Fig. 6

Fusidic acid inhibits the growth of S. aureus on HEEs. A Dose inhibiting effect via colony forming unit (CFU analysis) of HEEs topically applied with fusidic acid (FA, 1–10–100 µg/mL, 1% DMSO in water (0 µg/mL, vehicle)) 4 h after S. aureus ATCC 29213 colonization (dotted line: amount of CFUs at start of treatment) and harvested 24 h later (N = 3), and B H&E staining thereof. C CFU analysis on day 1 (N = 3 per treatment) and day 8 (0 µg/mL (N = 2) and 10–100 µg/mL (N = 4)), and (D) H&E staining of HEEs colonized with the S. aureus clinical isolate SA-DUS-011 subjected to the FA treatment protocol (10 and 100 µg/mL). HEEs were analyzed with a prolonged culture up to 8 days to study epidermal infections; 50% (2 out of 4) S. aureus HEEs infected after 96 h (FA applied at day 0, 2, 4, and 6) (of note, cultured at 32 °C (dry)). *p < 0.05 (Mann-Whitney U test, CFU outcome of fusidic acid dosages compared to the vehicle (0 µg/mL)). Mean ± SEM. Scale bar = 100 µm