Summary Background Probiotics are defined as live micro‐organisms which confer a health benefit on the host. Although most probiotics are bacteria, one strain of yeast, Saccharomyces boulardii, has been found to be an effective probiotic in double‐blind clinical studies. Aims To compare the main properties that differentiates yeast from bacteria and to review the properties of S. boulardii explaining its potential benefits as a probiotic. Methods The PubMed and Medline databases were searched using the keywords ‘probiotics’, ‘yeast’, ‘antibiotic associated diarrhea’, ‘Saccharomyces boulardii’,‘bacterial diarrhea’ and ‘inflammatory bowel disease’ in various combinations. Results Several clinical studies have been conducted with S. boulardii in the treatment and prevention of various forms of diarrhoea. Promising research perspectives have been opened in terms of maintenance treatment of inflammatory bowel diseases. The mechanism of S. boulardii’s action has been partially elucidated. Conclusion Saccharomyces boulardii is a strain of yeast which has been extensively studied for its probiotic effects. The clinical activity of S. boulardii is especially relevant to antibiotic‐associated diarrhoea and recurrent Clostridium difficile intestinal infections. Experimental studies clearly demonstrate that S. boulardii has specific probiotic properties, and recent data has opened the door for new therapeutic uses of this yeast as an ‘immunobiotic’.

Methods: Topic-focused reviews that examine the effects of ocean pollution on human health, identify gaps in knowledge, project future trends, and offer evidence-based guidance for effective intervention. Environmental Findings: Pollution of the oceans is widespread, worsening, and in most countries poorly controlled. It is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% arises from land-based sources. It reaches the oceans through rivers, runoff, atmospheric deposition and direct discharges. It is often heaviest near the coasts and most highly concentrated along the coasts of low-and middle-income countries. Plastic is a rapidly increasing and highly visible component of ocean pollution, and an estimated 10 million metric tons of plastic waste enter the seas each year. Mercury is the metal pollutant of greatest concern in the oceans; it is released from two main sources-coal combustion and small-scale gold mining. Global spread of industrialized agriculture with increasing use of chemical fertilizer leads to extension of Harmful Algal Blooms (HABs) to previously unaffected regions. Chemical pollutants are ubiquitous and contaminate seas and marine organisms from the high Arctic to the abyssal depths. Ecosystem Findings: Ocean pollution has multiple negative impacts on marine ecosystems, and these impacts are exacerbated by global climate change. Petroleum-based pollutants reduce photosynthesis in marine microorganisms that generate oxygen. Increasing absorption of carbon dioxide into the seas causes ocean acidification, which destroys coral reefs, impairs shellfish development, dissolves calcium-containing microorganisms at the base of the marine food web, and increases the toxicity of some pollutants. Plastic pollution threatens marine mammals, fish, and seabirds and accumulates in large mid-ocean gyres. It breaks down into microplastic and nanoplastic particles containing multiple manufactured chemicals that can enter the tissues of marine organisms, including species consumed by humans. Industrial releases, runoff, and sewage increase frequency and severity of HABs, bacterial pollution, and anti-microbial resistance. Pollution and sea surface warming are triggering poleward migration of dangerous pathogens such as the Vibrio species. Industrial discharges, pharmaceutical wastes, pesticides, and sewage contribute to global declines in fish stocks. Human Health Findings: Methylmercury and PCBs are the ocean pollutants whose human health effects are best understood. Exposures of infants in utero to these pollutants through maternal consumption of contaminated seafood can damage developing brains, reduce IQ and increase children's risks for autism, ADHD and learning disorders. Adult exposures to methylmercury increase risks for cardiovascular disease and dementia. Manufactured chemicals-phthalates, bisphenol A, flame retardants, and perfluorinated chemicals...

Use of the nonpathogenic yeastSaccharomyces boulardii is a thermophilic, nonpathogenic yeast administered in Western Europe for the prevention and treatment of a variety of diarrheal diseases (17, 29). However, the mechanisms by which S. boulardii controls diarrhea remain elusive. The efficacy of this yeast has been attributed to several of its properties, such as its effect on the mucosa leading to an increase in dissaccharidase activity (8) or stimulation of the immune response (7). In animals, administration of S. boulardii provides protection against intestinal lesions caused by several diarrheal pathogens (10,33). In vitro studies have demonstrated that S. boulardii exerts antagonistic activity against various bacterial pathogens (6). Recent studies have reported the adhesion of the Salmonella enterica serovars Typhimurium and Enteritis and of enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli to S. boulardii (24,25).EPEC is a major cause of diarrhea in the developing world (31, 34). The pathogenesis of EPEC infections involves a three-stage process. (i) EPEC adheres initially to intestinal epithelial cells in a pattern described as localized adherence (36). This pattern of adherence, characterized by microcolonies of bacteria associated with the epithelial cells, is dependent on the expression of the bacterial type IV bundle-forming pilus (BFP) (3). (ii) Next, the bacteria induce signal transduction pathways in host cells, leading to an elevation in the intracellular levels of Ca 2ϩ and inositol triphosphate (16, 23) and the phosphorylation of cellular proteins (4, 35, 41). (iii) These signaling events culminate in the formation of attachingand-effacing lesions which are characterized by localized degeneration of the microvilli, intimate contact between the bacteria and the infected cell, and the assembly of highly organized cytoskeletal structures in the epithelial cells just beneath the attached bacteria, forming cuplike pedestals (22,27,30). EPEC is also able to induce its internalization by nonphagocytic epithelial cells (2, 15).The aim of our study was to investigate in vitro the effect of S. boulardii against EPEC infection using the T84 cell line derived from a colon carcinoma. This cell line has been extensively used to elucidate the mechanism of EPEC-induced diarrhea. EPEC infection results in a modification of the T84 barrier function, characterized by a drop in transepithelial resistance, an increase in permeability, and modification of the distribution of the tight junction-associated protein 37). Our study reveals that S. boulardii maintains the barrier function and the viability of EPEC-infected T84 cells. Although the yeast does not modify the number of cell-associated bacteria, it reduces the number of intracellular bacteria. The phosphorylation of several proteins induced by EPEC in T84 cells is diminished in the presence of S. boulardii. Finally, the yeast interferes with the ERK1/2 mitogen-activated protein (MAP) kinase pathway that, as demonstrated in this study, is ...

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