This study will examine the different types of proteins present in the lungs of patients with pneumonia to explore the causes of different types of the disease. Pneumonia is a condition that causes lung inflammation AND is often caused by an infection. It is usually diagnosed by lung x-rays and listening to the chest with a stethoscope. This method can diagnose pneumonia, but it does not provide information on the cause of the inflammation - information that might be helpful in guiding treatment. This study will measure proteins in the lungs of patients to see if certain proteins are associated with specific forms of pneumonia, and can thus serve as biomarkers for disease.