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

Antimicrobial Chemotherapy for Recalcitrant Severe Human Periodontitis

This study evaluated a combined systemic and topical anti-infective periodontal treatment of 35 adults who had experienced ongoing periodontal breakdown following conventional surgical periodontics. The prescribed anti-infective therapy, based on microbiological testing, consisted of a single course of metronidazole plus ciprofloxacin (23 patients), metronidazole plus amoxicillin/clavulanic acid (10 patients), and metronidazole plus ciprofloxacin followed by metronidazole plus amoxicillin/clavulanic acid (2 patients). In addition, the study patients received 0.1% povidone-iodine subgingival disinfection during non-surgical root debridement and daily patient administered oral irrigation with 0.1% sodium hypochlorite. At 1 and 5 years post-treatment, all study patients showed gains in clinical periodontal attachment with no further attachment loss, and significant decreases in pocket probing depth, bleeding on probing, and subgingival temperature. The greatest disease resolution occurred in patients who at baseline harbored predominantly major periodontal pathogens which post-antibiotics became non-detectable and substituted by non-periodontopathic viridans streptococci. The personalized and minimally invasive anti-infective treatment regimen described here controlled periodontitis disease activity and markedly improved the clinical and microbiological status of the refractory periodontitis patients.

Efficacy of doxycycline release collagen membrane on surgically created and contaminated defects in rat tibiae: A histopathological and microbiological study

BACKGROUND

The effects of systemic antibiotics on controlling infective pathogens after guided bone regeneration(GBR) procedures especially in membrane exposures are limited. However, local administrations of antibiotics are rare in GBR techniques.

AIM

The aim of this study was to investigate the osteogenesis potential and the antibacterial effect of a doxycycline releasing collagen membrane in surgically created and contaminated defects in rat tibiae.

MATERIAL AND METHODS

Defects were created in 20 rats that were randomly divided in to two groups: control group (defect contaminated by Porphyromonas gingivalis, filled with bone graft and covered by collagen membrane); test group (defect contaminated by P. gingivalis filled with bone graft and covered by collagen membrane containing 1mg/cm(2) doxycycline. Animals were sacrificed post surgically on the 14th day for microbiologic evaluation and on the 28th day for histopathological evaluation.

RESULTS

The degree of osteogenesis in the test group was seen to be significantly higher than control group (p: 0.011; p<0.05). Furthermore in test group, no bacterial growth was observed. The bacteria counts were determined between 1×104 and 268×104CFU/g with a median of 1.32×104 for control group.

CONCLUSIONS

Within the limitations of this study, the results of the present study suggests that the use of a doxycycline releasing membrane has a positive effect on contaminated GBR procedures for limiting P. gingivalis infections leading to bone formation following GBR procedures in a rat model.

The effects of tetracycline-loaded silk fibroin membrane on proliferation and osteogenic potential of mesenchymal stem cells

BACKGROUND

The main objective of this study was to investigate the effect of tetracycline-loaded silk fibroin membranes (TC-SFMs) on the proliferation and the osteogenic differentiation of human mesenchymal stem cells.

MATERIALS AND METHODS

Four groups (0, 1, 5, and 10% concentration) of TC-SFMs were prepared for the experiments. We investigated cumulative tetracycline (TC) release profile for 7 d. Human gingiva-derived mesenchymal stem cells (GMSCs) were isolated from our previous study and seeded to the TC-SFMs. WST-8 assay (Cell Counting Kit-8; SigmaeAldrich Co, St. Louis, MO), staining of Phalloidin-FITC, and scanning electron microscope analyzed the cellular attachment and viability. Staining of Alizarin Red S (Sigma-Aldrich Co.) and osteogenic marker (osteocalcin) analyzed osteogenic differentiation. Additionally, quantitative polymerase chain reaction measured the expression of osteogenic lineage genes, including bone gamma-carboxyglutamic acid protein, bone sialoprotein, runt-related transcription factor 2, and collagen type I α1 according to TC concentration (0.05, 0.1, 0.25, and 0.5 mg/mL).

RESULTS

The release of TC from TC-SFMs plateaued and neared completion in 24 h. Significantly higher viability was noted achieved in 1% and 5% TC-SFMs. The morphology of GMSCs on TC-SFMs at 0% and 1% concentration showed spindle shapes, but cells in 10% TC-SFMs appeared spheroid. During Alizarin Red S staining at 21 d of osteogenic differentiation, calcium and osteocalcin formation were significantly lower in the 10% TC-SFM group than in the 0, 1, and 5 groups. Compared with the control group, bone gamma-carboxyglutamic acid protein showed significantly low expression rate at TC concentration ≥0.05 mg/mL. Bone sialoprotein was low at TC concentration ≥0.1 mg/mL. Likewise, runt-related transcription factor 2 and collagen type I α1 were low at TC concentration of 0.5 mg/mL.

CONCLUSIONS

Within the limits of this study, 1% and 5% TC-SFMs showed higher proliferation and osteogenic potential of GMSCs than 10% TC-SFM. Therefore, the use of 1% to 5% range of TC may be more suitable to silk fibroin membrane for stem cell tissue engineering.

Bacterial adhesion to antibiotic-loaded guided tissue regeneration membranes - a scanning electron microscopy study

BACKGROUND/PURPOSE

Bacterial contamination of sites undergoing guided tissue regeneration (GTR) therapy may reduce the efficiency of periodontal regeneration. This study compared bacterial adhesion onto various GTR membranes incorporated with antibiotics.

METHODS

Three barrier membranes, including expanded polytetrafluoroethylene (ePTFE) membrane, collagen membrane, and glycolide fiber membrane, were loaded with tetracycline or amoxicillin. The adhesion of Streptococcus mutans and Aggregatibacter actinomycetemcomitans onto the GTR membranes with or without antibiotics was analyzed using the scanning electron microscopy (SEM) analysis.

RESULTS

The SEM analysis showed no apparent alteration in the physical structure of the membranes loaded with antibiotics. Both S. mutans and A. actinomycetemcomitans attached best on the collagen membranes, followed by the ePTFE membranes, and then the glycolide fiber membranes without antibiotics. Moreover, higher numbers of bacteria were observed on the fibril areas than on the laminar areas of the ePTFE membranes. The amounts of attached bacteria on the GTR membranes increased after longer incubation. Incorporation of tetracycline or amoxicillin greatly reduced the adhesion of S. mutans and A. actinomycetemcomitans onto all of the GTR membranes examined.

CONCLUSION

Incorporation of tetracycline or amoxicillin greatly reduced adhesion of S. mutans or A. actinomycetemcomitans on the ePTFE, glycolide fiber, or collagen membranes. This finding indicates that it is valuable and effective to use the antibiotic-loaded GTR membranes for periodontal regeneration therapy.

Minocycline: old and new therapeutic uses

Since the introduction of minocycline HCl in the late 1960's, it has been used for disease states that have ranged from typical community-acquired infectious diseases to others that are non-infectious, such as resistant rheumatoid arthritis. Owing to its high penetration characteristics throughout the body, minocycline can be used in the treatment of a wide variety of extracellular and intracellular pathogens. This review examines the known and potential therapeutic uses of minocycline in a clinical setting.

Therapeutic Efficacy of Subgingivally Delivered Doxycycline Hyclate as an Adjunct to Non-surgical Treatment of Chronic Periodontitis

OBJECTIVES

Locally used doxycycline has been shown to concentrate in crevicular fluid and demonstrates a wide spectrum of activity against the periodontal pathogens. The aim of the present clinical study was to evaluate the efficacy of doxycyline hyclate 10% as an adjunct to scaling and root planing in the treatment of chronic periodontitis.

MATERIAL AND METHODS

60 systemically healthy, chronic periodontitis patients were included in the study. Randomized clinical trial was performed over the 6 month period. Test group was treated by scaling and root planing followed by local delivery of doxycycline hyclate 10%, while the control group was treated by scaling and root planing along with placebo.

RESULTS

Significantly greater (P < 0.001) reduction in the mean probing pocket depth was demonstrated in the test group (3.03 ± 0.92 mm) when compared with the control group (2.3 ± 0.65 mm). When the differences in clinical attachment level gain for the test group (2.0 ± 0.64 mm) versus control group (1.13 ± 1.07 mm) were analyzed by Student's unpaired t-test, test group showed statistically greater clinical attachment level gain (0.87 ± 0.22 mm, P < 0.001).

CONCLUSIONS

From the analysis of the results it can be concluded that the use of doxycyline hyclate 10% as an adjunct to scaling and root planing provides more favourable and statistically significant (P < 0.001) reductions in probing pocket depth and gains in clinical attachment level compared to scaling and root planing 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.

Characterization of minocycline transport by human neutrophils

BACKGROUND

Tetracyclines are used in periodontal therapy as antimicrobial agents and as inhibitors of matrix metalloproteinases. Neutrophils appear to accumulate minocycline and other tetracyclines through a mechanism that has not been fully characterized.

METHODS

The transport of minocycline and other tetracyclines by isolated human neutrophils was characterized by measuring the increase in cell-associated fluorescence.

RESULTS

Quiescent neutrophils took up minocycline through a saturable, concentrative, sodium-dependent mechanism with a Michaelis constant (K(m)) of 153 micro g/ml (501 microM) and a maximal velocity of 240 ng/minute/10(6) cells. The efficiency of minocycline transport was not influenced significantly by a two-unit variation in extracellular pH and was not enhanced upon cell activation with phorbol myristate acetate. Neutrophil incubation in medium containing 10 micro g/ml minocycline, doxycycline, or tetracycline yielded steady-state intracellular/extracellular concentration ratios of approximately 64.0, 7.5, or 1.8, respectively. The dilution of extracellular minocycline or doxycycline triggered efflux from cells loaded with these antibiotics. Minocycline transport was competitively inhibited by the organic cations carnitine, diphenhydramine, and verapamil, but penicillin and other organic anions failed to produce inhibition.

CONCLUSION

Transport of tetracyclines by neutrophils could potentially enhance the effectiveness of these agents in periodontal therapy by enhancing or sustaining their therapeutic levels at inflammatory sites and by enhancing the killing of phagocytosed bacterial pathogens.

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.

Antimicrobial susceptibility variation of 50 anaerobic periopathogens in aggressive periodontitis: an interindividual variability study

BACKGROUND/AIMS

The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient).

MATERIAL AND METHODS

A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test.

RESULTS

Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros.

CONCLUSIONS

The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.

The combined use of enamel matrix proteins and a tetracycline-coated expanded polytetrafluoroethylene barrier membrane in the treatment of intra-osseous defects

OBJECTIVES

The purpose of this split-mouth study was to evaluate the clinical response of enamel matrix proteins (EMPs, Emdogain Gel in intra-osseous defects with or without a combined application of a tetracycline-coated expanded polytetrafluoroethylene barrier membrane (e-PTFE, Gore-Tex).

METHODS

Twelve pairs of intra-osseous periodontal defects in 11 patients received the application of EMPs on the exposed root surface (EMP). One of the two defects received randomly, as an adjunct to EMP treatment, a tetracycline-coated e-PTFE membrane (MEMP). At baseline, 6- and 12-month probing pocket depth (PPD), clinical attachment level (CAL) and probing bone level (PBL) were measured.

RESULTS

After 12 months, the EMP defects showed a significant mean PPD reduction of 2.86+/-0.75 mm, a mean gain in CAL of 1.28+/-2.04 mm, a mean PBL gain of 1.63+/-1.21 mm and a mean increase of recession (REC) of 1.56+/-2.30 mm. The MEMP defects showed a significant mean PPD reduction of 3.02+/-1.55 mm, a mean gain in CAL of 1.65+/-1.29 mm, a mean PBL gain of 1.58+/-1.92 mm and a mean increase of REC of 1.38+/-1.63 mm. Except for significantly more post-operative discomfort at the MEMP sites, no significant differences were found between EMP and MEMP defects.

CONCLUSION

Within the limits of this study, it is concluded that in the treatment of intra-osseous defects with EMP, the adjunctive use of a tetracycline-coated e-PTFE membrane failed to show more gain of CAL and PBL.

Subantimicrobial dose doxycycline as adjunctive treatment for periodontitis. A review

BACKGROUND

Subantimicrobial dose doxycycline (SDD--20 mg doxycycline twice daily) is indicated as an adjunctive treatment for periodontitis. Doxycycline downregulates the activity of matrix metalloproteinases (MMPs), key destructive enzymes in periodontal disease. Current understanding of periodontal pathogenesis suggests that MMPs play a major role in the destruction of periodontal tissues, leading to the clinical signs of periodontitis. Research supports that downregulation of MMPs by SDD confers benefit to patients with periodontitis.

METHOD

We review the clinical, microbiological and safety data relating to the use of SDD in patients with periodontitis, and consider the historical events that led to the development of adjunctive SDD as a treatment for periodontitis.

RESULTS

Studies have shown that SDD, when prescribed as an adjunct to scaling and root planing (SRP), results in statistically and clinically significant gains in clinical attachment levels and reductions in probing depths over and above those that are achieved by SRP alone. SRP must be thorough and performed to the highest standard to maximise the benefits of adjunctive SDD. SDD does not result in antibacterial effects, or lead to the development of resistant strains or the acquisition of multiantibiotic resistance. The frequency of adverse events is low, and does not differ significantly from placebo.

CONCLUSIONS

Adjunctive SDD confers clinical benefit to patients with periodontitis. A comprehensive treatment strategy is suggested, involving patient education and motivation, reduction of the bacterial burden by SRP, host response modulation with SDD, and periodontal risk factor modification.

Intentional replantation for periodontally involved hopeless teeth

The aim of this study was to evaluate the clinical and radiographic results of intentional replantation of periodontally involved teeth after conditioning of root surfaces with tetracycline-HCl. Thirteen patients (seven female, six male; age range: 35-52 years) with 15 periodontally involved hopeless teeth were included in this study. During the replantation procedure, the affected teeth were gently extracted, then the granulation tissues, calculus, remaining periodontal ligament and necrotic cementum on the root surfaces were removed. Tetracycline-HCl, at a concentration of 100 mg ml(-1), was applied for 5 min to the root surfaces. The teeth were then replaced into the socket and splinted. Patients were clinically and radiographically evaluated at baseline (time of surgery) and 6 months after the surgery. The following measurements were recorded: probing depth (PD), gingival recession (R), the amount of bone loss (BL) and bone gain (BG). Results indicated a reduction in PD and in the amount of bone loss and healthy gingiva. Mean PD was decreased from 5.25 to 2.36 mm, gingival recession was increased from 3.73 to 4.0 mm, and BL was reduced from 73.20 to 56.86%. At the end of 6 months, no root resorption or ankylosis was observed radiographically. Even during the short period of evaluation, it may be suggested that intentional replantation can be an alternative approach to extraction in cases where advanced periodontal destruction is present and no other treatments could be considered.

An in vitro model of ciprofloxacin and minocycline transport by oral epithelial cells

BACKGROUND

Fluoroquinolones and tetracyclines can penetrate epithelial cells, but the mechanism by which they cross the plasma membrane is unclear. In this study, a cell line derived from oral epithelium was used as a model to demonstrate a role for active transport.

METHODS

Transport of ciprofloxacin and minocycline by confluent cell monolayers was assayed by measuring the increase in cell-associated fluorescence.

RESULTS

Uptake of both agents was saturable and was inhibited at low temperatures. At 37 degrees C, the cells transported ciprofloxacin and minocycline with Km values of 351 and 133 microg/ml, respectively, and maximum velocities of 5.11 and 13.4 ng/min/microg cell protein, respectively. When ciprofloxacin and minocycline were removed from the extracellular medium, the intracellular levels of both agents decreased. Ciprofloxacin efflux from loaded cells occurred more rapidly than with minocycline. Cells accumulated intracellular drug levels that were at least 8-fold higher than extracellular levels for ciprofloxacin and at least 40-fold higher for minocycline. Transport of ciprofloxacin and minocycline was significantly influenced by pH and was most favorable at pH 7.7 and 7.2, respectively. While ciprofloxacin transport was Na+ independent, minocycline transport was strongly inhibited when sodium in the medium was replaced with choline. Transport of both agents was inhibited by a variety of organic cations, but the pattern of inhibition was different. Papaverine, phenylephrine, and doxycycline competitively inhibited minocycline transport, but inhibited ciprofloxacin transport by a non-competitive mechanism.

CONCLUSIONS

Epithelial cells take up ciprofloxacin and minocycline via different active transport systems. These transporters may play an important role in enhancing the effectiveness of these agents against invasive pathogens.

Rationale for use of antibiotics in periodontics

The purpose of this review is to provide the clinician with some practical rationale for the selection and use of antibiotics in the treatment of destructive periodontal diseases. We have attempted to integrate approximately 20 years of periodontal literature describing antibiotic therapy with personal experience and 21st century ideas. This article addresses antibiotic use during treatment of aggressive periodontitis with emphasis on juvenile disease and adult refractory diseases. The literature review revealed few large, controlled studies that compared efficacy of adjunctive antibiotic use to mechanical therapy alone. Even fewer studies evaluated the efficacy of one antibiotic relative to another. However, based on the evidence available, certain conclusions were drawn. Adjunctive use of an antibiotic along with mechanical debridement is recommended for the treatment of Actinobacillus actinomycetemcomitans-associated periodontitis as an acceptable therapeutic regimen. Due to the emergence of tetracycline-resistant A. actinomycetemcomitans, the combination of metronidazole and amoxicillin may be preferable. In aggressive refractory periodontitis, compelling evidence exists that the use of an appropriate adjunctive antibiotic frequently gives a more favorable clinical response than mechanical therapy alone. Unfortunately, the selection of antibiotic is not as clear and is probably case-dependent. Positive responses have been reported with amoxicillin/clavulanic acid, clindamycin, metronidazole, and the combination therapy metronidazole plus amoxicillin. The introduction of local delivery antibiotics specifically for the treatment of periodontitis offers a novel concept for the treatment of localized disease. The latter, in particular, may prove useful in the treatment of recurrent disease activity or where only a few individual sites are involved.

In vitro antimicrobial susceptibility of oral strains of Actinobacillus actinomycetemcomitans to seven antibiotics

BACKGROUND/AIMS

Periodontal infections with Actinobacillus actinomycetemcomitans seem to be refractory to conventional therapy. The aim of the present study was to test the in vitro susceptibilities of A. actinomycetemcomitans strains to a panel of seven orally administrable antibiotics.

METHODS

A total of 60 isolates of A. actinomycetemcomitans recovered from 43 individuals with gingivitis or periodontitis were tested. In addition, laboratory strains UP-6 and JP2 were analysed. The E-test was employed in order to determine minimal inhibitory concentrations (MIC) of antibiotics ampicillin/sulbactam, roxithromycin, azithromycin, doxycycline, metronidazole, ciprofloxacin, and moxifloxacin.

RESULTS

A. actinomycetemcomitans was highly susceptible to both fluoro-quinolones (MIC90 of 0.006 microgram/mL of ciprofloxacin and 0.032 microgram/mL of moxifloxacin). Good susceptibilities were found for ampicillin/sulbactam and doxycycline (MIC90 of 0.75 microgram/mL and 1 microgram/mL, respectively), and moderate susceptibilities for azithromycin (MIC90 of 3 microgram/mL). Most strains were resistant to metronidazole and roxithromycin. Cluster analysis revealed two larger clusters of A. actinomycetemcomitans strains with the smaller cluster assembling isolates with significantly higher MICs of most antibiotics.

CONCLUSIONS

Due to reported favourable pharmacokinetics, the fluoro-quinolone moxifloxacin appeared to be a promising candidate for adjunctive systemic antibiotic therapy in periodontal infections with A. actinomycetemcomitans.

Effect of ciprofloxacin on killing of Actinobacillus actinomycetemcomitans by polymorphonuclear leukocytes

Actinobacillus actinomycetemcomitans, a pathogen associated with aggressive periodontitis, resists phagocytic killing by polymorphonuclear leukocytes (PMNs). It is susceptible to ciprofloxacin, which PMNs actively accumulate. This study tested the hypothesis that ciprofloxacin-loaded PMNs are more effective at killing A. actinomycetemcomitans than control PMNs. Isolated human PMNs were loaded by brief incubation with 0.5 microg of ciprofloxacin/ml. Opsonized bacteria (ATCC 43718) were incubated at 37 degrees C with control and ciprofloxacin-loaded PMNs and in the presence and absence of 0.5 microg of ciprofloxacin/ml. When assayed at bacteria-to-PMN ratios of 30:1 and 90:1, ciprofloxacin-loaded PMNs killed significantly more bacteria and achieved significantly shorter half times for killing than control PMNs (P < 0.05; Tukey's test). At ratios of 3:1 and 10:1, these differences were not significant.

In vitro activities of a new des-fluoroquinolone, BMS 284756, and seven other antimicrobial agents against 151 isolates of Eikenella corrodens

The des-fluoroquinolone BMS 284756 was active in vitro against all 151 clinical strains of Eikenella corrodens at a MIC of < or = 0.25 microg/ml and was comparable in activity to moxifloxacin and levofloxacin. The MIC at which 90% of the isolates were inhibited by penicillin G was 2 microg/ml; MICs for 8.6% of the strains (13 of 151) were > or = 4 microg/ml, including for two beta-lactamase-producing isolates. Amoxicillin-clavulanate and ampicillin-sulbactam inhibited all strains at a MIC of < or = 1 microg/ml.

The effects of subgingival calculus on the clinical outcomes of locally-delivered controlled-release doxycycline compared to scaling and root planing

BACKGROUND/AIM

The effect of subgingival calculus on the clinical outcomes of the local delivery of antimicrobials is unknown. This study examines the clinical outcomes of treatment with locally delivered controlled-release doxycycline (DH) or scaling and root planing (SRP) in subsets of adult periodontitis patients with known baseline levels of subgingival calculus.

METHODS

The data examined were obtained from 393 patients who participated in 2 multi-center trials. All patients had baseline subgingival calculus levels assessed and were then treated at baseline and month 4 with either DH or SRP. Clinical attachment levels (CAL), pocket depth (PD) and bleeding on probing (BOP) were assessed at baseline and months 1, 2, 4, 5, 6, 8 and 9.

RESULTS

Treatment with either DH or SRP resulted in significant statistical and clinical improvements in CAL, PD and BOP. These clinical outcomes were equivalent regardless of the extent of subgingival calculus present at baseline.

CONCLUSIONS

The results indicate that the primary clinical effects of these therapies are the result of a disruption and reduction of the subgingival plaque and not the effect of the removal of subgingival calculus and contaminated cementum.

Subantimicrobial dose doxycycline as an adjunct to scaling and root planing: post-treatment effects

BACKGROUND/OBJECTIVE

Subantimicrobial dose doxycycline (SDD 20 mg bid) plus scaling and root planing (SRP) significantly improved clinical attachment level (CAL) and reduced probing depth (PD) compared with placebo plus SRP in a double-blind, placebo-controlled, multicenter study of patients with adult periodontitis (AP). In a study conducted as a follow-up, the post-treatment effects of SDD were assessed in patients who completed the SRP study.

METHODS

The SRP study was a 9-month, active-treatment study and the follow-up was a 3-month, no-treatment study. In the SRP study, tooth sites in qualifying quadrants were scaled and root planed and patients were randomized to receive twice daily SDD 20 mg or placebo. In the follow-up, patients received no study drug; investigators and patients remained blinded to the previous treatment group assignments. Efficacy measures included the change in CAL and PD from baseline values determined at the start of the SRP study in tooth sites stratified by baseline PD (i.e., 0-3 mm, 4-6 mm, > or =7 mm). Safety was evaluated using adverse event data and the results of clinical laboratory tests, oral pathology examinations, and microbiological assessments.

RESULTS

Within each disease stratum, the incremental improvements in PD and CAL demonstrated in the SDD group over 9 months of active treatment were maintained through 3 additional months of no treatment. Treatment cessation did not result in an accelerated regression of periodontal health. No differences in the incidence of adverse events (including those related to infection) or laboratory or microbiological parameters were noted between the SDD group and the placebo group.

CONCLUSIONS

The administration of SDD 20 mg bid for a period of up to 9 months is not associated with rebound effects or delayed or negative after-effects for a 3-month period after cessation of therapy.

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.

Efficacy of subantimicrobial dosing with doxycycline. Point/counterpoint

BACKGROUND

This article addresses the role of subantimicrobial dosing with doxycycline, or SDD, in the treatment of chronic periodontitis. The authors discuss and debate 10 issues with regard to SDD's utility as an adjunct to scaling and root planing.

TYPES OF STUDIES REVIEWED

The authors reviewed reports of controlled clinical trials that assessed the efficacy of SDD. The main focus of this article is data from the U.S. Food and Drug Administration's phase 3 clinical trial that evaluated the efficacy of SDD in terms of alterations of probing depth, clinical attachment levels and disease progression.

RESULTS

The authors compared data from test groups, which underwent root planing plus SDD, with data from control groups, which underwent root planing alone. The mean data suggest that SDD provides a defined but limited improvement of periodontal status when used in conjunction with scaling and root planing. Furthermore, several in vivo studies indicated that a nine-month course of SDD did not cause development of drug-resistant bacterial strains or alteration of the subgingival microbiota.

CLINICAL IMPLICATIONS

Some patients may benefit from SDD. However, there are several issues that should be clarified before widespread use of SDD is recommended for patients with chronic periodontitis. The evidence indicates that suppression of the bacterial challenge, which reduces the host response, is the most efficient way to control periodontal diseases.

The clinical and microbiological effects of systemic ornidazole in sites with and without subgingival debridement in early-onset periodontitis patients

BACKGROUND

The purpose of this study was to evaluate the clinical and microbiological effects of systemic ornidazole (ORN) in sites with or without subgingival debridement in early-onset periodontitis (EOP) patients.

METHODS

Two pooled bacterial samples consisting of 4 sites each (scaled and non-scaled sites) were obtained from 30 individuals exhibiting EOP. All patients received oral hygiene instruction (OHI), supragingival scaling and ORN. Subgingival scaling and root planing (SRP) was carried out only in scaled sites. Bacterial samples were taken at baseline (BL) and 1 week and 2, 6, and 12 months after systemic ornidazole administration (500 mg/bid for 7 days). One more sample was taken at scaled sites, one week after SRP.

RESULTS

One week following SRP (scaled sites) Gram-negative facultative and anaerobic rods were significantly reduced while Gram-positive facultative cocci were significantly increased. After ORN administration, P. gingivalis, P. denticola, P. intermedia, B. forsythus, C. rectus, and S. sputigena were no longer detectable in either scaled or non-scaled sites. A statistically significant long-term (2, 6, and 12 months) reduction of P. gingivalis, P. intermedia, P. loescheii, B. forsythus, and C. rectus and a pronounced increase of S. milleri, S. oralis, and S. sanguis counts in both scaled and non-scaled sites were detected in comparison to baseline. A sustained reduction of bleeding tendency and of probing depth was also observed in both scaled and non-scaled sites.

CONCLUSIONS

ORN combined with SRP effects beneficial shifts in the bacterial population associated with substantial clinical improvement, thereby indicating that ORN is effective adjunct in the treatment of EOP deep periodontal pockets where anaerobic bacteria are predominant.

Long-term treatment with subantimicrobial dose doxycycline exerts no antibacterial effect on the subgingival microflora associated with adult periodontitis

BACKGROUND

The purpose of this study was to determine whether treatment with subantimicrobial dose doxycycline (SDD), 20 mg bid, exerted an antimicrobial effect on the microflora associated with adult periodontitis.

METHODS

Following the approval of the protocol and informed consent forms by the respective IRBs at the University of Florida and West Virginia University, 76 subjects with adult periodontitis were entered and randomly assigned to receive SDD or placebo. A split-mouth design was utilized, with each subject receiving subgingival scaling and root planing (SRP) in two quadrants immediately following baseline data collection, while the remaining two quadrants were left unscaled (non-SRP). Microbial samples were collected prior to treatment, after 3, 6, and 9 months of treatment, and after 3 months of no treatment. The samples were examined by microscopy and by enumeration on selective and non-selective media.

RESULTS

All treatments resulted in statistically significant decreases in the proportions of spirochetes and motile rods (P <0.05) and in an increase in the proportion of coccoid forms (P <0.0001) relative to baseline. No between-treatment differences were detected between the SDD and placebo treatments in either the SRP or non-SRP design, with the exception of the small and large spirochetal groups. The spirochetal proportions present in the SDD group were significantly lower (P<0.05) than the paired placebo group during the 9-month treatment and was preceded by a significant decrease (P<0.01) in the proportion of microbiologic sample sites that bled on probing. No between- treatment differences were detected in any of the other microbial parameters.

CONCLUSION

The microbial differences observed were attributed to the anticollagenase and anti-inflammatory properties of SDD and not to an antimicrobial effect.

Long-term use of subantimicrobial dose doxycycline does not lead to changes in antimicrobial susceptibility

BACKGROUND

Adjunctive subantimicrobial dose doxycycline (SDD) with scaling and root planing leads to improved clinical parameters of adult periodontitis, but has raised questions about potential changes in antibiotic susceptibility of the host microflora. Our four studies assessed whether long-term SDD changes antibiotic susceptibility of the oral microflora in adults with periodontitis.

METHODS

In studies 1 and 2, adult patients with periodontitis were randomized to receive SDD 10 mg qd, 20 mg qd, 20 mg bid, or placebo. In study 3, patients were randomized to receive SDD 20 mg bid or placebo. No medication was administered in study 4, a follow-up to study 3. Subgingival plaque samples were collected at baseline (all studies) and at 12, 15 to 18, and 24 months (study 1); 12, 18, and 27 months (study 2); 3, 6, and 9 months (study 3); and 3 months post-study 3 (study 4). Antimicrobial susceptibility of isolated bacteria was assessed by: 1) minimum inhibitory concentration (MIC) levels (studies 1 and 2); 2) cross-resistance to non-tetracycline antibiotics (studies 2 and 3); and 3) the proportion of doxycycline-resistant isolates (studies 3 and 4).

RESULTS

Organism MIC levels remained constant among all treatment groups at 18 and 24 months compared with baseline (study 1). Observed changes in susceptibility at 12 and 18 months for the 20 mg groups were attributed to the limited number of isolates tested (study 1). There were no statistically significant differences in the proportion of doxycycline-resistant isolates among treatment groups (studies 3 and 4), and no evidence of multi-antibiotic resistance (studies 3 and 4) or cross-resistance (studies 2 and 3) at any timepoint.

CONCLUSION

Long-term SDD does not contribute to changes in antibiotic susceptibility.

The effects of sustained release doxycycline on the anaerobic flora and antibiotic-resistant patterns in subgingival plaque and saliva

BACKGROUND

The purpose of this study was to determine the effects of periodontal treatment with a sustained-release, biodegradable gel containing 8.5% doxycycline on the anaerobic flora and on antibiotic susceptibility patterns associated with subgingival plaque and saliva.

METHODS

Forty-five subjects with adult periodontitis were entered into a parallel design, single-blind study of 6 months' duration. The subjects were randomized to receive either doxycycline treatment (n = 23) or oral hygiene instruction/reinforcement (n = 22). Saliva and subgingival plaque samples were collected prior to and at 7, 21, 91, and 182 days after initiation of treatment. The proportion of the cultivable flora resistant to 10 microg doxycycline/ml was determined relative to total anaerobic counts, and the 3 most predominant colony types resistant to doxycycline were individually enumerated. A representative of each was subcultured, identified to genus and species level, and tested for its susceptibilities to 6 antibiotics.

RESULTS

A significant decrease (P <0.01) in total anaerobic counts following doxycycline treatment caused a transient increase in the proportion, but not in the actual counts, of doxycycline-resistant bacteria recovered from both plaque and saliva at 7 and 21 days but not at 91 or 182 days. The same doxycycline-resistant taxa were recovered at all sample periods including baseline. Regardless of treatment, the isolates were similarly distributed and belonged to the same bacterial groups.

CONCLUSIONS

Doxycycline treatment significantly reduced the anaerobic population in plaque but did not result in a change in either the number of resistant bacteria present or the acquisition of antibiotic resistance.

The antimicrobial treatment of periodontal disease: changing the treatment paradigm

Over the last 100 years, methods of surgical periodontal treatment have enjoyed a history of success in improving oral health. The paradigm of care is based on the "non-specific plaque hypothesis"--that is, the overgrowth of bacterial plaques cause periodontal disease, and the suppression of this overgrowth reduces disease risk. The central feature of this approach to care is the removal of inflamed gingival tissue around the teeth to reduce periodontal pocket depth, thereby facilitating plaque removal by the dentist and by the patient at home. Over the last 30 years, with the recognition that periodontal disease(s) is caused by specific bacteria and that specific antimicrobial agents can reduce or eliminate the infection, a second paradigm has developed. This new paradigm, the "specific plaque hypothesis", focuses on reducing the specific bacteria that cause periodontal attachment loss. The contrast between the two paradigms can be succinctly stated as follows: The antimicrobial therapy reduces the cause, while the surgical therapy reduces the result of the periodontal infection. The specific plaque hypothesis has two important implications. First, with the increasing attention to evidence-based models for prevention, treatment, outcome assessment, and reimbursement of care, increasing attention and financial effort will be channeled into effective preventive and treatment methods. Second, the recent observations that periodontal infections increase the risk of specific systemic health problems, such as cardiovascular disease, argue for the prevention and elimination of these periodontal infections. This review highlights some of the evidence for the specific plaque hypothesis, and the questions that should be addressed if antimicrobial agents are to be used responsively and effectively.

Treatment with subantimicrobial dose doxycycline improves the efficacy of scaling and root planing in patients with adult periodontitis

BACKGROUND

In a previous study, subantimicrobial dose doxycycline (SDD) significantly improved clinical parameters associated with periodontal health in patients with adult periodontitis (AP) when used as an adjunct to a maintenance schedule of supragingival scaling and dental prophylaxis. In this double-blind, placebo-controlled, parallel-group, multicenter study, the efficacy and safety of SDD were evaluated in conjunction with scaling and root planing (SRP) in patients with AP.

METHODS

Patients (n = 190) received SRP at the baseline visit and were randomized to receive either SDD 20 mg bid or placebo bid for 9 months. Efficacy parameters included the per-patient mean changes in clinical attachment level (CAL) and probing depth (PD) from baseline, the per-patient percentages of tooth sites with attachment loss (AL) > or = 2 mm and > or = 3 mm from baseline, and the per-patient percentage of tooth sites with bleeding on probing. Prior to analysis, tooth sites were stratified by the degree of disease severity evident at baseline

RESULTS

In tooth sites with mild to moderate disease and severe disease (n = 183, intent-to-treat population), improvements in CAL and PD were significantly greater with adjunctive SDD than with adjunctive placebo at 3, 6, and 9 months (all P <0.05). In tooth sites with severe disease, the per-patient percentage of sites with AL > or = 2 mm from baseline to month 9 was significantly lower with adjunctive SDD than with adjunctive placebo (P<0.05). Improvements in clinical outcomes occurred without detrimental shifts in the normal periodontal flora or the acquisition of doxycycline resistance or multiantibiotic resistance. SDD was well tolerated, with a low incidence of discontinuations due to adverse events.

CONCLUSIONS

The adjunctive use of SDD with SRP is more effective than SRP alone and may represent a new approach in the long-term management of AP.

Fluoroquinolones in the treatment of Actinobacillus actinomycetemcomitans-associated periodontitis

BACKGROUND

Periodontitis patients harboring Actinobacillus actinmycetemcomitans (Aa) are prime candidates for systemic antibiotic therapy. Besides tetracycline and the combination of metronidazole and amoxicillin the fluoroquinolones are also believed to have antibacterial activity against Aa. The aim of the present study was to evaluate systemic ofloxacin therapy as adjunct to flap surgery.

METHODS

Twenty-five adult periodontitis patients with subgingival detection of Aa were treated with 2x200 mg/d ofloxacin for 5 days as adjunct to open flap surgery (test). Another 10 patients received only flap surgery (control). Probing depth (PD) and clinical attachment level (CAL) was recorded and subgingival plaque samples were cultivated on TSBV agar for detection of Aa at baseline as well as 3 and 12 months following therapy.

RESULTS

At 3 and 12 months following therapy mean PD at monitored sites in the test group changed from 6.8 mm (+/-1.3) to 3.6 mm (+/-1.0), 3.8 mm (+/-1.1) and CAL from 7.5 mm (+/-1.4) to 5.4 mm (+/-1.4), 5.5 mm (+/-1.3). In the control group PD changed from 6.5 mm (+/-0.7) to 4.0 mm (+/-1.7), 4.1 mm (+/-1.6) and CAL from 7.5 mm (+/-1.0) to 6.3 mm (+/-1.7), 6.4 mm (+/-1.8). P was <0.05 for CAL between groups. Three and 12 months following adjunctive systemic ofloxacin therapy, Aa was suppressed below detectable levels in 22 of 22, test patients, whereas Aa could not be recovered in only 2 of the 10 controls. (P<0.0001).

CONCLUSIONS

Systemic ofloxacin as adjunct to open flap surgery is able to suppress A. actinomycetemcomitans below detectable level in patients harboring this organism at baseline.

Heterogeneity of Actinobacillus actinomycetemcomitans strains in various human infections and relationships between serotype, genotype, and antimicrobial susceptibility

Actinobacillus actinomycetemcomitans, an oral pathogen, only occasionally causes nonoral infections. In this study 52 A. actinomycetemcomitans strains from 51 subjects with nonoral infections were serotyped and genotyped by arbitrarily primed PCR (AP-PCR) to determine whether a certain clone(s) is specifically associated with nonoral infections or particular in vitro antimicrobial susceptibility patterns. The promoter structure of leukotoxin genes was additionally investigated to find the deletion characteristic of highly leukotoxic A. actinomycetemcomitans strains. The nonoral A. actinomycetemcomitans strains included all five known serotypes and nonserotypeable strains, the most common serotypes being b (40%) and c (31%). AP-PCR distinguished 10 different genotypes. A. actinomycetemcomitans serotype b strains were more frequently found in blood samples of patients with bacteremia or endocarditis than in patients with focal infections. One AP-PCR genotype was significantly more frequently found among strains originating in focal infections than in blood samples. Resistance to benzylpenicillin was significantly more frequent among A. actinomycetemcomitans serotype b strains than among strains of other serotypes. No differences in the leukotoxin gene promoter region or benzylpenicillin resistance between nonoral and oral A. actinomycetemcomitans strains were observed. Nonoral A. actinomycetemcomitans strains showed great similarity to the oral strains, confirming that the oral cavity is the likely source of nonoral A. actinomycetemcomitans infections. The predominance of serotype b strains in endocarditis and bacteremia supports the hypothesis of a relationship between certain A. actinomycetemcomitans clones and some nonoral infections. The mechanisms behind the exceptionally high rate of occurrence of benzylpenicillin resistance among A. actinomycetemcomitans serotype b strains are to be elucidated in further studies.

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.

Resistance profile survey of 50 periodontal strains of Actinobacillus actinomyectomcomitans

BACKGROUND

Antibiotic resistance has been increasingly described among bacterial species colonizing periodontal pockets, particularly in Prevotella and Porphyromonas spp. strains producing beta-lactamases, and frequently associated with resistance to tetracycline and erythromycin. These resistance genes may be carried on motile genetic elements, or transposons, capable of interspecies and intergeneric transmission among bacterial strains colonizing a same ecological niche. The aim of this prospective study was to determine the resistance profile of Actinobacillus actinomycetemcomitans and the prevalence of A. actinomycetemcomitans strains producing beta-lactamases in periodontal pockets.

METHODS

Fifty strains of A. actinomycetemcomitans were isolated from 42 patients with adult periodontitis. No patient had periodontal or antibiotic therapy in the previous 6 months. Bacterial samples were collected from periodontal pockets > or =5 mm, appropriately diluted, inoculated onto selective medium (chocolate blood agar with bacitracin 75 microg/ml and vancomycin 5 microm/ml) and incubated for 5 days at 37 degrees C in air with 5% CO2. After conventional identification, susceptibility testing to 11 antibiotics was performed by the broth dilution method, in trypticase soy broth supplemented with yeast extract, hemin, and 0.1% NaHCO3 to maintain microaerophilic conditions in the microtitration plate wells by CO2 formation.

RESULTS

No strain demonstrated resistance to amoxicillin, amoxicillin-clavulanic acid combination, pristinamycin, or ciprofloxacin at the breakpoint, but 40% of the strains were slightly resistant to penicillin G, and 4% were resistant to erythromycin, 90% to spiramycin, 18% to clarythromycin, 4% to tetracycline, 72% to metronidazole, and 12% to ornidazole. Amoxicillin, followed by tetracycline and erythromycin, was the most effective antibiotic on A. actinomycetemcomitans. The phenotypic research of a beta-lactamase was negative for all the strains tested.

CONCLUSIONS

In this work, most A. actinomycetemcomitans strains were resistant to metronidazole, but the amoxicillin-metronidazole association may be of interest against subgingival anaerobic and capnophilic mixed flora. Pristinamycin and ciprofloxacin appeared as effective alternative monotherapies against A. actinomycetemcomitans. The threat of beta-lactam antibiotic resistance related to beta-lactamase production is currently not a problem with A. actinomycetemcomitans as it has been reported in oral anaerobes.

Longitudinal effect of non-surgical treatment and systemic metronidazole for 1 week in smokers and non-smokers with refractory periodontitis: a 5-year study

BACKGROUND

Periodontitis consists of a mixture of diseases, most of which respond favorably to traditional mechanical therapy. It is now recognized that advanced periodontitis does not always respond to conventional management with scaling, periodontal surgery, and oral hygiene measures. However, various types of antibiotics given systemically or locally improve the success rate of periodontal therapy. In short-term studies, it has been shown that metronidazole, when systemically administered after debridement, resulted in treatment benefits including less need for surgical intervention.

METHODS

In this double-blind study, we evaluated periodontal treatment involving initial non-surgical treatment, systemic administration of metronidazole for 1 week, and then follow-ups for scaling and root planing every 6 months, for 5 years. The study population consisted of 64 subjects (37 smokers and 27 non-smokers), mean age 36.3 (+/-3.0 SD) years, with severe periodontal disease. After initial scaling and root planing, patients were randomly assigned to the intervention or placebo groups: 400 mg metronidazole or a placebo administered at 8-hour intervals for 1 week. The participants underwent an extensive clinical periodontal examination. Gingival crevicular fluid (GCF) was analyzed for spirochetes and granulocytes. Samples were cultured for Actinobacillus actinomycetemcomitans (A.a.), Porphyromonas gingivalis (Pg.), and Prevotella intermedia (Pi.).

RESULTS

The number of patients infected with A.a., Pg., Pi., and spirochetes decreased during the study. Most patients who harbored spirochetes at the end of the study had these microorganisms at the beginning. Smokers responded less favorably to periodontal therapy than non-smokers. Non-smoking patients who required only non-surgical therapy in the intervention group showed statistically significant improvement in the clinical parameters after 5 years. Patients with complete healing, defined as the absence of inflamed sites > or =5 mm, after 5 years were found only in the intervention group. The patients considered healthy after 5 years were the same patients found to be healthy after 6 months.

CONCLUSIONS

Decisive factors in the sustained long-term improvement of patients who respond satisfactorily to treatment are probably initial scaling and root planing; a brief course of metronidazole; and regular follow-up examinations at 6-month intervals for oral hygiene and scaling and root planing.

A six-month comparison of three periodontal local antimicrobial therapies in persistent periodontal pockets

BACKGROUND

Currently, several local antimicrobial delivery systems are available to periodontists. The aim of this 6-month follow-up parallel study was to evaluate the efficacy of three commercially available local delivery systems as adjuncts to scaling and root planing in the treatment of sites with persistent periodontal lesions.

METHODS

Seventy-nine patients with 4 pockets > or = 5 mm and bleeding on probing and/or suppuration were randomized into 4 treatment groups which included: scaling and root planing alone (S) (20 patients), or in conjunction with the application of 25% tetracycline fibers (S+Tet) (19 patients), or 2% minocycline gel (S+Min) (21 patients), or 25% metronidazole gel (S+Met) (19 patients). Clinical measurements were taken at baseline, 6 weeks, 3 months, and 6 months after antimicrobial application. Treatments were applied using the distributors' recommended protocols.

RESULTS

All 4 therapies resulted in significant improvements from baseline in probing depth, attachment level, bleeding on probing, and the Modified Gingival Index (MGI) scores. The improvements in clinical parameters were greater in all 3 adjunctive treatment groups than scaling and root planing alone. The mean probing depth reductions at 6 months were: scaling + tetracycline = 1.38 mm; scaling + metronidazole = 0.93 mm; scaling + minocycline = 1.10 mm; and scaling alone = 0.71 mm. The probing depth reduction at all time points was significantly greater in the scaling plus tetracycline fiber group than the scaling and root planing alone group (P<0.01). There was also a significant improvement for scaling plus tetracycline fiber application over scaling and metronidazole at both 6 weeks and 3 months, although this did not remain significant at the 6-month visit. While the frequency of sites with suppuration was markedly reduced following all antimicrobial treatments, the most effective reductions were seen in the scaling plus tetracycline fiber group, followed by the minocycline group.

CONCLUSIONS

Although all 3 locally applied antimicrobial systems seem to offer some benefit over scaling and root planing alone, a treatment regimen of scaling and root planing plus tetracycline fiber placement gave the greatest reduction in probing depth over the 6 months after treatment.

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.

The use of locally delivered doxycycline in the treatment of periodontitis. Clinical results

The clinical safety and effectiveness of a subgingivally delivered biodegradable drug delivery system containing doxycycline hyclate (DH) has been evaluated in 3 large 9-month multicenter randomized parallel-design controlled clinical trials. A total of 1002 patients having at least 2 quadrants with a minimum of 4 qualifying pockets > or = 5 mm that bled on probing were enrolled. Each subject had > or = 7 mm probing depths in 2 of the qualifying pockets. Study 1 (n=180) compared DH to sanguinarine chloride (SC) and vehicle control (VC). Study 2 (n=411) and study 3 (n=411) compared DH to VC, scaling and root planing (SRP), and oral hygiene (OH). Clinical measurements included probing depth reduction (PDR), attachment level gain (ALG), bleeding on probing reduction (BOP) and plaque index (PI). Analysis of efficacy data from these 3 trials show all treatments gave significant positive clinical changes from baseline at most time points. Study 1 results indicate that DH was superior to SC and VC in PDR at all time points. Similar results were obtained for ALG when DH was compared to SC and VC. For BOP reductions, DH was superior to VC at all time points and to SC at months 5 through 9. For DH, mean ALG in deep (> or = 7 mm) pockets was 1.4 mm; mean PDR for DH was 2.6 mm. For moderate (5 to 6 mm) pockets, ALG was 0.8 mm and PDR 1.5 mm. Studies 2 and 3 reported mean month 9 ALG for SRP as 0.7 mm and 0.8 mm, respectively. For DH, ALG was 0.8 mm in both studies 2 and 3. At month 9 in studies 2 and 3, 29% and 31% of DH sites and 27% and 34% of SRP sites showed ALG > or = 2 mm. Probing depth reductions followed the same pattern, with 32% of DH sites and 32% of SRP sites showing > or = 2 mm PD reductions in study 2, and 41% of DH and 43% of SRP sites showing PDR of > or = 2 mm in study 3. Comparisons between DH, VC, and OH treatment groups in studies 2 and 3 showed DH treatment was statistically superior to VC and OH at most time points. Results of these 3 large clinical trials demonstrate that treatment of periodontitis with 10% doxycyline hyclate in a bioabsorbable delivery system is equally as effective as SRP and superior in effect to VC and OH in reducing the clinical signs of adult periodontitis.

Local delivery of tetracycline: from concept to clinical application

This manuscript reviews the development over the last 20 years of the evidence supporting the clinical application of a controlled delivery device for the treatment of human periodontitis. The device is a monolithic ethylene vinyl-acetate fibre loaded with 25% w/w tetracycline HCI (tetracycline fibre). It releases tetracycline at a steady state rate of 2 microg/cm x h and results in the maintenance of essentially constant, highly-effective concentrations of tetracycline at the site of action. A series of controlled, randomised, single-blind, phase-III clinical trials including a total of 463 patients has indicated that: (1) tetracycline fibres result in significantly better outcomes than the scaling and root planing positive control; (2) combination of tetracycline fibres with subgingival mechanical debridement results in significant improvement over debridement alone. Evidence from these studies has led to approval of this treatment modality by the US Food and Drug Administration and by the European Union Regulatory Bodies. A clinical usage study involving 2711 subjects treated by 68 clinicians in Europe and North America indicated that the magnitude of the observed clinical outcomes is clinically relevant and that adverse events were rarely observed. A variety of clinical investigations aimed at the optimal incorporation of tetracycline fibres in a treatment strategy provide guidance in case selection. Cost of therapy and concerns of unnecessary usage of antibiotics should be considered. It is nonetheless concluded that combination of tetracycline fibres with mechanical debridement represents a documented treatment alternative, the application of which may offer clinical benefits to many patients.

The use of locally delivered metronidazole in the treatment of periodontitis. Clinical results

Local delivery of antimicrobials has been investigated as a possible method for controlling and treating periodontal disease. A number of antimicrobial agents have been studied both as adjunctive therapies with scaling and root planing and as stand-alone chemotherapies. More recent investigations have focussed on the delivery of antimicrobials in sustained-release formulations designed to maintain effective concentrations of drug within the periodontal pocket. This article provides an overview of the development of the use of locally-delivered metronidazole in periodontal therapy and the current state-of-the-art of the technique. It is concluded that treatment with local delivery of metronidazole seems to be as effective as scaling and root planing in untreated as well as in recall subjects. However, there are reasons to suggest that local delivery of metronidazole should not be used as a substitute for conventional treatment of periodontal disease, since side-effects of long-term use and repeated use are not known. The antibiotic regimen should preferably be used as an adjunct to surgical and non-surgical therapy.

Local metronidazole application in maintenance patients. Clinical and microbiological evaluation

The purpose of this investigation was to evaluate the clinical and microbiological effect of local antibiotic therapy in comparison with subgingival scaling and root planing in a randomized semi-masked study. Forty-six recall patients who completed systematic periodontal therapy 6 to 24 months prior to the study were enrolled. The inclusion requirements were at least one site with probing depth > or = 5 mm in each quadrant, no scaling, and no antibiotic therapy during the last 6 months. After randomization each patient received 2 different treatments: in 2 quadrants metronidazole 25% dental gel was applied subgingivally to the pockets at day 0 and day 7; scaling and root planing was carried out in the 2 other quadrants, one at day 0 and in the remaining quadrant at day 7. Subgingival microbiological samples were taken from each patient before treatment and on days 21, 91, and 175 after the treatment. The analyses were carried out by indirect immunofluorescence assay. At all treated sites probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) were recorded on days 0, 21, 91, and 175. Both treatments resulted in PD reduction and CAL gain. PD reduction was statistically significant (P < 0.01) for both treatment modalities after 6 months. The CAL gain was not significant for either treatment. There was no statistical significance between scaling and antibiotic therapy. Treponema denticola, Porphyromonas gingivalis, and Prevotella intermedia were significantly reduced after therapy; however, there were no statistically significant differences between treatments. If Actinobacillus actinomycetemcomitans was present before therapy, it was also present after treatment in both groups. The conclusion is that, in recall patients, local application of metronidazole and scaling and root planing showed similar clinical and microbiological effects without statistically significant differences.

Tetracycline and its analogues: a therapeutic paradigm in periodontal diseases

This article discusses the use of tetracyclines in the clinical management of periodontal infections. A review of the drugs pharmacology, pharmacokinetics, and potential adverse effects shows that they are relatively safe if used in appropriate dosages and under controlled conditions. Current data suggest that the routine use of tetracyclines in conjunction with the treatment of periodontitis is unnecessary. However, their distinctive characteristics can be utilized in different delivery systems as an adjunctive aid to conventional treatment of juvenile and refractory forms of periodontitis.

Comparison of broth microdilution method using Haemophilus test medium and agar dilution method for susceptibility testing of Eikenella corrodens

Susceptibility testing of Eikenella corrodens is usually performed by a Mueller-Hinton sheep blood agar dilution (AD) method. However, this method is impractical for testing only a few strains. We compared AD with the broth microdilution method using Haemophilus test medium (HTM) in order to determine the susceptibility of 36 clinical isolates of E. corrodens to eight antimicrobial agents. MICs obtained by the HTM method yielded 95.5 and 84% agreement (within 2 and 1 log2 dilutions, respectively) with those obtained by AD. The HTM method with incubation in CO2 for 48 h was highly reproducible and constitutes an easy alternative for antimicrobial susceptibility testing of E. corrodens.