<p>Adult periodontitis is a chronic inflammatory disease characterized by microbial dysbiosis and host-microbe imbalance in the oral cavity. In this study, the composition and antibiotic susceptibility of the salivary microbiota in adults with mild periodontitis were analyzed to emphasize the influence of lifestyle factors on microbial ecology and resistance trends. Saliva samples collected from clinically diagnosed individuals were analyzed using selective culture-based methods and the Kirby-Bauer disc diffusion assay. Statistical analyses were performed to evaluate interspecies growth variability and antimicrobial responses. It revealed distinct salivary microbial profiles in patients with periodontitis compared to those of healthy individuals. <i>Fusobacterium nucleatum</i> exhibited the highest optical density, indicating increased proliferation and potential involvement in disease progression. Lifestyle variables, particularly smoking and dietary habits, significantly influenced microbial composition (r = 0.73 for smoking; r = 0.59 for tobacco use). Antibiotic susceptibility testing has revealed substantial interspecies variation, with ciprofloxacin and tetracycline showing the highest inhibitory efficacy, whereas azithromycin and clindamycin were largely ineffective. Moderate positive correlations between <i>Prevotella</i>, <i>Clostridium</i>, and <i>F. nucleatum</i> (r = 0.61–0.65) suggest possible shared resistance mechanisms or ecological adaptation. Overall, combined effects of behavioral and microbial factors can shape early periodontal dysbiosis and antibiotic resistance.</p> Graphical abstract <p></p>