Fig. 3

Detection of antibiotic resistance genes (ARGs) in oral biofilm samples of 179 study participants from three study centres divided into three different groups, based on metagenomic sequencing. A Prevalence of ARGs according to antibiotic classes and antibiotics; corresponding ARGs to specific antibiotics and antibiotic classes are listed in Additional file 1: Table S3; B Comparison of the 15 most prevalent ARGs in H, C, and P with significance determined by Firth’s logistic regression *p ≤ 0.05, **p ≤ 0.01 and ***p ≤ 0.001; C PCoA showing the ARG profiles of H, C, P (colours) and study centres (shapes); p = 0.0001; pairwise PERMANOVA: H vs C p = 0.001; H vs P p = 0.001; P vs C p = 0.001. Healthy (n = 63, 60.3% female), Caries (n = 61, 31.1% female), and Periodontitis (n = 55, 41.8% female)