Group B Streptococcus (GBS) is a common type of bacteria that frequently resides in the human body. It is often found in the intestines and the lower genital tract. While GBS can potentially cause illness, it is typically harmless in healthy adults.
Understanding Group B Streptococcus
Group B Streptococcus, also known as Streptococcus agalactiae, is a bacterium that naturally colonizes the gastrointestinal and genitourinary tracts of many healthy individuals. Most people who carry GBS bacteria do not experience any symptoms or illness. The presence of GBS in the body, without causing disease, is referred to as colonization.
How GBS Spreads
Group B Streptococcus is commonly acquired through vertical transmission, especially from a pregnant individual to their baby. This transmission occurs when the baby passes through the birth canal during a vaginal delivery. The baby can be exposed to GBS through the mother’s genital fluids or by inhaling or swallowing the bacteria during birth. In some cases, GBS can also spread from the vagina into the uterus before birth, particularly after the membranes rupture.
This asymptomatic carriage is not typically “spread” in the same way as a common cold or flu. While GBS can exist on surfaces or be passed through direct physical contact, symptomatic infection from casual contact is rare in healthy adults.
It is important to understand that GBS is not considered a sexually transmitted infection (STI). It is also not spread through contaminated food or water. The bacteria that causes GBS is different from the Group A Streptococcus bacteria, which is responsible for conditions like strep throat.
Populations at Higher Risk
While many people carry GBS without issue, certain populations face a higher risk of developing a serious infection if they are colonized with the bacteria. Newborns are particularly vulnerable to GBS infection due to their immature immune systems. They can acquire the bacteria during passage through the birth canal, leading to potential severe illness.
Pregnant individuals, though often asymptomatic carriers, are a focus because of the risk GBS poses to their babies. Factors such as preterm labor, prolonged rupture of membranes, or fever during labor can increase the risk of GBS transmission to the newborn.
Adults with underlying health conditions also face an elevated risk of GBS infection. Conditions like diabetes, liver disease, or weakened immune systems can make individuals more susceptible to the bacteria causing illness. Cancer, congestive heart failure, and obesity are also associated with increased risk. Additionally, elderly individuals are at a higher risk for serious GBS infections. This risk increases with age, particularly for those 65 years or older.
When GBS Becomes an Issue
However, GBS can lead to serious health problems, especially in newborns. In infants, GBS infection can cause severe conditions such as sepsis (bloodstream infection), meningitis (infection of the lining of the brain and spinal cord), and pneumonia (lung infection). These infections can manifest shortly after birth, often within the first 24 hours. While less common, GBS can also cause infections in adults, including urinary tract infections, skin infections, bloodstream infections, and pneumonia.