Antibiotic replacements? HMOs may prevent streptococcus infections in newborns

24 Aug 2021 --- Human milk oligosaccharides (HMOs), short strings of sugar molecules in breast milk, can help prevent group B Streptococcus bacteria (GBS) infections in human cells and tissues. This is according to research conducted by Vanderbilt University in the US and funded by the National Science Foundation.

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 are becoming increasingly resistant.

According to the researchers, in the future, HMOs may replace antibiotics for treating infections in infants and adults.

“HMOs have been around as long as humans have and bacteria have not figured them out. Presumably, that’s because there are so many in milk, and they’re constantly changing during a baby’s development,” says Steven Townsend, associate professor of chemistry, Vanderbilt University.Human milk oligosaccharides can help prevent GBS infections in human cells.

“But 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.”

The reason HMOs can treat and prevent GBS infection is likely two-fold, according to the researchers. The HMOs act as an anti-adhesive by preventing pathogens from sticking to tissue surfaces and forming a biofilm. They could act as a prebiotic by supporting the growth of good bacteria.

GBS infection explained
According to the US Centers for Disease Control and Prevention, about 2000 babies in the US get GBS each year, and four to six percent die from it. The bacteria are often transferred from mother to baby during labor and delivery.

An expectant mother who tests positive for GBS is usually given intravenous antibiotics during labor to help prevent early-onset infections during the first week of life.

The incidence of late-onset infections (which happen from one week to three months after birth) is higher in formula-fed infants than breastfed, suggesting that breast milk factors could help protect against GBS.

The researchers studied the effects of combined HMOs from several mothers on GBS infection of placental immune cells and the gestational membrane.

“The lab has previously shown that mixtures of HMOs isolated from the milk of several different donor mothers have antimicrobial and antibiofilm activity against GBS,” says Rebecca Moore, PhD candidate in Chemical Biology at Vanderbilt University.

“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 in pregnant mice,” says Jennifer Gaddy, assistant professor of medicine at Vanderbilt University Medical Center.

The researchers examined whether HMOs could prevent a GBS infection from spreading through the reproductive tract of pregnant mice.The bacteria from GBS is often transferred from mother to baby during labor and delivery.

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

HMOs and the microbiome
To distinguish which HMOs and other oligosaccharides have antimicrobial effects and the reason why, the researchers set up an artificial two-species microbiome with GBS and the beneficial Streptococcus salivarius species growing in a tissue culture plate, separated by a semipermeable membrane.

The researchers then added oligosaccharides commonly used in infant formula, called galacto-oligosaccharides (GOS), derived from plants. In the absence of sugar, GBS suppressed the growth of the “good” bacteria, but GOS helped this beneficial species grow.

“We concluded that GBS is producing lactic acid that inhibits growth, and then when we add the oligosaccharide, the beneficial species can use it as a food source to overcome this suppression,” Moore explains.

The study results will be presented by the researchers at the fall meeting of the American Chemical Society (ACS). ACS Fall 2021 is a hybrid meeting being held virtually and in person between 22 to 26 August. Additionally, on-demand content will be available between August 30 to September 30.

Surge in HMO potential
Over the last few months, industry players have shown a keen interest in HMOs.

Last week, Chr. Hansen and Glycom reached a settlement over HMO production patent disputes.

Standard Process launched GI Stability, a HMO supplement that supports digestive and immune health in adults.

By Nicole Kerr