Periodic Reporting for period 1 - MUCDIFF (Competition between the enteric pathogen Clostridium difficile and the commensal members of the gut microbiota for mucosal sugars)
Reporting period: 2015-09-01 to 2017-08-31
This project focuses on competition for host-derived nutrients as an important mechanism by which the colonic microbiota can suppress the growth of many gut pathogens. We are particularly interested in the pathogen Clostridium difficile, nowadays the most common cause of enteric infections associated with antibiotic therapy in developed countries. We seek to understand how C. difficile utilizes host mucosal sugars to establish and survive in the gut and how the presence of commensal bacteria competing for these mucosal sugars modify the outcome of C. difficile infections.
Using a combination of techniques such as genetic tools, in vivo colonization assays, and stable isotope probing (SIP) combined with fluorescence in situ hybridization (FISH) and high resolution secondary ion mass spectrometry (NanoSIMS), we aim to: 1) elucidate the role of mucosal sugars catabolism in C. difficile expansion in the gut; 2) identify commensal members of the gut microbiota that can efficiently catabolize these mucosal sugars in vivo; and 3) evaluate the ability of the identified organisms to outcompete C. difficile. Findings from this work will contribute to elucidate the mechanisms by which the gut microbiota prevents C. difficile colonization and to identify members of the gut microbiota that can be the basis for an effective, safe and standardized treatment to cure a C. difficile infection.
Clostridium difficile relies on the utilization of gut mucosal sugars to expand and cause infection and disease. Using stable isotope probing coupled to Raman Spectroscopy, we could observe stimulation of a significant part of the commensals from the gut mouse community when ammended with the same mucosal sugars that C.difficile utilizes during expansion in the gut. Using Raman-based single cell sorting, these efficient mucosal sugar utilizers were sorted and started to be identified. The ability of these commensal organisms (or closely related ones) to outcompete C. difficile will now be tested in vitro, and if successul results are achieved, then in vivo. If these organims reveal to be able to efficiently compete C. difficile, they can be used as the basis for an new bacterial-based treatment to erradicate C. difficile from the gut. C. difficile is currently a major concern is hospitals and health care institutions. In most European countries the number of deaths caused by CDI has more than quadrupled in the last decade, with medical costs associated with CDI also representing a major economic burden. Thus, the identification of organisms with potential to eradicate this pathogen will benefit the European economy and society in general.