control. Tetracycline irrigation alone and SC/RP alone had a similar effect in changing the subgingival microflora from one associated with disease to one associated with health. Thus, these treatment modalities are effective methods of producing statistically significant alterations in the subgingival microflora. The property of substantivity may contribute to the sustained duration of the effect of locally delivered tetracycline.

The non-specific theory in microbial etiology of inflammatory periodontal diseases

In the absence of toothbrushing, the gingival crevice is colonized by a complex indigenous microflora causing gingivitis, a non-specific inflammation. Subgingival plaque may develop by downgrowth into the inflamed pocket of those micro-organisms from supragingival plaque which can multiply there. By direct microscopy, increased proportions of motile rods and spirochetes have been found in diseased pockets. Cultures on selective media have demonstrated increased prevalence of various gram-negative rods. Cultures on non-selective media have revealed the complexity and variability of the subgingival microflora, comprising more than 200 species. Destructive periodontitis is the result of subgingival colonization, which is favored by such ecological changes as plaque accumulation, gingivitis, and gingival exudate. These changes increase the numbers of micro-organisms and alter their proportions, but no single species appears in active sites which is not also commonly present in inactive sites. The subgingival micro-organisms have several virulence factors which promote colonization of the pockets, destroy host defense mechanisms, and provoke inflammation. It appears that different combinations of indigenous bacteria, rather than just a single species, can produce the pathogenic potential necessary to cause progression from gingivitis to destructive periodontitis.

Concentration of doxycycline in human gingival fluid

Doxycycline is a synthetic tetracycline compound whose main advantages over tetracycline hydrochloride are increased oral absorption, prolonged serum half-life and decreased gastrointestinal side-effects. The purpose of this study was to measure the concentration of doxycycline in gingival fluid and blood after oral administration. 4 volunteers were given doses of 100 mg doxycycline every 12 h on the first day of antibiotic administration followed by a maintenance dose of 100 mg per day for an additional 4 days. 3 of these volunteers were also given tetracycline hydrochloride every 6 h for 5 days either 1 month before or after doxycycline administration to compare gingival fluid levels of these 2 tetracycline compounds. Gingival fluid was sampled from 4 gingival sites in each volunteer at hourly intervals from hours 0 to 6, 9, 24, 27, 48 to 54, 57, 72, 75, 96 to 102 and 105. Blood was sampled by finger puncture at hours 0, 3, 6, 24, 48, 54, 72, 96 and 102. Antibiotic levels in gingival fluid and blood were measured using an agar diffusion assay method. The results demonstrated that doxycycline achieved much higher levels in the gingival fluid than in blood and yielded comparable gingival fluid levels to those achieved by tetracycline hydrochloride. Doxycycline levels in gingival fluid ranged between 1.2 micrograms/ml and 8.1 micrograms/ml in the first 24 h and generally achieved 3-10 micrograms/ml after 48 h. Blood levels after 48 h ranged between 2.1 micrograms/ml and 2.9 micrograms/ml. Tetracycline hydrochloride in gingival fluid after 48 h was generally in the range of 4 micrograms/ml-10 micrograms/ml with blood levels between 2.2 micrograms/ml and 3.4 micrograms/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

A simplified laboratory procedure to select an appropriate antibiotic for treatment of refractory periodontitis

THE FEASIBILITY OF USING A simplified laboratory procedure to select an appropriate antibiotic for treatment of refractory periodontitis was investigated. Six different antibiotics were added to commercially available CDC-agar plates. Plaque samples from periodontal pockets were inoculated onto the plates. The percentage kill was determined by comparing colony counts on the antibiotic-containing medium with those on the control plates. The three most effective antibiotics were ranked by visual inspection as well as by colony count. It was determined that visual inspection may be used to determine an effective antibiotic.

Clinical and microbiologic effects of single-dose metronidazole or scaling and root planing in treatment of adult periodontitis

Sites affected with adult periodontitis were observed for 3 months to compare their clinical and microbiologic responses to a single 2 g dose of metronidazole, scaling and root planing, or no treatment. 2 sites with probing depths greater than or equal to 5 mm in each of 18 female subjects (6 in each treatment group) were evaluated clinically (plaque and bleeding indices, probing depth, attachment loss) and microbiologically (%s of cocci, motile rods, non-motile rods and spirochetes, and of obligate anaerobic colony-forming units, black-pigmented Bacteroides, Fusobacterium and Actinobacillus actinomycetemcomitans in subgingival plaque). No significant differences in these variables existed between the 3 groups at baseline. The no-treatment (control) group showed no substantial clinical or microbiologic changes during the study. After 1 month, scaling and root planing had effected significant clinical improvement and significant shifts in the subgingival flora to a pattern more consistent with periodontal health; these changes were still evident at 3 months. In contrast, 1 month after metronidazole, there was some clinical improvement and a significant increase in cocci and a decrease in motile rods, but at 3 months these changes were no longer evident. The results show that the benefits of scaling and root planing are sustained for at least 3 months. However, the benefits of a single 2 g dose of metronidazole are both few and transient, indicating that this regimen, while effective against anaerobic infections in other organ systems, is not clinically or microbiologically effective in the treatment of adult periodontitis.

Antibiotic susceptibilities of periodontal bacteria. In vitro susceptibilities to eight antimicrobial agents

In vitro susceptibilities of 369 to 966 bacterial isolates from periodontal lesions to eight antibiotics were determined by agar dilution technique as a means of determining which antimicrobial agents were inhibitory for bacteria frequently associated with destructive periodontal diseases. Although most bacteria were relatively susceptible to the penicillins, greater activity was generally noted with amoxicillin than with either penicillin or ampicillin with the exception of Selenomonas sputigena and Peptostreptococcus. Antibacterial activities obtained with minocycline were significantly higher than with tetracycline for Actinobacillus actinomycetemcomitans and Streptococcus but comparable for most other taxa. Clindamycin and metronidazole both demonstrated excellent activity against the anaerobic Gram-negative rods but were less effective against some of the capnophilic and facultative organisms. Eikenella corrodens was exceptionally resistant to both of these drugs; and A. actinomycetemcomitans was generally resistant to clindamycin but relatively susceptible to metronidazole. Erythromycin was considerably less active than the other antibiotics against the majority of the periodontal bacteria. No single antibiotic, at concentrations equivalent to those achieved in body fluids, was uniformly effective in inhibiting all bacteria currently implicated or suspected as etiologic agents of periodontal diseases.

Efficacy of clindamycin hydrochloride in refractory periodontitis. 12-month results

The purpose of this study was to evaluate the use of clindamycin hydrochloride as an adjunct to conventional periodontal therapy in the treatment of patients who had previously been unsuccessfully treated with scaling, periodontal surgery and the use of tetracycline. Thirteen patients with a history of "refractory" periodontitis were thoroughly scaled and monitored by repeated attachment level measurements for the presence of active destructive periodontitis. Disease activity was defined as a 3-mm loss in attachment from baseline measurements or the occurrence of a periodontal abscess. When active disease was detected, each patient was scaled again and placed on clindamycin hydrochloride 150 mg qid for 7 days. Following the adjunctive use of clindamycin in combination with scaling, the incidence of gingival sites demonstrating active disease in the group of 13 patients decreased from an annual rate of 10.7 to 0.5%. Each patient demonstrated a decreased incidence of active sites per unit of time. Clinical parameters such as probing depth, gingival redness, bleeding on probing and suppuration showed dramatic improvement at 12 months after clindamycin therapy. The percentage of pockets with probing depths greater than 6 mm, 4 to 6 mm and 1 to 3 mm changed from 11 to 2%, 38 to 24% and 51 to 74% respectively, following clindamycin therapy as compared to scaling alone. The percentage of sites bleeding on probing decreased from 33% after scaling alone to 8% following clindamycin and scaling. Gingival redness decreased from 36 to 1% of sites. Suppuration also decreased from 8% of buccal or lingual surfaces after scaling alone to 1% of surfaces following scaling and clindamycin.(ABSTRACT TRUNCATED AT 250 WORDS)