Virulent strains of Staphylococcus aureus secrete exfoliative toxins (ETs) that cause the loss of cell‐cell adhesion in the superficial epidermis. S. aureus ETs are serine proteases, which exhibit exquisite substrate specificity, and their mechanisms of action are extremely complex. To date, four different serotypes of ETs have been identified and three of them (ETA, ETB and ETD) are associated with toxin‐mediated staphylococcal syndromes related to human infections leading to diseases of medical and veterinary importance.
Part of the book: The Rise of Virulence and Antibiotic Resistance in Staphylococcus aureus
The human gut microbiota makes fundamental contributions to host metabolism and immune system. Therefore, perturbations in its composition, a process known as dysbiosis, have an important role in the development of several chronicle diseases, mainly intestinal inflammatory disorders. Culture-independent molecular methods are allowing scientific community to uncover substantive findings, thus giving a more detailed description of the human intestinal microbiota. This chapter presents a review on current metagenomic approaches, based on next-generation sequencing technologies, for investigating bacterial taxonomic classification and predictive function associated with the human gut in health and disease. In this context, we describe recent studies that have been trying to elucidate important alterations in microbiome composition across individuals according to delivery mode, aging, diet and medication that might be linked to susceptibility to immune-mediated diseases. A description of the main bacterial taxa and genes acting in dysbiosis during inflammation, focusing on chronic inflammatory bowel diseases and colorectal cancer, is also explored in this chapter.
Part of the book: Metagenomics for Gut Microbes
This chapter will address the main omics approaches used in studies involving the genus Corynebacterium, Gram-positive microorganisms that can be isolated from many diverse environments. Currently, the genus Corynebacterium has more than 130 highly diversified species, many of which present medical, veterinary and biotechnological importance, such as C. diphtheriae, C. pseudotuberculosis, C. ulcerans and C. glutamicum. Due to the wide application in these fields, several omics methodologies are used to better elucidate the species belonging to this genus, such as genomics, transcriptomics and proteomics. The genomic era has contributed to the development of more advanced and complex approaches that enable the increase of generated data, and consequently the advance on the structural, functional and dynamic knowledge of biological systems.
Part of the book: Basic Biology and Applications of Actinobacteria
Staphylococcus aureus is a pathogen of great importance to clinical and veterinary medicine. Recently, there has been a growing interest in S. aureus extracellular vesicles (EVs) in the pathogenesis of this bacterium. Released by living cells into the extracellular milieu, EVs are membranous structures carrying macromolecules such as proteins, nucleic acids, and metabolites. These structures play several physiological roles and are, among others, considered a mechanism of intercellular communication within S. aureus populations but also in trans kingdom interactions. S. aureus EVs were shown to transport important bacterial survival and virulence factors, such as β-lactamases, toxins, and proteins associated with bacterial adherence to host cells, and to trigger the production of cytokines and promote tissue inflammation. In this chapter, we will review the main studies regarding S. aureus EVs, including their composition and roles in host-pathogen interactions, and the possible applications of EVs for vaccines and therapy development against staphylococcal infections.
Part of the book: Insights Into Drug Resistance in Staphylococcus aureus
Propionibacterium freudenreichii is a Gram-positive dairy probiotic bacterial species that has been used as a ripening starter in the production of Swiss-type cheese for a long time. It has been exploited for the optimization of cheese production, including ripening capacities and aroma compounds production, but also for the production of vitamin B12 and organic acids. Furthermore, it has emerged in the probiotics landscape owing to several beneficial traits, including tolerance to stress in the gastrointestinal tract, adhesion to host cells, anti-pathogenic activity, anticancer potential and immunomodulatory properties. These beneficial properties have been confirmed with in vitro and in vivo investigations, using several omics approaches that allowed the identification of important molecular actors, such as surface proteins, short-chain fatty acids and bifidogenic factors. The diversity within the species was shown to be an important aspect to take into consideration, since many of these properties were strain-dependent. New studies should dive further into the molecular mechanisms related to the beneficial properties of this species and of its products, while considering the complexities of strain diversity and the interactions with the host and its microbiota. This chapter reviews current knowledge on the possible impact of P. freudenreichii on human health.
Part of the book: Prebiotics and Probiotics