Some food products or supplements may contain Brewers yeast. These will appear in the Gram Stain, but this yeast is not alive and doesn't cause problems in the bird, therefore, it should not be treated as a yeast infection. Yeast that have been affected by antifungal treatments will appear as hollow blue shells. It is important to take your parrot to a knowledgeable Avian Veterinarian and to follow their advice. Remember, a few yeast are considered normal in the Gram Stain of a healthy bird.
Preventative measures are always better than the treatment of a disease condition.
Make sure your birds are on healthy balanced diets. Make sure their environment is reasonably clean. Cage papers should be changed daily. Wash and disinfect food and water bowls daily. Fresh foods should be offered, but never left for more than a few hours in the cage.