Specific bacteria and overall diversity linked to severity of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is an inflammation of the gut that occurs due to bacterial infection in premature infants.  It has long been considered that a ‘healthy’ microbiome is important to preventing NEC in low birth weight infants, and, as we have written about before, there is a lot of science that supports this.  Still though, it is not known which bacteria are most responsible for causing NEC, and how overall diversity is associated with the disease.  Many studies have tried to nail this down, but there has been conflicting results.  Scientists at Louisiana State University thought that perhaps these conflicting results were from neglecting to consider the severity of the NEC as a variable in each study.  They hypothesized that the infants’ microbiomes would vary depending on the severity of the NEC, and that the most severe cases would show a characteristic microbiome that may be important to understanding the disease.  They published their results in the Journal Microbiome last week.  

The scientists studied the microbiomes of 74 healthy infants and 21 infants suffering from NEC.  They then categorized the NEC infants into three groups based on the severity of the disease.  The scientists learned that two bacterial genera, Veillonella and Streptococcus, were more abundant in all the NEC microbiomes compared to non-NEC controls.  They also discovered that overall microbiome diversity was decreased in NEC versus controls.  When the researchers looked microbiome differences that were a function of NEC severity they discovered that Clostridia were completely absent from the microbiomes of infants suffering from the most severe NEC and its increased with decreasing severity of NEC (15% in controls, 12% in mild NEC, 3% in moderate NEC, and 0% in severe NEC).  In addition, a similar trend was seen with diversity, it decreased with severity of NEC.

Many Clostridia species have been associated with a healthy microbiome, and they may be critically important to maintaining a homeostasis in the gut.  According to this study, their abundance appears to be of upmost importance in premature infants, and this should be considered moving forward.  Many countries administer probiotics to low birthweight infants who are at risk for NEC, but this is not yet down in the United States.  Fortunately, there are a number of clinical trials that are trying to nail down the science so that the FDA has enough evidence to make a recommendation.

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