Prototheca wickerhamii

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Prototheca wickerhamii
Prototheca wickerhamii.hematoxylin eosin stain.jpg
Scientific classification
Domain: Eukaryota
Kingdom: Viridiplantae
Phylum: Chlorophyta
Class: Trebouxiophyceae
Order: Chlorellales
Family: Chlorellaceae
Genus: Prototheca
Species: P. wickerhamii
Binomial name
Prototheca wickerhamii

Prototheca wickerhamii is a ubiquitous green alga that does not have chlorophyll. It is widely present in the environment and is a rare cause of infection in humans (protothecosis) and most commonly presents as nodules of the skin.[1] Most cases reported have a suppressed immune system (from drugs or disease). Infection usually results by direct traumatic inoculation.[2][full citation needed]


Diagnosis can be made through culture of infected fluid in Sabouraud dextrose agar or by visualization of sporangia containing sporangiospores on tissue biopsy (using hematoxylin/eosin, GMS, or PAS histochemical stains). The organism incites a chronic granulomatous inflammation with infiltrate of histiocytes, lymphocytes, giant cells and occasional eosinophils. The organism has thick wall, internal septations, measures 3-11 µm in diameter. The sporangia have very small wedge-shaped endospores arranged radially and moulded (morula-like form).[2]

Differential diagnosis: Protothecal sporangia may be confused with Coccidioides immitis, which are much larger

Antimicrobial therapy[edit]

Treatment is not standardized. Amphotericin B, itraconazole, posaconazole and voriconazole have all been tried.[1]


  1. ^ a b Curbelo A & Pankey GA (2009). "A man presenting with nodules on hands and elbows". Clin Infect Dis. 48 (8): 1160–1161. doi:10.1086/597466. PMID 19292636. 
  2. ^ a b John R. Goldblum (ed.). Foundations in diagnostic pathology.  Missing or empty |title= (help)