How can we protect newborn babies from dangerous germs?

Did you know that the youngest babies carry a lot of potentially harmful bacteria in their guts?

They have plenty of unpleasant bacteria like Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae. 

These are all potentially dangerous bacteria with genes that make them resistant to antibiotic treatment.

With underdeveloped immune systems, infants are at a higher risk of infections. The situation can become very serious if the bacteria causing the infection turn out to be resistant to treatment with antibiotics.

Fortunately, more friendly bacteria, such as bifidobacteria, can push the bad bacteria out as the babies’ guts mature, along with help from their developing immune systems.

And by being born vaginally, babies seem to get a head start in the fight against bad bacteria in the transition to a healthier gut flora.

Fewer antibiotic resistance genes

Researchers from UiT The Arctic University of Norway have carried out one of the largest meta-studies on newborn gut flora. They found that WHO's recommendations are spot-on when it comes to preventing antibiotic resistance in society's youngest and most vulnerable members. 

The international research team found 14 studies on babies’ gut health from 10 different countries in Europe, Southern Africa, and North America.

After extracting the available data from these studies, they ended up with 3,981 high-quality samples of genetic material from bacteria in 1,270 infants and 415 mothers. The researchers then performed advanced data analyses of the bacteria's DNA.

Stick to the original plan, if you can

What the researchers found was clear evidence that sticking to mother nature’s original plan paid off:

Carrying the pregnancy to full term, giving birth vaginally, not using antibiotics unless absolutely necessary, and not rushing to start a solid food diet. These are factors that help with the development of a balanced microbiota in the gut.

"We found that infants delivered via Caesarean section and babies born prematurely have a higher load of antibiotic resistance genes compared to those born vaginally," says PhD candidate Ahmed Bargheet.

The researchers found that this also reduces the occurrence of antibiotic-resistant genes in the gut. The lower the number of antibiotic-resistant genes, the lower the chances of getting an infection that cannot be treated with antibiotics.

"We also found that infants who were exposed to antibiotics had more antibiotic resistance genes and mobile genetic elements than those who were not treated with antibiotics," he says.

Less resistance over time

Antibiotic resistance often spreads by mobile genetic elements such as plasmids – small, ring-shaped DNA molecules that bacteria have in their cells. 

The meta-analysis also showed that even though there are plenty of plasmids in the infant gut when the baby is born, these genetic elements, which easily jump between bacterial cells, gradually disappear during infancy.

This development is accompanied by a simultaneous decline of antibiotic-resistant genes and E. coli bacteria, which are the main bacteria carrying the antibiotic-resistant genes.

Clear differences between regions

The researchers found clear geographical variations. 

In Southern Africa, there was higher diversity and more antibiotic resistance genes and mobile genetic elements, the so-called resistome, than in Europe.

In contrast, the US cohorts showed higher diversity of resistance genes, but their abundance was lower.

"These geographical variations underscore the need for a global strategy to address the variations in the antibiotic resistance burden," says Veronika K. Pettersen, associate professor at UiT.

Reference:

Bargheet et al. Dynamics of gut resistome and mobilome in early life: a meta-analysis, eBioMedicine, vol. 114, 2024. DOI: 10.1016/j.ebiom.2025.105630 

This content is paid for and presented by UiT The Arctic University of Norway

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