Bacterial dysbiosis in sinonasal fungal ball: a paired 16S rRNA gene sequencing study

Abstract Purpose Sinonasal fungal ball is usually classified as a non-invasive fungal disease. However, the bacterial changes that accompany the lesion are still not well defined. This study compared bacterial community structure and predicted functional potential between the affected sinus and the contralateral healthy side in patients with sinonasal fungal ball. Methods Using high-throughput 16S rRNA gene sequencing, 29 paired sinus samples were analysed, including fungal ball diseased-side samples (FBDS) and matched healthy-side samples (FBHS). The cohort included 25 maxillary sinus fungal ball pairs and 4 sphenoid sinus fungal ball pairs. Taxonomic composition, alpha diversity, beta diversity, genus-level differential abundance, co-abundance networks, and PICRUSt-predicted KEGG functional profiles were compared. Results FBDS and FBHS had distinct bacterial profiles. FBDS showed enrichment of Proteobacteria, Bacteroidetes and Fusobacteria, reduced alpha diversity, altered Bray-Curtis structure, and greater dispersion. Sixteen robust differential genera were identified, including FBDS-enriched Achromobacter and FBHS-enriched Ochrobactrum, Desulfovibrio, Lactobacillus, Lentzea, Sphingomonas, Staphylococcus and Corynebacterium . FBHS also showed a denser co-abundance network. PICRUSt predicted FBDS enrichment in lipopolysaccharide/glycan biosynthesis and translation-related pathways, whereas FBHS was linked to xenobiotic degradation and lipid metabolism. Most findings persisted in maxillary-only analysis. Conclusion Sinonasal fungal ball was associated with local bacterial dysbiosis on the affected side. The main features were reduced diversity, altered community composition, higher inter-individual variation, a simpler co-abundance structure, and different predicted functional potential. These findings suggest that fungal ball disease may involve localized bacterial ecological remodeling, not only fungal colonization.