Pneumonia refers to inflammation and infection of the lungs. The air sacs may contain pus. Patients also commonly suffer from oxygen deprivation. This serious disease can result in death. Pneumonia has roughly 30 different possible causes, but the most common are bacteria, viruses and mycoplasmas. If you suspect you have pneumonia, see your doctor immediately. Your doctor will run tests, which may include a CAT scan of your chest, blood tests, including checking blood oxygen level, and tests for fluid in your lungs.