What is GBS?

Group B strep – or GBS – is a normal bacterium that is carried around by about 30 per cent of adults at any one time. Many of the organisms that cause disease are present in our bodies although they are not active – it’s as though something triggers them into activity and that’s when they start causing problems.

Labour can be the trigger for this bacterium. About 10 to 20 per cent of women carry GBS in their vaginas and rectums without knowing they are carriers. But when they give birth, there is a risk that they will transmit GBS to their newborn.

Most babies are not affected by their mother being a carrier and do not get infected but those who do can develop serious, life-threatening conditions, including sepsis (blood poisoning), pneumonia and meningitis. GBS is the most common cause of blood infections and meningitis in newborns. The good news is that up to 90 per cent of GBS diseases in newborns can be prevented by giving certain pregnant women antibiotics during labour.

Professor David Hall of the Department of Gynaecology and Obstetrics at Tygerberg Academic Hospital, University of Stellenbosch, says, “It’s important to place this in perspective. Although colonised women have a 70 per cent chance of passing GBS on to their babies, only one to two per cent of babies will develop illness, and most of these will be preterm babies.

“They are more susceptible because the closer to full-term the baby is, the more antibodies the mother will have passed on to the baby. The prevalence – that is the number of carriers – varies according to socio-economic status. It is very much lower in the higher socio-economic groups.”

Who gets GBS, and how?
GBS is a bacterium that may be present in the vagina or rectum of about 10 to 20 per cent of healthy, adult women. It may be passed by sexual contact, but it is not classified as a sexually transmitted disease. There are usually no symptoms, so the only way to find out if you are a carrier is to have a test.

Prof Hall points out that testing is not routine in SA because the prevalence is not high enough in normal, healthy pregnancies. “If a risk factor is identified, then we would investigate,” he says. There are no statistics locally, but in the UK around 700 babies get GBS infections each year; and between 70 and 100 of these babies die. A further 40 more are left with serious long-term mental or physical problems.

How do I get tested?
The test is painless and involves having a swab inserted into your vagina and rectum to take a sample to see whether the bacteria can be cultured, ie. grown in a laboratory. It may take a couple of days for your doctor to get the results.

Risk factors & treatment

When should I be tested?
The test can be done at any time during pregnancy, but it only reflects the amounts of bacteria in your body on that day. This means that even if your test result is negative, there could still be small amounts of bacteria present, so you might have more bacteria on the day you give birth. The US Centres for Disease Control recommends screening at 35 to 37 weeks to give a more accurate reflection of the bacterial activity closer to delivery.

What if I test positive?
Testing positive for GBS does not mean your baby is automatically at risk. Studies have shown that the greater the amount of bacteria, the greater the risk. If your doctor thinks you are likely to pass GBS on to your baby, after considering various risk factors, he or she will probably suggest you have preventive treatment, ie. anti­biotics during labour.

Can I take antibiotics before labour to get rid of the bacteria?
Unfortunately, a course of antibiotics taken before the time is no guarantee that you will be free of the bacteria on the day you give birth. You need to have intravenous antibiotics DURING labour.

What are the risk factors for passing on GBS?
Your baby is at greater risk of developing GBS infection if:

• You have a high temperature (more than 38ºC) during labour
  
• You go into preterm labour (before 37 completed weeks of pregnancy)
  
• Your waters have broken early
  
• Your waters have broken for more than 12 hours.
  

If any of these risk factors is present, your doctor should discuss the possibility of giving you antibiotics during labour.

What antibiotics are used?
Penicillin is commonly used, so if you have ever had an allergic reaction to penicillin or any other antibiotic, it’s important to tell your doctor. Even if you have discussed this beforehand, remind your doctor and the nurses of any allergies at the time of labour.

How does GBS infection affect newborn babies?
GBS infection occurs as either early-onset GBS (within the first week) or late-onset GBS (after seven days and up to three months). GBS infections can affect the blood, lungs, brain and spinal cord of newborns, causing septicaemia (blood poisoning), pneumonia or meningitis (infection of the lining of the brain).

All of these are life-threatening conditions, and although many babies who survive these infections have no long-
term damage, some may suffer permanent disabilities: mild learning disabilities, mental disability, loss of sight or hearing, and lung problems.

Are there any symptoms of GBS in newborns?
The symptoms are similar to other common problems in newborns – fever, difficulty feeding, lethargy. If you’ve had preventive treatment, your baby will be monitored for signs of infection and a blood test will be done. Treatment for the baby is intravenous antibiotics and intensive-care monitoring.

Can I breastfeed my baby if I’ve tested positive for GBS?
Yes, women who are GBS-positive can breastfeed safely.