# Unmasking Prototheca wickerhamii: A rare case of cutaneous infection and its implications for clinical practice

## TL;DR

A rare skin infection caused by Prototheca wickerhamii in an older man is reported, emphasizing the need for accurate diagnosis and effective treatment.

## Contribution

This paper presents a rare case of Prototheca wickerhamii infection in an immunocompetent individual and its successful treatment.

## Key findings

- Prototheca wickerhamii infection was diagnosed using metagenomic sequencing and confirmed with fluorescence staining and electron microscopy.
- The patient was successfully treated with itraconazole and dipotassium glycyrrhizinate.
- The case underscores the importance of early and accurate diagnosis for managing Prototheca infections.

## Abstract

Prototheca, an opportunistic pathogenic algae widely found in nature, has emerged as a potential public health concern. Most cases occur in immunocompromised individuals, with infections in immunocompetent patients being relatively rare. Due to their non-specific clinical presentation and limited awareness among clinicians, Prototheca infections are often misdiagnosed, resulting in delayed treatment. Recent advances in species identification and antifungal susceptibility testing have provided important tools for diagnosis and therapy. Here, we report a case of recurrent facial infection in a 76-year-old immunocompetent man. Skin biopsy revealed an infectious granuloma, and fungal culture identified yeast-like colonies. Fluorescence staining and scanning electron microscopy revealed abundant spores, while metagenomic sequencing confirmed the infection as Prototheca wickerhamii. The patient was successfully treated with long-term itraconazole and dipotassium glycyrrhizinate capsules. This case highlights the importance of early and accurate diagnosis in the management of Prototheca skin infections and reviews the therapeutic strategies used.