The definitions and epidemiology of pleural space infection.

Infections of the pleural space are caused by a diverse group of clinical conditions that include trauma, post-operative states, and pneumonia. Although pleural effusions accompany bacterial pneumonia in up to 60% of patients, they uncommonly influence management because the effusion in most patients disappears with antibiotic administration. Unfortunately, the large number of patients with pneumonia provide an abundant supply of patients who fail to respond to antibiotic administration alone and subsequently present with pleural fluid loculation, pleural sepsis, or empyema. This article provides an overview of the classification schemes that have been used to characterize pleural space infections and highlight the epidemiology of those patients who present with complicated parapneumonic effusions and empyema.