Management of Parapneumonic Effusions

Pleural effusions associated with pneumonia (parapneumonic effusions) are one of the most common causes of exudative pleural effusions in the world [1]. Approximately 20 to 40% of patients hospitalized with pneumonia will have an accompanying pleural effusion [1]. The presence of a pleural effusion is associated with worse outcomes in patients with pneumonia. In one study of patients hospitalized with pneumonia the mortality risk was 6.5 times higher if the patient had bilateral pleural effusion and 3.7 times higher if the effusion was unilateral than if the patient had no pleural effusion [2]. At least part of the increased mortality with parapneumonic effusions is due to mismanagement of the pleural effusion. The likelihood of developing a pleural effusion with a bacterial pneumonia is dependent upon the organism responsible for the pneumonia. The distribution of organisms responsible for parapneumonic effusions is quite different from the distribution of organisms responsible for pneumonia in general. Organisms responsible for community and hospital acquired pneumonia with complicated parapneumonic effusions also differed considerably in a recent multicenter study from the United Kingdom [3]. For the 336 patients with community acquired pneumonias with parapneumonic effusions in whom the responsible bacteria were identified, the most common organisms were Strept. Milleri group 32%, anaerobes 16%, Strep. pneumoniae 13% and Staph. aueus 11%. For the 60 patients with hospital-acquired pneumonia, the most common organisms were multiple resistant Staph. aureus 28%, other Staph. 18%, Enterobacteriacea 15% and Enterococci 13% [3]. These numbers should be kept in mind when selecting antibiotics for patients with parapneumonic effusions.