Impact of bread diet on intestinal dysbiosis and irritable bowel syndrome symptoms in quiescent ulcerative colitis: A pilot study.

Gut microbiota may be involved in the presence of irritable bowel syndrome (IBS)-like symptomatology in ulcerative colitis (UC) patients in remission. Bread is an important source of dietary fiber, and a potential prebiotic. To assess the effect of a bread baked using traditional elaboration, in comparison with using modern elaboration procedures, in changing the gut microbiota and relieving IBS-like symptoms in patients with quiescent ulcerative colitis. Thirty-one UC patients in remission with IBS-like symptoms were randomly assigned to a dietary intervention with 200 g/d of either treatment or control bread for 8 weeks. Clinical symptomatology was tested using questionnaires and inflammatory parameters. Changes in fecal microbiota composition were assessed by high-throughput sequencing of the 16S rRNA gene. A decrease in IBS-like symptomatology was observed after both the treatment and control bread interventions as reductions in IBS-Symptom Severity Score values (p-value < 0.001) and presence of abdominal pain (p-value < 0.001). The treatment bread suggestively reduced the Firmicutes/Bacteroidetes ratio (p-value = 0.058). In addition, the Firmicutes/Bacteroidetes ratio seemed to be associated with improving IBS-like symptoms as suggested by a slight decrease in patient without abdominal pain (p-value = 0.059). No statistically significant differential abundances were found at any taxonomic level. The intake of a bread baked using traditional elaboration decreased the Firmicutes/Bacteroidetes ratio, which seemed to be associated with improving IBS-like symptoms in quiescent ulcerative colitis patients. These findings suggest that the traditional bread elaboration has a potential prebiotic effect improving gut health (ClinicalTrials.gov ID number of study: NCT05656391).

New fecal bacterial signature for colorectal cancer screening reduces the fecal immunochemical test false-positive rate in a screening population.

Guidelines recommend routine screening for colorectal cancer (CRC) in asymptomatic adults starting at age 50. The most extensively used noninvasive test for CRC screening is the fecal immunochemical test (FIT), which has an overall sensitivity for CRC of approximately 61.0%-91.0%, which drops to 27.0%-67.0% for advanced adenomas. These figures contain a high false-positive rate and a low positive predictive value. This work aimed to develop a new, noninvasive CRC screening tool based on fecal bacterial markers capable of decreasing FIT false-positive rates in a FIT-positive population. We defined a fecal bacterial signature (RAID-CRC Screen) in a proof-of-concept with 172 FIT-positive individuals and validated the obtained results on an external cohort of 327 FIT-positive subjects. All study participants had joined the national CRC screening program. In the clinical validation of RAID-CRC Screen, a sensitivity of 83.9% and a specificity of 16.3% were obtained for the detection of advanced neoplasm lesions (advanced adenomas and/or CRC). FIT 20 µg/g produced 184 false-positive results. Using RAID-CRC Screen, this value was reduced to 154, thus reducing the false-positive rate by 16.3%. The RAID-CRC Screen test could be implemented in CRC screening programs to allow a significant reduction in the number of colonoscopies performed unnecessarily for FIT-positive participants of CRC screening programs.

Reduction of faecal immunochemical test false-positive results using a signature based on faecal bacterial markers.

BACKGROUND: Colorectal cancer is the second commonest cause of cancer mortality. Some countries are implementing colorectal cancer screening to detect lesions at an early stage using non-invasive tools like the faecal immunochemical test. Despite affordability, this test shows a low sensitivity for precancerous lesions and a low positive predictive value for colorectal cancer, resulting in a high false-positive rate. AIM: To develop a new, non-invasive colorectal cancer screening tool based on bacterial faecal biomarkers, which in combination with the faecal immunochemical test, could allow a reduction in the false-positive rate. This tool is called risk assessment of intestinal disease for colorectal cancer (RAID-CRC). METHODS: We performed both the faecal immunochemical test and the bacterial markers analysis (RAID-CRC test) in stool samples from individuals with normal colonoscopy (167), non-advanced adenomas (88), advanced adenomas (30) and colorectal cancer (48). All the participants showed colorectal cancer-associated symptoms. RESULTS: Performance of the faecal immunochemical test for advanced neoplasia (ie advanced adenoma and colorectal cancer) was determined by using the cut-off value established in Catalonia (20 µg haemoglobin/g of faeces) for a population-based screening approach. Sensitivity and specificity values of 83% and 80%, respectively, and positive and negative predictive values of 56% and 94%, respectively, were obtained. When both the immunological and the biological analysis were combined, the corresponding values were 80% and 90% for sensitivity and specificity, respectively, and 70% and 94% for positive and negative predictive values, respectively, resulting in a 50% reduction of the false-positive rate. CONCLUSIONS: RAID-CRC test allows a substantial reduction in the faecal immunochemical test false-positive results (50%) in a symptomatic population. Further validation is indicated in a colorectal cancer-screening scenario.

Anti-tumour Necrosis Factor Treatment with Adalimumab Induces Changes in the Microbiota of Crohn's Disease.

BACKGROUND: The composition of the intestinal microbiota is altered in Crohn's disease [CD] patients. The objective of this study was to evaluate the qualitative and quantitative changes in the microbiota of CD patients in 3 months of treatment with adalimumab [ADA], and determine whether or not these changes are produced towards the recovery of the normal, healthy-like microbiota. METHODS: The microbiota composition, and the Faecalibacterium prausnitzii / Escherichia coli quantitative relationship as dysbiosis indicator, were studied at baseline [T0], one month [T1], and 3 months [T3] after starting treatment using a polymerase chain reaction-denaturing gradient gel electrophoresis [PCR-DGGE] of 16S rRNA gene fragments and quantitative PCR, respectively, in rectal mucosal biopsies from 15 CD patients and four healthy subjects. RESULTS: T0 and T3 fingerprints were different in all patients; whereas T1 and T3 presented similar patterns. Recovered phylogroups were Firmicutes [79.1%], Bacteroides [12.5%], and Actinobacteria [6.25%]. The prevalence of E. coli decreased during treatment. Relative E. coli loads in CD samples were significantly reduced at every analysed step [T1 and T3] [p < 0.005] whereas no significant changes were observed in relative F. prausnitzii counts. CONCLUSION: Treatment with ADA induces short-term changes in the microbiota composition which seem to parallel the partial recovery of the gut bacterial ecology, with recovery parameters tending to eubiosis recovery. The quantitative determination of dysbiosis-representative bacteria, such as E. coli, may provide a fast and reliable indicator of the healing state of the intestinal mucosa.