Group B Streptococcus (Beta Strep) Infection

What is group B streptococcus (beta strep)?

Group B streptococcus (also called beta strep, or GBS), is a very common type of bacteria. Ten to thirty percent of pregnant women carry GBS bacteria, most often in the vagina or rectum. GBS bacteria are different from the type of bacteria that cause strep throat (group A streptococcus). Beta strep is not a sexually transmitted disease.

Healthy adults carrying GBS may not have any symptoms or problems. However, sometimes, the bacteria can cause an infection in the uterus, bladder, or kidneys. These infections are usually not serious and can be treated with antibiotics. The bacteria also usually do not cause any problems for babies. However, if a baby does get sick form the bacteria, the baby can develop very serious problems and could possibly die.

How does it occur?

Both women and men may have GBS. These bacteria often live in the mouth, bowel, bladder, vagina, and rectum. Parts of the body where GBS bacteria are living are said to be colonized. Being colonized means you are a carrier of the bacteria. A woman who carries GBS can pass it to her baby during labor or delivery.

How is it diagnosed?

GBS can be found by testing urine or samples from the vagina or rectum. The samples are cultured in a lab. A test result is positive if beta strep bacteria are found in the culture and negative if they are not found.

The Centers for Disease Control (CDC) recommends screening all pregnant women for GBS in the 35th to 37th weeks of pregnancy. The screening is down by taking a swab of the vagina and rectum and culturing the samples in the lab.

A rapid test for GBS may be done when you go to the hospital to deliver your baby. The results of this test can be known in 2 to 3 hours. However, it is less accurate than cultures and is rarely used earlier in a pregnancy.

If a baby gets infected with GBS, it may be detected only after the baby becomes sick, especially if all the mother’s tests have been negative. Once the baby is sick, it is often difficult to treat the baby effectively. for this reason, many women are treated automatically in labor if they have any risk factors. These risk factors are listed in the treatment section below.

How is it treated?

If your tests for beta strep are positive, you will probably not be treated until you are in labor. During labor you will then be given intravenous (IV) antibiotics. If you are treated earlier in the pregnancy, the bacteria could come back again before the baby is born. The one exception is when a urine culture, one at any time during pregnancy, shows that GBS is causing a bladder infection. In this case the doctor will probably prescribe an oral antibiotic right after receiving the test results to treat the bladder infections.

Because infection of the baby can cause serious problems, you may be treated automatically during labor if you have any risk factors for beta strep infection, even if test results are negative. The risk factors are:

  • pre-term (labor that begins before 37 weeks of pregnancy)
  • pre-term premature rupture of membranes (water breaking before 37 weeks of pregnancy)
  • membranes ruptured for longer than 18 hours
  • a previous child with beta strep infection
  • fever (higher than 100.4°F, or 38.0°C) during labor.

Treatment with IV antibiotics during labor is usually very effective. Babies rarely develop the serious side effects of early GBS infections with this treatment.

If a newborn develops any signs or symptoms of possible GBS infection, the baby is treated with IV antibiotics and observed very closely. The baby may be placed in a special intensive care unit.

How long will the effects of GBS last?

A woman who has GBS does not usually have any symptoms of illness or long-lasting effect. The main risk is that the newborn will be sick at or after birth. When a newborn is infected with GBS, the infection can affect the blood, brain, spinal cord, or lungs. These infections can be very serious. The baby may have long-term problems that affect hearing, vision, or learning abilities if meningitis develops. The baby might die.

GBS infections can be very dangerous to your baby. For this reason, if you have a positive GBS test or any of the risk factors, you will probably be treated with antibiotics during labor. This greatly reduces the risk to your baby.