Presentación de resultados

After giving birth, participants were asked to come to the clinic with their infants, within three days. Following this birth visit, women and their infants were asked to return approximately one week afterwards for a final visit, during which fecal, oral, vaginal and breast milk samples were collected from mothers and oral and fecal samples from the infants. The number of samples used in the final analysis was less than samples analyzed at baseline due to women either withdrawing from the study or not giving birth by the time the study closed; samples not being provided at time of visit, or due to the death of infants (one in the UN group and one in the NP group). Furthermore, only fecal samples from infants between the ages of 10 to 20 days, and from mothers in the probiotic group who had compliance greater than 80% during the month before their final visit were used. This resulted in a total of 29 infant fecal samples used in the final analysis (UN=9,

UNP=6, N=3, NP=7 (two twin sets), O=4). After sequencing and filtering, 170 OTUs annotated at the genus level were present in the infant fecal samples with an average number of 16,124 ± 14878 reads/sample. Figure 23 is a bar plot summarizing the

representative OTUs at the genus level in the fecal samples of the infants and Figure 24 is a bar plot summarizing the relative abundance of phyla detected in the infant fecal

samples. One hundred and seventy genera were detected in the infant fecal samples, belonging to thirteen phyla. The top six OTUs found in the infant fecal samples annotated to the taxa Bifidobacterium, Enterobacteriaceae, Veillonella, Streptococcus, Bacteroides

and Prevotella. The most abundant phyla found within the infant fecal samples were

Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes. The age of the infants in each of the five groups at the time of the final visit is seen in Figure 25, and there was no significant difference between the groups.

Figure 23: Bar plot of OTUs annotated at the genus level for infant fecal samples at the final visit. The top 25 OTUs are given in the legend in descending order of abundance. UN=Undernourished, UNP=Undernourished Probiotic, N=Nourished,

NP=Nourished Probiotic, O=Obese. The y-axis denotes the relative abundance of each taxa.

Figure 24: Bar plot summarizing relative abundance of phyla detected in the infant fecal samples at the final visit. The 13 phyla detected are given in the legend in

descending order of abundance. UN=Undernourished, UNP=Undernourished Probiotic, N=Nourished, NP=Nourished Probiotic, O=Obese. The y-axis denotes the

Figure 25: Age of infants in each of the five groups in days at the time of sample collection for the final visit. Each symbol (, for example) indicates a participant

sample.

As shown earlier, analysis of the gut microbial composition of this study population at baseline did not show any differences using our definitions of nutritional status. Also, due to filtering, numbers of the final infant fecal samples were low among the groups.

Therefore, in order to increase the power of analysis, the infant fecal samples from mothers receiving probiotic yogurt were grouped UNP and NP and fecal samples from infants whose mothers were not receiving probiotic yogurt were grouped UN and N, and ALDEx2 was used to assess differences in the representative OTUs annotated at the genus and phyla level. In addition, the results from these two groups were compared to the infants from obese mothers. To begin, groups were analyzed at the genus level. When performing ALDEx2 analysis between infant fecal samples from mothers who received

probiotic yogurt and infant fecal samples from mothers who did not receive probiotic yogurt, there was no difference (Figure 26A). In addition, there was no difference when comparing infant fecal samples from mothers receiving probiotic yogurt and obese mothers, nor when comparing infant fecal samples from mothers not receiving probiotic yogurt and obese mothers (Figure 26B and C, respectively). However when calculating the proportional representation of the top two genera (Bifidobacterium and an unknown

Enterobacteriaceae, Figure 23) in the infant fecal samples from mothers not receiving

probiotic yogurt and from mothers who did receive probiotic yogurt, significant differences were observed. Specifically, an unknown genera from Enterobacteriaceae

was thirteen times more abundant in the infant fecal samples from mothers who did not receive the probiotic yogurt and Bifidobacterium was three times more abundant in infant

Figure 26: ALDEx2 results showing no difference in OTUs annotated to the genus level between infant fecal samples from mothers who received probiotic yogurt and

those who did not (A), infant fecal samples from mothers who received probiotic yogurt and infant fecal samples from obese mothers (B) and infant fecal samples from mothers who did not receive probiotic yogurt and infant fecal samples from

Figure 27: Proportion of sequences aligned to an unknown Enterobacteriaceae (A) and Bifidiobacterium (B) in infant fecal samples from mothers who received probiotic yogurt (blue squares, both UNP and NP groups combined) and mothers who did not receive probiotic yogurt (red circles, both UN and N groups combined).

Each symbol (, for example) indicates a participant sample.

When comparing the infant fecal samples at the phyla level from mothers who received probiotic and those who did not, OTUs representing the phyla Actinobacteria were significantly more abundant in infant fecal samples from mothers who received the probiotic yogurt (p=0.03, using a Welch’s t-test with a Benjamini Hochberg correction) (Figure 28A). However, there was no significant difference in either the OTUs

representing phyla between infants from the probiotic group and infants from the obese group or between infants from the non-probiotic group and infants from the obese group (p > 0.05) (Figure 28B and C). The differences between phyla represented in the infant fecal samples from the UN group and infants from the UNP group were investigated further with ALDEx2. In addition to Actinobacteria being significantly more abundant in the infants from the UNP group (p=0.049), Proteobacteria was found to be significantly more abundant in infants from the UN group using a Welch’s t-test with a Benjamini Hochberg correction (p=0.044) (Figure 29).

Figure 28: ALDEx2 results of comparisons of OTUs annotated to the phyla level between infant fecal samples from mothers who received probiotic yogurt and those

who did not (A), infant fecal samples from mothers who received probiotic yogurt and infant fecal samples from obese mothers (B) and infant fecal samples from mothers who did not receive probiotic yogurt and infant fecal samples from obese

mothers (C). Representative phyla that have significantly different abundance between and within the samples are depicted as red dots as seen in A, this dot

Figure 29: ALDEx2 results of comparisons of OTUs annotated to the phyla level between infant fecal samples from the UN and UNP groups. The red dots indicate

significant phyla that are differentially abundant within and between the two groups and are representative of Actinobacteria and Proteobacteria.