ANTIBIOTIC THERAPY IN TREATING PERIODONTAL DISEASES

理想情况下，旨在控制致病口腔微生物的疗法将抑制或废除这些微生物，留下一个稳定的与宿主兼容的微生物群。然而，有时试图消除牙周病原体会导致微生物区系发生不希望看到的变化。其中最明显的两个是口腔微生物区系中不常见的致病物种的过度生长和抗生素耐药物种的出现。该项目将关注用于控制牙周感染的治疗方法，特别是抗生素治疗的安全性。目前的目标是确定抗生素治疗对牙周微生物区系的组成和抗生素耐药性的影响。第一个目标是通过使用棋盘杂交监测120种细菌的水平，确定抗生素治疗如何改变龈下微生物区系的组成。24名受试者将在基线、治疗结束时和治疗后一年检查共收集的龈下菌斑样本中的牙龈下物种，这些受试者接受洁治和根面平整(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、基因和表型。在为目标1描述的三组中，12名受试者将在每个时间点选择60个菌落。通过16S rRNA测序的棋盘杂交方法对分离株进行鉴定，并通过Southern杂交确定耐药基因。抗生素耐药表型将通过平板培养确定。对多种抗生素具有抗药性的物种将被识别出来，并提供给研究抗药性基因的合作者。

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.