Staphylococcus aureus nasal colonization increases the risk of cedar pollinosis

BACKGROUND: One‐third of the people in Japan are colonized with Staphylococcus aureus (S. aureus) and suffer from virulence factor‐mediated subclinical inflammation of the nares. We investigated whether subclinical inflammation contributed to cedar pollinosis affecting 20 million people annually. METHODS: The study participants were 814 inhabitants of the A or B prefectures. We compared the colonization rate and population structure of S. aureus, in association with the prevalence of cedar pollinosis, between participants in these two areas. RESULTS: A prefecture had twice the annual amount of airborne cedar pollen compared with B. The prevalence of cedar pollinosis was significantly higher in A (23.5%) than in B (13.1%) (p = 0.0004). Moreover, the prevalence of cedar pollinosis was higher in female participants (23.3%) than in male participants (14.7%) (p = 0.003). In addition, the prevalence of cedar pollinosis was higher in S. aureus carriers (24.2%) than in S. aureus noncarriers (17.9%) (p = 0.03). The isolation rate of clonal complex (CC) 508 was higher in the A group (21%) than in the B group (7%) (p = 0.015). CONCLUSION: Nasal colonization of S. aureus is a major risk factor for cedar pollinosis. However, the direct mechanism of this risk is currently unknown.