The gold standard for diagnosis of pleural space infection is a microbiological culture of pathogens in pleural fluid. Pleural fluid is secreted by mesothelial cells from both pleural layers and acts to lubricate their surfaces. Pleural infection should also be suspected in those with a non-resolving pneumonia despite appropriate antibiotic therapy (i.e., ongoing fevers, poorly resolving C-reactive protein, or high white cell count). The pleurae perform two major functions: They produce pleural fluid (serous fluid) and create cavities that separate the lungs from each other and other thoracic structures. However, it was the Greek physician Hippocrates who, recognizing the severity of these infections, first attempted drainage of the pleural cavity over 2000 years ago. The pleural cavity is the space between the visceral and parietal layers. Pleural space infections have been recognized as a cause of disease since at least 3000 BC when first described by the Egyptian physician Imhotep. The visceral and parietal pleurae connect to each other at the hilum. In contrast, the parietal pleura is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm.
