Fungal Abscess, Cerebral

Abstract

Fungal brain abscess is a complication of immunosuppression and is rarely seen in immunocompetent patients, with the exception of Blastomyces dermatitidis. Infection with this fungus is primarily related to occupation, specifically soil-associated occupations such as mining. Cryptococcus neoformans, Histoplasma capsulatum, and Coccidioides immitis may cause brain abscess(es) in seemingly immunocompetent individuals. The fungi that cause brain abscesses, either solitary or multiple, in immunocompromised hosts are Aspergillus species, Candida species, and rare fungi. The Zygomycetes are a group of ubiquitous molds that cause fungal brain abscesses in immunocompetent diabetic patients with ketoacidosis and in diabetic transplant recipients receiving immunosuppressive therapy. In general, in immunocompromised patients, the risk of a fungal brain abscess increases when pulmonary colonization by a fungus occurs in the setting of retransplantation, hemodialysis, ventilator dependence, and/or multiple operations. Diagnosis of Aspergillus central nervous system (CNS) infection typically requires culture of brain abscess pus or culture of a surgical specimen from a brain biopsy. Aspergillus galactomannan is sensitive for invasive Aspergillus infections and should be sent as part of the routine diagnostic studies. 1,3-Beta-d-glucan is a sensitive diagnostic test for invasive fungal infections. Intracranial mass lesions in immunocompromised patients, detected on computed tomographic or magnetic resonance imaging scan, are less likely to show enhancement due to an inadequate inflammatory response than are similar lesions in nonimmunocompromised patients. Aspergillus brain abscess or abscesses require aggressive management. A combination of aspiration or excision with antifungal therapy is the standard of care. Voriconazole is the preferred antifungal agent. CNS Candida infections are treated with a combination of amphotericin B and flucytosine. Rhinocerebral mucormycosis requires aggressive surgical debridement of devitalized infected tissue in addition to amphotericin B therapy.