The ‘first 1000 days of life’ determine the gut microbiota composition and can have long-term health consequences. In this study, the simulator of the human intestinal microbial ecosystem (SHIME^®) model, which represents the main functional sections of the digestive tract, was chosen to study the microbiota of young children. The aim of this study was to reproduce the digestive process of toddlers and their specific colonic environment. The ascending, transverse and descending colons of SHIME^® model were inoculated with feces from three donors aged between 1 and 2 years-old, in three separate runs. For each run, samples from colon vessels were collected at days 14, 21 and 28 after microbiota stabilization period. Short chain fatty acid concentrations determined by HPLC showed that microbiota obtained in SHIME^® model shared characteristics between adults and infants. In addition, microbial diversity and bacterial populations determined by 16S rRNA amplicon sequencing were specific to each colon vessel. In conclusion, the SHIME^® model developed in this study seemed well adapted to evaluate prebiotic and probiotic impact on the specific microbiota of toddlers, or medicine and endocrine disruptor metabolism. Moreover, this study is the first to highlight some biofilm development in in vitro gastrointestinal modelling systems.

Clostridioides difficile is an anaerobic spore-forming Gram-positive bacterium. C. difficile carriage and 16S rDNA profiling were studied in three clinical groups at three different sampling times: inflammatory bowel disease (IBD) patients, C. difficile infection (CDI) patients and healthcare workers (HCWs). Diversity analysis was realized in the three clinical groups, the positive and negative C. difficile carriage groups and the three analysis periods. Concerning the three clinical groups, β-diversity tests showed significant differences between them, especially between the HCW group and IBD group and between IBD patients and CDI patients. The Simpson index (evenness) showed a significant difference between two clinical groups (HCWs and IBD). Several genera were significantly different in the IBD patient group (Sutterella, Agathobacter) and in the CDI patient group (Enterococcus, Clostridioides). Concerning the positive and negative C. difficile carriage groups, β-diversity tests showed significant differences. Shannon, Simpson and InvSimpson indexes showed significant differences between the two groups. Several genera had significantly different relative prevalences in the negative group (Agathobacter, Sutterella, Anaerostipes, Oscillospira) and the positive group (Enterococcus, Enterobacteriaceae_ge and Enterobacterales_ge). A microbiota footprint was detected in C. difficile-positive carriers. More experiments are needed to test this microbiota footprint to see its impact on C. difficile infection.

Introduction. In the context of the global pandemic due to SARS-CoV-2, procurement of personal protective equipment during the crisis was problematic. The idea of reusing and decontaminating personal surgical masks in facilities was explored in order to avoid the accumulation of waste and overcome the lack of equipment. Hypothesis. Our hypothesis is that this work will show the decontamination methods assessed are effective for bacteria, such as Staphylococcus aureus and Pseudomonas aeruginosa . Aim. We aim to provide information about the effects of five decontamination procedures (UV treatment, dry heat, vaporized H₂O₂, ethanol treatment and blue methylene treatment) on S. aureus and P. aeruginosa . These bacteria are the main secondary bacterial pathogens responsible for lung infections in the hospital environment. Methodology. The surgical masks and the filtering facepiece respirators were inoculated with two bacterial strains ( S. aureus ATCC 29213 and P. aeruginosa S0599) and submitted to five decontamination treatments: vaporized H₂O₂ (VHP), UV irradiation, dry heat treatment, ethanol bath treatment and blue methylene treatment. Direct and indirect microbiology assessments were performed on three positive controls, five treated masks and one negative control. Results. The five decontaminations showed significant (P<0.05) but different degrees of reductions of S. aureus and P. aeruginosa . VHP, dry heat treatment and ethanol treatment adequately reduced the initial contamination. The 4 min UV treatment allowed only a reduction to five orders of magnitude for face mask respirators. The methylene blue treatment induced a reduction to two orders of magnitude. Conclusions. The three methods that showed a log₁₀ reduction factor of 6 were the dry heat method, VHP and ethanol bath treatment. These methods are effective and their establishment in the medical field are easy but require economic investment.