Case of the Month - August 2020
"A big thanks - and a big welcome - to Rebecca Marrero Rolon, our new Associate Director of Microbiology, who prepared this month's case."
A 74-year-old male was hospitalized for shortness of breath, weakness, and syncope.
His medical history was notable for hypertension, type 2 diabetes, hyperlipidemia, hypothyroidism, stents for coronary atherosclerosis, and a left lung transplant in 2019 for pulmonary fibrosis that caused chronic hypoxic respiratory failure and significant shortness of breath at rest. He had a long post-operative course due to several episodes of bacterial pneumonia that was treated empirically with broad-spectrum antibiotics; no bacteria were recovered from cultures. Since leaving the hospital he had been doing well, requiring supplemental oxygen only occasionally, with shortness of breath only when exerting himself. Bronchoscopy was done at his scheduled 6 month post-transplant evaluation, and specimens were collected via bronchoalveolar lavage for bacterial, mycobacterial, and fungal cultures, and biopsies done to assess for rejection. At that time a small left pleural effusion was noted on a CT scan of the chest.
One month after the bronchoscopy, he was hospitalized with shortness of breath and weakness, after having briefly passed out. Another chest CT showed new ill-defined nodules in the transplanted lung, with an increase in the size of the pleural effusion. The patient was started on voriconazole for suspected fungal pneumonia and broad-spectrum antibacterials.
Several days after hospitalization, growth was noted from the respiratory fungal cultures obtained at the bronchoscopy a month earlier and plated on the inhibitory mold agar plate. The colonies were black, moist and shiny when viewed from above, with a black reverse (i.e., when viewed through the agar, Figure 1). A few budding yeast-like cells were seen on microscopic examination. After subculture and further growth, a lactophenol cotton blue stain was performed, which showed pigmented septate hyphae and round to oval, single-celled, pale brown conidia that accumulated at the apex of the conidiophore (Figure 2).
Name the fungus or its category.
Figure 1: growth on inhibitory mold agar.
Figure 2: lactophenol blue stain.