10-28-2014, 03:24 PM
A 41-year-old woman with a history of severe rheumatoid arthritis presents with persistent nonproductive cough, chest pain aggravated by inspiration, and shortness of breath for the past few weeks. The patient also notes new diffuse joint pain, fatigue, and night sweats. She lives with her husband in Arizona, smokes 1 pack per day, and denies any recreational drug use or recent travel overseas. She currently takes methotrexate, prednisone, and etanercept. Her temperature is 38.3°C (101°F), pulse is 98/min, respiratory rate is 22/min, and blood pressure is 130/72 mm Hg. Physical examination is significant for a maculopapular rash on the lower extremities and mild respiratory crackles bilaterally. Initial Gram stain of sputum is negative. X-ray of the chest is notable for nodular infiltrates and mediastinal adenopathy. Which of the following is a laboratory characteristic of the most likely etiology of this patient's symptoms?
A. Red stain following carbol-fuchsin, heat, acid alcohol, and methylene blue preparation.
B. Growth requires buffered charcoal yeast extract with L-cysteine
C. Growth as hyphae at 25 C on Sabouraud's agar and as spores at 37 C on blood agar.
D. Fried egg appearance and dome-shaped colonies in culture containing cholesterol and nucleic acids.
E. Capsule swelling after application of antiserum and methylene blue.
Please explain your answer
A. Red stain following carbol-fuchsin, heat, acid alcohol, and methylene blue preparation.
B. Growth requires buffered charcoal yeast extract with L-cysteine
C. Growth as hyphae at 25 C on Sabouraud's agar and as spores at 37 C on blood agar.
D. Fried egg appearance and dome-shaped colonies in culture containing cholesterol and nucleic acids.
E. Capsule swelling after application of antiserum and methylene blue.
Please explain your answer