Introduction: Acute invasive fungal rhinosinusitis (AIFR) is a severe condition with high morbidity and mortality, despite established management protocols. Adjuvant therapies may improve disease control. This study aimed to investigate the in vitro antifungal effects of acetic acid (AA) and hydrogen peroxide (HP) on fungi implicated in AIFR.

Materials and Methods: Sinonasal tissue biopsies obtained during endoscopic sinus surgery (ESS) from patients with AIFR, fungal ball, or allergic fungal rhinosinusitis (AFRS) were collected. Biopsies were exposed to 0.25% AA or 1.5% HP for 10 minutes and subsequently cultured on Sabouraud dextrose agar. Untreated tissue portions served as controls. Fungal growth was assessed and identified using macroscopic and microscopic characteristics.

Results: Of 48 collected samples, 10 did not grow in any culture medium and were excluded. Among the remaining 38 samples, AA inhibited fungal growth in 7 samples (18.5%), and HP inhibited growth in 3 samples (8%). The majority of isolates were Aspergillus species (87%), with Mucorales representing 5.26%. Two samples demonstrated growth only in AA- or HP-supplemented media, with no growth in standard media. Statistical analysis showed no significant differences in growth across the three media.

Conclusion: Although AA and HP exhibited some antifungal activity in vitro, their effects on clinically relevant fungal pathogens, particularly Aspergillus and Mucorales, were limited. Therefore, these compounds may not be suitable as standalone adjuvant therapies for AIFR. Further research is required to explore alternative or combinatorial adjuvant approaches.