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. 2024 Jun 22;12(7):1271.
doi: 10.3390/microorganisms12071271.

Gut Dysbiosis in the First-Passed Meconium Microbiomes of Korean Preterm Infants Compared to Full-Term Neonates

Sae Yun Kim  1 , Young-Ah Youn  1
Affiliations

Gut Dysbiosis in the First-Passed Meconium Microbiomes of Korean Preterm Infants Compared to Full-Term Neonates

Sae Yun Kim et al. Microorganisms. .

Abstract

Since gestational age (GA) is an important factor influencing the presence of specific microbiomes, we aimed to characterize the core microbiomes of preterm infants compared to full-term (FT) infants. This study investigated the differences in microbiota composition between very preterm (VP), moderate-to-late preterm (MLP), and FT neonates by examining the core microbiomes of a large cohort of Korean neonates. Meconium samples from 310 neonates with a GA range of 22-40 weeks were collected, and 16S rRNA analyses were performed; 97 samples were obtained from the FT, 59 from the VP, and 154 from the MLP group. Firmicutes, Bacteroidetes, and Proteobacteria were the phylum-level core microbiomes. Infants born before 37 weeks showed a disruption in the core microbiomes. At the phylum level, the relative abundance of Bacteroidetes was positively (r = 0.177, p = 0.002) correlated with GA, while that of Proteobacteria was negatively (r = -0.116, p = 0.040) correlated with GA. At the genus level, the relative abundances of Bacteroides and Prevotella were positively correlated with GA (r = 0.157, p = 0.006; r = 0.160, p = 0.005). The meconium of preterm infants exhibited significantly lower α-diversities than that of FT infants. β-diversities did not appear to differ between the groups. Overall, these findings underscore the importance of GA in shaping the early gut microbiome.

Keywords: dysbiosis; meconium; microbiome; very preterm.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Flow chart of the study cohort. NICU, neonatal intensive care unit.
Figure 2
Figure 2
Relative abundances of bacterial taxa at the (a) phylum and (b) genus levels according to gestational age. Microbiomes of the first-passed stool samples obtained within 72 h after birth showed both phylum- and genus-level dysbiosis in neonates born before 37 weeks of gestation. At the phylum level, Firmicutes and Bacteroidetes were the most dominant phyla in the first meconium microbiome. At the genus level, Prevotella and Bacteroides were the most predominant species in the meconium samples. FT, full term; MLP, moderate-to-late preterm; VP, very preterm.
Figure 3
Figure 3
Meconium microbiome comparison between very preterm, moderate-to-late preterm, and full-term neonates. The bacterial composition of meconium was dominated by a few genera. Relative abundances and types of bacteria at the phylum level. The preterm group showed significantly lower abundances of Fermicutes and Bacteroidetes and a greater abundance of Proteobacteria (a). At the genus level, there were significant differences in the relative abundances of the 20 most dominant microbiota (b). The different colors correspond to different species names, and the length of the color block indicates the relative abundance of the species represented by the color block. The abscissa is the group name, and the ordinate is the relative abundance of the species.
Figure 4
Figure 4
Scatter plots showing the correlation between GA and the relative abundances of the microbiota, which showed significant differences between groups at the phylum level (a) and at the genus level (b). At the phylum level, the relative abundances of Firmicutes and Bacteroidetes were positively correlated with GA. The relative abundance of Proteobacteria was negatively correlated with GA. The F/B ratio is calculated as the ratio between the two phyla Firmicutes and Bacteroidetes. At the genus level, the relative abundances of Bacteroides and Prevotella were positively correlated with GA, and the relative abundance of Ralstonia was negatively correlated with GA. The abundances of Bifidobacterium and Lactobacillus were not correlated with GA. Each point shows the median relative abundance for each gestational age. The red lines are the line of best fit at total through linear regression, and the blue lines are by the linear interpolation between elements in array. The abscissa is GA (week), and the ordinate is the relative abundance (%) of the species. The Pearson correlation coefficient was calculated. F/B ratio, Firmicutes to Bacteroidetes ratio; GA, gestational age.
Figure 5
Figure 5
α-and β-diversities. Comparison of the α-diversities (Shannon Index) and β-diversities (Bray–Curtis dissimilarity) of preterm and full-term infants compared to those of full-term infants revealed that very preterm and moderate-to-late preterm infants had significantly lower α-diversities. The abscissa is the group name, the ordinate is the Shannon index of the species (a), and principal coordinate analysis (PCoA) reflects the distribution of the different samples (R2 = 0.027, p = 0.001). The dispersion of preterm infants and term infants was similar in the meconium (b). Each point represents one sample and is colored based on the group. FT, full-term; IQR, interquartile range; MLP, moderate-to-late preterm; VP, very preterm.
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