To group B or not to group B, that is the question…

Group B Strep is a controversial topic. It seems like you can’t swing a stethoscope without hitting someone with a strong opinion about GBS. Recently, I’ve been researching the topic to have a better understanding of GBS to pass along to others.

GBS is a type of bacteria that is gram positive, which means its protective wall is easier to breach with antibiotics or disinfectants than its cousin, the gram negative bacteria. GBS is a common environmental bacteria, meaning that is can be found in a lot of places and can be picked up in a whole host of ways (as opposed to the weaker bacteria responsible for STD’s).

GBS is commonly found on our skin or mucous membranes, but should not be found in areas that normally are sterile, such as the blood or spinal fluid. When someone has GBS on their mucous membranes (intestines, vagina etc) but not in areas of the body usually sterile, this person is said to be colonized with GBS. We are all colonized with a host of different bacteria, so being colonized with GBS isn’t a problem. In fact as many as one in three women are colonized with GBS and it causes no problems. So, why are we making such a big deal about GBS in labor and birth? The reason is that if GBS crosses the membranes and finds its way into the blood or other areas usually sterile, it can cause a severe infection. At this point we refer to it as GBS disease.GBS disease is particularly problematic in newborns as it is the most common cause of newborn sepsis, a severe infection. GBS disease can be life-threatening to newborns (about 5% of babies with GBS disease die) or cause other long term problems such as hearing loss, brain damage, or vision problems. Babies can sometimes fully recover from GBS but it is a severe disease. Because we know that mothers who are colonized with GBS are more likely to have a baby with GBS disease than mothers who are not colonized, GBS colonization becomes an issue during late pregnancy.

The first challenge with GBS is figuring out who is colonized and who is not. Testing for GBS takes around a week in real world practice. Consequently, we must test women at the end of pregnancy instead of in labor to allow for the turn-around time. This becomes problematic when we realize that GBS is transient, meaning that the same woman may test both positive and negative during a short period of time. Sometimes the immune system effectively eradicates GBS from the body and sometimes it simply holds it in check on the membranes. So a woman may be colonized at the time of testing and not colonized at the time of birth or vice versa. A test to determine in a matter of hours is not yet available, so the issue becomes checking a woman as close as possible to the time of birth, but still having time to get results back before labor begins. It’s a system filled with inaccuracy, but currently is the most effective factor in determining who is at risk for developing GBS disease. Health practioners also take into account a few other risk factors, such as a fever in labor, prolonged length of time with ruptured membranes, or a baby born prematurely.

Since around 1970, when we first found GBS to be a cause of newborn sepsis, we have been battling this infection.Great advances have been made, both in reducing the number of babies infected and reducing the number of infected babies who die. We have tried all sorts of methods to combat this infection, but we keep hitting roadblocks. Of course, the ideal treatment to combat GBS is to prevent GBS disease from ever happening while causing no ill effects in the process. But that’s like saying the ideal dessert tastes like cheesecake, yet has 6 calories and is made from spinach. It’s a nice thought, but it fails to hit the realm of reality. So it is with the reality of GBS treatment, any intervention that we do has a side effect.

Currently, the CDC recommends all women be tested for GBS at the end of their pregnancy. For mothers who are colonized (test positive) with GBS, they recommend IV antibiotics in labor. The reasoning behind this recommendation is simple. Mothers who test positive for GBS have higher chance of having an infected child than mothers who test negative. So we give these moms IV antibiotics, which will serve several purposes. First, the antibiotics destroy the bacteria in the mother’s vagina, secondly the IV antibiotics will cross the placenta and enter the babies blood stream and destroy any bacteria the baby may pick up as it is born through the GBS colonized vagina (routes besides IV, such as IM or oral cannot cross the placenta in time). This will result in fewer babies becoming infected. Again, it’s a nice thought. Who wouldn’t want to reduce the number of sick babies by administering antibiotics to a laboring mom? But, unfortunately, this treatment has a cost associated with it and it doesn’t always work either.

The main problem with this treatment is that we are massively over treating. One in three moms are colonized with GBS, but only 1 in 100 moms colonized with GBS have a baby who develops GBS disease. Treating all GBS colonized women exposes many mothers and babies to unnecessary antibiotics and their risks and side-effects. These risks include very minor things such as yeast infection, thrush, etc. to very major things such as life threatening allergic reactions (anaphylaxis). Severe problems from antibiotics are extremely rare and many consider the benefits to outweigh the risks. Others continue to hypothesize that we do not yet fully understand the risk of antibiotics and consequently are needlessly exposing mothers and babies who are not at risk for GBS disease to risks we do not yet understand.

Unfortunately, we also have only poor evidence to prove that IV antibiotics actually reduce the number of babies dying from GBS disease. Most of our solid evidence is over 20 years old, highly biased and based on too few women to actually be accurate. Regrettably, we no longer have opportunity to do new prospective studies because IV antibiotics have become general practice. But we have several retrospective studies that seem to indicate IV antibiotics are effective. One of the most convincing proofs is the rate of babies affected by GBS disease in the 1990 vs. 2010


Roughly 1 in 500 babies developed GBS disease

Fatal in 1 of 1,000 births


Roughly 1 in 4,000 babies developed GBS disease

Fatal in 1 in 80,000 births

So, antibiotics for GBS colonization become a hotly debated topic. The truth, in short, is that it’s always someone’s opinion.Two experts can look at the same studies and come up with different conclusions. It is important for parents to communicate with their care provider to help develop the best strategy to protect their baby. Not all parents will fall in the same risk category, some may have higher or lower chances of their babies becoming sick with GBS. Some moms may choose not to test for GBS while other moms may choose to test and both moms passionately defend their position. Some moms may choose antibiotics while other moms may choose more alternative or natural means. Because the controversy is hotly debated it can easily feel like one way is better than another when in reality circumstances surrounding GBS greatly effect and change from one situation to another. As with all subjects of controversy, discussing GBS within the context of the individual situation leads to the best solution. Because GBS is a complex problem it will not have a simple solution. Informed consent is crucial in determining if you should group B or not group B.