Clinical Potential of C-Reactive Protein and Procalcitonin Serum Concentrations To Guide Differential Diagnosis and Clinical Management of Pneumococcal and Legionella Pneumonia

Abstract

We retrospectively analyzed the records of 61 hospitalized patients with community-acquired pneumonia (CAP) caused by S treptococcus pneumoniae or L egionella pneumophila . We found that serum procalcitonin and sodium concentrations were significantly lower, and ferritin levels were significantly higher, in patients infected with L. pneumophila than in those infected with S. pneumoniae . The ratio of C-reactive protein to procalcitonin significantly distinguished between the groups. High procalcitonin levels were associated with an adverse clinical course.