Impact of Systemic Antimicrobials on the Microbiota of Aggressive Periodontitis

Aim: To evaluate the effect of systemic amoxicillin (AMX) plus metronidazole (MET) associated to an enhanced mechanical therapy on the subgingival microbiota of generalized aggressive periodontitis (GAP). Methods: The study was a 6-month randomized, double-blinded, placebo-controlled clinical trial. Thirty-one subjects received full-mouth ultra-sonic debridement followed by scaling and root planing with chlorhexidine rinsing, brushing and irrigation. During mechanical therapy, subjects received either systemic AMX (500mg) + MET (250mg) or placebo, 3X per day for 10 days. Fourteen subgingival samples were obtained from each patient and analyzed for their composition by checkerboard at baseline, 3 and 6 months post-therapy. Significant differences between groups over time were examined by GLM of repeated measures. Results: High prevalence and levels of periodontal pathogens, as well as “unusual” periodontal species were observed. Most of the periodontal pathogens decreased significantly over time (p<0.05), whereas “unusual” periodontal bacteria tended to increase in both groups. Sites that showed attachment loss and PD increase harbored higher baseline levels of Dialister pneumosintes, Campylobacter rectus and Peptostreptococcus anaerobius than sites that improved after both therapies (p<0.05). Conclusions: Systemic AMX+MET did not provide an additional benefit to the enhanced mechanical therapy in suppressing putative periodontal pathogens. Species not commonly associated with GAP were less affected by both therapies. Supported by FAPERJ, CAPES, CNPq, Brazil.