HMN 2026: How Antibiotic-resistant bacteria is found in many healthy birthing moms and their newborns

A recent study has found gut bacteria resistant to common antibiotics (ampicillin and ceftriaxone) in a sizable percentage of healthy birthing moms and their newborns. In this study, 38% of bacterial strains resistant to ceftriaxone transmitted from mother to infant were E. coli, which is a major cause of urinary and bloodstream infections, as well as meningitis in infants.

Results are published in Open Forum Infectious Diseases.

The study, the first of its kind in the U.S., was led by researchers from Ann & Robert H. Lurie Children’s Hospital of Chicago.

“Perinatal transmission and early life colonization with ceftriaxone-resistant bacteria are important, since infections with these bacteria are associated with higher morbidity and health care costs,” said lead author Leena B. Mithal, MD, infectious diseases expert at Lurie Children’s and Associate Professor of Pediatrics at Northwestern University Feinberg School of Medicine.

“Our finding that healthy pregnant people had a significant burden of these bacteria was surprising, as it was a much higher percentage than previously reported for high-income countries. It shows that this is truly a global problem with potential adverse impacts on neonatal health.”

The study enrolled healthy pregnant people during labor and their newborns, collecting 293 maternal rectal samples and 261 infant stool samples within the first 10 days of life. Ampicillin-resistant bacteria were found in 91% of mothers and 76% of infants. Ceftriaxone-resistant bacteria were found in 12% of mothers and 7% of infants. Premature births were excluded, as well as mothers who were exposed to antibiotics during pregnancy.

To confirm that the bacteria were perinatally transmitted and investigate characteristics of these bacteria, researchers performed whole genome sequencing analysis of the ceftriaxone-resistant strains.

“We found that the bacteria in the mother–infant pairs were genetically identical in most cases, which provides more proof that they are shared between mothers and infants,” said senior author Mehreen Arshad, MD, MBBS, infectious diseases researcher at Lurie Children’s and Adjunct Associate Professor of Pediatrics at Northwestern University Feinberg School of Medicine.

“Our study is unique in that it combined clinical, epidemiological and lab research,” she said. “In our future work, we are examining how long the antibiotic-resistant bacteria persist in the gut of infants, as well as how they impact infant health and overall growth,” said Dr. Arshad.

The content is provided for information purposes only.