English: This micrograph depicted details seen in a lung tissue specimen from a Knoxville patient with fatal pneumonia due to Legionnaires’ disease. The tissue was stained using hematoxylin-eosin (H&E) stain. Legionella pneumophila are Gram-negative bacteria. Using H&E stain, these organisms, if present in the specimen, would stain a pink or red color. Note how the alveolar spaces are so congested with a leukocytic infiltrate in response to the infection.