The first case of intracerebral lesions caused by Prototheca wickerhamii

Abstract

• First case of intracerebral lesions due to Prototheca wickerhamii. • Specialist review of histology helped determine the diagnosis. • The diagnosis was confirmed by both culture and molecular techniques. • Antimicrobial susceptibility testing for Prototheca is challenging to interpret. • There is a lack of evidence for best treatment regimens. This paper describes the first case in the literature of Prototheca wickerhamii infection causing intracerebral lesions. A 55 year old female presented with progressive neurology and multiple lesions on brain MRI scanning. Initial histology from a brain biopsy was reported to show changes compatible with toxoplasmosis. There was no evidence of immunocompromise and this diagnosis was felt to be unlikely. A specialist infectious disease histopathology opinion was requested and results were reported as consistent with protothecosis. Repeat biopsy grew Prototheca wickerhamii confirming the diagnosis. Antimicrobial susceptibility testing was arranged but was challenging to interpret due to lack of clinical break points for this species . A number of treatments were trialled but stopped due to toxicity, antimicrobial resistance on testing or lack of efficacy. Eventually treatment with liposomal amphotericin B was given for 18 months. Two years after treatment ceased the patient remains stable and appears cured of infection. This case highlights Prototheca spp. as a rare cause of central nervous system infection and reports the first case of intracerebral lesions caused by Prototheca wickerhamii . Lack of evidence for treatment, antifungal drug toxicity, difficulties with antimicrobial susceptibility and drug tissue penetration were a challenge. Also demonstrated is the importance of a specialist opinion, in this case histopathology, which ultimately determined the diagnosis.