Purpose: Previous studies reported that staphylococcal enterotoxin-specific IgE (SE-IgE) sensitization was associated with asthma prevalence and severity in adults. We hypothesize that Staphylococcus aureus (SA) nasal colonization would have synergistic impact with SE-IgE sensitization on clinical characteristics in adults with late-onset asthma.

Methods: Patients with late-onset asthma (onset age ?40 years) were prospectively enrolled. Nasal swabs were taken to evaluate SA colonization. SE-IgE levels were measured in serum. Subjects were classified into 4 groups according to SA colonization and SE sensitization positivity. We analyzed the demographic and clinical parameters in relation to SA and SE status.

Results: A total of 181 asthmatic subjects were recruited. The proportion of SA/SE (?/?), SA/SE (+/?), SA/SE (?/+), and SA/SE (+/+) was 33.7%, 15.5%, 28.2%, and 22.6%, respectively. Severe asthma was significantly more common in subjects with SA/SE (+/+) than in those with SA (?/?) (41.5% vs. 13.1%; p=0.001). The relationships between SA/SE (+/+) and severe asthma were significant in multivariate logistic regression analysis. The degree of associations with other clinical parameters such as FeNO levels or FEV1/FVC ratio<0.70 was stronger with SA/SE (+/+) than with SA/SE (+/?) or SA/SE (?/+) (vs. SA/SE (?/?)).

Conclusion: Intranasal SA colonization may have synergistic effects with SE-IgE sensitization on asthma severity and clinical outcomes in adults with late-onset asthma.