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Pathogenicity and Virulence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Endotoxins were so named by early investigators because they are contained within the bacterial cell, rather than being secreted. Exotoxins were defined as secreted products of microbes that damage host cells directly or interfere with host cell metabolism. Molecular and genetic characterization of exotoxins revealed that they are enzymes, often coded by genes located on plasmids or bacteriophages.
An unsteady pensioner
Published in Tim French, Terry Wardle, The Problem-Based Learning Workbook, 2022
Some strains of C. difficile secrete two exotoxins: exotoxins A and B. Both A and B bind to receptors on epithelial cells resulting in fluid secretion and mucosal damage. Exotoxin B is used for the diagnosis, based on its response during culture.
Emergency Surgery
Published in Tjun Tang, Elizabeth O'Riordan, Stewart Walsh, Cracking the Intercollegiate General Surgery FRCS Viva, 2020
Alastair Brookes, Yiu-Che Chan, Rebecca Fish, Fung Joon Foo, Aisling Hogan, Thomas Konig, Aoife Lowery, Chelliah R Selvasekar, Choon Sheong Seow, Vishal G Shelat, Paul Sutton, Colin Walsh, John Wang, Ting Hway Wong
Clinically the patient improves with antibiotic therapy but the erythema continues to spread. What is happening?In this case the infection is likely to be due to an endotoxin producing organism such as staph aureus. The bacterial exotoxins are released on bacterial cell death. The exotoxins cause a local inflammatory reaction in tissues even though the infective process is resolving and the patient improves systemically.
Tracing the origins of extracellular DNA in bacterial biofilms: story of death and predation to community benefit
Published in Biofouling, 2021
Davide Campoccia, Lucio Montanaro, Carla Renata Arciola
Analogous cytotoxins have been identified in other pathogens. For instance, in P. aeruginosa, rhamnolipid has been reported to determine the lysis of neutrophil cells by acting as a biosurfactant ( Van Gennip et al. 2009). The ExoU cytotoxin and exolysin (ExlA) have also been described as two important exotoxins of P. aeruginosa (Tamura et al., 2004; Basso et al. 2017). Other examples of toxins expressed by other pathogens and capable of causing host cell death include the α-hemolysin of E. coli, the cytolysin of Vibrio cholerae, and the listeriolysin O of Listeria monocytogenes (Steinmoen et al. 2002). The action of cytolytic, necrotizing or pro-apoptotic mechanisms/factors can result in cell death and contribute to the release of substantial quantities of nucleic acids.
Prevalence, clinical expression, invasiveness and outcome of Staphylococcus aureus containing Panton-Valentine leukocidin in children treated in a university hospital of Lithuania
Published in Infectious Diseases, 2020
Birute Petraitiene, Pablo Rojo Conejo, Lina Jankauskaite, Rimantas Kevalas, Giedre Trumpulyte, Ausra Snipaitiene, Astra Vitkauskiene, Vaidotas Gurskis
Staphylococcus aureus (S. aureus) is a significant cause of purulent infections, prevalent in both community and hospital acquired settings. It can produce several types of exotoxins differing in their effect [1]. Panton-Valentine leukocidin (PVL) is one of the S. aureus’s synergohymenotropic exotoxin belonging to pore-forming toxin family [2]. PVL consists of two subunits; LukF-PV and LukS-PV proteins, that act synergistically to induce a strong lytic effect on host defence cells, notably with polymorphonuclear leucocytes but especially on neutrophils [2]. Research shows that the pvl gene can be transmitted via bacteriophages from one strain to another [3,4]. PVL positive S. aureus [SA-PVL(+)] is most commonly isolated strain from previously immunocompetent older children and young adults [5,6]. SA-PVL(+) is the predominant causes of skin and soft tissue infections (SSTIs) [7–9], but can also cause severe invasive conditions such as osteoarthritis [10], pyomyositis [11], necrotizing fasciitis [12], necrotizing pneumonia [13] and sepsis [14]. PVL’s impact in respect to invasiveness and infection severity is complex [15,16]. An increasing body of research demonstrates that SA-PVL(+) strains are associated with less invasive infections [7,17]. However, in case of invasive SA-PVL(+) infections, clinical manifestation is more severe [10–14,18].
Multifaceted toxin profile, an approach toward a better understanding of probiotic Bacillus cereus
Published in Critical Reviews in Toxicology, 2019
Yifang Cui, Erwin Märtlbauer, Richard Dietrich, Hailing Luo, Shuangyang Ding, Kui Zhu
The role of B. cereus and other members of the B. cereus group in gastrointestinal and nongastrointestinal diseases has not always gained sufficient attention in the past, particularly in view of their use as probiotics. In fact, strains of the B. cereus group show high diversity in phenotype and toxin production ability. Production of exotoxins is, however, the major virulence factor in foodborne and systemic diseases by pathogenic B. cereus. More than a dozen of toxins are discovered so far, but less than half of the toxins have been structurally analyzed, and the toxic mechanisms and toxicokinetics are only partly resolved. Also, our understanding of other properties of B. cereus, such as quorum sensing, evasion from host immune system, and antibiotic resistance is yet at the beginning. Nevertheless, all these factors have to be considered for the safety assessment of new probiotics.