Pneumococcal pneumonia in adults: Epidemiology, clinical features, diagnosis, and therapy

Rates of early mortality, within the first week after the onset of illness, have remained high for over 40 years, suggesting that, despite the availability of potent antimicrobials and intensive care support, prevention must be the keystone of the effective control of pneumococcal disease. A multivariate analysis of 129 adults hospitalized with community-acquired pneumococcal pneumonia in Edmonton, Canada, identified a history of smoking, fever, myalgia, chest pain, altered mental state, abdominal pain, and tachycardia as significant predictors of bacteremia. The presence of radiographic findings is key in establishing the diagnosis of pneumonia. Physicians may overdiagnose pneumonia based on patient histories and physical findings alone. With Gram staining and culture of expectorated sputum, rates of pathogen detection in comprehensive epidemiologic studies of CAP are only 30 to 50%, often with paired acute and convalescent serology for atypical organisms. The isolation of Streptococcus pneumoniae from cultures of specimens from normally sterile sites is relatively insensitive. Pneumococcal surface adhesin A (PsaA) is a conserved and highly immunogenic protein of S. pneumoniae expressed at the cell surface in all 90 pneumococcal serotypes. Underlying malignancy (both pulmonary and extrapulmonary) and the absence of fever also predicted lethal infection in most of the studies in which the variables were examined. The goal for clinicians and patients is improved survival, the more rapid resolution of disease and thus decreased need for admission and decreased length of hospital stays, and decreased cost.