Aromatic Compound-DependentStaphylococcus aureusIs Safe in a Nasal Colonization Leukopenic Murine Model

Abstract

Staphylococcus aureusnasal carriage is a risk factor for individuals suffering from trauma, surgical procedures, invasive devices, and/or decreased immunity. Recently, we demonstrated that artificial nasal colonization with an attenuatedS. aureusmutant reduced by bacterial interference with the colonization of pathogenic strains ofS. aureus. This could be an optional tool to diminish the rate ofS. aureusinfections in hospitalized patients. The aim of this study was to construct a safe ΔaroAmutant ofS. aureusand to discriminate it from nasal colonizing and osteomyelitisS. aureusisolates bySmaI pulsed-field gel electrophoresis (PFGE) typing. The ΔaroAmutant, named RD17, exhibited an LD50(3.2 × 106colony-forming unit (CFU)) significantly higher than that of the parental strain (2.2 × 103 CFU). The colony number of the RD17 mutants recovered from nares of leukopenic mice was similar to that observed in the animals of the control group. Therefore, the ΔaroAmutant was demonstrated to be safe due to maintaining low growth levels in the nares regardless of immune status of the animals. PFGE typing allowed the unequivocal identification of theS. aureusand differentiation ofaroAmutants in nasal colonizing and osteomyelitis isolates. This information could be important to discriminate endogenous infections from laboratory strains ofS. aureus.