Wow. The wonders of human milk for preventing infections.

Presented at the American Chemical Society (ACS) this week, researchers suggest special sugars in breast milk called human milk oligosaccharides (HMO) could possibly help prevent or even treat group B Strep (GBS) infections in newborns.

The results presented at ACS Fall 2021 show that HMO sugars help prevent GBS infections in human cells and tissues taken from pregnant mothers, and also in mice.

About group B Strep (GBS)

As discussed in our group B Strep course, group B Streptococcus (GBS) is a common type of bacteria that can colonise the gastrointestinal and genital tracts of pregnant women.

As discussed in the course, if an expectant person is colonised with group B Strep during pregnancy, they could transfer GBS during labour and birth. This can result in the baby developing a serious infection. Group B Streptococcus (GBS) are a common cause of blood infections, meningitis and stillbirth in newborns.

Around the world, there are different approaches to prevent early-onset group B Strep infections that occur in the first week of life.

The different approaches include universal screening of all pregnant women at 35-37 weeks gestation for GBS colonization, with intrapartum antibiotics offered to those with positive results; universal screening of all pregnant women, with intrapartum antibiotics offered only to those with positive results, as well as other risk factors for GBS transmission; and intrapartum antibiotics offered to those with risk factors for GBS transmission without prior screening.

If a baby develops a Group B Strep infection, the infection can be treated with antibiotics.

However, bacteria are becoming increasingly resistant to antibiotics. As discussed in our group B Strep course, emerging evidence suggests antibiotics used to prevent or treat group B Strep infections could also be killing beneficial bacteria in the infant gut. This could have implications for later infant health.

In the presentation this week at the American Chemical Society (ACS) Fall 2021 event, researchers say that perhaps someday, human milk oligosaccharides might be able to replace antibiotics for treating infections both in infants and adults.

The new study

Previously, researchers found that HMOs from several milk donors had "antimicrobial and antibiofilm activity" against group B Strep in in vitro studies.

This new study takes it one step further. The researchers looked at whether HMOs could prevent infections in cells and tissues from a pregnant woman, and also in pregnant mice.

The researchers studied the effects of the combined HMOs from several donors on group B Strep infection on placental immune cells (called macrophages).

They also studied the effects of the sugars on the gestational membrane (the sac surrounding the fetus).

The results

According to Rebecca Moore, a graduate student in the labs of Steven Townsend, Ph.D., at Vanderbilt University and Jennifer Gaddy, Ph.D., at Vanderbilt University Medical Center:

“We found that HMOs were able to completely inhibit bacterial growth in both the macrophages and the membranes, so we very quickly turned to looking at a mouse model”

The researchers looked at whether HMOs could prevent a GBS infection from spreading through the reproductive tract of pregnant mice. Moore said:

“In five different parts of the reproductive tract, we saw significantly decreased GBS infection with HMO treatment”

Why is this happening?

More research is needed, but according to the researchers, there could be two likely reasons why HMOs can potentially treat prevent group B Strep infections.

Reason 1. HMO sugars act as an anti-adhesive by preventing pathogens from sticking to tissue surfaces and forming a biofilm.

Reason 2: HMO sugars could act as a prebiotic to support the growth of beneficial bacteria.

This line of research could present opportunities for HMOs to perhaps be a substitute for antibiotics in the future.

According to Steven Townsend, Ph.D., at Vanderbilt University, “If we could learn more about how they work, it’s possible that we could treat different types of infections with mixtures of HMOs, and maybe one day this could be a substitute for antibiotics in adults, as well as babies.”

My take-home message:

Human milk is amazing!

Link to article & press release:

The results were presented at a meeting of the American Chemical Society in August 2021.

Antimicrobial properties of human milk oligosaccharides in Group B Streptococcus, ACS Fall 2021.

ACS Fall 2021 is a hybrid meeting being held virtually and in-person Aug. 22-26, and on-demand content available Aug. 30-Sept. 30.


Press release:

For more on GBS, take our full-length course featuring 5 leading GBS experts:

More information on GBS is available on the website from the UK charity Group B Strep Support:


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