Meningoencephalitis due to Blastomyces dermatitidis: case report and literature review

Infection of the central nervous system by Blastomyces dermatitidis is a rare cause of meningoencephalitis. The existence of exclusive clinical infection of the meninges in the absence of pulmonary or other foci of infection has been debated. We describe a 20-year-old man presenting with meningoencephalitis caused by B dermatitidis. Blastomycotic infection was confirmed by isolation of the organism from brain tissue obtained at biopsy. Magnetic resonance imaging demonstrated progressive enhancement of basal meninges with involvement of bilateral basal ganglia and thalami. Treatment with amphotericin B arrested further neurologic decline. However, clinical and radiographic follow-up suggested damage to diencephalic structures. The diagnosis of blastomycotic meningoencephalitis is difficult to establish because no sensitive serologic test exists, and attempts to isolate the organism in cerebrospinal fluid obtained by lumbar puncture generally fail. A biopsy specimen of brain tissue is frequently necessary for the diagnosis. Survival is possible with timely initiation of therapy.