The pioneer gut microbiota in human neonates vaginally born at term - a pilot study.

The pioneer microbiota of the neonate may affect future actions of the immune system. This study aimed to map the pioneer microbiota in healthy neonates vaginally born at term. A subgroup of neonates born large for gestational age (LGA) was compared with the neonates appropriate for gestational age (AGA). Fecal samples were collected, within 48 hours after birth, from 79 neonates. Quantitative polymerase chain reaction was used for enumeration of Lactobacillus, a subgroup of Lactobacillus common in the vagina, Bifidobacterium, Enterococcus, Enterobacteriaceae and the Bacteroides fragilis group. Cloning and sequencing were applied for subgroups of neonates born LGA or AGA. Lactobacillus was detected in all neonates while other bacterial groups were detected only in 14-30% of the subjects. The prevalence of Gram-negative Proteobacteria was higher in neonates born LGA while Gram-positive Firmicutes was more prevalent in neonates born AGA (P<.001). This study contributed to increased knowledge of the pioneer microbiota and indicates that neonates born LGA had significantly different microbiota compare to those born AGA. As the early microbiota can be important for maturation of the immune system, the outcome from this study may be relevant in the care of pregnant woman and newborns. LIST OF ABBREVIATIONS: