Adjunctive Azithromycin vs. Amoxicillin/Metronidazole for SRP – Microbiology and Biomarkers

Objectives: To determine the effect of systemic adjunctive use of azithromycin in comparison with amoxicillin/metronidazole to scaling and root planing (SRP) in a private dental practice on microbiological and biomarker variables.

Methods: 60 volunteers (29 female, 31 male, mean age 54±8 years) with moderate or severe chronic periodontitis participated in a randomized clinical trial for 12 months. All participants underwent a full-mouth SRP. In the test group the adjunctive antibiotic was azithromycin (3x 500 mg/d), in the control group amoxicillin/metronidazole (3x 500/400mg7d for 7 days) were administered. Clinical variables were recorded at baseline as well as after 3 and 12 months. Samples of GCF were collected at the deepest site per quadrant (additionally 14 days after SRP), pooled and analyzed (ELISA) for levels of MMP-8 and IL-1β. Samples of the subgingival biofilm from the same sites were analyzed by using nuleic-acid based methods for 11 bacterial species associated with periodontitis. Nonparametric tests (Friedman/Wilcoxon and Mann-Whitney-U-tests) were used for statistical analysis.

Results: No significant intra- and inter-group differences occurred at MMP-8. In the test group, MMP-8 decreased by trend (p=0.061) while IL-1β level was significantly lower (p = 0.030) after 14 days than at baseline. No other significant intra-group changes were seen for IL-1β. There was no significant difference between test and control groups for IL-1β at any time. After three months lower counts of Prevotella intermedia, Treponema denticola, Fusobacterium nucleatum, and Campylobacter rectus were detected in the test group than in the control group (p = 0.031, 0.016, 0.017, 0.020). After 12 months still the counts of T. denticola were significantly lower in the test group (p = 0.002). Only in the test group, P. intermedia, T. denticola, C. rectus and Eikenella corrodens were significantly reduced after three months (p = 0.020, 0.047, 0.022, 0.037), and T. denticola and C. rectus also after 12 months (p = 0.004, 0.026) each compared with baseline.

Conclusions: The biomarker and microbiological results support the adjunctive administration of azithromycin as an alternative antibiotic during SRP.