Background: Faecal calprotectin (FC) levels correlate directly with the endoscopic activity of inflammatory bowel disease (IBD). Microbiota plays a role in the etiopathogenesis of IBD. In this context, the presence of specific genotypes of bacteroidetes has been shown to be associated with the activity of the disease. The aim of this study was to evaluate the correlation between the presence of genotypes of bacteroidetes and the FC levels in relation to the endoscopic activity of IBD.
Methods: A single-center, observational cross-sectional study was designed. Consecutive patients with Crohn's disease (CD) and ulcerative colitis (UC) who performed a colonoscopy were included. Colonic biopsies were taken to characterize microbiota by using a restriction fragment length polymorphism (RFLP) analysis on PCR products targeting the 16SrRNA genes of Bacteroidetes digested with HinfI, PciI, DpnII and AciI. FC levels were measured in faecal samples with a quick test (Quantum blue) the day before starting colon cleansing for colonoscopy. Inactive UC was defined as a Mayo endoscopic score of 0. Inactive CD was defined as a SES-CD ≤2. Results are shown as prevalence and median, and they were analyzed by the Mann-Withney test, Spearman correlation test and multivariate lineal regression.
Results: 22 patients with IBD (12 CD and 10 UC) were included. Endoscopic activity was detected in 15 patients (9 CDa and 6 UCa). 7 different genotypes of Bacteroidetes called N1, C1-C5 and CB10 were detected. The presence of genotype N1 and C1 was constant in patients with active and inactive IBD, while genotype C4 was present in 82.3% of patients with UCa and CDa, and in 17.6% of patients with inactive IBD (p=0.009). The median of FC was 30 μg/g (range 30–101) in patients with inactive disease and 315 μg/g (range 30–1128) in patients with active IBD (p=0.019). In patients with genotype C4 the median of FC was 280 μg/g (range 30–460), whereas in patients with other genotypes the median of FC was 41μg/g (range 30–101) (p=0.01). A positive correlation was found between C4 genotype and FC levels (r=0.429). After multivariable analysis, FC levels were associated with endoscopic activity (coef 473.8, p=0.018) and the presence of genotype C4 in biopsies (coef 67.9, p=0.014).
Conclusions: FC levels and genotype C4 of bacteroidetes in colon biopsies are associated with the endoscopic activity of IBD. The association of these two biomarkers could help to determinate endoscopic activity in the future.