Group B strep can also cause serious diseases in pregnant women, the elderly, and adults with other illnesses. In adults, group B strep usually causes no symptoms. However, in rare cases, it can lead to serious bloodstream infections, urinary tract infections, skin infections, and pneumonia, especially in people with weakened immune systems and other health problems, such as diabetes. Group B strep bacteria are different from many other types of bacteria that can cause disease. This means that they carry the bacteria in their bodies but are not infected and do not become sick.
Adults can carry the bacteria in the gastrointestinal tract, genital tract, or urinary tract.
Colonization with group B strep is usually harmless. The bacteria can become deadly, though, if something happens that allows them to invade the bloodstream. In adults, weakened immunity resulting from cancer treatment or a chronic illness can prompt an infection. More often, pregnant women who carry the bacteria can unknowingly transmit group B strep to their newborns at birth. Newborns can acquire early-onset group B strep disease either before or during delivery.