Maternal Antibiotics Affect Infant Gut Microbiome Diversity

The composition of the developing gut microbiome is thought to have crucial roles in maturation of the immune system.

This article is written live from ID Week 2017 Annual Meeting in San Diego, CA. MPR will be reporting news on the latest findings from leading experts in infectious diseases. Check back for more news from IDWeek 2017.

SAN DIEGO—Mothers’ use of antibiotics affects infant gut composition up to a month later, according to findings from a prospective study of 22 mothers and their infants, reported at IDWeek 2017.

“Our preliminary study clearly showed a disruptive effect of maternal antibiotic consumption on the nursing infant’s gut microbiome with an impact on the important early colonizers of the infant gut,” reported lead study author Rachel Rock, MD, of the Assaf Harofeh Medical Center in Zerifin, Israel.

Additional, larger studies are needed to compare the effects of different antibiotics on infant gut microbiomes and to develop empirical recommendations for breastfeeding women, she cautioned.

“The intestine of a newborn is considered sterile in utero and is rapidly populated with different bacteria following birth,” Dr. Rock reminded attendees. “The composition of the developing gut microbiome is thought to have crucial roles in maturation of the immune system and prevention of various diseases.”

Researchers suspect that antibiotics can disrupt early-life gut microbiome development (alpha and beta diversity), but as much as 20% of women receive antibiotic therapy in the year after giving birth, according to Dr. Rock. 

“Though many antibiotics are considered safe during breastfeeding, it is well known that some degree of accumulation will occur in the breast milk,” she noted. “Little is known about the influence of maternal antibiotic consumption during breastfeeding on the infant’s gut microbiome.”

To evaluate changes in the infant gut microbiome and the associations between breast milk antibiotic levels and glycobiome changes, the authors conducted a prospective longitudinal cohort study of the infants of breastfeeding mothers who were prescribed antibiotics. Twenty-two mother-infant pairs completed the study (mean infant age: 4 months).

Breast milk and infant fecal samples were collected at 6 different time points: Day 0, 2–3 days, 1 week, 2 weeks, and 1 month post-antibiotic initiation. Infants’ glycobiomes and gut microbiomes “were characterized by 16S ribosomal RNA gene sequencing,” Dr. Rock said.  

Interim analysis of the first 17 mother-infant pairs showed no signifiant differences in beta diversity of the infant gut microbiome before and after maternal antibiotic treatment. The authors reported an increase in lactobacillus abundance after antibiotic treatment in most of the infant gut samples (P<0.05).

“Unexpectedly in about 50% of the cases an increase in alpha diversity was observed,” Dr. Rock stated. At the same time, the authors saw a reduction in milk glycobiome diversity after antibiotic treatment. 

These initial findings point to changes in infant gut microbiome in mothers who were given antibiotics, “the exact nature of which are yet to be elucidated.” Where maternal exposures were shown to influence the developing infant gut microbiome, glycobiome and antibiotic level in breast milk are still being studied. 

For continuous infectious disease news coverage from the IDWeek 2017, check back to MPR’s IDWeek page for the latest updates.


Rock R, Ben-Amram H, Neuman H, Hanya H, Koren O, Youngster I. The Impact of Antibiotic Use in Breastfeeding Women on the Infant’s Gut Microbiome – A Prospective Cohort Study. Poster presented at IDWeek; October 4–8, 2017; San Diego, CA.