(539) Pulmonary Blastomycosis and the Role of Bronchoscopy in Diagnosis

Introduction: Pulmonary blastomycosis is a rare and potentially serious fungal infection caused by Blastomyces dermatitidis(B. dermatitidis), a dimorphic fungus endemic to the central and southeastern United States, that primarily affects the respiratory system. Pulmonary blastomycosis poses a significant health concern due to its broad symptoms.

Description: A 50 year old male with a past medical history of uncontrolled type 2 Diabetes mellitus and a recent trip to Mississippi who had recently completed a course of oral antibiotics for pneumonia was admitted with sepsis secondary to a suspected right-sided bacterial pneumonia. He endorsed night sweats, fatigue and a 20 pound weight loss over the past 2 weeks. He was febrile on admission with a temperature of 100.6 degrees fahrenheit. Initial laboratory investigations were significant for elevated inflammatory markers including a white blood cell count of 27,000/µL and a procalcitonin of 1.14 ng/mL. A computerized tomography scan of the chest showed a worsening confluent airspace opacity in the right lung with additional patchy/nodular infiltrates bilaterally. Broad-spectrum antibiotics with intravenous meropenem and doxycycline were initiated in consult with the Infectious Diseases team. The pulmonology team performed a diagnostic bronchoscopy notable for copious purulent secretions in the right upper lobe, with broad-based budding yeast resembling B. dermatitidis seen on a fungus smear of the collected samples. He also tested positive for serum Blastomyces antigens. The antibiotics were switched to liposomal amphotericin B and the patient was briefly admitted to the intensive care unit due to a high likelihood of clinical decline and risk of pulmonary hemorrhage from extensive pulmonary infiltration.

Discussion: B.dermatitidis usually causes pulmonary infection in immunocompetent individuals. Disseminated infection to the brain, gastrointestinal tract and skin can occur in immunocompromised patients. Because the symptoms mimic other conditions and the slow-growing nature of the fungus limits culture analysis, diagnosis is often delayed. Rapid diagnosis can be made on microscopic examination of samples obtained from bronchoalveolar lavage, which should be performed as soon as possible in suspected cases to prevent mortality.