Fungal Infections of the CNS

Infections with fungi cause significant morbidity in the immunocompromised host and invasion of the CNS may lead to devastating consequences. Vulnerable individuals include those with haematological malignancies, transplant recipients, and those infected with HIV. Potential pathogens include yeasts, Aspergillus spp., other moulds of an increasing variety, and a range of dimorphic fungi, often associated with particular geographical locations. Antifungal treatments include polyenes such as amphotericin B and its lipid formulations, azoles such as fluconazole and itraconazole, and the more recent voriconazole and posaconazole. The new antifungal class of echinocandins, such as caspofungin, micafungin and anidulafungin, typically lack CNS penetration. Amphotericin B and flucytosine are used to initiate treatment for CNS yeast infections caused by Candida and Cryptococcus neoformans. Voriconazole is preferred for aspergillus, although amphotericin B, particularly in lipid formulation, is also useful. Reliable treatment data are lacking for CNS infections with most of the non-aspergillus moulds; posaconazole holds promise for the zygomycetes and perhaps some of the rarer pigmented fungi, but amphotericin B preparations are still recommended. Oral fluconazole is effective for the CNS manifestations of coccidioides, while histoplasmosis and blastomycoses typically require amphotericin B therapy. Effective treatment requires a definitive diagnosis, which is often challenging in the population at risk of CNS fungal infections.