Breast milk shows benefit against antibiotic resistance
Breast milk may offer babies a new health benefit: helping to limit the presence of antibiotic resistance genes in their gut. That is the conclusion of an international study led by Spain’s National Research Council (CSIC), which has examined how certain components of human milk influence the bacteria that colonise the gut during the first months of life.
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The study, published in “Cell Reports Medicine (source in Spanish)“, finds that exclusive breastfeeding is associated with a lower abundance and diversity of antimicrobial resistance genes in babies’ intestines.
“Promoting breastfeeding appears to be an effective strategy for reducing antimicrobial resistance genes present in intestinal bacterial communities during a critical stage in the development of the microbiota“, explains M. Carmen Collado, a CSIC researcher at the Institute of Agrochemistry and Food Technology (IATA).
How does breast milk influence antibiotic resistance?
One of the keys lies in human milk oligosaccharides (HMOs), molecules that occur naturally in breast milk which babies do not digest directly, but which serve as food for certain beneficial gut bacteria and help maintain a balanced microbiota.
The researchers have found that some of these components are associated with a lower presence of certain genes conferring resistance to antibiotics.
“HMOs act as ecological modulators of the gut microbiota: they promote the growth of microorganisms capable of using them and may limit the spread of bacteria carrying specific resistance genes”, says Collado.
To reach these conclusions, the researchers analysed faecal samples from 57 one-month-old babies in Valencia, along with milk samples from their mothers. The results were later validated with data from another 199 breastfed babies in the Netherlands.
Mode of delivery also plays a role
The study notes that both the mode of delivery and feeding are decisive factors in the composition of the intestinal resistome, that is, the collection of antimicrobial resistance genes present in gut bacteria.
The researchers found differences in the diversity of these genes between babies born by caesarean section and those born by vaginal delivery, while exclusive breastfeeding was associated with a lower abundance and diversity of resistance genes.
“The first months of life represent a critical window in which the gut microbiota is being established and in which different environmental factors, such as mode of delivery or feeding, can leave a lasting imprint”, explains Anna Samarra, a researcher trained at IATA-CSIC and now a postdoctoral researcher at the University of California, San Diego.
