Management of Cryptococcus gattii meningoencephalitis

Abstract

Cryptococcosis is a fungal disease caused by Cryptococcus neoformans and Cryptococcus gattii. By inhalation and subsequent pulmonary infection, it may disseminate to the CNS and cause meningitis or meningoencephalitis. Most cases occur in immunosuppressed hosts, including patients with HIV/AIDS, patients receiving immunosuppressing drugs, and solid organ transplant recipients. However, cryptococcosis also occurs in individuals with apparently healthy immune systems. A growing number of cases are caused by C gattii, with infections occurring in both immunosuppressed and immunocompetent individuals. In the majority of documented cases, treatment of C gattii infection of the CNS requires aggressive management of raised intracranial pressure along with standard antifungal therapy. Early cerebrospinal fluid evacuation is often needed through placement of a percutaneous lumbar drain or ventriculostomy. Furthermore, pharmacological immunosuppression with a high dose of dexamethasone is sometimes needed to ameliorate a persistently increased inflammatory response and to reduce intracranial pressure. In this Grand Round, we present the case of an otherwise healthy adolescent female patient, who, despite aggressive management, succumbed to C gattii meningoencephalitis. We also present a review of the existing literature and discuss optimum clinical management of meningoencephalitis caused by C gattii.

Figure 1

T2-weighted axial images demonstrating hyperintense lesions (arrows) at the basal ganglia consistent with multiple gelatinous pseudocysts in the perivascular spaces (dilated Virchow-Robin spaces with mucoid capsular material of Cryptococcus spp)

Figure 2

Coronal sectioning through the brain showing numerous pseudocysts throughout the basal ganglia bilaterally containing fungal organisms histologically consistent with Cryptococcus spp

Figure 3

Micrographs of brain parenchyma showing a pseudocyst. Cryptococcus spp was identified in the perivascular space where it induced marked oedema, inflammation, and necrosis of the surrounding parenchyma. Haematoxylin and eosin staining 40× magnification.

Figure 4

Cryptococcus gattii isolated on canavanine-glycine bromothymol blue (CGB) agar. C. gattii turns the medium blue by assimilation of glycine, which changes the pH. Cryptococcus neoformans does not grow in the presence of canavanine and will not affect the colour change.