The role of intestinal microbiota in inflammatory bowel diseases is intensively researched. Pediatric studies on the relation between microbiota and treatment response are sparse. We aimed to determine whether absolute abundances of gut microbes characterize the response to infliximab induction in pediatric inflammatory bowel disease.
We recruited pediatric patients with inflammatory bowel disease introduced to infliximab at Children's Hospital, University of Helsinki. Stool samples were collected at 0, 2, and 6 weeks for microbiota and calprotectin analyses. We defined treatment response as fecal calprotectin value <100 µg/g at week 6. Intestinal microbiota were analyzed by 16S ribosomal RNA gene amplicon sequencing using the Illumina MiSeq platform. We analyzed total bacterial counts using quantitative polymerase chain reaction and transformed the relative abundances into absolute abundances based on the total counts.
At baseline, the intestinal microbiota in the treatment responsive group (n = 10) showed a higher absolute abundance of Bifidobacteriales and a lower absolute abundance of Actinomycetales than nonresponders (n = 19). The level of inflammation according to fecal calprotectin showed no statistically significant association with the absolute abundances of fecal microbiota. The results on relative abundances differed from the absolute abundances. At the genus level, the responders had an increased relative abundance of Anaerosporobacter but a reduced relative abundance of Parasutterella at baseline.
High absolute abundance of Bifidobacteriales in the gut microbiota of pediatric patients reflects anti-inflammatory characteristics associated with rapid response to therapy. This warrants further studies on whether modification of pretreatment microbiota might improve the outcomes.
We studied absolute and relative abundances of fecal microbiota in relation to response to induction therapy with infliximab in pediatric inflammatory bowel disease. We discovered that a high absolute abundance of anti-inflammatory Bifidobacteriales at baseline associated with response.