Su1985 – Preliminary Data on Oral and Fecal Microbiota in Patients Affected by Lynch Syndrome

Aim Colorectal cancer (CRC) is the third most commonly diagnosed cancer all over the world.The gut microbiota play a crucial role in CRC development.Intestinal microbiota can become biomarkers in present and future.But, there has been few reports of gut microbiome change regarding to CRC stage and posttreatment.Therefore, we analyzed the gut microbiome before the treatment and after 6 months of surgery or chemotherapy using a metagenomic analysis.Also, we confirmed the intestinal microbiota composition from fecal sample of Korean CRC patients by stages I,II,III,IV and isolated microbes through culture-based method.Methods: All obtained CRC (total 42 patients) fecal samples were classified into stages I,II,III,IV with the surgery or chemotherapy.Together the followup(6months after surgery or chemotherapy) samples were also collected.Sequencing was based on the 16S rRNA gene amplicon on the Illumina MiSeq platform.The bacteria strains were subcultivated on the agar plate medium in aerobic and anaerobic and further identified by using the 16s rRNA gene sequencing.Result In the metagenome analysis, bacteria diversity was recovered at 6 months after surgery or chemotherapy compared to before treatment.The relative abundance of the phylum Proteobacteria was increased while the phylum Bacteroidetes was significantly decreased after 6 months of surgery or chemotherapy.Also, The relative abundance of Faecalibacterium, Acidobacteria was increased at 6 months after the surgery or chemotherapy while Bacteroides and Akkermansia was decreased at 6 months after the surgery or chemotherapy.The relative abundance of Facalibacterium and Streptococcus was decreased in stage IV CRC than stage I,II,III.Together, the relative abundance of Ruminococcaceae was increased in stage IV CRC than stage I,II,III.Comparing between surgery and chemotherapy, the surgery groups showed the less microbiota diversity than chemotherapy group.In the surgery group, the level of genus such as Bacteroides, Prevotella, Collinsella, Megamonas and the level of family Enterobacteriaceae were observed highly.On the contrary, Fusobacterium and Ruminococcus were decreased in surgery group.Using culture method, we isolated diverse bacteria of species level that are known to be involved in CRC, including 8 strains of Bacteroides; B. ovatus, B. uniformis, B. salyersiae, B. vulgatus, B. fragilis, B. faecis, B. plebeius, B. xylanisolvens and 2 strains of Fusobacterium; F. gonidiaformans, F. necrophorum.Conclusion: The relative abundance of Facalibacterium and Streptococcus was decreased in CRC stage IV than stage I,II,III.Together, microbial diversity was recovered at 6 months after the surgery or chemotherapy compared to before CRC treatment.In terms of comparing between surgery and chemotherapy, we found the decrease of gut microbiome diversity after CRC surgery than after CRC chemotherapy.