Abstract 17908: Changes in Gut Microbiome Early After Fontan Operation

IntroductionA growing body of evidence supports the role of the gut microbiome in human health and well-being. The unique physiological conditions imposed by the Fontan operation (FO) may influence intestinal circulation and oxygen delivery thus altering the gut microbiome.MethodsStool samples were obtained in children just prior to FO (T1), early postop within 5-7 days after FO (T2), and late postop 3-9 months after FO (T3). At early postop T2 all subjects were taking oral feeds, had at least one well-formed bowel movement and were off all cardiovascular infusions. Shotgun metagenomic sequencing of the microbiota was performed. Community-level differences between time points were assessed by PERMANOVA tests of Bray-Curtis distance between samples. Differentially abundant taxa were identified by generalized linear mixed models. Enteric protein loss was measured by level of stool alpha-1-antitrypsin concentration and its relationship to the gut microbiota was explored.ResultsSpecimens from 32 subjects with single ventricle and bidirectional Glenn undergoing FO were studied. Mean age at surgery was 39 +/- 8 months. A significant difference in species composition was noted between T1 and T2 (p=0.043) and T2 and T3 (p=0.003), but not between T1 and T3. Significant differences in specific taxa abundance were seen at T2, with increased Escherichia and decreased Eubacterium and Faecalibacterium as compared to T1 and T3. Two subjects with subclinical enteric protein loss post-operatively had a unique alteration of bacterial populations, with increased abundance of Coprobacillus and decreased abundance of Bacteroides and Ruminococcus as compared to the rest of the population.ConclusionsThe gut microbiota is acutely perturbed at the time of FO with re-establishment of the populations within a few months after surgery. Whether this change is related to the stressors of cardiac surgery in the child in general, or specific to the acute imposition of a Fontan circulation with subsequent accommodation is uncertain. Additionally, children with subclinical enteric protein loss have altered gut microbiome as compared to those without. Further study of the impact of the Fontan circulation on the gut microbiome in the older child and adult is warranted.