Everything you need to know about Group B Streptococcus (GBS) during pregnancy and in general

What is GBS?

GBS is short for the bacteria called Group B Streptococcus. This bacteria is sometimes also referred to as Streptococcus Agalactiae.

Where does GBS originate? Is it only found in pregnant women?

Remember how the human body holds millions of bacteria? Well, in approximately 20% of the general population, this bacteria is simply part of the natural flora found in the intestines. That is, it can be simply one of many other bacteria that live in our bodies naturally, and cause absolutely no harm.

So, the answer to this question is that it is not only found in pregnant women but in a large proportion of the general population.

How does one catch this bacteria?

This bacteria is often naturally found in some people’s gastrointestinal system, and it presents a part of the fine balance of bacteria found in their intestines. One can either carry this bacteria in their body temporarily for short period of time, or for longer periods of time.

What can GBS cause?

GBS can cause several different types of invasive infections, in people of different age groups, irrelevant of whether or not they are pregnant, from infancy all the way to adulthood. Some of these infections are mild (such as urinary tract infections) and some are invasive (such as sepsis and meningitis).

The majority of morbidity is in infants 1 week old, whose mothers are GBS.

Is carrying the bacteria during pregnancy dangerous?

This is an important point to understand. The bacteria is essentially not dangerous during pregnancy for the course of the pregnancy itself but it poses a threat to the baby if it is passed on to them during the delivery. There is a concern that the neonate will get infected during their passage through the birth canal, which could increase their risk of developing early sepsis, during their first week of life.

For neonates, this infection is associated with severe morbidity, mortality in the short-term and a risk for neuro-developmental complications in the long-run.

Isn’t it, then, important to identify this bacteria and treat pregnant women who turn out to be positive for GBS?

Absolutely! The guidelines for pregnant women in most countries in the world include screening for GBS and treatment of those who are found positive prior to delivery.

So, how can we tell if a woman is positive for GBS?

According to national guidelines set in most countries, pregnant women have to undergo screening for GBS during the time between the 35-37th weeks’ gestation.

How is this screening performed?

Since the bacteria is carried in the intestines, a cotton swab is used to collect a sample from the rectum and vagina.

Where can this test be done?

Pregnant women can do this test by themselves, with the use of a cotton swab. This cotton swab can be kept in room temperature but needs to be sent for culture within 24 hours. Most obstetrics/gynecology practices or family practices are able to provide you with the swab for testing.

How long does it take to get the results?

This can vary depending on your practice, but it usually takes about 2-3 days for the culture results to come back. The result is either positive or negative for the bacteria.

Are there women who do not need to take this test?

Yes. Women who undertook a urine test and urine culture during pregnancy and were found positive for GBS and those who have a child who suffered from an invasive GBS infection in their first week of life do not need to take the test. In both cases it is assumed that the woman is positive for GBS.
Why? The idea is that if the woman suffered a urinary tract infection that was caused by GBS in their current pregnancy then they must have been carrying a large quantity of the bacteria, and therefore there is no point in screening them.
As for the woman with a child who had an infection, the idea is similar.

If results indicate that I am positive for GBS, do I need to start antibiotics immediately?

No, there is no need for immediate treatment.
There is a need for intravenous antibiotic treatment during the delivery and it is important to receive at least one dose, 4 hours before the delivery. Therefore, you need to make sure you arrive to the hospital early when the contractions begin or as soon as your water breaks.

What happens if a woman misses her screening test?

There are two options, depending on where you plan on having your delivery.
In women who have not been tested, some birth centers can perform PCR tests that provide results within an hour.
Another option is to treat women who are at increased risk of infection, but have an unknown GBS status, with antibiotics. Factors that increase risk for infection include:
• Preterm delivery prior to 37 weeks’ gestation.
• Prolonged rupture of membranes greater than 18 hours.
• Women with fever of 38 degrees Celsius or higher during labour.

Are antibiotics also required for caesarean delivery?

The concern for transmission of infection is during passage through the birth canal. In caesarean deliveries, where there has been no rupture of membrane (when the woman’s water does not break), the neonate does not pass through the birth canal and therefore there is no need for preventive antibiotic treatment even if the woman is GBS positive.

I am scheduled for a Caesarean Section, do I still need to get screened for GBS?

According to national guidelines, a culture should be taken even in women who are scheduled for C-Sections because women may go into spontaneous labor prior to the scheduled delivery date.

What type of antibiotics are given to a woman who is found positive for GBS?

Treatment includes an antibiotic from the penicillin family, usually “ampicillin”. Treatment is always given intravenously. Of course, there are alternative treatment options for women who are allergic to penicillin. You can read more about penicillin allergy here.
Please note that treatment for the prevention of GBS in the neonate must be administered intravenously. Therapy administered orally prior to labour is ineffective for this purpose.

If I was positive for GBS in my previous pregnancy but I am negative in my current pregnancy, do I still need to be treated?

If a woman was positive in her previous pregnancy but is negative in her current pregnancy, there is no need for treatment.
Exceptions to this rule are the cases that I mentioned previously, including having a urinary tract infection due to GBS in the current pregnancy or having had a previous child who suffered an invasive GBS infection following birth.

What if I should have received antibiotics but did not receive them on time?

This can happen sometimes. Keep in mind that the chances of transmitting the infection to the neonate is quite small to begin with, even without preventive antibiotic treatment. However, if the mother hasn’t received treatment and is a carrier of the bacteria, the pediatric team will have to monitor the infant closely for any signs of infection, and treat him/her accordingly, as needed.

In summary, this is a very important topic that I feel everyone should be aware of, especially pregnant women. It is important to get screened and to receive preventive antibiotic treatment if needed.

Good luck everyone!