The presence of staphylococcal superantigens in nasal swabs and correlation with activity of granulomatosis with polyangiitis (GPA) in own material.

Objective: We investigated the association between a presence of staphylococcal superantigens (SAg) in nasal swabs and activity of disease in granulomatosis with polyangiitis (GPA) patients taking into account correlation with antineutrophil cytoplasmic antibodies (ANCA) and antimicrobial treatment. Methods: In a prospective study of all 150 GPA patients hospitalized in the period 2009-2016 nasal swabs were examinated for presence of Staphylococcus aureus and SAg. Subsequently, the association with disease activity was assessed. Results: Of 362 Staphylococcus aureus – positive nasal swab culture a presence at least one SAg in 126 samples (34,8%) from 56 patients (48,7%) was found. We did not find the significant correlation between presence of SAg and disease activity (p=0,986), although when individual SAg were analyzed separatively, SED and TSST-1 were more frequently present in active disease. Additionaly, the results of the analysis demonstrated a significant correlation between ANCA and activity of GPA (0R 1.42, p=0,0034) and a protective effect of trimethoprim/sulfamethoxazole (T/S) treatment (0R 0.52, p Conclusion: The association between staphylococcal SAg in nasal swabs and activity of GPA is not evident. Multiple mechanisms that may lead to disease activation still need to be investigated.