Tropicoporus tropicalis: A Newly Recognised Pathogen in Eumycetoma and Refractory Mycoses in Humans

Abstract

Tropicoporus tropicalis (formerly Phellinus tropicalis) is a saprophytic basidiomycete that has been implicated in refractory mycoses in humans, particularly in patients with chronic granulomatous disease. Despite its clinical significance, T. tropicalis is an under-recognised cause of eumycetoma, with no prior reports available. We present a case of white grain eumycetoma with associated osteomyelitis of the left foot, caused by T. tropicalis, confirmed through 18S-ITS1-5.8S-ITS2-28S rRNA gene amplification and sequencing. The patient was treated with itraconazole 200 mg daily, leading to gradual improvement. A review of the literature on T. tropicalis infections in humans reveals its characteristic manifestations, which include osteomyelitis, soft tissue abscesses, pulmonary nodules and keratitis. These infections are locally destructive but have the potential to disseminate. Diagnosis is often delayed and relies on molecular techniques. Amphotericin B combined with an azole appears to be the most effective treatment, often necessitating concurrent surgical drainage. In conclusion, T. tropicalis is a newly recognised pathogen associated with eumycetoma and poses an increased risk of osteomyelitis. Molecular identification, such as sequencing the internal transcribed spacer (ITS) region from cultures or tissue specimens, is crucial for accurate identification of this pathogen.