From black particles to molecular proof: PD-associated peritonitis by Daldinia eschscholtzii.

Fungal infection in peritoneal dialysis (PD) is rare but devastating, especially with filamentous molds. We report a 60-year-old man on continuous ambulatory PD who presented with black particulate material in the PD transfer set and mild abdominal discomfort without cloudy effluent. PD effluent showed low-grade neutrophilic inflammation, and microscopy revealed dematiaceous septate hyphae. A slow-growing pigmented mold, initially misidentified as Cladosporium, was definitively identified as Daldinia eschscholtzii by multi-locus sequencing, supported by galactomannan positivity. This first report of PD-associated peritonitis due to D. eschscholtzii positions black intraluminal particles as an early visual warning sign of PD catheter-associated dematiaceous mold infection, underscoring the need for integrated mycological diagnostics before overt peritonitis develops.