Effect of Locally Delivered Minocycline on the Profile of Subgingival Bacterial Genera in Patients with Periodontitis: A Prospective Pilot Study

This prospective pilot study aimed to evaluate the effect of minocycline-HCl ointment (MO), locally delivered as an adjunct to scaling and root planing (SRP), on subgingival microflora. A total of 59 periodontitis patients received SRP as an initial periodontal therapy. In the selected periodontal pockets with probing depths (PD) of 6–9 mm, the sites that exhibited a positive reaction following a bacterial test using an immunochromatographic device were subsequently treated with MO (SRP + MO group, <i>n</i> = 25). No additional treatment was performed at sites showing a negative reaction (SRP group, <i>n</i> = 34). In addition to subgingival plaque sampling, measurement of clinical parameters including PD, clinical attachment level (CAL), bleeding on probing (BOP), plaque index and gingival index (GI) were performed at baseline and 4 weeks after the initial periodontal therapy. The subgingival microflora were assessed by terminal restriction fragment-length polymorphism analysis. Relative to baseline values, the mean scores for PD-, CAL-, BOP-, and GI-sampled sites were significantly decreased post treatment in both groups (<i>p</i> < 0.01). The intra-comparisons showed a significant decrease in the counts of the genera <i>Eubacterium</i>, <i>Parvimonas</i>, <i>Filifactor</i>, <i>Veillonella, Fusobacterium</i>, <i>Porphyromonas</i>, <i>Prevotella</i>, and unknown species in the SRP + MO group (<i>p</i> < 0.05). Inter-comparisons indicated a significant decrease in the genera <i>Veillonella</i> in the SRP + MO group (<i>p</i> = 0.01). Combination therapy of SRP and local MO induced a change in the subgingival microbial community: particularly, the number of <i>Veillonella</i> spp. was markedly reduced.