Intrapartum antibiotics associated with altered infant gut microbiome

1. Infants of women who received intrapartum antibiotics were more likely to have an altered gut microbiome at 3 months of life.

2. The health consequences of these altered microbiomes was not assessed.

Evidence Rating Level: 2 (Good)

Study Rundown: In North America, it is routine practice to administer prophylactic intrapartum antibiotics in the setting of vaginal Group B Streptococcus (GBS) colonization. This is due to the extremely high morbidity and mortality associated with GBS septicemia in infants. Intrapartum prophylaxis has been demonstrated to drastically reduce the risk of these severe morbidities among infants delivered to women colonized with GBS. Among women who undergo cesarean delivery, prophylactic antibiotics are administered within 30min minutes of skin incision to reduce the risk of infectious morbidity associated with cesarean section. Both of these practices are evidence-based and represent the standard of care in the United States. In European countries, however, prophylactic antibiotic administration is much less common. At the same time, basic science research in the microbiome literature in recent years highlights a difference in the gut microbiome among infants delivered via cesarean compared with vaginal delivery. There is no solid evidence, however, that this difference in microbiome is the causal factor in any health consequences for infants, however. The impact of neonatal and pediatric antibiotic use on gut microbiome has been widely studied, but perinatal antibiotic exposure has been less well studied. One recent study evaluated the microbiome diversity at one week of life among infants whose mothers received intrapartum antibiotics for GBS prophylaxis. In this secondary analysis, researchers assessed the impact of prophylactic intrapartum antibiotics on the infant gut microbiome at 3 months and 1 year of life and also evaluated how breastfeeding and delivery type modifies this relationship.

Maternal intrapartum antibiotic exposure was associated with an altered infant gut microbiome at 3 months and 1 year of life but the health consequences of these differences remains entirely unknown. Strengths included a population-based cohort and assessment of maternal postpartum antibiotic use, a limitation of prior studies. Limitations include secondary analysis, retrospective study design and limited generalizability due to disagreement with standard of care in the U.S. Further, lack of evaluation of associated health outcomes precludes discussion of possible health impacts to these infants. The field of microbiome research remains relatively young and it remains unclear what, if any, long-term health impacts are causally related to any bacterial aberrations. Future studies might assess clinically relevant infant health outcomes, like admissions for upper respiratory infection or asthma exacerbation, are warranted prior to any discussion of altering clinical practice recommendations.

Click to read the study in BJOG

Click to read the associated commentary in BJOG

Relevant Reading: Influence of intrapartum antibiotic prophylaxis against group B Streptococcus on the early newborn gut composition and evaluation of the anti-Streptococcus activity of Bifidobacterium strains

In-Depth [retrospective cohort study]: A secondary analysis was performed using a representative sub-sample of 198 healthy term infants from the Canadian Healthy Infant Longitudinal Development (CHILD) Study. Maternal exposure to antibiotic prophylaxis during delivery and mode of delivery were collected from hospital records and breastfeeding was self-reported. The primary outcome of infant gut microbiota was assessed using fecal samples at 3 and 12 months of life.

A total of 43 percent of mothers received antibiotic prophylaxis during delivery, 21 percent during vaginal delivery (n = 42), 9 percent during elective C-section (n = 18), and 13 percent during emergency C-section (n = 25), while 57 percent (n = 113) had a vaginal delivery with no antibiotics. At 3 months, infants born to women who received intrapartum antibiotics had a lower median abundance of Bacteroidetes compared to infants whose mothers did not receive intrapartum antibiotics (p < 0.05 for all).

Image: PD

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