Probiotics may increase gut bacteria diversity in extremely preterm infants

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A new clinical study has shown that supplements of a lactic acid bacterium may have positive effects by increasing the diversity of intestinal bacteria in these infants, according to new research by Linköping University in Sweden published in the journal Cell Reports Medicine.

Extremely preterm infants can suffer from a life-threatening inflammation of the gut, the researchers said. Preterm infants can be affected by a very severe inflammation of the intestines, which almost only occurs in such infants. The condition, necrotizing enterocolitis (NEC), leads to parts of the intestine dying. One of three infants who contract the infection die, and those who survive often suffer from long-term complications such as short gut syndrome and neurodevelopmental disabilities.

The bacteria in the intestine of preterm infants differ from those in full-term infants. This has led many people to investigate whether giving probiotic supplements that contain certain bacteria has a positive effect. One finding is that the lactic acid bacterium Lactobacillus reuteri (L. reuteri) can reduce the risk of NEC in preterm infants. It is, however, not clear whether this is true also for extremely preterm infants, nor is the mechanism behind the positive effect known.

For the study, researchers looked at 132 infants who had been born extremely prematurely, between week 23 and 28 of pregnancy, or 17 to 12 weeks before the due date. All weighed less than a kilogram at birth. Each infant was randomly assigned to one of two groups, to receive either oil drops that contained the probiotic or a placebo. The treatment was given daily during the neonatal period. The scientists investigated how the intestinal bacterial flora was influenced by the supplement of L. reuteri, and analyzed bacteria in the stools at several time points.

The researchers found that the composition of bacteria in the intestine differed during the first month of the probiotic treatment. During the first week of life, the bacterial groups Staphylococcus and Klebsiella, which may cause disease, were more common in the group that received placebo. Klebsiella can cause inflammation and has been associated with NEC and sepsis. However, the current study does not allow any conclusions about whether the probiotic treatment influences the risk of these diseases in these extremely premature infants, and larger studies will be required.

Supplementation with probiotics is used in increasing numbers of neonatal clinics. The scientific evidence that supplements of probiotics to preterm infants have a positive effect and can be used safely is considered to be sufficiently strong, the researchers said.

"The supplemented probiotic L. reuteri survives in the intestine, even though these extremely premature infants are treated with large doses of antibiotics that kill bacteria,” said Thomas Abrahamsson, MD, PhD, lead author of the study, pediatrician at the neonatal intensive care unit at Crown Princess Victoria Children´s Hospital, and associate professor at the Department of Biomedical and Clinical Sciences at Linköping University, in a statement. “The positive effect of the treatment in increasing the diversity of intestinal bacteria may be one mechanism behind the positive effects of this probiotic shown in previous studies.”