INFLUENCE OF ORAL CONDITIONS ON COLONIZATION BY HIGHLY TOXIGENIC STAPHYLOCOCCUS AUREUS STRAINS

OBJECTIVES: As the oral cavity is regarded as a relevant site for Staphylococcus aureus colonization and interhu- man transmission, this study aimed to investigate whether different oral conditions influence the rates of S. aureus oral carriage and genetic characters of S. aureus isolates. SUBJECTS AND METHODS: Staphylococcus aureus was searched in samples collected from cheek, gingival mar- gin, and anterior nares of 45 healthy subjects, 27 peri- odontitis affected subjects, and 29 subjects with fixed prosthetic restorations. Isolates were screened for 17 genetic determinants, and Partial Least Square Discri- minant Analysis was performed to evaluate whether specific characters correlated with oral condition or site of isolation. RESULTS: The three subject groups showed comparable nasal carriage rates but, both the periodontitis and prosthetic restoration groups showed significantly higher oral carriage rates, as compared to healthy subjects (P = 0.01 and 0.02, respectively). Moreover, periodontitis affected subjects hosted strains possessing a distinct genotypic and phenotypic background, characterized by the presence of a larger number of exotoxins encoding genes. CONCLUSIONS: These data confirm that the oral cavity is an important site of S. aureus colonization and dem- onstrate that conditions modifying the oral environment, as the presence of periodontitis and of fixed prosthetic restorations, promote S. aureus carriage and may favor the spread of more pathogenic strains.