ESDR133 - Oral fusidic acid for the treatment of mild to moderate hidradenitis suppurativa

Hidradenitis suppurativa (HS) is characterized by recurrent nodules, abscesses and fistulas in the intertriginous areas. Recommended therapies include surgery, biologicals and systemic antibiotics (tetracyclines and clindamycin-rifampicin). Also, other antibiotics have been used in HS, one of which is fusidic acid (FA). This study aimed to investigate the efficacy of systemic FA for the treatment of HS. In this retrospective cohort study, 55 FA therapy cycles (TC) in 49 HS patients were analyzed. An average of 6409mg FA per week (range 5250mg-9800mg) was administered for 2 to 12 weeks. Outcome was evaluated by physicians’ global assessment comparing pre- to end-of treatment. Therapy response was defined as any reduction of inflammatory activity without the occurrence of new lesions. We also characterized adverse events and investigated predictors for treatment success. FA treatment (55TC; male 25TC, 45.5%; female 30TC, 54.5%) showed an overall response rate of 70.9% (39TC). No disease worsening was observed. Significantly higher response rates were observed in females compared to males (83.3%, 50,0%, p=.026) and Hurley I compared to Hurley II patients (90.9%, 57.6%, p=.008). After multivariate adjustment, higher response rates were associated with the Hurley grade (p=.046) but not with sex (p=.0174). In contrast BMI (p=.303) and patients’ age (p=.742) did not affect treatment response. Adverse reactions occurred in 27.3% (15TC), mostly within the first 4 weeks of treatment (63.6%). 21.8% (12TC) of them were gastrointestinal symptoms and led to therapy discontinuation in 12.7%. Oral FA improved symptoms in most patients. Especially women of reproductive age who should not receive tetracyclines, could benefit from FA. FA is safe with only every fourth patient experiencing mild adverse reactions.