A study presented at ESCMID Global 2026 has found that antibiotic resistance genes can be present in newborns within the first hours of life, highlighting how early exposure to resistant bacteria may occur (1).

Researchers analyzed meconium samples – the first stool passed by newborns – from 105 infants admitted to a neonatal intensive care unit (NICU) within 72 hours of birth. Meconium was once thought to be sterile, but modern molecular testing has shown that microbial genetic material can be present at this stage.

Using molecular methods, the team screened for 56 resistance genes linked to commonly used antibiotics. Most infants carried multiple resistance genes, with a median of eight detected per sample. The most common genes were associated with resistance to widely used antibiotics, and genes linked to resistance to last-line treatments, such as carbapenems, were also identified in a proportion of cases.

These findings suggest that the neonatal gut may already contain a range of resistance genes at birth. Importantly, this does not mean the infants have infections, but it indicates the presence of genetic material that could contribute to antibiotic resistance if transferred between bacteria.

The study also identified factors linked to the presence of these genes. Maternal hospitalization during pregnancy and early medical interventions, such as central line placement, were associated with higher numbers of resistance genes. This suggests that both maternal factors and early hospital exposure may influence the types of microbes and resistance genes present in newborns.

The study highlights the value of molecular testing in detecting resistance genes that would not be identified using standard culture-based methods. It also shows that early-life samples may provide useful information about microbial exposure and resistance patterns.

The findings reinforce the importance of infection prevention and antimicrobial stewardship in neonatal care. Monitoring resistance patterns at an early stage may help improve understanding of how resistance develops and spreads.

Overall, the study indicates that exposure to antibiotic resistance can begin very early in life, and that molecular diagnostics can play an important role in identifying and tracking these patterns.

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