Having group B streptococcus bacteria, or strep, in the urine is not uncommon, nor is it usually a sign of an illness, according to Mayo Clinic. Many healthy people carry strep in their bodies, often in their rectums vaginas or bladders, and urine is easily contaminated from any of these sites.
Although group B strep is not dangerous in most healthy adults, the bacteria can cause serious infections in susceptible individuals, particularly infants, pregnant women and anyone over 65, explains Mayo Clinic. In infants, infections often cause life-threatening complications, such as pneumonia, meningitis and bacteremia, an infection in the blood. Pregnant women are at risk for streptococcal infection of the urinary tract, amniotic fluid, uterine lining and blood. Older persons are susceptible to pneumonia; urinary tract infections; and bone, joint or skin infections due to group B strep.
Doctors don't know why some people develop infections from the streptococcus bacteria while others don't, explains MedicineNet. However, they know that mothers who carry the bacteria sometimes transmit it to their unborn children during and prior to delivery. Since the 1990s, routine screening for group B strep in pregnant women and the administration of antibiotics during labor to those who test positive has decreased the incidence of neonatal streptococcal disease by about 80 percent. As of 2015, there is no vaccine that prevents the disease.