Antibiotics affect breast milk microbiota in mothers of preterm infants,
study finds

Date:
September 3, 2020
Source:
University of Toronto
Summary:
Researchers have found that mothers of preterm babies have highly
individual breast milk microbiomes, and that even short courses of
antibiotics have prolonged effects on the diversity and abundance
of microbes in their milk.



FULL STORY ==========================================================================
A team led by researchers at the University of Toronto and The Hospital
for Sick Children has found that mothers of preterm babies have highly individual breast milk microbiomes, and that even short courses of
antibiotics have prolonged effects on the diversity and abundance of
microbes in their milk.


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The study is the largest to date of breast milk microbiota in mothers
of preterm infants, and it is the first to show that antibiotic class,
timing and duration of exposure have particular effects on the most
common microbes in breast milk -- many of which have the potential to
influence growth and immunity to disease in newborns.

"It came as quite a shock to us that even one day of antibiotics was
associated with profound changes in the microbiota of breast milk," says Deborah O'Connor, who is a professor and chair of nutritional sciences
at U of T and a senior associate scientist at SickKids. "I think the
take-home is that while antibiotics are often an essential treatment for mothers of preterm infants, clinicians and patients should be judicious
in their use." Most antibiotic stewardship programs in neonatal intensive
care focus on limiting use in newborns themselves. The current study adds
to growing evidence that these programs should include a focus on mothers
as well, says O'Connor, principal investigator on the study who is also
a scientist in the Joannah & Brian Lawson Centre for Child Nutrition.

The journal Cell Host and Microbe published the study today.

The researchers looked at 490 breast milk samples from 86 mothers
whose infants were born preterm, during the first eight weeks after
delivery. They found that the mothers' body mass index and mode of
delivery influenced the breast milk microbiota, consistent with some
other studies.



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But the effects of antibiotics were the most pronounced, and in some cases
they lasted for weeks. Many of the antibiotic-induced changes affected
key microbes known to play a role in fostering disease, or in gut health
and metabolic processes that promote babies' growth and development.

"Overall we saw a decrease in metabolic pathways, and increase in more pathogenic pathways in bacteria over time," says Michelle Asbury, a
doctoral student in O'Connor's lab and lead author on the paper. "Of
particular concern was an association between antibiotics and a member
of the Proteobacteria phylum called Pseudomonas. When elevated,
Proteobacteria in a preterm infant's gut can precede necrotizing enterocolitis." About seven per cent of babies born preterm develop necrotizing enterocolitis, a frequently fatal condition in which part
of the bowel dies. A class of antibiotics called cephalosporins also
had a big effect on the overall diversity of breast milk microbiota.

Asbury says it is too early to know what the findings mean for preterm
infant health and outcomes. She and her colleagues will dive into those questions over the next year, as they compare their findings with stool
samples from the preterm infants involved in the study. This should
reveal whether changes in the mothers' milk microbiomes are actually
seeding the infants' guts to promote health or increase disease risk.

Meanwhile, she says it's important that mothers with preterm infants
continue to take antibiotics for some cases of mastitis, blood infections
and early rupture of membranes. Roughly 60 per cent of women in the
current study took antibiotics -- highlighting both the vast need for
these drugs and the potential for some overuse.

Sharon Unger is a co-author on the study and a professor of paediatrics
at U of T, as well as a scientist and neonatologist at Sinai Health
and SickKids. She says that the benefits of breast feeding far outweigh
the risk that antibiotics can disrupt the breast milk microbiome, and
that mothers should without question continue to provide their own milk
when possible.

"But I think we can look to narrow the spectrum of antibiotics we use
and to shorten the duration when possible," Unger says. She adds that
advances in technology may allow for quicker diagnoses of infection and
better antibiotic stewardship in the future.

As for the rapidly moving field of microbiome research, Unger says
it holds great promise for preterm infants. "Clearly the microbiome
is important for their metabolism, growth and immunity. But emerging
evidence on the gut-brain axis and its potential to further improve neurodevelopment for these babies over the long term warps my mind."

========================================================================== Story Source: Materials provided by University_of_Toronto. Original
written by Jim Oldfield.

Note: Content may be edited for style and length.


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Link to news story: https://www.sciencedaily.com/releases/2020/09/200903114206.htm

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