A complicação mais frequente da pneumonia pneumocócica é:

Pleural effusions are a common finding in patients with pneumonia. More than 40% of patients with bacterial pneumonia and 60% of patients with pneumococcal pneumonia develop parapneumonic effusions.

Uncomplicated parapneumonic effusions: These are exudative, predominantly neutrophilic effusions reflecting increasing passage of interstitial fluid as a result of inflammation associated with pneumonia. The fluid may be slightly cloudy or even clear, without any organisms noted on Gram stain or culture. They resolve with appropriate antibiotic treatment of the pneumonia.

Complicated parapneumonic effusions: These occur as a result of bacterial invasion into the pleural space that leads to an increased number of neutrophils, decreased glucose levels, pleural fluid acidosis, and an elevated lactic dehydrogenase (LDH) concentration. These effusions often are sterile because bacteria are usually cleared rapidly from the pleural space. The fluid is typically cloudy and is classified as complicated because it requires drainage for resolution.

Empyema thoracis: This develops as frank pus accumulates in the pleural space. Laboratory studies indicate that preexisting pleural fluid is required for the development of an empyema because empyema is not seen after direct inoculation into a "dry" pleural space. The pus is seen after thoracentesis or any drainage procedure of the pleural space and is generally characterized as thick, viscous, and opaque.
 

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