Abstract
Inflammatory bowel diseases (IBD) affect millions of people worldwide with increasing incidence. Ulcerative colitis (UC) and Crohn's disease (CD) are the two most common IBDs. There is no definite cure for IBD, and response to treatment greatly vary among patients. Therefore, there is urgent need for biomarkers to monitor therapy efficacy, and disease prognosis. We aimed to test whether qPCR analysis of common candidate bacteria identified from a patient's individual fecal microbiome can be used as a fast and reliable personalized microbial biomarker for efficient monitoring of disease course in IBD. Next generation sequencing (NGS) of 16S rRNA gene region identified species level microbiota profiles for a subset of UC, CD, and control samples. Common high abundance bacterial species observed in all three groups, and reported to be associated with IBD are chosen as candidate marker species. These species, and total bacteria amount are quantified in all samples with qPCR. Relative abundance of anti-inflammatory, beneficial Faecalibacterium prausnitzii, Akkermansia muciniphila, and Streptococcus thermophilus was significantly lower in IBD compared to control samples. Moreover, the relative abundance of the examined common species was correlated with the severity of IBD disease. The variance in qPCR data was much lower compared to NGS data, and showed much higher statistical power for clinical utility. The qPCR analysis of target common bacterial species can be a powerful, cost and time efficient approach for monitoring disease status and identify better personalized treatment options for IBD patients.