SEP 06, 2016 1:52 PM PDT

Necrotizing enterocolitis: a microbiome story

WRITTEN BY: Kerry Evans
Necrotizing enterocolitis is a nasty ailment. It’s a condition common in premature infants in which the intestines become inflamed and necrotic, sometimes leading to death. Often, bacteria invade the damaged bowel wall, further complicating things.

For the clinically-inclined, necrotizing enterocolitis (NEC) is dividied into Bell’s three stages of disease. The first, stage 1, encompasses “suspected disease”. Stage 1 symptoms include temperature instability, abdominal distension, and bloody stools. Stage 2 is defined as “definite disease”, and symptoms include metabolic acidosis and thrombocytopenia. Finally, stage 3 is “advanced disease”, with symptoms ranging from severe abdominal distension to metabolic and respiratory acidosis.
 
Intestines damaged by necrotizing enterocolitis.
Early on, investigators thought that NEC was caused primarily by ischemic injury in premature infants (NEC occurs in up to 5% of ICU admission) - for whatever reason, the intestines did not receive adequate blood flow and died. Various other risk factors are now recognized. These include formula feeding and abnormal intestinal microbiota. If you’re reading this article for the microbiology content, here we go.

As with many things these days, researchers recognize a connection between the intestinal microbiome and NEC. Such NEC-inducing changes to the microbiome include a decrease in commensals and an increase in pathogens; these changes are associated with the use of antibiotics and acid-suppressing medications.

We still have much to learn about the neonatal microbiome. (It’s still in its infancy, you could say. See what I did there?) What’s clear is that the gut undergoes enormous changes after birth; it must cultivate a healthy population of commensal bacteria (to digest food and produce vitamins, for starters). Among the first residents of the gut are Enterobacteriae, Enterococci, and Staphylococci.

The big question is, do infants at risk for developing NEC have different microbiomes than other infants? Several studies report that changes to the microbiome can be observed anywhere from 72 hours to 3 weeks before NEC develops. A culture-based study from some 20 years ago associated NEC with increases in the abundance of E. coli and Enterobacter cloacae. More recently, sequencing-based methods report decreases in the abundance of Bifidobacteria and Klebsiella species before NEC was diagnosed. It’s worth pointing out that it’s not clear whether these changes to the microbiome cause NEC or whether some other, unidentified change causes NEC and also disrupts the microbiome.

Whether microbes are fully to blame for NEC, it’s clear they can complicate things. NEC is associated with bloodstream infections, typically with Gram-negative bacteria like E. coli and Klebsiella. Again, it’s not clear whether NEC weakens the intestinal barrier, leading to systemic infection, or whether the systemic infection occurs upstream of NEC.

So, what can be done about NEC? We can harness the power of the microbiome, of course! It seems that many news headlines tout probiotics as a panacea - for the record, I’m not convinced. There appears to be good data, however, for using probiotic bacteria like Bifidobacteria and Lactobacillus to prevent and treat NEC. After all, probiotics are reported to attenuate NF-κB activation (reducing inflammation), increase the expression of cytoprotective genes, and decrease cell death.  

A study from 2010 showed that 20 out of 24 randomized controlled trials demonstrated the efficacy of probiotics for reducing NEC severity and overall mortality. Groups in Canada and Germany also report a drop in cases of NEC in hospitals that regularly use probiotic therapy.

Sources: Wikipedia, Drugs, The Journal of Pediatrics, Cochrane Library, Pediatric Research
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
AUG 16, 2020
Microbiology
Newly Discovered Gut Enzyme Could Function as Disease Biomarker
AUG 16, 2020
Newly Discovered Gut Enzyme Could Function as Disease Biomarker
Bacteria in the gut have a powerful influence on our health, in part because all of those microbes have genes of their o ...
SEP 17, 2020
Microbiology
Animals May Sense the Magnetic Field Because of Bacteria
SEP 17, 2020
Animals May Sense the Magnetic Field Because of Bacteria
Animals can sense magnetism, an ability called magnetoreception. Scientists have been trying to understand this sense, w ...
SEP 28, 2020
Microbiology
The Flu Vaccine Will Not Increase the Risk of COVID-19
SEP 28, 2020
The Flu Vaccine Will Not Increase the Risk of COVID-19
Scientists and clinicians want people to get their flu shots this year, especially because of the ongoing pandemic.
OCT 26, 2020
Immunology
Gearing up for Life: The First 7 Days of the Immune System
OCT 26, 2020
Gearing up for Life: The First 7 Days of the Immune System
The mother’s placenta serves as a shield for the developing fetus inside the womb, protecting it from the constant ...
OCT 26, 2020
Microbiology
A Network of Fungi Helps Trees Grow
OCT 26, 2020
A Network of Fungi Helps Trees Grow
Trees rely on a network of fungal friends for good health. Communities of trees can share nutrients and other essentail ...
NOV 04, 2020
Coronavirus
Damaging Antibodies Can Lead to Blood Clots in COVID-19 Patients
NOV 04, 2020
Damaging Antibodies Can Lead to Blood Clots in COVID-19 Patients
COVID-19, the illness caused by the pandemic virus SARS-CoV-2, is known to cause blood clots all over the body in some p ...
Loading Comments...