Colonization of Supplemented M-16V in Low Birth Weight Infants and Its Effects on Their Gut Microbiota Weeks Post-administration.

The colonization and persistence of probiotics introduced into the adult human gut appears to be limited. It is uncertain, however, whether probiotics can successfully colonize the intestinal tracts of full-term and premature infants. In this study, we investigated the colonization and the effect of oral supplementation with M-16V on the gut microbiota of low birth weight (LBW) infants. A total of 22 LBW infants (12 infants in the M-16V group and 10 infants in the control group) were enrolled. M-16V was administrated to LBW infants in the M-16V group from birth until hospital discharge. Fecal samples were collected from each subject at weeks (3.7-9.3 weeks in the M-16V group and 2.1-6.1 weeks in the control group) after discharge. qPCR analysis showed that the administrated strain was detected in 83.3% of fecal samples in the M-16V group (at log 8.33 ± 0.99 cell numbers per gram of wet feces), suggesting that this strain colonized most of the infants beyond several weeks post-administration. Fecal microbiota analysis by 16S rRNA gene sequencing showed that the abundance of Actinobacteria was significantly higher ( < 0.01), whereas that of Proteobacteria was significantly lower ( < 0.001) in the M-16V group as compared with the control group. Notably, the levels of the administrated strain and indigenous bacteria were both significantly higher in the M-16V group than in the control group. Our findings suggest that oral administration of M-16V led to engraftment for at least several weeks post-administration and we observed a potential overall improvement in microbiota formation in the LBW infants' guts.