An empyema is a collection of thick, purulent fluid in the pleural space, usually developing after pneumonia. It is caused by bacterial infections such as streptococcus pneumoniae and staphylococcus aureus entering the pleural space through the lung or bloodstream. Risk factors include lung diseases and conditions weakening the immune system. Treatment involves needle aspiration, antibiotics, and sometimes surgery to remove infected tissue and drainage tubes. Nursing care focuses on airway clearance, nutrition, vital sign monitoring, and chest tube management.