I agree that it is extremely unlikely for a immune competent 13 month
old child to have a Candidal infection into the lungs.  Even if he were
taking steroids.  You can't make a diagnosis of a cause of pneumonia by
the x-ray.

If it were Candida, you would not expect nystatin, which works locally,
and not absorbed by the gut, to work on infection in the lung.  I would
be extremely concerned about a Candidal infection in the lung, and would
treat aggressively with fluconazole--if it were Candida, which I doubt.
Probably much more likely viral.

Jack Newman, MD, FRCPC