Abstract:

Established during infancy, the initial colonisation and development of the complex gut microbial community of our gastrointestinal tract can be shaped by common medical interventions, such as caesarean section and antibiotic use. This chapter provides evidence on the gut microbial impact of four medical interventions: (1) caesarean delivery, (2) maternal intrapartum antibiotic prophylaxis (IAP), (3) hospitalisation post birth, and (4) postnatal infant antibiotic treatment. Reductions in bifidobacteria and members of the Bacteroidaceae family (e.g. Bacteroides fragilis) are by far the most common perturbations in microbial composition following each of these interventions, especially after elective or emergency caesarean section. On the other hand, genus Clostridium and the Enterbacteriaceae (e.g. Klebsiella, Escherichia coli) are likely to become more abundant in infants delivered by caesarean, exposed to maternal antibiotics, hospitalised post birth and treated with antibiotics. Often, the enterococci and staphylococci also become more abundant. Differential impact on gut microbiota is observed by type of caesarean delivery and antibiotic administered to the mother or infant. IAP with penicillin or cefazolin, or newborn treatment with intravenous penicillin (plus gentamicin) is associated with higher abundance of Enterococcus and Staphylococcus aureus. Klebsiella emerge after newborn intravenous ampicillin (plus gentamicin) treatment. The Veillonella become more abundant in the infant gut after emergency (but not elective caesarean), whereas they are found to be depleted two months after newborn treatment with oral cephalexin. Of note, dysbiosis from perinatal medical interventions also occurs in the early breastfed infant and is enhanced by prematurity.