A patient undergoing chemotherapy develops a cough. Acid-fast stain of his sputum shows rods and slightly longer forms, with some branching; they vary in their acid-fast reaction from one area of the slide to the next. The acid-fast stain was performed by an experienced medical technologist and, when redone, showed the same variation. The growth was done aerobically. What is the most likely agent?
Either Nocardia or MAI is possible from the clinical scenario, but the most likely agent from the acid-fast stain description, the focus of the question, is Nocardia. Also, MAI would not grow in 2days (so some mention of time would be made) and Actinomyces would only grow anaerobically, which would also be stated. Chlamydophila would not grow except in tissue culture.
Actinomyces
Chlamydophila
Mycobacterium an-intracellular (MAIor MAC)
Nocardia
Systemic Bacteriology (Gram Positive Bacilli, Gram Negative Bacilli)