INTRODUCTION: Aureobasidium species are environmental dimorphic fungi that have been commonly implicated in allergic disease but have rarely been reported to cause true infection in humans. We report an unusual case of Aureobasidium pulmonary infection in an elderly woman with underlying Mycobacterium avium complex (MAC).
CASE PRESENTATION: A 78-year-old woman presented with one year of nonproductive cough, increasing dyspnea on exertion, intermittent fevers (101o F), night sweats and a 10% unintentional weight loss. She denied hemoptysis or upper respiratory tract symptoms. She was an avid gardener who lived in rural Ohio, never smoked, and denied travel. On examination she was afebrile, HR 100, RR 20, BP 182/100, SpO2 96% on room air. She appeared comfortable, cachectic, had a one centimeter palpable anterior cervical lymph node and a faint systolic murmur. The remainder of the physical exam, including the pulmonary exam, was unremarkable. A computed tomography (CT) of the chest revealed multifocal cavitary lesions and pulmonary nodules in the lungs, and bronchiolitis in association with bronchiectasis predominately in the lower lobes, middle lobe and lingula. A bronchoscopy was performed and the patient's airways appeared grossly normal. Bronchoalveolar lavage (BAL) review demonstrated marked acute inflammation (94% neutrophils) with necrosis as well as intra- and extracellular budding yeast with narrow-based budding. Acid fast cultures were positive for light growth of MAC. Fungal cultures revealed moderate growth of Aureobasidium species, and the minimum inhibitory concentration (MIC) of itraconazole was low at 0.12 μg/mL. The patient completed a three-month course of itraconazole with improvement of both her respiratory and constitutional symptoms.
DISCUSSIONS: Aureobasidium is a ubiquitous environmental dimorphic fungus that, in addition to causing allergic disease, can be a contaminant of external cultures. It is a dematiceous fungus that is often referred to as “black yeast.” Aureobasidium is infrequently encountered as a true opportunistic infection; most commonly reported is peritonitis associated with peritoneal dialysis cathethers. Tan et al1 reported the first known case of Aureobasidium pulmonary infection in a liver transplant patient. In our case, the large number of intracellular fungal elements identified on BAL smear and marked acute inflammation both indicate that the positive cultures are not the result of external contamination. Likewise, her clinical response to antifungal therapy suggests true symptomatic airway infection rather than colonization alone. This patient's mycobacterial infection most likely led to underlying lung disease (“Lady Windermere Syndrome”) predisposing her to infection by this typically benign environmental saprophyte. This is the first reported case of true pulmonary infection in a patient without severe immunocompromise.
CONCLUSION: Aureobasidium species can cause pulmonary infection in patients with immunologic abnormalities or underlying lung disease and may respond favorably to treatment with itraconazole.
DISCLOSURE: Meghan McCullers, No Financial Disclosure Information; No Product/Research Disclosure Information