Can develop when pyogenic bacteria, fungi, parasites, or mycobacteria invade the pleural space, either from adjacent pneumonia or from direct inoculation (i.e. blunt trauma) or other source
Shen, K., Bribriesco, A., Crabtree, T., Denlinger, C., Eby, J., Eiken, P., Jones, D., Keshavjee, S., Maldonado, F., Paul, S., Kozower, B. The American Association for Thoracic Surgery consensus guidelines for management of empyema. J Thoracic and Cardiovascular surgery. 2017. 153(6):e129-e146.