BackgroundTo explore the influences of prenatal antibiotic exposure, the intensity of prenatal and postnatal antibiotic exposure on gut microbiota of preterm infants and whether gut microbiota and drug resistant strains in the neonatal intensive care unit (NICU) over a defined period are related.MethodsAmong 28 preterm infants, there were two groups, the PAT (prenatal antibiotic therapy) group (12 cases), and the PAF (prenatal antibiotic free) group (12 cases). Fecal samples from both groups were collected on days 7 and 14. According to the time of prenatal and postnatal antibiotic exposure, cases were divided into two groups, H (high) group (11 cases) and L (low) group (11 cases), and fecal samples on day 14 were collected. Genomic DNA was extracted from the fecal samples and was subjected to high throughput 16S rRNA amplicon sequencing. Bioinformatics methods were used to analyze the sequencing results.ResultsPrenatal and postnatal antibiotic exposure exercised influence on the early establishment of intestinal microflora of preterm infants. Bacteroidetes decreased significantly in the PAT group (p < 0.05). The number of Bifidobacterium significantly decreased in the PAT group and H group (p < 0.05). The early gut microbiota of preterm infants with prenatal and postnatal antibiotic exposure was similar to resistant bacteria in NICU during the same period.ConclusionPrenatal and postnatal antibiotic exposure may affect the composition of early gut microbiota in preterm infants. Antibiotic-resistant bacteria in NICU may play a role in reshaping the early gut microbiota of preterm infants with prenatal and postnatal antibiotic exposure.Electronic supplementary materialThe online version of this article (10.1186/s12941-018-0264-y) contains supplementary material, which is available to authorized users.

BackgroundThis case-control study investigated an association between breast milk jaundice (BMJ) and infants’ gut microbiome. The study included determination of the diversity of the gut microbiome and identification of bacterial genera associated with BMJ.MethodsThe study population consisted of 12 infants with BMJ and 22 breastfed infants without jaundice (control). DNA collected from feces was analyzed by PCR amplification and 1% agarose gel electrophoresis, and then sequenced with a MiSeq system. Relative quantification bioinformatics was employed to analyze the DNA sequencing data. An Illumina high-throughput sequencing platform was used to analyze 16S rRNA variable (V) regions V3 and V4 in stool samples. ResultsIn the control group, the proportion of Escherichia/Shigella (genus level) in the gut microbiome (64.67%) was significantly higher than that of the BMJ group. However, the prevalence of Bifidobacterium or Enterococcus in the gut microbiome of the two groups was similar. The Simpson index indicated that the diversity of the bacterial population in the BMJ infants was significantly narrower than in the normal infants.ConclusionThe prevalence of Escherichia/Shigella in the gut of breastfed infants is important for lowering BMJ development.