ABSTRACT
Introduction There are a number of ways that bacteria can cause disease. Pharyngitis and vaginitis are examples of infections occurring on epithelial surfaces. In addition to these superficial infections, bacteria can cause disease by invasion of a site usually considered to be sterile, such as the bladder or the blood. When Streptococcus pneumoniae enters the blood, it is distributed throughout the body, and can invade other organs including the brain and heart, causing meningitis and endocarditis respectively.
