Rambling on group B streptococcus

Somewhere between 35 and 37 gestation the topic of GBS testing will arise. What is GBS? Well, Group B Streptococcus, or group B strep (GBS) is part of normal vaginal flora; all female humans carry it at some point in their lifetime. According to research, the gastrointestinal tract acts as a reservoir for GBS and is most likely the source of vaginal colonization during pregnancy.  In the 1970’s GBS was a leading cause of infection and neonatal morbidity (disease,) and mortality (death,) which is why this test is offered today.
 
The test is a simple vaginal-rectal swab. If you are under the care of a midwife, they will likely explain how to do the swab and encourage you to do it yourself. If so, you can scurry your little butt of to the loo to administer it. If you are under the care of a physician, they quite often encourage you to be more passive and lay down while they themselves do the swab. However, you can advocate for yourself and say no, and do it yourself in private. Does it hurt? NO, not generally. It’s nothing like a pap if that’s what your thinking!
 
Once the swab has been completed it is sent to a lab to be cultured and tested for GBS. You're either positive or negitive. You’re likely thinking, okay so what does that really mean? Well, GBS if left untreated can transfer to the baby and cause health issues, remember above….the leading cause of morbidity (disease) or mortality (death) in the 1970’s.
 
Let’s break this down so you don’t freak out because we are no longer in the 1970’s! My goal is to encourage informed choice and empowerment, remember. The Ontario Association of Midwives has taken the data and translated it into simple terms. I'm going to borrow their written details below. The prevalence of GBS positive, meaning the number of people who test positive lingers between 10%-35%. Of that, between 40%-50% of babies born are colonized by GBS, of that 1%-2% of the 40%-50% will develop something called Early Onset Group B Streptococcus Disease (EOGBSD). Of that 1%-2% of babies with EOGBSD, there is a 5%-9% mortality rate.
 
Yes, babies sometimes pass away. It’s terrible and unfair and for anyone who has experienced this, I’m sorry. However, I’m going to present this from a bigger picture for all the first-time parents out there who are either considering a GBS test, or know they are positive. I am aware that the language around this subject is hella freaky!
 
Using the stats above, if you were to apply this to a group of 17 500 – 50 000 pregnant people:

• 5000 pregnant people would test positive
• 2000 - 2500 babies would be colonized by GBS
• 20 – 50 babies would develop EOGBSD presenting as:

                                Bactermia (64% - 83%)
                                Pneumonia (9% - 23%)
                                Meningitis (7% - 12.5%)

• Of the 20 – 50 babies with EOGBS, 1 – 4.5 will pass away from the initial 17 500 – 50 000 births.

 
Still hella scary? Hopefully not as much. The numbers and risks are really low, but they are there nonetheless and the results can be devastating. However, I’d like to brush on prevention as solutions are much more helpful than fear. Historically, strategies such as oral maternal antibiotics, an intramuscular injection of penicillin or a vaginal disinfection with chlorhexidine were administered and tested. While the above had some success, none were statistically significant enough to bring it into full scale evidence-based practice.

Those of you who are more holistically minded.  Probiotics, which affect gut health, have been shown to prevent GBS growth and MAY be a positive prevention with little to no side effects, therefore safe (AOM, 2010).  Keep in mind there is an absence of research and therefore a lack of efficacy data.  You can make your own call there, but I do remember my care providers talking about good strains of probiotics such as kimchi, kombucha and yogurts to help keep GBS levels normal. Alternatively, Genestra makes a clean line of oral probiotics.

Moving forward, it is recommended that all pregnant people be offered Group B Strep testing between 35-37 weeks gestation and a re-screening if 5 weeks has passed since their last test and they have not delivered. Today, the most common way to treat people who are GPS positive in Canada (note, not all industrialized countries even test for GBS) is with antibiotics during labour. This can be done both in hospital or during a home-birth. There are essentially three approaches to antibiotic use.

1) Universal screening, meaning everyone completes the GBS test and those who are positive receive antibiotics during labour.

2) Risk-factor screening, meaning anyone who tests positive AND presents with one of the following risk factors should be offered antibiotics:
          pre-term labour (before 37 weeks gestation)
          prolonged rupture (18 hours +) of the membranes (water)
         or a maternal fever
         also offered to any person who has delivered a previously infected baby

3) Any one who declines a GBS test is considered “unknown” and those who develop the above risk factors should be offered antibiotics during labour.
 
The approach isn’t perfect, and "women should be informed that there is limited research upon which to compare the relative efficacy of this approach to a screening strategy, nor are there well-designed randomized controlled trials that compare this approach against no treatment" (AOM, 2010.) You can test positive for GBS AND then test negative a week/day later. You might also only have GBS in your colon and not your vagina based upon the current testing standards. Needless to say, the use of antibiotics is a point of contention for many. Some care providers are much more inclined to frame antibiotic use from a universal perspective, whereas some are more comfortable practicing from a risk-factor screening model.

There are so many variables to consider as part of informed care. For instance, if a GBS positive person, or any person for that matter, declines  antibiotics and tested positive or was "unknown" and the baby experiences delays during normal transition in the immediate post-partum, experiences any fever or signs of infection, they WILL most likely be treated as if they have EOGBS disease. That means your infant receives IV antibiotics for 48h in the nicu and potentially further testing which can be very invasive.

I’d really encourage you to do some deeper research. There are certain risks/benefits to not using antibiotics and with using antibiotics during labour. Resistance, postnatal thrush, mobility issues in labour etc. There are also variables that you cannot predict, such as what happens if you test positive, but didn't have tine to have antibiotics administered? There are also things to consider such as what happens if you decline a test an a baby shows symptoms etc. This published article from the Ontario Association of Midwives is detailed, but it will help you understand the full risk/benefit picture.

In the end, you as a pregnant person, must balance out the benefits and risks to any procedure, test or prenatal screening. Taking into account the short and long term benefits and risks, many of which I do not discuss in this blog. As always, be sure to have a detailed conversation with your care provider about the whole picture as I can in no way replace medical advice or current community standards. The point of this blog was to simply introduce you to GBS and a few of the complexities that may present themselves around this topic.

With gratitude and gumption,
Rhea

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