Staphylococcus aureus bacteremia is a serious infection that can be caused by the bacteria present in the nasal passages. A study found that in 82.2% of patients with S. aureus bacteremia, the bacteria in the bloodstream were identical to those found in the nasal passages. This suggests that many cases of S. aureus bacteremia may originate from the nasal flora, rather than from external sources. The study involved two parts: one with 219 patients and another with 1278 patients over five years. In both studies, the bacteria isolated from the nasal passages were found to be clonally identical to those in the blood. This supports the idea that eliminating nasal carriage of S. aureus could help prevent systemic infections. The study also showed that nasal carriage is a significant risk factor for infections, especially in hospitalized patients. The results highlight the importance of preventing nasal carriage to reduce the incidence of S. aureus infections. The study used molecular methods to compare the bacteria from the nasal passages and blood, showing that they were often the same. This indicates that S. aureus bacteremia may have an endogenous origin, and that strategies to eliminate nasal carriage could be effective in preventing such infections. The study was supported by a grant and conducted in multiple hospitals. The findings suggest that nasal carriage is a major source of S. aureus infections and that eliminating it could help prevent systemic infections.Staphylococcus aureus bacteremia is a serious infection that can be caused by the bacteria present in the nasal passages. A study found that in 82.2% of patients with S. aureus bacteremia, the bacteria in the bloodstream were identical to those found in the nasal passages. This suggests that many cases of S. aureus bacteremia may originate from the nasal flora, rather than from external sources. The study involved two parts: one with 219 patients and another with 1278 patients over five years. In both studies, the bacteria isolated from the nasal passages were found to be clonally identical to those in the blood. This supports the idea that eliminating nasal carriage of S. aureus could help prevent systemic infections. The study also showed that nasal carriage is a significant risk factor for infections, especially in hospitalized patients. The results highlight the importance of preventing nasal carriage to reduce the incidence of S. aureus infections. The study used molecular methods to compare the bacteria from the nasal passages and blood, showing that they were often the same. This indicates that S. aureus bacteremia may have an endogenous origin, and that strategies to eliminate nasal carriage could be effective in preventing such infections. The study was supported by a grant and conducted in multiple hospitals. The findings suggest that nasal carriage is a major source of S. aureus infections and that eliminating it could help prevent systemic infections.