August 13, 2014
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Gut microbiota of premature infants influenced by genetics, gestational age

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Recent data show premature infants’ gut microbiota may depend more on biological makeup and gestational age than environmental factors.

Patricio S. La Rosa, MD, of the Washington University School of Medicine in St. Louis, and colleagues used 16S rRNA gene pyrosequencing to assess the gut microbiota of 58 premature infants admitted to the St. Louis Children’s Hospital neonatal ICU. Infants weighed 1,500 g or less at birth. Researchers sequenced 922 specimens. Infants were categorized into gestational age groups of less than 26 weeks, 26 to 28 weeks or more than 28 weeks.

Patricio LaRosa

Patricio S. La Rosa

 

Gammaproteobacteria (54%), Bacilli (19.3%) and Clostridia (18.4%) accounted for 91.7% of all bacterial sequences. Together, they accounted for more than 90% of sequences generated in 85% of all specimens.

Researchers observed frequent abrupt shifts in bacterial composition. The shifts were unpredictable in direction and magnitude, according to researchers. Some changes were progressive and others were random, quick deviations from the directional progression pattern.

Bacilli were predominantly found in early stool samples. The greatest abundance of Clostridia was in samples from older infants.

Bacilli tended to decrease, whereas Clostridia increased and Gammaproteobacteria flourished soon after birth. Infants born most prematurely had the greatest gradual progression to Clostridia abundance.

Day of life was significantly associated with decreasing proportions of Bacilli and increasing proportions of Clostridia among all gestational age groups.

Antibiotic use was associated with increased proportions of Gammaproteobacteria among infants with a gestational age of 26 weeks or more. Among infants with a gestational age of 28 weeks or less, antibiotic use was associated with a decreased amount of Clostridia in stool samples.

Breast-feeding was associated with an increase of Gammaproteobacteria among infants with a gestational age of 28 weeks or less.

Potential exogenous drivers of gut microbiota did not fundamentally alter the trend of population evolution, only its pace, according to researchers.

Barbara Warner

Barbara Warner

 

Therefore, their next focus is on less healthy premature infants, particularly those with necrotizing enterocolitis, according to a press release.

“Research has not made an impact in either prevention or treatment of [necrotizing enterocolitis]. The Holy Grail is prevention, and if so much of what happens in the gut depends on the host, this research may help us identify just what increases an infant’s risk for developing [necrotizing enterocolitis] and help us target therapies,” study researcher Barbara Warner, MD, said in the release.

Disclosure: The researchers report no relevant financial disclosures.