Antibiotic resistance genes (ARGs) – segments of DNA that help bacteria survive the effects of antibiotics – can be present in newborns within hours of birth, according to research presented at ESCMID Global 2026.
The study analyzed meconium samples taken from 105 infants admitted to neonatal intensive care units (NICUs) within 72 hours of birth from July 2024 to July 2025. The study was part of an interdisciplinary research project led by Professor Elias Iosifidis of Aristotle University of Thessaloniki, and included pediatric infectious disease experts, neonatologists, and molecular microbiology researchers.
Meconium, the first stool a newborn passes, was traditionally thought to be sterile. However, recent molecular studies have detected microbial genetic material in meconium samples, suggesting that the newborn’s intestines may be exposed to bacteria during pregnancy. It is thought that this early microbial exposure may potentially contribute to the development of antibiotic resistance. ARGs have been detected in meconium samples, and their presence at this early stage may facilitate the spread of resistance through horizontal gene transfer between bacteria. Based on this, the researchers screened the samples for 56 different resistance genes related to commonly used antibiotics.
This is the largest study of its kind to investigate the influence of the hospital environment on the collection of ARGs in the neonatal intestine. We analyzed meconium samples within 72 hours of birth to obtain the earliest snapshot of microbial and genetic exposure in newborns. At this stage, the collection of resistance genes is primarily formed by mother-to-child transmission, delivery methods, and very early hospital exposures. ”
Dr. Argyro Ftergioti, first author
The most common genes detected are: oqxA (in 98% of the samples) and qnrS (96%), which is associated with resistance to several commonly used antibiotics. The study also identified several genes encoding beta-lactamases, enzymes that break down widely used antibiotics. The most widespread of these was braCTXM (55%), braCMY (51%) and braSHV (39%). Genes associated with resistance to carbapenems, the final class of antibiotics, were detected in 21% of the samples. Each sample contained a median of eight resistance genes.
“This finding suggests that the pattern of ARGs is already established at this stage. There is a diverse resistome in the neonatal intestine, and the presence of clinically important ARGs so early in life is alarming,” added Dr. Ftergioti.
“Although some ARGs were expected, the high prevalence in most samples was surprising, especially for clinically important genes conferring carbapenem resistance.”
The study also identified associations between resistance genes and several maternal and neonatal factors. existence of msrA (macrolide streptogramin resistance) genes were associated with maternal hospitalization during pregnancy, while more resistance genes were associated with central venous catheter placement within 24 hours of birth. Both findings may reflect exposure to healthcare-associated microorganisms in hospital settings.
“Surprisingly, resuscitation shortly after birth was associated with a reduction in resistance genes. However, we caution that this finding should be interpreted with caution as it may reflect differences in early microbial exposure or other clinical factors,” Dr. Ftergioti noted.
Overall, the results of this study suggest that both maternal infection and early exposure to the hospital environment may contribute to the establishment of ARGs in the neonatal gut.
“While further research is needed to understand how early carriage of resistance genes influences microbiome development and infection risk, these findings highlight the importance of surveillance, infection prevention, and control in neonatal care,” concluded Dr. Futergioti.
sauce:
European Society of Clinical Microbiology and Infectious Diseases
