Effect of Periodontal Therapy on Subgingival Taxa Identified Using HOMIM

Objectives: To investigate the effects of non-surgical periodontal therapy on the subgingival microbiota using the Human Oral Microbe Identification Microarray (HOMIM).

Methods: Subgingival biofilm samples were collected from 28 chronic periodontitis patients (average:10 sites/patient) at baseline and 3 months after treatment (SRP+ systemic amoxicillin and metronidazole). Bacterial profiles were examined using HOMIM for the presence of 422 taxa. Frequency of detection of each taxon was determined separately in each subject and averaged across subjects before and after therapy. Significance of differences between visits for the prevalence of each test taxon was determined using the Wilcoxon signed rank test.

Results: 53 of 422 probe targets differed significantly post therapy (p<0.05). Reduction in prevalence (mean±SD, before vs. after therapy) was observed for several pathogenic taxa, including Porphyromonas gingivalis (35±32 vs. 15±35; p=0.093); Tannerella forsythia (47±31 vs. 16±35; p=0.041); Eubacterium nodatum (64±30 vs. 18±35; p=0.009); Parvimonas micra (89±17 vs. 50±37; p=0.0009); Prevotella intermedia (19±23 vs. 2±6; p=0.008); Campylobacter rectus/concisus (39±27 vs. 20±29; p=0.086). Filifactor alocis (66±32 vs. 22±39; p=0.007); Eubacterium yurii (64±31 vs. 21±31; p=0.0005) and Pseudoramibacter alactolyticus (7±15 vs 0±0; p=0.036). Disease-associated uncultivated taxa were also reduced post-therapy, including Synergistetes sp. oral taxon (ot) 360 (56±42 vs. 32±41; p=0.006) and Desulfobulbus sp. ot 041 (42±35 vs. 6±21; p=0.003). Conversely, post-therapy increase in prevalence was observed for Veillonella parvula (5±11 vs. 20±3; p=0.029); Kingella oralis (20±28 vs. 43±32; p=0.034); Gemella haemolysans (26±34 vs. 49±43; p=0.011); Rothia dentocariosa/mucilaginosa (17±28 vs. 51±41; p=0.022); Bergeyella sp. ot 322 (3±8 vs. 10±17; p=0.056); Granulicatella adiacens (7±13 vs. 32±35; p=0.003) and 4 species of Streptococcus.

Conclusions: HOMIM detected post-therapy reduction in prevalence of known periodontal pathogens. Reduction was also observed for taxa typically not associated with periodontitis, suggesting their potential association with periodontitis. Periodontal treatment led to microbial shifts compatible with periodontal health.