title: PCR monitoring for tetracycline resistance genes in subgingival plaque following site-specific periodontal therapy. A preliminary report.
abstract: BACKGROUND
  The selection of antibiotic resistance genes during antibiotic therapy is a critical problem complicated by the transmission of resistance genes to previously sensitive strains via conjugative plasmids and transposons and by the transfer of resistance genes between gram-positive and gram-negative bacteria. The purpose of this investigation was to monitor the presence of selected tetracycline resistance genes in subgingival plaque during site specific tetracycline fiber therapy in 10 patients with adult periodontitis.
  
  
  METHODS
  The polymerase chain reaction (PCR) was used in separate tests for the presence of 3 tetracycline resistance genes (tetM, tetO and tetQ) in DNA purified from subgingival plaque samples. Samples were collected at baseline, i.e., immediately prior to treatment, and at 2 weeks, and 1, 3, and 6 months post-fiber placement. The baseline and 6-month samples were also subjected to DNA hybridization tests for the presence of 8 putative periodontal pathogenic bacteria.
  
  
  RESULTS
  PCR analysis for the tetM resistance gene showed little or no change in 5 patients and a decrease in detectability in the remaining 5 patients over the 6 months following tetracycline fiber placement. The results for tetO and tetQ were variable showing either no change in detectability from baseline through the 6-month sampling interval or a slight increase in detectability over time in 4 of the 10 patients. DNA hybridization analysis showed reductions to unmeasurable levels of the putative periodontal pathogenic bacteria in all but 2 of the 10 patients.
  
  
  CONCLUSIONS
  These results complement earlier studies of tet resistance and demonstrate the efficacy of PCR monitoring for the appearance of specific resistance genes during and after antibiotic therapy.
authors.affiliation: Department of Oral Biology, School of Dentistry, University of Missouri-Kansas City 64108, USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Manch-Citron
authors.forename: G H
authors.initials: GH
authors.lastname: Lopez
authors.forename: A
authors.initials: A
authors.lastname: Dey
authors.forename: J W
authors.initials: JW
authors.lastname: Rapley
authors.forename: S R
authors.initials: SR
authors.lastname: MacNeill
authors.forename: C M
authors.initials: CM
authors.lastname: Cobb
mesh_terms: D000328:Adult; D001483:Base Sequence; D002482:Cellulose / Q000037:antagonists & inhibitors*; D015342:DNA Probes; D004269:DNA, Bacterial / Q000235:genetics; D003773:Dental Plaque / Q000188:drug therapy / Q000235:genetics* / Q000382:microbiology; D016503:Drug Delivery Systems; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics*; D005881:Gingiva; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010518:Periodontitis / Q000188:drug therapy / Q000235:genetics* / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000706:statistics & numerical data; D017422:Sequence Analysis, DNA; D013752:Tetracycline / Q000037:antagonists & inhibitors*; D013753:Tetracycline Resistance / Q000235:genetics*; D013997:Time Factors
chemical_list: C116585:Actisite; D015342:DNA Probes; D004269:DNA, Bacterial; D002482:Cellulose; D013752:Tetracycline