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Salmonella enterica serovar Typhi is the etiologic agent of typhoid fever which is responsible for about 21,600 deaths annually, a large proportion of which is reported in developing countries. The organism is capable of evading the host defense mechanism to establish pathogenesis and this is enabled by the presence of specific virulence genes clus...
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Context 1
... in PltA or PltB genes can result in a total loss of the CdtB dependent toxicity. Also, CdtB, PltA and PltB have been observed to form a complex to cause toxicity (Figure 1) (Spanò et al., 2008). It is also believed that the typhoid toxin evolved from the exotoxin ancestors; CDT and pertussis toxins (Galan, 2016). ...
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... has been reported to bind cell surface prohibit in, thus dampening inflammation through MAPK signaling and IL-8 production ( Sharma and Qadri, 2004). Reduced TLR5-and TLR4-mediated secretion of IL-8 leads to low levels of neutrophil influx (Figure 1), which is one of the characteristics of S. enterica serovar Typhi infection that make it distinct from the S. enterica serovar Typhimurium (Johnson et al., 2018). ...
Citations
... Salmonella typhi is a significant intracellular pathogen, and out of the more than 2,300 closely-related Salmonella serovar bacteria that have been identified, S. typhi is the only one that exclusively causes disease in humans [5,6]. It specifically leads to typhoid or enteric fever. ...
Typhoid fever is still a deadly disease in developing regions, including Iraq. The disease is an important cause of morbidity and mortality in the pediatric and adult population. Therefore, this study was conducted on the bacteria involved in patients with typhoid fever symptoms by isolating Salmonella typhi and some enteric bacteria from stool culture and establishing early diagnosis using laboratory serological parameters. Stool and blood samples were collected from 300 patients in different age who visited hospitals in Kirkuk city in northern Iraq during the period from December 2019 to March 2021. Data analysis showed that out of a total of 275 patient cases, the percentage of infected females was higher (51%) compared to the percentage of infected males (49%). The results indicated that (7%) of patients showed a positive stool result compared to (93%) a negative stool result, Widal test also showed a positive result in most of the samples tested (67%). In conclusion, it is necessary to adopt more accurate tests, such as blood tests, and more advanced laboratory techniques to detect and identify Salmonella typhi.
... Several genes related to virulence are located in Salmonella pathogenicity islands (SPIs), a large region of chromosomes that encode virulence-related genes. So far, 17 SPI have been described; however, the most studied are SPI-1 and SPI-2 [26]. The SPI-1 encoded type III secretion system (T3SS) is an invasion island in all Salmonella species and subspecies with genes for invading nonphagocytic cells. ...
Salmonella is a foodborne zoonotic pathogen causing diarrhoeal disease to humans after consuming contaminated water, animal, and plant products. The bacterium is the third leading cause of human death among diarrhoeal diseases worldwide. Therefore, human salmonellosis is of public health concern demanding integrated interventions against the causative agent, Salmonella enterica. The prevention of salmonellosis in humans is intricate due to several factors, including an immune-stable individual infected with S. enterica continuing to shed live bacteria without showing any clinical signs. Similarly, the asymptomatic Salmonella animals are the source of salmonellosis in humans after consuming contaminated food products. Furthermore, the contaminated products of plant and animal origin are a menace in food industries due to Salmonella biofilms, which enhance colonization, persistence, and survival of bacteria on equipment. The contaminated food products resulting from bacteria on equipment offset the economic competition of food industries and partner institutions in international business. The most worldwide prevalent broad-range Salmonella serovars affecting humans are Salmonella Typhimurium and Salmonella Enteritidis, and poultry products, among others, are the primary source of infection. The broader range of Salmonella serovars creates concern over multiple strategies for preventing and controlling Salmonella contamination in foods to enhance food safety for humans. Among the strategies for preventing and controlling Salmonella spread in animal and plant products include biosecurity measures, isolation and quarantine, epidemiological surveillance, farming systems, herbs and spices, and vaccination. Other measures are the application of phages, probiotics, prebiotics, and nanoparticles reduced and capped with antimicrobial agents. Therefore, Salmonella-free products, such as beef, pork, poultry meat, eggs, milk, and plant foods, such as vegetables and fruits, will prevent humans from Salmonella infection. This review explains Salmonella infection in humans caused by consuming contaminated foods and the interventions against Salmonella contamination in foods to enhance food safety and quality for humans.
... SPI-11 to SPI-14 are not reportedly found in S. Typhi, while SPI-15 serves a vague role with effector proteins attached to secretion systems. Genes and proteins for tRNA and lipopolysaccharide are encoded by SPI-16 and SPI-17, respectively [133]. ...
Salmonella enterica serovar Typhi (S. Typhi) is a Gram-negative pathogen that causes typhoid fever in humans. Though many serotypes of Salmonella spp. are capable of causing disease in both humans and animals alike, S. Typhi and S. Paratyphi are common in human hosts only. The global burden of typhoid fever is attributable to more than 27 million cases each year and approximately 200,000 deaths worldwide, with many regions such as Africa, South and Southeast Asia being the most affected in the world. The pathogen is able to cause disease in hosts by evading defense systems, adhesion to epithelial cells, and survival in host cells in the presence of several virulence factors, mediated by virulence plasmids and genes clustered in distinct regions known as Salmonella pathogenicity islands (SPIs). These factors, coupled with plasmid-mediated antimicrobial resistance genes, enable the bacterium to become resistant to various broad-spectrum antibiotics used in the treatment of typhoid fever and other infections caused by Salmonella spp. The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains in many countries of the world has raised great concern over the rise of antibiotic resistance in pathogens such as S. Typhi. In order to identify the key virulence factors involved in S. Typhi pathogenesis and infection, this review delves into various mechanisms of virulence, pathogenicity, and antimicrobial resistance to reinforce efficacious disease management.
... Most virulence-related genes in Salmonella are found in Salmonella Pathogenicity Islands (SPIs). SPIs cover large regions of the chromosome that encode several virulence factors (Dos Santos et al., 2021) and, so far, 17 SPIs have been described (Fowoyo, 2020). ...
The occurrence of disease outbreaks involving low‐water‐activity (aw) foods has gained increased prominence due in part to the fact that reducing free water in these foods is normally a measure that controls the growth and multiplication of pathogenic microorganisms. Salmonella, one of the main bacteria involved in these outbreaks, represents a major public health problem worldwide and in Brazil, which highlights the importance of good manufacturing and handling practices for food quality. The virulence of this pathogen, associated with its high ability to persist in the environment, makes Salmonella one of the main challenges for the food industry. The objectives of this article are to present the general characteristics, virulence, thermoresistance, control, and relevance of Salmonella in foodborne diseases, and describe the so‐called low‐water‐activity foods and the salmonellosis outbreaks involving them.
Foodborne infections caused by Salmonella have been linked to a variety of poultry products. The aim of this study was to compare the molecular profile of virulence genes considering different serotypes of Salmonella, isolates were from chicken breast sampled during the last two decades (1999 to 2010 and 2011 to 2018). The resistance to antimicrobials was also evaluated, establishing a comparative epidemiological parameter on the pathogenic potential on this bacterium over time. We tested 238 Salmonella isolates, and 18 different serotypes were observed. These being S. Enteritidis (42.3%, 58/137) and S. Ohio (28.3%, 36/137), the most frequent in the first decade; and S. Heidelberg (25.7%, 26/101) and S. Typhimurium (21.8%, 22/101), in the second. We found four (1.68%) multidrug resistant isolates from the first decade and 28 (11.76%) in the second. All extended spectrum beta-lactamase (ESBL) positive isolates belonged to the S. Heidelberg serotype, and were also detected in the second decade. Considering the nine different antimicrobial classes tested, an increase in the number of resistant isolates was observed over time: from five classes with resistant isolates in the first decade to eight classes in the, with cefotaxime being the antimicrobial with the highest number of resistant isolates in both decades. All isolates(100%) presented the invA, sitC and tolC genes. In sequence, the most frequent genes were flgL (99.58%), sopB (98.31%), flgK (97.88%), fljB (96.61%), sipA (94.92%), sipB (88.56%), sifA (86.44%), sipD (66.10%), ssaR (51.27%), sopD (37.29%) and spvB (34.32%) was the least frequent; and 13 isolates showing all 14 virulence genes investigated. The ability of these isolates to resist certain antimicrobials, and to express genes encoding virulence factors, reinforce their marked pathogenic potential; while the possibility to trigger diseases in humans through the food chain is a serious public health threat through.
