ANTIBIOTIC THERAPY IN TREATING PERIODONTAL DISEASES

理想情况下，设计用于控制致病性口腔微生物的疗法将抑制或消灭这些微生物，留下一个稳定的与宿主相容的微生物群。然而，有时，试图消除牙周病原体会导致微生物群发生不希望的变化。其中最明显的两个是口腔微生物群中不常见的大量致病性物种的过度生长和抗生素耐药物种的出现。本项目将关注治疗的安全性，特别是用于控制牙周感染的抗生素治疗。当前的目标是确定抗生素治疗对牙周微生物群的组成和抗生素耐药性的影响。第一个目的是确定抗生素治疗如何通过使用棋盘杂交监测120种细菌的水平来改变龈下微生物群的组成。将在基线、治疗完成时和治疗后1年对24名受试者进行龈下菌斑样本的检查，这些受试者分别接受刮治和根刨（SCR）、SCR加局部四环素或SCR加全身阿莫西林和甲硝唑治疗。第二个目标将确定抗生素治疗如何影响菌斑细菌的抗生素耐药性基因型和表型。在目标1中描述的三组中的12名受试者将在每个时间点选择60个菌落。采用16S rRNA测序的Checkboard杂交鉴定分离株，采用Southern杂交鉴定耐药基因型。抗生素耐药性表型将通过平板培养确定。将确定对多种抗生素具有耐药性的物种，并将其提供给检查抗性基因的合作者。

Ideally, therapies designed to control pathogenic oral microorganisms will suppress or abolish those organisms, leaving a stable host-compatible microbiota in place. At times, however, attempts to eliminate periodontal pathogens lead to undesired changes in the microbiota. Two of the most obvious are overgrowth of pathogenic species not commonly found din high numbers in the oral microbiota and the emergence of antibiotic resistant species. This Project will be concerned with the safety of therapies, particularly antibiotic therapies, employed to control periodontal infections. The immediate goal is to determine the consequences of antibiotic therapy on the composition and antibiotic resistance of the periodontal microbiota. The first aim is to determine how antibiotic therapy shift the composition of the subgingival microbiota by monitoring levels of 120 bacterial species using Checkerboard hybridization. Subgingival species in pooled subgingival plaque samples will be examined at baseline, at the completion of therapy, and at 1-year post therapy for 24 subjects treated by either scaling and root planing (SCR), SCR plus local tetracycline, or SCR plus systemic amoxicillin and metronidazole. The second aim will determine how antibiotic therapy affects antibiotic resistance genotype and phenotype of plaque bacteria. Twelve subjects in the three groups described for Aim 1 will have 60 colonies picked for each time point. The isolates will be identified by Checkboard hybridization of 16S rRNA sequencing, and the antibiotic resistance genotype will be determined by Southern hybridization. Antibiotic resistance phenotype will be determined by plate culture. Species that are resistant to multiple antibiotics will be identified and made available to collaborators examining resistance genes.