What is Group B Strep and should you worry about it?
Group B Streptococcus (GBS) is a type of bacteria that can cause illness in people of all ages. In newborns, GBS is a major cause of meningitis (infection of the lining of the brain and spinal cord), pneumonia (infection of the lungs), and sepsis (infection of the blood).
Group B strep lives in the intestines and migrates down to the rectum, vagina, and urinary tract. All around the world, anywhere from 10-30% of pregnant women are “colonized” with or carry GBS in their bodies.
Sometimes GBS can cause a urinary or vaginal infection in pregnant women. That is why you have the urine test at the beginning of the pregnancy.
How often do newborns become infected with GBS?
There are 2 main types of GBS infection in newborns: early infection and late infection. Early infection occurs in the first 7 days after birth. When a baby has an early GBS infection, symptoms usually appear within the first 12 hours, and almost all babies will have symptoms within 24-48 hours.
Early infection is caused by direct transfer of GBS from the mother to the baby, usually after the water breaks. The bacteria travel up from the vagina into the amniotic fluid, and the fetus may swallow some of the bacteria into the lungs—leading to an early GBS infection. Babies can also get GBS on their body (skin and mucous membranes) as they travel down the birth canal. However, most of these “colonized” infants stay healthy.
In Australia between 1 and 4 in 1000 babies develop early GBS disease.
If a mother who carries GBS gives birth, the baby’s risk of becoming colonized (getting it on their skin, or in their lungs or gut) with GBS is approximately 50% and the risk of developing a serious, life-threatening GBS infection is 1 to 2%. Please remember, however that nearly all colonized babies stay healthy.
How is it treated by Dr Wilson at Norwest Private Hospital?
I suggest you are screened for GBS and consider treatment if positive. Side effects of the antibiotic are possible – anaphylaxis, thrush, mastitis while breastfeeding. The evidence shows a trend towards a reduction in sick babies but no reduction in deaths with treatment. Still worthwhile if you’re the parent!!
If after careful consideration you decide you wish to receive treatment for a positive GBS swab result, we offer you IV antibiotics in labour at Norwest Private Hospital. The antibiotic is checked against your allergy status. You are free to move around the labour ward as the drip is not connected to an IV pole. I do not suggest immediate induction with ruptured membranes if you are GBS positive.
You do not require treatment if you elect to deliver via caesarean section and your waters are intact prior to the birth. Testing is still performed in case yo break your waters early. Some local obstetricians suggest oral antibiotic treatment at the time of diagnosis and again in labour. This is not evidence based and increases the chances of you developing an antibiotic related complication or a resistant strain of bacteria which is harder to treat.
What is the risk of death if the baby has an early GBS infection?
Researchers have estimated that the death rate from early GBS infection is 2 to 3% for full-term infants. This means of 100 babies who have an actual early GBS infection, 2-3 will die. Death rates from GBS are much higher (20-30%) in infants who are born at less than 33 weeks gestation.
Although the death rate of GBS is relatively low, infants with early GBS infections can have long, expensive stays in the intensive care unit. Researchers have also found that up to 44% of infants who survive GBS with meningitis end up with long-term health problems, including developmental disabilities, paralysis, seizure disorder, hearing loss, vision loss, and small brains. Very little is known about the long-term health risks of infants who have GBS without meningitis, but some may have long-term developmental problems.
Are some newborns more likely to get early GBS disease?
The primary risk factor for early GBS infection is when the mother carries GBS. However, there are some things that increase the risk of early GBS infection:
- Being born at less than 37 weeks
- A long period between water breaking and giving birth (greater tha 18 hours)
- Water broke before going into labor (premature rupture of membranes)
- High temperature during labor (> 99.5 F or 37.5 C)
- Infection of the uterus
- Mother previously gave birth to an infant who had an early GBS infection
- Fetal distress diagnosed in labour
- Difficult vaginal delivery
However, about 60% infants who develop early GBS infection have no major risk factors, except for the fact that their mothers carry GBS.
How accurate is testing for GBS?
Testing is performed using a vaginal swab test at 35 – 37 weeks. My patients do this themselves at home and bring the swab in to a visit.
Of the women who screen negative for GBS at 35-36 weeks, 91% are still GBS-negative at the time of birth.
Of the women who screen positive for GBS at 35-36 weeks, 84% are still GBS positive during labor.
There is a small false negative rate and a larger false positive rate.
What is the evidence for antibiotics during labor to prevent early GBS infection?
The evidence for treatment is ambiguous. Not all Australian obstetricians screen and treat for GBS. The evidence shows that screening does not reduce the chance of your baby dying from GBS, but it will reduce the chances of your baby becoming sick and requiring nursery admission and treatment. This is still a very stressful process for new parents!
In the late 1980’s, three groups of researchers randomly assigned women with GBS to either receive IV antibiotics during labor or no antibiotics.
In a recent review, researchers combined the results of these 3 studies that had a total of 500 pregnant women. They found that when women with GBS had antibiotics during labor, their infants risk of catching early GBS infection dropped by 83%. The chances of dying were not reduced.
How will antibiotics during labor affect my baby’s microbiome?
There is little evidence available on this topic.
We see increasing rates of mastitis in mothers when antibiotics are used for GBS in labour.