Streptococcus pneumoniae

Streptococcus pneumonia are gram-positive bacteria responsible for most community-acquired pneumonia cases and 1-2 million infant deaths worldwide each year. There are over 100 serotypes of the bacteria, and they are found to naturally colonize in the nasopharynx without symptoms. However, in susceptible individuals such as babies and older adults, the bacteria can migrate to sterile tissues and organs and cause pneumonia over time. Diagnosis is by culture, antigen detection, or PCR. Rapid antigen testing using urine specimens is the most widely used test and relies on the detection of the group C polysaccharide cell wall antigen common to all pneumococcal strains.