Chest ImagingStreptococcus pneumonia
Streptococcus pneumoniae is a Gram-positive diplococcus with a well-formed
capsule. This organism is one of the commonest seen in community-acquired pneumonias, accounting for up to 25% of these infections. In the preantibiotic era streptococcal pneumonia or pneumococcal pneumonia had a high fatality rate, being a frequent cause of death in the elderly. Today certain serotypes of
S. pneumoniae will rarely produce necrotizing abscesses in the lung. Usually, however, pneumococcal pneumonia presents as homogeneous
air space consolidation occupying a portion of a segment or lobe of lung particularly in the periphery.
Air bronchograms are frequently identified as evidence of
parapneumonic effusion (
Fig.1). Both single and multiple lobes may be involved.
Radiographic evidence of
resolution is generally identified within a few days of appropriate antibiotic therapy. Complete
resolution of the pneumonia, however, may be delayed for several weeks. Clinically patients present with high fever, chills, productive cough, and occasionally pleuritic pain. In patients with a healthy immune system the prognosis with appropriate antibiotic therapy is very good. However, in patients with a failure to develop leukocytosis the mortality rate is very high.
PGO
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A PA chest film demonstrates homogeneous opacity in the left upper lobe and lingula and a second focus of homogeneity in the right midlung. Air bronchograms are seen in the lingular component and there is a small left pleural effusion identified. These findings are typical of S. Pneumoniae infections. Resolution is generally rapid with complete clearance seen within 2 weeks in the majority of patients on appropriate antibiotic therapy. Parapneumonic effusions are common.
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Streptococcus pneumonia, Fig.1 | |