Bronchopneumonia. Light micrograph of a section through lung tissue showing bronchopneumonia. This is an infection of the air spaces (alveoli) in the lungs. The alveoli are filled with white blood cells (dark purple, centre left) here. This filling up of the alveoli leads to chest pain, a cough (often with green expectorate), fever, nausea and shortness of breath. In the case of a bacterial infection, treatment with antibiotic drugs is usually effective. In severe cases, oxygen may need to be administered. If left untreated, it can be fatal.