Delivery Mode Shapes the Composition of the Lower Airways Microbiota in Newborns.

Elisa Cardelli,Mauro Pistello,Fabrizio Maggi,Francesco Celandroni,Marco Calvigioni,Alessandra Vecchione,Paolo Mannella,Diletta Mazzantini,Lisa Macera,Emilia Ghelardi,Adelaide Panattoni

doi:10.3389/fcimb.2021.808390

Abstract

Radical alterations in the human microbiota composition are well-known to be associated with many pathological conditions. If these aberrations are established at the time of birth, the risk of developing correlated pathologies throughout life is significantly increased. For this reason, all newborns should begin their lives with a proper microbiota in each body district. The present study aimed at demonstrating a correlation between the mode of delivery and the development of a well-balanced microbiota in the lower airways of newborns. 44 pregnant women were enrolled in this study. Microbiological comparative analysis was carried out on tracheobronchial secretions of babies born through vaginal delivery (VD) or caesarean section (CS). All samples showed the presence of bacterial DNA, regardless of the mode of delivery. No viable cultivable bacteria were isolated from the CS samples. On the contrary, VD allowed colonization of the lower airways by alive cultivable bacteria. The identification of bacterial species revealed that Lactobacillus spp. and Bacteroides vulgatus were the most common microorganisms in the lower airways of vaginally-delivered newborns. Data obtained from quantitative PCRs showed a significantly higher total bacterial load, as well as Firmicutes and Lactobacillus spp. amount, in VD samples than CS ones, while no statistically significant difference was found in Torque Teno Virus (TTV) load between samples. Taken together, our findings confirm the hypothesis that passage through the maternal vaginal canal determines more beneficial colonization of the lower airways in newborns.

Highlights

A total of 1.05 × 105 ± 6.47 × 103 colony-forming units (CFUs)/mL was recorded for vaginal delivery (VD) samples
No CFUs were found from plates on which caesarean section (CS) samples were streaked, suggesting that no viable cultivable bacteria were present in these samples after collection and processing
This study aimed at inferring a correlation between the mode of delivery and the microbial composition of the infant’s lower airways microbiota

Summary

Introduction

Through countless mechanisms of action, the local microbial flora positively interferes with the host’s physiology, by determining protective effects such as the reduction of inflammation (Delgado-Diaz et al, 2019) and infection rate by pathogens (Oscariz and Pisabarro, 2001; Smith and Ravel, 2017), the modulation of the local immune system (Leong and Ding, 2014), the protection from neoplastic transformation (Greten et al, 2004), and the development of organs and Delivery Shapes Lower Airways Microbiota systems (Singh et al, 2017). The onset of infections (Aroutcheva et al, 2001; Witkin et al, 2011; Smith and Ravel, 2017), inflammatory pathologies (Arend, 2002; Matsuzawa et al, 2017; Delgado-Diaz et al, 2019), tumors (Greten et al, 2004), and allergic pathologies (Li et al, 2019) and reduced development of functional organs and immune system (Singh et al, 2017) are the most evident and considerable consequences If these alterations in the microbiota composition are established at the time of birth or in the perinatal period, subjects may be more susceptible in developing pathological conditions throughout their lives, with a significantly higher occurrence (Sevelsted et al, 2015). It is important that all newborns acquire a proper and biodiverse microbiota since birthtime

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