Isolation and genomic analysis of otomycosis pathogens, and genomics-informed antimicrobial peptide design with...

Fungal infections are increasingly recognized as a major public health challenge, and superficial diseases such as otomycosis remain clinically consequential because persistence, recurrence, and treatment failure are common when the causative species and susceptibility profile are not clearly defined. However, otomycosis associated isolates are often insufficiently characterized at the genomic level. Furthermore, the development of antifungal candidates, particularly for short antimicrobial peptides, remains heterogeneous in terms of the integration of efficacy, biosafety, and mechanistic endpoints.

Here, we combined clinical otoscopy and cerumen culture with whole genome sequencing and multi-database annotation of an otomycosis derived Aspergillus terreus AT-1 isolate, including targeted analyses of cytochrome P450 families, secondary metabolite biosynthetic gene clusters, curated pathogenicity resources, and antimicrobial/antibiotic resistance signatures. Then, we rationally designed five C-terminally amidated, phenylalanine based short peptides with controlled physicochemical parameters and assessed antifungal activity by broth microdilution MIC assays against A. terreus AT-1 and yeast pathogens, complemented by hemolysis testing and propidium iodide based flow cytometry and microscopy to evaluate membrane permeabilization.

Otoscopy was consistent with otomycosis, and culture yielded colonies identified as A. terreus AT-1 from the affected ear but not from recovered controls. Genome annotation defined a functionally diverse repertoire spanning metabolism, transport, secondary metabolism, pathogenicity linked features, and a structured resistance gene landscape. The peptide panel showed measurable antifungal activity with distinct hemolysis profiles, and peptide C3 increased A. terreus AT-1 conidial membrane permeability.

Overall, this study establishes an integrated and reproducible workflow that couples clinical isolation and genome resolved characterization of an otomycosis associated A. terreus AT-1 isolate with biosafety aware, mechanism informed triage of phenylalanine based short peptides.