Pneumonia due to Legionella pneumophila and pneumococcal pneumonia: similarities and differences on presentation.

We compared clinical, radiological and laboratory data from 32 cases of community-acquired pneumonia due to Legionella pneumophila, with 37 cases of pneumococcal pneumonia (PP). This study revealed few clinical differences between the two types of pneumonia: in our experience Legionnaire's disease presents like a "typical" bacterial pneumonia. Given the difficulty of making a diagnosis on clinical data alone, we propose early aetiological diagnostic measures and recommend that the choice of initial treatment be based not only on the features at the time of presentation, but also on a consideration of the epidemiology of different types of pneumonia in a given area.