Materiały źródłowe

• #1

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9203224/

  Salmonella enterica is a gastroenteric Gram-negative bacterium that can infect both humans and animals and causes millions of illnesses per year around the world. Salmonella has developed multiple strategies to invade and establish a systemic infection in the host. Different cell types, including epithelial cells, macrophages, dendritic cells, and M cells, are important in the infection process of Salmonella. Dissemination throughout the body and colonization of remote organs are hallmarks of Salmonella infection. This review summarizes the current understanding of the infection mechanisms of Salmonella. […] Salmonella typhimurium initiates infection in mice by infecting and destroying the specialized epithelial M cells and then traveling to the mesenteric lymph nodes. […] Salmonella directly invades M cells but can also transform follicle-associated epithelial cells into M cells to provide additional routes for intestinal invasion.

• #2 Salmonella Infection and Pathogenesis | IntechOpen

  https://www.intechopen.com/chapters/80044

  Salmonella genus represents most common food borne pathogens isolated from food producing animals and is responsible for causing zoonotic infections in humans and other animal species, including birds. […] Salmonella can be transferred to humans at any point along the farm-to-fork chain, most commonly through infected animal-derived foods such as poultry and poultry related products (eggs), pork, fish, and so on. […] Globally Salmonella infection causes huge mortality and the infection plays a huge role in immune response by evolving multiple mechanism to subvert immunity to its own benefit. […] Numerous infectivity markers and determinants have indeed been reported to play essential role in Salmonella pathogenesis to colonize its host by invading and avoiding the hosts intestinal shielding system.

• #3 Salmonella Infection (Salmonellosis): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/228174-overview

  Salmonellosis is caused by all nontyphoid serotypes of the Salmonella genus except for S typhi and Salmonella paratyphi A, B, and C. Salmonellosis-causing serotypes are isolated from humans and animals, including livestock. Serotypes Salmonella Typhimurium, Salmonella enteritidis, Salmonella newport, and Salmonella heidelberg most often are responsible for food poisoning; Salmonella Cholerasuis and Salmonella Dublin also cause diarrheic diseases. […] Although the infectious dose varies among Salmonella strains, a large inoculum is thought to be necessary to overcome stomach acidity and to compete with normal intestinal flora. Large inocula are associated with higher rates of illness and shorter incubation periods. In general, about 106 bacterial cells are needed to cause infection. Low gastric acidity, which is common in elderly persons and among individuals who use antacids, can decrease the infective dose to 103 cells, while prior vaccination can increase the number to 109 cells.

• #4 Pathogenesis of Egg Infections by Salmonella and The Implementation of Preventive Measures | Engormix

  https://en.engormix.com/poultry-industry/salmonella-poultry/pathogenesis-egg-infections-salmonella_a48120/

  Chickens usually are infected by oral uptake of bacteria from the environment. Salmonella bacteria are able to survive gastric acidity and can pass the stomach to reach the intestinal tract of the animal. The caeca are the predominant colonisation sites. The bacteria can adhere to and invade caecal epithelial cells, by rearranging the actin cytoskeleton of the epithelial cells in such a way that bacteria are engulfed by ruffles on the host cell membrane, resulting in uptake by the epithelial cell. This process of invasion is mediated by a type three secretion system, encoded by genes of the Salmonella pathogenicity island I, and is essential for caecal colonisation. Immune cells are attracted to the gut wall and the macrophages may take up bacteria penetrating through the caecal mucosa. This is the start of the systemic phase of the infection as Salmonella bacteria can survive within and replicate in these macrophages. These cells spread the bacteria to the internal organs, such as liver, spleen, ovary and oviduct, where the bacteria can be found in large numbers. All this is serotype and strain dependent, and some strains are more invasive than others while others are less or not efficient in persistent caecal or organ colonisation.

• #5 Salmonella Infection (Salmonellosis): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/228174-overview

  The Salmonella infection cycle starts after the ingestion of microbes. Through the stomach, the bacteria reach the small intestine. Infection with salmonellae is characterized by attachment of the bacteria by fimbriae or pili to cells lining the intestinal lumen. Salmonellae selectively attach to specialized epithelial cells (M cells) of the Peyer patches. The bacteria then are internalized by receptor-mediated endocytosis and transported within phagosomes to the lamina propria, where they are released. Once there, salmonellae induce an influx of macrophages (typhoidal strains) or neutrophils (nontyphoidal strains). […] The Vi antigen of S typhi is important in preventing antibody-mediated opsonization and complement-mediated lysis. Through the induction of cytokine release and via mononuclear cell migration, S typhi organisms spread through the reticuloendothelial system, mainly to the liver, spleen, and bone marrow. Within 14 days, the bacteria appear in the bloodstream, facilitating secondary metastatic foci (eg, splenic abscess, endocarditis). In some patients, gallbladder infection leads to long-term carriage of S typhi or S paratyphi in bile and secretion to the stool.

• #6 Salmonella Infection (Salmonellosis): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/785774-overview

  Salmonellosis is caused by all nontyphoid serotypes of the Salmonella genus except for S typhi and Salmonella paratyphi A, B, and C. Salmonellosis-causing serotypes are isolated from humans and animals, including livestock. Serotypes Salmonella Typhimurium, Salmonella enteritidis, Salmonella newport, and Salmonella heidelberg most often are responsible for food poisoning; Salmonella Cholerasuis and Salmonella Dublin also cause diarrheic diseases. […] The Salmonella infection cycle starts after the ingestion of microbes. Through the stomach, the bacteria reach the small intestine. Infection with salmonellae is characterized by attachment of the bacteria by fimbriae or pili to cells lining the intestinal lumen. Salmonellae selectively attach to specialized epithelial cells (M cells) of the Peyer patches. The bacteria then are internalized by receptor-mediated endocytosis and transported within phagosomes to the lamina propria, where they are released. Once there, salmonellae induce an influx of macrophages (typhoidal strains) or neutrophils (nontyphoidal strains).

• #7 Salmonella Infection and Pathogenesis | IntechOpen

  https://www.intechopen.com/chapters/80044

  After invasion, organism has ability to proliferate intra-cellularly thereby escalating to mesenteric lymph nodes and all over the body by systematic circulation; absorbed by reticulo-endothelial cells that limits and checks the expansion of an organism. […] After invading the intestine, most of Salmonellae brings on an acute inflammatory response that may lead to ulceration, also they might elaborate cytotoxins that forbid protein synthesis. […] One of the features of Salmonella is non-phagocytic nature on human host cells during invasion, where it literally induces its own phagocytosis in order to gain access to its host cell. […] The ability of the Salmonella strains to remain in the host cell is important for pathogens as strains lacking this capability are non-virulent. […] The mechanisms of Salmonella gastroenteritis and diarrhea are well known now. […] The secretion of fluid and electrolytes by the small and large intestines causes the diarrhea. […] Following the invasion of the intestinal mucosa, activation of mucosal adenylate cyclase occurs; that results in the increase in cyclic AMP that causes secretion.

• #8 Salmonella – Wikipedia

  https://en.wikipedia.org/wiki/Salmonella

  Salmonella pathogenicity and host interaction has been studied extensively since the 2010s. Most of the important virulent genes of Salmonella are encoded in five pathogenicity islands the so-called Salmonella pathogenicity islands (SPIs). These are chromosomal encoded and make a significant contribution to bacterial-host interaction. More traits, like plasmids, flagella or biofilm-related proteins, can contribute in the infection. SPIs are regulated by complex and fine-tuned regulatory networks that allow the gene expression only in the presence of the right environmental stresses. […] Much of the success of Salmonella in causing infection is attributed to two type III secretion systems (T3SS) which are expressed at different times during the infection. The T3SS-1 enables the injection of bacterial effectors within the host cytosol. These T3SS-1 effectors stimulate the formation of membrane ruffles allowing the uptake of Salmonella by nonphagocytic cells. Salmonella further resides within a membrane-bound compartment called the Salmonella-Containing Vacuole (SCV). The acidification of the SCV leads to the expression of the T3SS-2. The secretion of T3SS-2 effectors by Salmonella is required for its efficient survival in the host cytosol and establishment of systemic disease.

• #9 Salmonella Infection in Poultry: A Review on the Pathogen and Control Strategies

  https://www.mdpi.com/2076-2607/11/11/2814

  Salmonella is the leading cause of food-borne zoonotic disease worldwide. Non-typhoidal Salmonella serotypes are the primary etiological agents associated with salmonellosis in poultry. The principal virulence genes linked to Salmonella pathogenesis in poultry are located in Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2). Salmonella pathogenesis can be divided into several stages, including adhesion and invasion of gut epithelial cells, survival, multiplication within the host cells, and extraintestinal spread. Upon reaching the small intestine, Salmonella invades and adheres to the intestinal epithelial cells using fimbrial adhesins. Salmonella’s entry into the intestinal mucosa is facilitated mainly through M cells located over the Peyer’s patches (mucosal-associated lymphoid tissues). Macrophages can internalize Salmonella but are unable to kill them as the bacteria can inhibit the fusion of phagosomes with secondary lysosomes, the mechanism used by macrophages to destroy intracellular pathogens. Salmonella proliferates inside the macrophages within a structure called the Salmonella-containing vacuole (SCV) and eventually translocates widely to the draining mesenteric lymph nodes, leading to bacteremia and invasion of systemic organs such as the liver, spleen, ovary, and gallbladder. Salmonella pathogenic factors are controlled by virulence genes and plasmids, which are located within Salmonella pathogenicity islands (SPIs). SPIs are a group of genes located in specific areas of the bacterial chromosomes that encompass multiple virulence factors, including invasins, adhesins, and toxins. Salmonella has two types of type III secretion systems, T3SS-1 and T3SS-2, found in SPI-1 and SPI-2, respectively. T3SS-1 is responsible for transferring effector proteins needed for bacterial invasion, SCV (Salmonella containing vacuoles) biogenesis, and inflammation. On the other hand, T3SS-2 facilitates the transport of effector proteins that favor SCV maturation, SIF (Salmonella-induced filaments) biogenesis, intracellular survival of the pathogen, and its movement inside Salmonella-containing vacuoles. Salmonella-induced filaments (SIFs) are specialized endosomal tubule projections that extend from the SCV. These SIFs inside the host cell cytoplasm form a complex replicative niche. The exact role of SIFs in Salmonella infection is still unknown. Salmonella has orchestrated mechanisms to co-evolve with their hosts by altering cellular processes that favor bacterial survival and intracellular proliferation.

• #10 SciELO Brazil – Pathogenesis of Salmonella-induced enteritis Pathogenesis of Salmonella-induced enteritis

  https://www.scielo.br/j/bjmbr/a/F8rjHQVDh9fXvPF9QZrNyxp/

  The SPI-1-encoded type III secretion system translocates effector proteins into the cytosol of host cells. This system is required for invasion of nonphagocytic host cells and enteropathogenesis, while the SPI-2-encoded type III secretion system is required for intracellular survival in murine macrophages. […] A remarkable aspect of Salmonella pathogenesis is its ability to invade nonphagocytic cells in a process that morphologically resembles phagocytosis. […] Upon contact with intestinal epithelial cells, Salmonella typhimurium translocates bacterial effector proteins into the host cell cytosol via the SPI-1-encoded type III secretion system. […] These morphological and cytoskeletal changes, characterized by formation of ruffle-like structures, mediate bacterial internalization into epithelial cells.

• #10 SciELO Brazil – Pathogenesis of Salmonella-induced enteritis Pathogenesis of Salmonella-induced enteritis

  https://www.scielo.br/j/bjmbr/a/F8rjHQVDh9fXvPF9QZrNyxp/

  Infections with Salmonella serotypes are a major cause of food-borne diseases worldwide. […] The microbe has developed mechanisms to exploit the host cell machinery to its own purpose. Bacterial proteins delivered directly into the host cell cytosol cause cytoskeletal changes and interfere with host cell signaling pathways, which ultimately enhance disease manifestation. […] Here, we discuss the molecular basis of the pathogenesis of Salmonella-induced enteritis. […] Recently, a large amount of information on the molecular level of interactions between bacteria and host cells has allowed us to propose molecular mechanisms determining the pathologic and clinical manifestations of nontyphoidal Salmonella infections. […] Many of the Salmonella virulence genes are clustered in certain areas of the chromosome known as „Salmonella pathogenicity islands” (SPI).

• #11 Understanding the Molecular Mechanisms of Salmonella Infection

  https://www.cssb-hamburg.de/news_amp_events/articles/2023/understanding_the_molecular_mechanisms_of_salmonella_infection/index_eng.html

  To initiate infection, many Gram-negative bacteria inject bacterial proteins into human cells. The bacteria accomplish this by building a complex, syringe-like molecular machine known as the type III secretion system (T3SS). When Salmonella infects human cells its TS33 releases bacterial effectors some of which are actin-binding proteins (ABPs). The ABPs bind to the actin filaments in the human cell causing the cellular membrane to ruffle at the injection site. This local membrane ruffle enables the bacteria to be engulfed in the human host cell and propagate infection. […] The researchers wanted to understand the specific interplay between two bacterial substrates, the translocator protein SipC and the effector protein SipA, which play a key role in the subversion of the actin cytoskeleton.

• #12

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9203224/

  The type III secretion system is involved in the priming of the bacteria for invasion. […] The type III secretion system (T3SS) is the most important virulence factor for Salmonella species, and one is encoded on Salmonella pathogenicity island 1 (SPI1) and the other is encoded on Salmonella pathogenicity island 2 (SPI2). […] The trigger mechanism is activated by the type III secretory system. […] The binding of pattern recognition receptors (PRRs) with pathogen-associated molecular patterns (PAMPs), including peptidoglycan, lipopolysaccharide, flagellin, can mediate Salmonella invasion. […] Dendritic cells are exploited by Salmonella typhimurium as Trojan horses to enable systemic dissemination. […] Salmonella can modify macrophage polarization during chronic infection. […] Salmonella can induce host cell death during infection. […] Salmonella can activate apoptosis of Salmonella-infected macrophages using effectors encoded in pathogenicity island-1 through both intrinsic and extrinsic pathways. […] Salmonella can persist in the hemophagocytic macrophages of MLN.

• #13 Salmonellosis: An Overview of Epidemiology, Pathogenesis, and Innovative Approaches to Mitigate the Antimicrobial Resistant Infections

  https://www.mdpi.com/2079-6382/13/1/76

  Studies suggest that the interaction between the TLR and LPS in NTS species plays a vital role in developing septic shock. […] However, the typhoidal serovars, including S. Typhi, evade recognition by TLR4, thus preventing the recruitment of neutrophils and the expression of pro-inflammatory molecules such as TNF-α and Interleukin 1β (IL-1β) and preventing a typical antimicrobial response in the host. […] Invasion and colonization of Salmonella in the host cells rely on several virulence factors, including virulence plasmids, Type III secretion systems, and fimbriae. […] Type III secretion systems (T3SSs) are responsible for translocating effector proteins from prokaryotic cytoplasm to the eukaryotic cytosol. […] Salmonella possesses fimbrial gene clusters (FGCs) within its genome, which encodes extracellular fimbriae.

• #14 Conservation of Salmonella Infection Mechanisms in Plants and Animals | PLOS One

  https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0024112

  Salmonella enterica subsp. enterica ser. Typhimurium (S. Typhimurium) has two distinct T3SSs, T3SS-1 and T3SS-2, encoded by the Salmonella Pathogenicity Islands (SPI) SPI-1 and SPI-2 respectively. […] T3SS-1 secretes at least 14 proteins of which 6 were shown to interact with the host signaling cascades and the cytoskeleton. […] T3SS-2 secretes at least 19 Salmonella enterica specific effector proteins that are involved in survival and multiplication within the Salmonella containing vesicle (SCV). […] To investigate whether Salmonella require these secretion apparatuses to infect plants, we tested the in planta performance of Salmonella mutants that are unable to assemble a functional T3SS. […] When compared to wild type S. Typhimurium 14028s, both tested mutants (prgH and ssaV) showed reduced proliferation in plants.

• #15 Understanding the Molecular Mechanisms of Salmonella Infection

  https://www.cssb-hamburg.de/news_amp_events/articles/2023/understanding_the_molecular_mechanisms_of_salmonella_infection/index_eng.html

  We found that SipA binds to filamentous actin in a unique binding pattern and uses a specific binding site not utilized by the majority of actin-binding proteins, notes Biao Yuan (CSSB, UKE) the papers first author. […] To initiate infection the needle part of the syringe-like T3SS latches on to the human host cell at the translocator proteins. „To our surprise, we found that the translocator protein SipC, which also contains an actin-binding-domain, cooperates in conjunction with SipA to efficiently decorate actin filaments. […] Overall understanding the interactions between these two substrates, helps to shed light on the coordinated sequence of infection events initiated by the T3SS in the host cell, explains Thomas Marlovits the papers corresponding author. Given the unique nature of this binding mechanism, we plan to investigate the possibilities of inhibiting this process which could ultimately interfere with Salmonella invasion of host cells.

• #16 SciELO Brazil – Pathogenesis of Salmonella-induced enteritis Pathogenesis of Salmonella-induced enteritis

  https://www.scielo.br/j/bjmbr/a/F8rjHQVDh9fXvPF9QZrNyxp/

  Although sopE is absent in many S. typhimurium strains, a homologue, sopE2, is present in all strains of S. typhimurium. […] Therefore, SopE2 is required for optimal invasion of cultured epithelial cells by S. typhimurium. […] The effect of SptP antagonizing the action of other bacterial effector proteins clearly indicates that S. typhimurium is able to finely regulate cellular pathways in favor of its own purposes. […] Although the complete mechanism of Salmonella-induced diarrhea is still not clear, some previous reports indicate that it is distinct from secretory diarrheas such as those caused by cholera toxin. […] Therefore, neutrophils are proposed to play a very important role in the pathogenesis of Salmonella-induced diarrhea. […] Current data indicate that epithelial cells play an important role in the outcome of infection by influencing the host inflammatory response.

• #17 Secreted Proteins and Virulence in Salmonella enterica

  https://www.caister.com/hsp/abstracts/bacterial-secreted-proteins/11.html

  Secreted proteins are of major importance for the pathogenesis of infectious diseases caused by the facultative intracellular gastrointestinal pathogen Salmonella enterica. […] The host cell invasion and intracellular proliferation are two hallmarks of Salmonella pathogenesis. […] Salmonella deploys two type III secretion systems (T3SS) to translocate complex cocktails of effector proteins. […] Effectors translocated by the Salmonella Pathogenicity Island 1 (SPI1)-T3SS mainly act on the host cell actin cytoskeleton resulting in the invasion of non-phagocytic cells. […] After entry, Salmonella resides in the so-called Salmonella-containing vacuole, from which translocation of a second set of effector proteins by the SPI2-T3SS initiated. […] The function of the SPI2-T3SS results intracellular replication and the modification of host cell vesicular traffic involving microtubules. […] The concerted action of various secreted proteins allows Salmonella to breach multiple barriers of host defense resulting in systemic infection and be development of a carrier state in some infected individuals.

• #18 Immunopathogenesis of Salmonellosis | IntechOpen

  https://www.intechopen.com/chapters/67327

  After initial invasion through PPs, the ultimate fate of infection is decided in the lymphatic system. […] Salmonella can survive and replicate within modified intracellular vesicles, termed as Salmonella-containing vacuoles (SCV). […] The ability of Salmonella to survive within the phagosome is mediated by SPI-2, which prevents movement of RNS and ROS into the phagosome where the bacteria reside. […] The development of robust protective immunity against Salmonella infection requires the coordination of B and T cells. […] The initial invasion induces a massive inflammatory response, characterised by recruitment of neutrophils, DCs, inflammatory monocytes and macrophages. […] The process of Salmonella host adaptation is believed to be involving either the loss of genes or the acquisition of novel genetic elements that encode specific virulence factors. […] The expression of serovars pathogenicity is affected by the environmental and genetic factors influencing each host during adaptation.

• #19 Salmonella-induced SIRT1 and SIRT3 are crucial for maintaining the metabolic switch in bacteria and host for successful pathogenesis

  https://elifesciences.org/reviewed-preprints/93125

  Salmonella Typhimurium exhibited increased intracellular fold proliferation within anti-inflammatory M2 polarized macrophages in comparison to the pro-inflammatory M1 polarized RAW264.7 macrophages. […] SIRT1 and SIRT3 play crucial role in mediating metabolic switch in infected macrophages. […] SIRT1 and SIRT3 knockdown or catalytic inhibition in peritoneal macrophages resulted in increased protein expression of host glycolytic genes such as Phosphoglycerate kinase (Pgk), Phosphofructokinase (Pfk) with concomitant reduction in protein expression of TCA cycle gene like Pyruvate dehydrogenase (Pdha1) and fatty acid oxidation genes such as Hadha and Acox1. […] Collectively, these data suggest the role of SIRT1 and SIRT3 in mediating the Salmonella induced host metabolic shift in the infected macrophages.

• #20 Group 3 innate lymphoid cell pyroptosis represents a host defence mechanism against Salmonella infection | Nature Microbiology

  https://www.nature.com/articles/s41564-022-01142-8

  Group 3 innate lymphoid cells (ILC3s) produce interleukin (IL)-22 and coordinate with other cells in the gut to mount productive host immunity against bacterial infection. […] Here we show that S. Typhimurium exploits ILC3-produced IL-22 to promote its infection in mice. […] Specifically, S. Typhimurium secretes flagellin through activation of the TLR5-MyD88-IL-23 signalling pathway in antigen presenting cells (APCs) to selectively enhance IL-22 production by ILC3s, but not T cells. […] Deletion of ILC3s but not T cells in mice leads to better control of S. Typhimurium infection. […] We also show that S. Typhimurium can directly invade ILC3s and cause caspase-1-mediated ILC3 pyroptosis independently of flagellin. […] Genetic ablation of Casp1 in mice leads to increased ILC3 survival and IL-22 production, and enhanced S. Typhimurium infection. […] Collectively, our data suggest a key host defence mechanism against S. Typhimurium infection via induction of ILC3 death to limit intracellular bacteria and reduce IL-22 production.

• #21 Salmonellosis pathophysiology – wikidoc

  https://www.wikidoc.org/index.php/Salmonellosis_pathophysiology

  Typhoidal and nontyphoidal Salmonella (NTS) serovars elicit different immune responses in humans. NTS serovars induce a greater inflammatory interaction with human gut mucosa compared to typhoidal serovars. In animal models, S. enterica colonizes the intestine and localizes to the apical epithelium, inducing inflammatory changes. These changes include PMN infiltration, necrosis of the epithelium, crypt abscesses, and edema. The recruitment of neutrophils to the intestinal epithelium is the histopathological hallmark of intestinal disease. The various S. enterica serovars that are able to cause intestinal disease do so by attracting PMNs, specifically by inducing interleukin-8. With serovar Typhimurium, this recruitment occurs within the first few hours of infection. Massive migration of neutrophils and exudate secretion into the intestinal lumen occurs approximately 8-10 hours after infection. The onset of diarrhea begins between 8-72 hours after colonization. Salmonella serovar Typhimurium enterocolitis is the most severe in the caudal ileum, cecum, and proximal colon. Disease among humans usually occurs after ingesting more than 50 000 bacteria.

• #21 Salmonellosis pathophysiology – wikidoc

  https://www.wikidoc.org/index.php/Salmonellosis_pathophysiology

  The pathogenesis of salmonellosis varies among the different Salmonella serovars. Typhoidal and nontyphoidal Salmonella (NTS) interact with host defense mechanisms, eliciting variable immune responses in humans. NTS colonizes the intestine, induces neutrophil migration into the intestinal lumen, and causes a self limiting inflammatory diarrhea. Bacteremia due to NTS is rare but can occur, especially in persons infected with HIV. Individuals with type I cytokine pathway deficiencies are at increased risk of developing NTS infection. […] The pathogenesis of salmonellosis varies between different Salmonella serovars and depends on the interaction of multiple virulence programs with host defense mechanisms. These interactions occur in different tissues and at various stages of infection leading to variable host morbidity and mortality. Salmonella enterica serovar Typhi (S. Typhi) and Salmonella Paratyphi A both cause bacteremia. Non-typhoidal Salmonella (NTS) usually cause self-limiting diarrhea although NTS may lead to secondary bacteremia. Immunocompromised individuals and infants in sub-Saharan Africa may develop primary NTS bacteremia.

• #22 SciELO Brazil – Pathogenesis of Salmonella-induced enteritis Pathogenesis of Salmonella-induced enteritis

  https://www.scielo.br/j/bjmbr/a/F8rjHQVDh9fXvPF9QZrNyxp/

  Importantly, although IL-8 and PEEC act in concert to promote neutrophil migration through the lamina propria and epithelia, respectively, secretion of these two chemotactic factors is mediated by distinct signaling pathways. […] Salmonella-induced macrophage apoptosis results in release of active IL-1, which is thought to play a significant role in Salmonella-elicited inflammation. […] The ability of S. typhimurium to induce macrophage cell death has been demonstrated in vivo in mice intravenously inoculated with small infectious doses. […] There is clearly a difference between Salmonella genes required for virulence in mice, where the Salmonella virulence plasmid and SPI-2-encoded genes are essential for virulence, and those involved in eliciting diarrhea, in which SPI-1-encoded genes are essential but SPI-2 and the Salmonella virulence plasmid play only minor roles.

• #23 Salmonellosis – Wikipedia

  https://en.wikipedia.org/wiki/Salmonellosis

  From an immunological point of view Salmonellosis is an infection caused by gram-negative bacteria infiltrating epithelial cells of the small intestine in the distal ileum whereby inducing acute inflammatory response called enteritis. […] Salmonella can infect M-cells population overlying the Payers patches in the intestine, cells located in lamina propria of the intestinal mucosa and other epithelial cells. […] This process requires migration dependent on a factor known as CCR7. Once in the mesenteric lymph nodes, Salmonella can then enter the bloodstream, leading to a systemic infection that spreads throughout the body. […] Virulence of the Salmonella is given by the Salmonella Pathogenicity Island 1 (SPI-1). […] This needle-like structure, formed by a set of proteins, is known as the Type III secretion system. It enables Salmonella to effectively invade neighboring cells by injecting bacterial proteins directly into them, facilitating its spread and evasion of the host’s immune defenses.

• #24 Mechanisms of Toxic Effects of Salmonella Typhi – Creative Diagnostics

  https://www.creative-diagnostics.com/molecular-mechanism-of-salmonella-typhi-pathogenesis.htm

  Salmonella Typhi is a unique human pathogen, which can cause serious systemic diseases. […] The pathogen is invasive, but usually does not rapidly trigger an inflammatory or diarrheal response. […] The Vi capsule can inhibit phagocytosis and enhance serum resistance, probably by protecting O-antigen from antibody attack. […] The genes encoding the Vi capsule include the viaB locus in Salmonella Pathogenicity Island (SPI)-7, which also encodes the type III secretion system (T3SS) effector SopE and the type IVB pilus. […] TviA is a positive regulator that promotes the expression of the viaB locus, whereas it down-regulates the expression of the flagellar and the SPI-1 gene under high osmolarity conditions. […] Vi has been reported to bind cell surface prohibitin, thereby suppressing inflammation through MAPK signaling and IL-8 production.

• #25 Mechanisms of Toxic Effects of Salmonella Typhi – Creative Diagnostics

  https://www.creative-diagnostics.com/molecular-mechanism-of-salmonella-typhi-pathogenesis.htm

  S. Typhi is unique in that it expresses the typhoid toxin. […] Typhoid toxin is an atypical AB-type toxin consisting of two enzymatically active (A) subunits (CdtB and PltA) and a binding (B) subunit (PltB). […] CdtB induces G2/M cell cycle arrest by damaging host cell DNA and inducing a DNA damage response through its DNase I-like activity. […] The role of typhoid toxin in disease and pathogenesis remains unclear. […] Typhoid toxin is thought to be involved in the process of promoting chronic Salmonella Typhi infection, but its potential mechanism remains to be further studied.

• #26 Salmonellosis: An Overview of Epidemiology, Pathogenesis, and Innovative Approaches to Mitigate the Antimicrobial Resistant Infections

  https://www.mdpi.com/2079-6382/13/1/76

  Salmonella is a major foodborne pathogen and a leading cause of gastroenteritis in humans and animals. […] The transmission of Salmonella to a healthy host occurs through the consumption of contaminated food and water. […] The pathogenesis of Salmonella serotypes starts with the adherence of the bacteria to the host cell surface. After adhesion, bacteria’s internalization occurs either through the uptake of bacteria via phagocytosis or by active invasion of both phagocytic and non-phagocytic cells. […] The phagocytosis process involves intricate mechanisms that rely on the engagement of multiple receptors, such as Pattern Recognition Receptors (PRRs). […] The PRRs include toll-like receptors (TLRs) and cytosolic nucleotide-binding receptors, which recognize pathogen-associated molecular patterns (PAMPs) like lipopolysaccharides (LPS) and flagellin located on either the cell surface or within phagosomes.

• #27 Salmonellosis – Wikipedia

  https://en.wikipedia.org/wiki/Salmonellosis

  The first cells recruited to the Salmonella infection site are neutrophils, monocytes, and dendritic cells. […] Neutrophils play a key role in early defense against Salmonella, preventing its spread into the bloodstream. […] Studies in mice have shown that without neutrophils, there’s an increase in the extracellular bacterial load during Salmonella infection. […] Several other pro-inflammatory cytokines have been also observed after the infection of the epithelia such as IL-1, TNF, IL-12, IL-18 and IL-15, affecting the body-temperature by inducing fever, increase mucus production, activation of B and T leukocytes and polymorphonuclear leukocytes and macrophages recruitment to the site of infection. […] Resident macrophages can also recognize flagellin and activate NLRC4 inflammasome complex to activate caspase-1 and IL-1 and IL-18 release.

• #28 Salmonellosis – Wikipedia

  https://en.wikipedia.org/wiki/Salmonellosis

  While monocytes help in containing the bacteria initially, the inability to effectively present antigens can delay or weaken the activation of T cells, which are necessary for a strong and specific immune response. […] In contrast, dendritic cells experience maturation through both direct pathways, mediated by bacteria, and indirect pathways, facilitated by cytokines in vivo, enhancing their ability to present antigens optimally. […] Recruitment of these cells to follicles plays a crucial role in initiating early T-cells mediated responses to Salmonella infection. […] Protective immunity against Salmonella appears to be primarily mediated by CD4+ T cells. […] This is evident in mice lacking a thymus, T cells, MHC class-II, or T-bet+ Th1 cells, as they demonstrate an inability to resolve the infection.

• #29 Salmonellosis – Wikipedia

  https://en.wikipedia.org/wiki/Salmonellosis

  The presence of different cytokines in combination with cytokines produced from Th1 cells however suggests additional effect of Th17 response. […] Conversely, mice lacking B-cells or T cells can successfully clear the primary attenuated Salmonella infection, but a robust B-cell response is essential for resolving virulent Salmonella infections. […] Different study revealed that B-cells are essential for protective immunity against Salmonella independent of antibody secretion because B-cells unable to secrete antibodies were still protective against Salmonella, suggesting that B-cells can serve as antigen presenting cells in this context and activate T-cells responses. […] Further experiments focused on CD8+ cytotoxic lymphocytes revealed their crucial role in Salmonella clearance. […] These findings strongly suggest that CD4+-mediated protection is facilitated by the contribution of CD8+ cytotoxic T cells in the immune response against Salmonella.

• #30 Salmonella – Wikipedia

  https://en.wikipedia.org/wiki/Salmonella

  Salmonella species are facultative intracellular pathogens. Salmonella can invade different cell types, including epithelial cells, M cells, macrophages, and dendritic cells. As facultative anaerobic organism, Salmonella uses oxygen to make adenosine triphosphate (ATP) in aerobic environments (i.e., when oxygen is available). However, in anaerobic environments (i.e., when oxygen is not available) Salmonella produces ATP by fermentation that is, by substituting, instead of oxygen, at least one of four electron acceptors at the end of the electron transport chain: sulfate, nitrate, sulfur, or fumarate (all of which are less efficient than oxygen). […] Most infections are due to ingestion of food contaminated by animal feces, or by human feces (for example, from the hands of a food-service worker at a commercial eatery). Salmonella serotypes can be divided into two main groups: typhoidal and nontyphoidal. Typhoidal serotypes include Salmonella Typhi and Salmonella Paratyphi A, which are adapted to humans and do not occur in other animals. Nontyphoidal serotypes are more common, and usually cause self-limiting gastrointestinal disease. They can infect a range of animals, and are zoonotic, meaning they can be transferred between humans and other animals.

• #31 Clinical and microbiological characterization of Salmonella spp. isolates from patients treated in a university hospital in South America between 2012–2021: a cohort study | BMC Infectious Diseases | Full Text

  https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-023-08589-y

  Salmonella is a rod-shaped gram-negative facultative pathogen capable of infecting many hosts and various cell types. Its ability to survive and thrive in all the cell population indicates how the pathogen gets an upper hand in the infected host. […] Salmonella enterica is a species consisting of more than 2,600 different serovars that can be divided into typhoidal (Salmonella typhi) and non-typhoidal Salmonellae (NTS) serovars. […] Symptoms consist of prolonged fever, fatigue, headache, nausea, abdominal pain, constipation, and diarrhea. In severe cases, complications may include confusion, neurological deterioration, gastrointestinal perforations, myocarditis, hepatitis, sepsis, shock, disseminated intravascular coagulation, and death. […] On the other hand, enteric fever caused by typhoidal serovars differs dramatically from the gastroenteritis normally associated with NTS. Patients infected by typhoidal serovars most typically present with a gradual onset of sustained fever, chills, abdominal pain, hepatosplenomegaly, rash, nausea, anorexia, diarrhea or constipation, headache, and a dry cough. Individuals infected with NTS have self-limiting, acute gastroenteritis, and diarrhea.

• #32 Salmonella infection – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/salmonella/symptoms-causes/syc-20355329

  If salmonella infection enters your bloodstream (bacteremia), it can infect tissues throughout your body, including: The urinary system (urinary tract infection), The tissues surrounding the brain and spinal cord (meningitis), The lining of the heart or valves (endocarditis), The bones or bone marrow (osteomyelitis), The lining of blood vessels, especially if you’ve had a vascular graft, such as heart vessel bypass surgery.

• #33

  https://www.jci.org/articles/view/12561

  Nontyphoid Salmonella are a common cause of bacterial gastroenteritis, which is usually a self-limited illness in previously healthy adults. However, nontyphoid Salmonella can also cause a variety of life-threatening extraintestinal infections. […] Despite the fact that they are genetically closely related, there is enormous variation in the virulence and epidemiology of different serotypes of S. enterica (I). […] The biological and genetic mechanisms underlying the phenotypic diversity of Salmonella strains are beginning to be understood. Genetic variations, or polymorphisms, are particularly prominent in two general classes of loci: (a) genes encoding surface structures such as LPS, flagella, and fimbriae, and (b) specific virulence genes encoding factors that modify host cell physiology or protect the bacteria from the antimicrobial systems of the host.

• #34 Salmonella infection – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/salmonella/symptoms-causes/syc-20355329

  Infection can also occur if people touch something that is contaminated and then put their fingers in their mouths. […] Animals and pets, especially birds and reptiles, may carry salmonella bacteria on their feathers, fur or skin or in their feces. Some pet foods may be contaminated with salmonella and can infect animals. […] The body has many natural defenses against salmonella infection. For example, strong stomach acid can kill many types of salmonella bacteria. But some medical problems or medications can short-circuit these natural defenses. […] Some medical problems or medications appear to increase your risk of catching salmonella by weakening your immune system. This interferes with your body’s ability to fight infection and disease. […] Salmonella infection usually isn’t life-threatening. However, in certain people especially infants and young children, older adults, transplant recipients, pregnant women, and people with weakened immune systems the development of complications can be dangerous.

• #35 Pathogenesis of Salmonella Bacteremia | National Agricultural Library

  https://www.nal.usda.gov/research-tools/food-safety-research-projects/pathogenesis-salmonella-bacteremia

  In immunocompetent individuals, non-typhoidal Salmonella serotypes (NTS) are associated with gastroenteritis, a localized infection with low mortality manifesting as diarrhea, vomiting and intestinal cramping. […] However, in immunocompromised individuals, a breach of mucosal barrier functions can result in the development of a life threatening bacteremia. […] The incidence of disseminated NTS infections has reached epidemic status in sub-Saharan Africa, where these infections are associated with bacteremia, meningitis and sepsis, and often have a fatal outcome. […] The objective of this application is to use our recently developed murine co-infection model of malaria and NTS to identify effects of malaria on the immune response to a subsequent bacterial infection. […] Our central hypothesis is that in pediatric patients, underlying malaria parasite infection leads to both a breach in intestinal barrier function and a reduced ability to check growth at systemic sites by interfering with neutrophil recruitment and bacteriocidal activity.

• #36

  https://journals.lww.com/co-infectiousdiseases/Fulltext/2000/10000/Molecular_mechanisms_of_Salmonella_pathogenesis.14.aspx?generateEpub=Article%7Cco-infectiousdiseases:2000:10000:00014%7C%7C

  The success of a pathogen depends on its capacity to enter a host, circumvent host defense barriers and establish infection. […] The Gram-negative bacterium Salmonella enterica has evolved different strategies to subvert normal host cellular functions, which allow it to enter into and proliferate within host cells.

• #37 Molecular and Cellular Mechanisms of Salmonella Pathogenesis | SpringerLink

  https://link.springer.com/chapter/10.1007/978-3-642-78624-2_8

  Salmonellae are among the most resourceful and successful of human pathogens, and as such have long beguiled microbiologists, epidemiologists, and clinicians. However, we have begun to gain insight into some of the mechanisms used by these pathogens to cause disease. These mechanisms reveal that the bacterium must possess several traits which are needed for each stage of the infection, allowing the salmonellae to establish an intimate relationship with the host. […] Thus, throughout this review emphasis will be placed on both the bacterial components and host contributions to these interactions. Work in this field has revealed several unexpected findings about bacterial and host cell mechanisms that are applicable to other systems. […] However, despite this enthusiasm, it has also reinforced how little we really know about these interactions and the bacterial and host processes involved.

• #38 Salmonella infection – prevention and treatment by antibiotics and probiotic yeasts: a review | Microbiology Society

  https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000709?crawler=true

  Global Salmonella infection, especially in developing countries, is a health and economic burden. […] The use of antibiotic drugs in treating the infection is proving less effective due to the alarming rise of antibiotic-resistant strains of Salmonella, the effects of antibiotics on normal gut microflora and antibiotic-associated diarrhoea, all of which bring a growing need for alternative treatments, including the use of probiotic micro-organisms. […] Clinical trials, animal trials and in vitro investigations into the prophylactic and therapeutic efficacies of probiotics have demonstrated antagonistic properties against Salmonella and other enteropathogenic bacteria. […] Nonetheless, there is a need for further studies into the potential mechanisms, efficacy and mode of delivery of yeast probiotics in Salmonella infections. […] This review discusses Salmonella infections and treatment using antibiotics and probiotics.

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