Risk factors for community-acquired pneumonia include human immunodeficiency virus (HIV) infection, alcoholism, influenza in the community, injection drug use, smoking, diabetes, and chronic obstructive pulmonary disease (COPD). In adults, Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. In addition, it is a leading cause of bacteremia and meningitis.
S. pneumoniae is capable of producing very severe disease and often life-threatening infections upon entering the bloodstream and the meninges. It is a leading cause of bacteremia and meningitis, and also a major cause of sinusitis and acute otitis media. The virulence of the organism is primarily due to the antiphagocytic properties of the polysaccharide capsule.
The pneumococcal vaccine is most effective in older individuals, who can still mount an antibody response, although somewhat compromised in the elderly. Antibody responses are minimal or absent in the under 2-year-old age group of children. Vaccination is recommended for the following:
- Adults over age 65
- Individuals with chronic pulmonary, cardiac, renal, or liver disease
- Anyone with a compromised immune system, including HIV
- Patients that have undergone a spleenectomy
- Individuals with sickle cell