title: Sensitive Quantitative Analysis of the Meconium Bacterial Microbiota in Healthy Term Infants Born Vaginally or by Cesarean Section.
abstract: For decades, babies were thought to be born germ-free, but recent evidences suggest that they are already exposed to various bacteriain utero. However, the data on population levels of such pioneer gut bacteria, particularly in context to birth mode, is sparse. We herein aimed to quantify such bacteria from the meconium of 151 healthy term Japanese infants born vaginally or by C-section. Neonatal first meconium was obtained within 24-48 h of delivery; RNA was extracted and subjected to reverse-transcription-quantitative PCR using specific primers forClostridium coccoidesgroup,C. leptumsubgroup,Bacteroides fragilisgroup,Atopobiumcluster,Prevotella, Bifidobacterium,Lactobacillus,Enterococcus, Enterobacteriaceae,Staphylococcus,Enterococcus,Streptococcus,C. perfringens, andC. difficile. We detected several bacterial groups in both vaginally- and cesarean-born infants.B. fragilisgroup, Enterobacteriaceae,Enterococcus,Streptococcus, andStaphylococcuswere detected in more than 50% of infants, with counts ranging from 105to 108cells/g sample. About 30-35% samples harboredBifidobacteriumandLactobacillus(104-105cells/g); whereasC. coccoidesgroup,C. leptumsubgroup andC. perfringenswere detected in 10-20% infants (103-105cells/g). Compared to vaginally-born babies, cesarean-born babies were significantly less often colonized withLactobacillusgenus (6% vs. 37%;P= 0.01) andLactobacillus gasserisubgroup (6% vs. 31%;P= 0.04). Overall, sevenLactobacillussubgroups/species, i.e.,L. gasserisubgroup,L. ruminissubgroup,L. caseisubgroup,L. reuterisubgroup,L. sakeisubgroup,L. plantarumsubgroup, andL. breviswere detected in the samples from vaginally-born group, whereas only two members, i.e.,L. gasserisubgroup andL. breviswere detected in the cesarean group. These data corroborate that several bacterial clades may already be present before birth in term infants' gut. Further, lower detection rate of lactobacilli in cesarean-born babies suggests that the primary source of lactobacilli in infant gut is mainly from maternal vaginal and-to a lesser extent-anal microbiota during vaginal delivery, and that the colonization by some importantLactobacillusspecies is delayed in babies delivered via cesarean-section.
authors.affiliation: Probiotics Research Laboratory, Graduate School of Medicine, Juntendo University Tokyo, Japan.
authors.forename: Ravinder
authors.initials: R
authors.lastname: Nagpal
authors.affiliation: Yakult Central Institute Tokyo, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsuji
authors.affiliation: Yakult Central Institute Tokyo, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Gonohashi Obstetrics and Gynecology Hospital Tokyo, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Kawashima
authors.affiliation: Department of Pediatrics, School of Medicine, Tokyo Women's Medical University Tokyo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nagata
authors.affiliation: Yakult Central Institute Tokyo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nomoto
authors.affiliation: Probiotics Research Laboratory, Graduate School of Medicine, Juntendo University Tokyo, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yamashiro
keywords: C-section; Lactobacillus; RT-qPCR; dysbiosis; gut bacteria; intestinal microbiota; meconium