Pneumococcal disease (PD) is infectious disease caused by Streptococcus pneumoniae (pneumococcus). PD is particularly common in younger children and in older adults and is roughly divided into invasive and non-invasive disease; the former refers to infections in which the microorganism is isolated from normal sterile body sites, such as the blood or the cerebrospinal fluid. Non-invasive PD can principally be divided into sinusitis, acute otitis media, and community-acquired pneumonia. S. pneumoniae remains the most common bacterial cause of community-acquired pneumonia. The invasive PD burden is mainly determined by pneumococcal meningitis, bacteremic pneumococcal pneumonia, and pneumococcal bacteremia without a primary focus. Incidence and mortality rates of both non-invasive and invasive disease have changed as a result of pneumococcal vaccination in children. However, especially elderly patients with comorbidities remain vulnerable to morbidity and mortality caused by PD.
