Overview
Protothecosis is a rare opportunistic infection caused by achlorophyllous algae of the genus Prototheca, typically manifesting as cutaneous lesions or disseminated systemic infections in immunocompetent and immunocompromised individuals 123.Diagnosis
Clinical Presentation: Often involves cutaneous lesions, tenosynovitis, or atypical presentations like gouty arthritis 13.
Physical Examination: Look for ulcers, erythema, swelling, and exudative changes 1.
Laboratory Tests: Elevated neutrophil percentage may be seen; serum uric acid levels can be misleading 1.
Imaging: MRI can suggest differential diagnoses like gouty arthritis but lacks definitive urate crystal evidence 1.
Microbiological Confirmation: Culture of Prototheca species from clinical samples is definitive 13.
Differential Diagnosis: Consider conditions mimicking protothecosis, such as fungal infections or other granulomatous diseases 2.Management
First-Line Treatment: Itraconazole is commonly used, often requiring prolonged courses (e.g., 8 months) 23.
Adjunctive Therapy: Surgical débridement may be necessary, especially in localized infections like tenosynovitis 3.
Alternative Agents: Amphotericin B and ketoconazole have been used in refractory cases, though specific dosing is not detailed in abstracts 2.
Duration: Treatment duration varies; prolonged therapy is often required to ensure eradication 23.Special Populations
Immunocompetent Individuals: Protothecosis can occur in immunocompetent individuals, as seen in cases of tenosynovitis 3.
Elderly: Increased susceptibility may be noted, as evidenced by a case report in an elderly patient with recurrent symptoms 1.
Comorbidities: Presence of conditions like hypertension does not preclude protothecosis but may complicate management 1.Key Recommendations
Confirm Diagnosis via Culture: Definitive diagnosis requires isolation of Prototheca species from clinical specimens (Evidence: Moderate 13).
Initiate Itraconazole Therapy: Start with itraconazole as first-line treatment, considering prolonged duration (Evidence: Moderate 23).
Consider Surgical Intervention: For localized infections like tenosynovitis, surgical débridement can be adjunctive to medical therapy (Evidence: Weak 3).References
1 Wang R, Xue Y, Wu Z, Wei M, Wu N, Guo J. Prototheca wickerhamii causing toe infection presenting initially as gouty arthritis: A rare case report. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases 2025. link
2 Melo RR, Rodrigues FT, Baka JLLCES, Almeida MD, Alves MFGS, Gripp AC. An exuberant case of protothecosis: an emergent disease in tropical dermatology. Dermatology online journal 2022. link
3 Lee JS, Moon GH, Lee NY, Peck KR. Case report: protothecal tenosynovitis. Clinical orthopaedics and related research 2008. link