Streptococcus pneumoniae (pneumococcus) is a Gram-positive bacterium that is responsible for the majority of community-acquired pneumonia. It is a commensal organism in the human respiratory tract, meaning that it benefits from the human body, without harming it. However, infection by pneumococcus may be dangerous, causing not only pneumonia, but also bronchitis, otitis media, septicemia, and meningitis. Pneumococcal infection is responsible for 1-2 million infant deaths worldwide, every year. S. pneumoniae is alpha-hemolytic, meaning that it can break down red blood cells through the production of hydrogen peroxide (H2O2). The production of H2O2 by the bacterial infection can also cause damage to DNA, and kill cells within the lungs.