Unveiling the Relevance of the Oral Cavity as a Colonization Site and Potential Source of Antimicrobial Resistance.

is both a human commensal and a pathogen, that causes serious nosocomial and community-acquired infections. Despite nostrils being considered its preferred host habitat, the oral cavity has been demonstrated to be an ideal starting point for auto-infection and transmission. The antibiotic resistance assessment of is a priority and is often reported in clinical settings. This study aimed to explore the prevalence and antimicrobial susceptibility of in the oral and nasal cavities of healthy individuals. The participants ( = 101) were subjected to a demographic and clinical background survey, a caries evaluation, and to oral and nasal swabbing. Swabs were cultured in differential/selective media and isolates were identified (MALDI-TOF MS) and tested for antibiotic susceptibility (EUCAST/CLSI). Similar prevalence was found exclusively on nasal (13.9%) or oral (12.0%) habitats, whereas 9.9% of the population were simultaneous nasal and oral carriers. In oro-nasal cavities, similar antibiotic resistance rates (83.3-81.5%), including MDR (20.8-29.6%), were observed. Notably, 60% (6/10) of the simultaneous nasal and oral carriers exhibited different antibiotic resistance profiles between cavities. This study demonstrates the relevance of the oral cavity as an independent colonization site for and as a potential source of antimicrobial resistance, a role which has been widely neglected so far.