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New biological strategies for the treatment of Salmonella infection are needed in response to the increase in antibiotic-resistant strains. Escherichia coli L1000 and Bifidobacterium thermophilum RBL67 were previously shown to produce antimicrobial proteinaceous compounds (microcin B17 and thermophilicin B67, respectively) active in vitro against a panel of Salmonella strains recently isolated from clinical cases in Switzerland. In this study, two three-stage intestinal continuous fermentation models of Salmonella colonization inoculated with immobilized faeces of a two-year-old child were implemented to study the effects of the two bacteriocinogenic strains compared with a bacteriocin-negative mutant of strain L1000 on Salmonella growth, as well as gut microbiota composition and metabolic activity. Immobilized E. coli L1000 added to the proximal colon reactor showed a low colonization, and developed preferentially in the distal colon reactor independent of the presence of genetic determinants for microcin B17 production. Surprisingly, E. coli L1000 addition strongly stimulated Salmonella growth in all three reactors. In contrast, B. thermophilum RBL67 added in a second phase stabilized at high levels in all reactors, but could not inhibit Salmonella already present at a high level (>107 c.f.u. ml−1) when the probiotic was added. Inulin added at the end of fermentation induced a strong bifidogenic effect in all three colon reactors and a significant increase of Salmonella counts in the distal colon reactor. Our data show that under the simulated child colonic conditions, the microcin B17 production phenotype does not correlate with inhibition of Salmonella but leads to a better colonization of E. coli L1000 in the distal colon reactor. We conclude that in vitro models with complex and complete gut microbiota are required to accurately assess the potential and efficacy of probiotics with respect to Salmonella colonization in the gut.

Background Non-optimal medication use among older adults is a public health concern. A concrete picture of potentially inappropriate medication (PIM) use is imperative to ensure optimal medication use. Objective To assess the prevalence of PIMs in community-dwelling older adults and identify associated factors. Methods A retrospective population-based cohort study was conducted using the Quebec Integrated Chronic Disease Surveillance System (QICDSS). The QICDSS includes data on drug claims for community-dwelling older adults with chronic diseases or at risk of developing chronic diseases aged ≥65 years who are insured by the public drug insurance plan. Individuals aged ≥66 years who were continuously insured with the public drug plan between 1 April 2014 and 31 March 2016 were included. PIMs were defined using the 2015 Beers criteria. We conducted multivariate robust Poisson regression analyses to explore factors associated with PIM use. Results A total of 1 105 295 individuals were included. Of these, 48.3% were prescribed at least one PIM. The most prevalent PIMs were benzodiazepines (25.7%), proton-pump inhibitors (21.3%), antipsychotics (5.6%), antidepressants (5.0%) and long-duration sulfonylureas (3.3%). Factors associated with PIM exposure included being a woman [rate ratio (RR): 1.20; 95% confidence interval (CI): 1.20–1.21], increased number of medications and having a high number of chronic diseases, especially mental disorders (RR: 1.50; 95% CI: 1.49–1.51). Conclusion Almost one out of two community-dwelling older adults use a PIM. It is imperative to reduce the use of PIMs, by limiting their prescription and by promoting their deprescribing, which necessitates not only the active involvement of prescribers but also patients.