ABSTRACT
Although a healthy human fetus develops in a sterile environment, the human host’s bacterial cells outnumber its eukaryotic cells 10-fold (Hooper et al., 2002). Newborns are rst colonized based upon their mode of delivery. Heavily colonized by microbes, the mammalian birth canal provides the initial inoculum for all mammals delivered vaginally. At time of delivery, the vaginal ecosystem is typically comprised of Lactobacillus, >50% of all bacteria present, and Prevotella spp. (Dominguez-Bello et al., 2010). It appears that the vaginal community changes to provide newborns with benecial bacteria (Dominguez-Bello et al., 2011). Bacteria identied on newborn’s skin and mouth and present in the rst meconium are noted to be the same as the mother’s vaginal bacteria in vaginally delivered newborns (Dominguez-Bello et al., 2011). In contrast, babies birthed by cesarean section (C-section) harbor bacterial communities that resemble those of the skin, comprising Staphylococcus, Corynebacterium, and Propionibacterium spp. (Dominguez-Bello et al., 2010; Mackie et al., 1999). Because C-section babies do not receive that rst vaginal maternal inoculum, it may not only inuence the gut microbiota development but also contribute to the vulnerability they have to certain pathogens (Dominguez-Bello et al., 2011). C-section-delivered babies have a higher incidence of atopic disease (Penders et al., 2007), allergies, and asthma (Bager, 2008; Negele, 2004), and 64%–82% of cases of skin infection with methicillin-resistant Staphylococcus aureus in newborns occurs in C-section babies (Watson et al., 2004).
