title: Microbiological changes associated with four different periodontal therapies for the treatment of chronic periodontitis.
abstract: OBJECTIVE
  To examine subgingival microbiological changes in chronic periodontitis subjects receiving scaling and root planing (SRP) alone or with systemically administered azithromycin, metronidazole or a sub-antimicrobial dose of doxycycline.
  
  
  METHODS
  Ninety-two periodontitis subjects were randomly assigned to receive SRP alone or combined with azithromycin, metronidazole or sub-antimicrobial dose doxycycline. Subgingival plaque samples taken at baseline, 2 weeks, and 3, 6, and 12 months were analyzed for 40 bacterial species using checkerboard DNA-DNA hybridization. Percentage of resistant species and percentage of sites harboring species resistant to the test antibiotics were determined at each time-point.
  
  
  RESULTS
  All treatments reduced counts of red complex species at 12 months, although no significant differences were detected among treatment groups for most species at all time-points. Both antibiotics significantly reduced counts of red complex species by 2 weeks. Percentage of resistant isolates increased in plaque samples in all adjunctive treatment groups, peaking at the end of administration, but returned to pretreatment levels by 12 months.
  
  
  CONCLUSIONS
  The significant reduction of red and orange complex species at 2 weeks in the subjects receiving SRP plus azithromycin or metronidazole may have contributed to a better clinical response in these treatment groups. Therapy did not appear to create lasting changes in the percentage of resistant isolates or sites harboring resistant species.
authors.affiliation: Department of Periodontology, The Forsyth Institute, Boston, MA 02115, USA. ahaffajee@forsyth.org
authors.forename: A D
authors.initials: AD
authors.lastname: Haffajee
authors.forename: M
authors.initials: M
authors.lastname: Patel
authors.forename: S S
authors.initials: SS
authors.lastname: Socransky
mesh_terms: D000328:Adult; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D017963:Azithromycin / Q000627:therapeutic use; D002908:Chronic Disease; D003773:Dental Plaque / Q000382:microbiology*; D012534:Dental Scaling; D004318:Doxycycline / Q000627:therapeutic use; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use; D008875:Middle Aged; D010518:Periodontitis / Q000628:therapy*; D016037:Single-Blind Method
chemical_list: D000890:Anti-Infective Agents; D008795:Metronidazole; D017963:Azithromycin; D004318:Doxycycline