title: Change of antibiotic susceptibility following periodontal therapy. A pilot study in aggressive periodontal disease.
abstract: BACKGROUND
  The hypothesis was tested that bacterial susceptibilities in aggressive periodontitis change upon administration of systemic antibiotics as adjuncts to periodontal therapy.
  
  
  METHODS
  In 23 subjects (average age 38.9+/-6.7 years) with aggressive periodontitis, microbial parameters were assessed prior to and 1 year after completion of comprehensive mechanical/surgical and systemic antimicrobial therapy. Following identification of five selected pathogens with the Rapid ID 32 A system, their susceptibilities towards amoxicillin/clavulanate potassium, metronidazole, and tetracycline were examined with the E-test. Antibiotics were administered according to the test results, and the minimal inhibitory concentrations (MIC90) were reevaluated after 1 year. Statistical analysis was performed on a patient basis, with the site data used for evaluation of the MIC levels.
  
  
  RESULTS
  Bacterial MIC levels remained constant among the three antibiotic treatment groups compared with baseline. Mean MIC90 values ranged from <0.02 to 0.11 microg/ml (amoxicillin/clavulanate potassium), <0.02 to 0.27 microg/ml (metronidazole), and <0.02 to 0.11 microg/ml (tetracycline). Observed changes in susceptibility were attributed to the elimination of single bacterial taxa in the subgingival environment after antibiotic therapy. There were no statistically significant differences in clinical parameters among the treatment groups. Single tetracycline MICs were 1.5- to 6-fold enhanced compared to amoxicillin/clavulanate potassium and metronidazole.
  
  
  CONCLUSIONS
  The periodontal pathogens investigated prior to and 1 year after periodontal therapy are tested sensitive to the antimicrobial agents. In aggressive periodontitis, changes in bacterial susceptibility upon the administration of systemic antibiotics are associated with the limited number of isolates tested following therapy.
authors.affiliation: Department of Periodontology and Oral Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA. rainer_buchmann@yahoo.de
authors.forename: Rainer
authors.initials: R
authors.lastname: Buchmann
authors.forename: Rüdiger F
authors.initials: RF
authors.lastname: Müller
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Van Dyke
authors.forename: Dieter E
authors.initials: DE
authors.lastname: Lange
mesh_terms: D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D003773:Dental Plaque / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010510:Periodontal Diseases / Q000188:drug therapy* / Q000382:microbiology; D010518:Periodontitis / Q000188:drug therapy / Q000382:microbiology; D010865:Pilot Projects; D018709:Statistics, Nonparametric; D013752:Tetracycline / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D008795:Metronidazole; D019980:Amoxicillin-Potassium Clavulanate Combination; D013752:Tetracycline