Pneumococcal pneumonia.

Pneumococci remain the most common cause of community-acquired pneumonia, and there are still important questions concerning the pathogenesis, management, and prevention of this disease. Infection begins by aspiration of pneumococci from the oropharynx. Alveolar macrophages, granulocytes, and extra-cellular factors, including opsonins, are necessary for control of bacterial proliferation and cure of the infection. Clinically, pneumococcal pneumonia often presents with sudden onset of productive cough, fever, and a rigor, but symptoms may be muted in the young, elderly, or debilitated. About one-fourth of patients have a positive blood culture. Examination of sputum by Gram's stain and culture can provide useful information, but are not definitive. Tests for soluble pneumococcal antigen or the direct quellung reaction on sputum have not proved helpful. Pneumococci isolated from blood and spinal fluid should be tested for penicillin sensitivity routinely. Penicillin G and erythromycin are the mainstays of specific treatment, and rapid subjective improvement on narrow-spectrum therapy is an important point in diagnosis. The mortality rate continues to be about 18%, and prevention by vaccination remains a highly desirable goal.