Fungi associated with enterocolitis for those with Hirschsprung's disease

Plot of the fungal populations in the stool of children without enterocolitis (left), and those with enterocolitis (right).  Notice the substantially larger population of Candida, and Candida albicans in the population with enterocolitis.

Plot of the fungal populations in the stool of children without enterocolitis (left), and those with enterocolitis (right).  Notice the substantially larger population of Candida, and Candida albicans in the population with enterocolitis.

Hirschsprung's disease (HD) occurs when an infant is born without ganglion cells in their colon.  The result is that the portion of the colon that lacks these cells cannot relax and pass stool.  It is normally treated surgically by bypassing this portion of the colon with a normally functioning part of the colon.  Unfortunately, around 25% of patients that undergo this procedure eventually get enterocolitis (i.e. colon infection), which can be life threatening. 

Researchers have long believed there to be a bacterial cause for this type of Hirschsprung's associated enterocolitis (HAEC), however the connection has remained elusive.  Researchers, primarily from Cedars-Sinai, published the results of a study this week that suggests fungi, not bacteria, are primarily responsible for causing HAEC.  They published their results in the journal PLoS ONE.

The researchers developed a cohort of seventeen children that suffered from HD as an infant, and who had surgery to correct it.  Eight of these children developed HAEC, while the other nine remained healthy.  The researchers took stool samples from each of the children and measured their bacterial and fungal populations.  Surprisingly to the researchers, there was no statistical difference in the abundance of various bacteria between the two groups.  However, there was a much different story with the fungi.  The normal HD patients had a higher diversity of fungi than the HAEC patients.  In addition, HAEC patients were dominated by Candida species, while the others were not.  Moreover, an average of 90% of the Candida was Candida albicans, a pathogenic fungus that we have written about on the blog in the past.

The scientists were not able to say whether or not Candida albicans was responsible for causing the enterocolitis in these patients, however they do suggest it as a possibility.  To that end, they suggest that perhaps antifungals, rather than antibiotics, should be used to combat HAEC, especially given the fact that antibiotics can lead to ‘blooms’ in fungal species.  We often discuss the importance of all the aspects of the microbiome beyond just the bacteriome (bacteria), such as the virome (viruses), and mycobiome (fungi), and this paper shows another example of why these various ‘omes’ should not be neglected during microbiome research.

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