Sugars in breast milk can help prevent Group B Streptococcus (GBS) infections in human cells and tissues as well as in mice, researchers have found.

The GBS bacteria are a common cause of blood infections, meningitis, and stillbirth in newborns. Although GBS infections can often be treated or prevented with antibiotics, the bacteria is becoming increasingly resistant.

"Our lab has previously shown that mixtures of HMOs isolated from the milk of several different donor mothers have anti-microbial and anti-biofilm activity against GBS," said Rebecca Moore, graduate student at the varsity.

"We wanted to jump from these in-vitro studies to see whether HMOs could prevent infections in cells and tissues from a pregnant woman and mice," she added.

The researchers studied the effects of combined HMOs from several mothers on GBS infection of placental immune cells (called macrophages) and of the gestational membrane (the sac surrounding the foetus).

"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," Moore said.

They examined whether HMOs could prevent a GBS infection from spreading through the reproductive tract of pregnant mice. "In five different parts of the reproductive tract, we saw significantly decreased GBS infection with HMO treatment," Moore added.

An expectant mother, who tests positive for GBS is usually given intravenous antibiotics during labour to help prevent early-onset infections which occur during the first week of life. Interestingly, the incidence of late-onset infections (which happen from one week to three months after birth) is higher in formula-fed than breastfed infants, which suggests that factors in breast milk could help protect against GBS.

If so, the sugars could perhaps replace antibiotics, which in addition to killing beneficial bacteria, are becoming less effective because of the rise in antibiotic resistance, the researchers said.

The findings will be presented at the upcoming fall meeting of the American Chemical Society (ACS).