Clostridioides difficile is an anaerobic Gram-positive and spore-forming bacterium. The majority of C. difficile strains produce two toxins, A and B, associated with the development of acute diarrhea and/or colitis. In this review, two situations are distinguished: C. difficile infection (CDI) and asymptomatic colonization (AC). The main objective of this review is to explore the available data related to the link between the gut microbiota and the development of CDI. The secondary aim is to provide more information on why some people colonized with toxigenic C. difficile develop an infection while others show no signs of disease. Several factors, such as the use of antibiotics and proton pump inhibitors, hospitalization, and age, predispose individuals to C. difficile colonization and/or C. difficile infection. The gut microbiota of people with AC showed decreased abundances of Prevotella, Alistipes, Bacteroides, Bifidobacterium, Dorea, Coprococcus, and Roseburia. The gut microbiota of people suffering from CDI showed reductions in the abundances of Lachnospiraceae, Ruminococcaceae, Blautia spp., Prevotella spp., Dialister spp., Bifidobacterium spp., Roseburia spp., Anaerostipes spp., Faecalibacterium spp. and Coprococcus spp., in comparison with healthy people. Furthermore, increases in the abundances of Enterococcaceae and Enterococcus were associated with C. difficile infection.

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.

Clostridioides difficile is a spore-forming anaerobic Gram-positive bacterium responsible for a broad spectrum of intestinal symptoms and healthcare associated diarrhoea. The hypothesis of this work was that different in vitro conditions, notably pH and human faecal microbiota composition impact the germination or/and the growth of C. difficile. This study aimed to correlate growth kinetics of the bacterium with these two physiochemical parameters by using a static in vitro model. To better understand the initial gut colonization, several growth curve assays were carried out to monitor the behaviour of the spores and vegetative forms of a C. difficile strain 078 under different conditions mimicking the gut environment. When the faeces were added, no spore germination or growth was observed but C. difficile spores germinated in vitro when the pH was maintained between 6.6–6.9 regardless of four faeces donor. The evolution of microbiota studied by 16S rDNA profiling showed high proportions of Enterobacteriaceae and E. coli/Shigella when C. difficile grew regardless of the inoculated faeces. This model helped us to understand that the germination and the growth of C. difficile is strongly pH dependent, and further research is needed to evaluate the potential impact of the gut microbiota composition on C. difficile.

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.

Clostridioides difficile is an anaerobic, spore‐forming, Gram‐positive pathogenic bacterium. This study aimed to analyze the effect of two samples of healthy fecal microbiota on C. difficile gene expression and growth using an in vitro coculture model. The inner compartment was cocultured with spores of the C. difficile polymerase chain reaction (PCR)‐ribotype 078, while the outer compartment contained fecal samples from donors to mimic the microbiota (FD1 and FD2). A fecal‐free plate served as a control (CT). RNA‐Seq and quantitative PCR confirmation were performed on the inner compartment sample. Similarities in gene expression were observed in the presence of the microbiota. After 12 h, the expression of genes associated with germination, sporulation, toxin production, and growth was downregulated in the presence of the microbiota. At 24 h, in an iron‐deficient environment, C. difficile activated several genes to counteract iron deficiency. The expression of genes associated with germination and sporulation was upregulated at 24 h compared with 12 h in the presence of microbiota from donor 1 (FD1). This study confirmed previous findings that C. difficile can use ethanolamine as a primary nutrient source. To further investigate this interaction, future studies will use a simplified coculture model with an artificial bacterial consortium instead of fecal samples.