HIV infection in mothers can disrupt the development of the gut microbiome of their HIV-uninfected babies, potentially explaining why these infants are more vulnerable to death and disease, a study suggested Wednesday.

Conducted in 50 Haitian mother and infant pairs, the study published in the US journal Science Translational Medicine, linked microbiome disruptions in these infants to changes in the composition of the HIV-positive mother's breast milk.

The findings could open the door to treating these at-risk babies with probiotics or prebiotics to help ensure normal microbiome development, researchers from the Saban Research Institute of Children's Hospital Los Angeles (CHLA) said.

Worldwide, more than a million infants are born annually to HIV-infected mothers. While most of these children escape HIV infection, they still are at greater risk of morbidity and at nearly twice the risk of mortality than infants who are not exposed to HIV.

In the new study, Jeffrey Bender and colleagues at the CHLA compared the microbiomes of 50 Haitian babies and their mothers, half of whom were HIV-positive and the other half HIV-negative.

"In contrast to the mostly consistent microbial communities identified in all of the mothers, the microbiomes of HIV-exposed, uninfected infants were strikingly different from infants born to HIV-negative women in the same community," said Bender.

The gut microbiomes of HIV-exposed, uninfected infants were less diverse and less mature, and displayed altered composition of the bacterial community, it found.

Furthermore, the oligosaccharide composition of breast milk, one of the key routes by which moms pass bacteria to their babies, differed between HIV-infected and uninfected mothers.

Oligosaccharides, indigestible carbohydrates in milk, are thought to serve as a prebiotic that promotes the growth of "good" gut bacteria.

Altogether, it may be the combination of slight disturbances in the HIV-infected mothers' own microbiome and differences in the oligosaccharide composition of breast milk that may explain changes in their infants' microbiome.

"Providing infants with important beneficial bacteria (probiotics) or potentially specific milk oligosaccharides (prebiotics) may potentially improve long-term outcomes, although this remains to be thoroughly investigated and tested," they wrote in the paper.