First Report of Onychomycosis Caused by Chaetomium globosum in Iraq: A Case of A University Athlete

Onychomycosis is a common chronic fungal infection of the nails, typically caused by dermatophytes, but increasingly recognized as involving non-dermatophytic moulds. Chaetomium globosum is known to be a rare etiological agent of opportunistic human onychomycosis and skin infections. A 30-year-old healthy male football player from the University of Basrah presented with a year-long history of brownish-yellow discoloration and thickening of the right big toenail. Nail scrapings and clippings were cultured on Sabouraud dextrose agar (PDA) with and without cycloheximide at 25°C for one week, resulting in rapid fungal growth. Microscopic and macroscopic identification was based on perithecial morphology and ascospore characteristics. The isolate was confirmed through repeated culturing and comparison with established diagnostic criteria. Abundant dark perithecia developed on SDA without cycloheximide, showing charac-teristic features of C. globosum: dark brown ostiolate perithecia surrounded by septate hairs and lemon-shaped, olive-brown ascospores (8.75-12.5 × 7.5-10 µm). No growth was observed on cycloheximide-containing media. These features are consistent with previously described C. globosum morphology. This report documents the first confirmed case of onychomycosis caused by C. globosum in Iraq, expanding the known geographic distribution of this rare fungal pathogen.