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Microbiology and Molecular Biology... Dec 2013Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to... (Review)
Review
Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S. Typhi, S. Dublin, and S. Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S. Enteritidis and S. Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S. Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S. Kentucky and S. Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today.
Topics: Animals; Chickens; Salmonella; Salmonella enterica; Virulence
PubMed: 24296573
DOI: 10.1128/MMBR.00015-13 -
Vaccine Jun 2015Salmonella enterica serovar Typhi produces significant morbidity and mortality worldwide despite the fact that there are licensed Salmonella Typhi vaccines available.... (Review)
Review
Salmonella enterica serovar Typhi produces significant morbidity and mortality worldwide despite the fact that there are licensed Salmonella Typhi vaccines available. This is primarily due to the fact that these vaccines are not used in the countries that most need them. There is growing recognition that an effective invasive Salmonella vaccine formulation must also prevent infection due to other Salmonella serovars. We anticipate that a multivalent vaccine that targets the following serovars will be needed to control invasive Salmonella infections worldwide: Salmonella Typhi, Salmonella Paratyphi A, Salmonella Paratyphi B (currently uncommon but may become dominant again), Salmonella Typhimurium, Salmonella Enteritidis and Salmonella Choleraesuis (as well as other Group C Salmonella). Live attenuated vaccines are an attractive vaccine formulation for use in developing as well as developed countries. Here, we describe the methods of attenuation that have been used to date to create live attenuated Salmonella vaccines and provide an update on the progress that has been made on these vaccines.
Topics: Africa; Antibodies, Bacterial; Asia; Humans; Salmonella; Salmonella Infections; Salmonella Vaccines; Salmonella paratyphi A; Salmonella typhi; Salmonella typhimurium; Serogroup; Typhoid Fever; Typhoid-Paratyphoid Vaccines; Vaccines, Attenuated
PubMed: 25902362
DOI: 10.1016/j.vaccine.2015.04.029 -
Microbiology Spectrum Dec 2022Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) is the etiological agent of swine enzootic pneumonia (EP), which has been associated with considerable economic losses...
Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) is the etiological agent of swine enzootic pneumonia (EP), which has been associated with considerable economic losses due to reduced daily weight gain and feed efficiency. Adhesion to the cilia is important for Mhp to colonize the respiratory epithelium. Therefore, a successful vaccine must induce broad Mhp-specific immune responses at the mucosal surface. Recombinant attenuated Salmonella strains are believed to act as powerful live vaccine vectors that are able to elicit mucosal immune responses against various pathogens. To develop efficacious and inexpensive vaccines against Mhp, the immune responses and protection induced by recombinant attenuated Salmonella vaccines based on the P42 and P97 antigens of Mhp were evaluated. In general, the oral inoculation of recombinant rSC0016(pS-P42) or rSC0016(pS-P97) resulted in strong mucosal immunity, cell-mediated immunity, and humoral immunity, which was a mixed Th1/Th2-type response. In addition, the levels of specific IL-4 and IFN-γ in the immunized mice were increased, and the proliferation of lymphocytes was also enhanced, confirming the production of a good cellular immune response. Finally, both vaccine candidate strains were able to improve the weight loss of mice after a challenge and reduce clinical symptoms, lung pathological damage, and the inflammatory cell infiltration. These results suggest that the delivery of protective antigens with recombinant attenuated Salmonella vectors may be an effective means by which to combat Mhp infection. Mhp is the main pathogen of porcine enzootic pneumonia, a highly infectious and economically significant respiratory disease that affects pigs of all ages. As the target tissue of Mhp infections are the mucosal sites of the respiratory tract, the induction of protective immunity at the mucosal tissues is the most efficient strategy by which to block disease transmission. Because the stimulation of mucosal immune responses is efficient, Salmonella-vector oral vaccines are expected to be especially useful against mucosal-invading pathogens. In this study, we expressed the immunogenic proteins of P42 and P97 with the attenuated Salmonella Choleraesuis vector rSC0016, thereby generating a low-cost and more effective vaccine candidate against Mhp by inducing significant mucosal, humoral and cellular immunity. Furthermore, rSC0016(pS-P42) effectively prevents Mhp-induced weight loss and the pulmonary inflammation of mice. Because of the effectiveness of rSC0016(pS-P42) against Mhp infection in mice, this novel vaccine candidate strain shows great potential for its use in the pig breeding industry.
Topics: Animals; Mice; Swine; Mycoplasma hyopneumoniae; Bacterial Vaccines; Immunization; Vaccines, Synthetic; Salmonella; Salmonella enterica; Pneumonia of Swine, Mycoplasmal; Immunity, Mucosal
PubMed: 36377878
DOI: 10.1128/spectrum.02361-22 -
Microbiology Spectrum Mar 2019Systemic infections are a major cause of mortality worldwide and are becoming increasingly untreatable. Recent single-cell data from a mouse model of typhoid fever show... (Review)
Review
Systemic infections are a major cause of mortality worldwide and are becoming increasingly untreatable. Recent single-cell data from a mouse model of typhoid fever show that the host immune system actually eradicates many cells, while other organisms thrive at the same time in the same tissue, causing lethal disease progression. The surviving cells have highly heterogeneous metabolism, growth rates, and exposure to various stresses. Emerging evidence suggests that similarly heterogeneous host-pathogen encounters might be a key feature of many infectious diseases. This heterogeneity offers fascinating opportunities for research and application. If we understand the mechanisms that determine the disparate local outcomes, we might be able to develop entirely novel strategies for infection control by broadening successful host antimicrobial attacks and closing permissive niches in which pathogens can thrive. This review describes suitable technologies, a current working model of heterogeneous host- interactions, the impact of diverse subsets on antimicrobial chemotherapy, and major open questions and challenges.
Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Disease Progression; Host-Pathogen Interactions; Humans; Mice; Salmonella Infections; Salmonella enterica; Spleen; Stress, Physiological; Typhoid Fever
PubMed: 30953427
DOI: 10.1128/microbiolspec.BAI-0009-2019 -
Food Microbiology Aug 2021The microbial composition of the food production environment plays an important role in food safety and quality. This study employed both 16 S rRNA gene sequencing... (Comparative Study)
Comparative Study
The microbial composition of the food production environment plays an important role in food safety and quality. This study employed both 16 S rRNA gene sequencing technology and culture-based techniques to investigate the bacterial microbiota of an egg production facility comprising of both free-range and conventional cage housing systems. The study also aimed to detect the presence of Salmonella enterica and determine whether its presence was positively or negatively associated with other taxa. Our findings revealed that microbiota profiles of free-range and cage houses differ considerably in relation to the relative abundance and diversity with a number of taxa unique to each system and to individual sampling sites within sheds. Core to each housing system were known inhabitants of the poultry gastrointestinal tracts, Romboutsia and Turicibacter, as well as common spoilage bacteria. Generally, free-range samples contained fewer taxa and were dominated by Staphylococcus equorum, differentiating them from the cage samples. Salmonella enterica was significantly associated with the presence of a taxa belonging to the Carnobacteriaceae family. The results of this study demonstrate that the diversity and composition of the microbiota is highly variable across egg layer housing systems, which could have implications for productivity, food safety and spoilage.
Topics: Animal Husbandry; Animals; Bacteria; Chickens; Eggs; Female; Male; Microbiota; Oviposition; Salmonella enterica
PubMed: 33653527
DOI: 10.1016/j.fm.2021.103754 -
Journal of Microbiology, Immunology,... Feb 2020Zoonotic Salmonella enterica serovar Choleraesuis (S. Choleraesuis), causing paratyphoid in pigs and bacteremia in humans, commonly carry a virulence plasmid and...
BACKGROUND
Zoonotic Salmonella enterica serovar Choleraesuis (S. Choleraesuis), causing paratyphoid in pigs and bacteremia in humans, commonly carry a virulence plasmid and sometimes a separate antimicrobial-resistant plasmid or merging together. This study aimed to analyze the likely mechanism of how to form a virulence-resistance chimera of plasmid in S. Choleraesuis.
METHODS
Whole plasmid sequence of pOU7519 in S. Choleraesuis strain OU7519 was determined using shotgun cloning and sequencing. Sequence annotation and comparison were performed to determine the sequence responsible for the formation of a chimeric virulence-resistance pOU7519. Other chimeric plasmids among the collected strains of S. Choleraesuis were also confirmed.
RESULTS
The sequence of pOU719, 127,212 bp long, was identified to be a chimera of the virulence plasmid pSCV50 and a multidrug-resistant plasmid pSC138 that have been found in S. Choleraesuis strain SC-B67. The pOU7519 is a conjugative plasmid carrying various mobile DNAs, including prophages, insertion sequences, integrons and transposons, especially a Tn6088-like transposon. By dissecting the junction site of the pSCV50-pSC138 chimera in pOU7519, defective sequences at integrase gene scv50 (int) and its attachment site (att) were found, and that likely resulted in a stable chimera plasmid due to the failure of excision from the pSCV50-pSC138 chimera. Similar structure of chimera was also found in other large plasmids.
CONCLUSION
The deletion of both the int and att sties could likely block chimera excision, and result in an irreversible, stable pSCV50-pSC138 chimera. The emergence of conjugative virulence and antimicrobial-resistant plasmids in S. Choleraesuis could pose a threat to health public.
Topics: Anti-Bacterial Agents; DNA Transposable Elements; Drug Resistance, Multiple, Bacterial; Genes, Bacterial; Microbial Sensitivity Tests; Plasmids; Salmonella enterica; Sequence Analysis, DNA; Virulence
PubMed: 29273286
DOI: 10.1016/j.jmii.2017.11.004 -
Infection and Immunity Apr 2022Viral respiratory infections predispose lungs to bacterial coinfections causing a worse outcome than either infection alone. Porcine reproductive and respiratory...
-Based Direct-Fed Microbial Reduces the Pathogenic Synergy of a Coinfection with Salmonella enterica Serovar Choleraesuis and Porcine Reproductive and Respiratory Syndrome Virus.
Viral respiratory infections predispose lungs to bacterial coinfections causing a worse outcome than either infection alone. Porcine reproductive and respiratory syndrome virus (PRRSV) causes pneumonia in pigs and is often associated with bacterial coinfections. We examined the impact of providing weanling pigs a -based direct-fed microbial (DFM) on the syndrome resulting from infection with either Salmonella enterica serotype Choleraesuis alone, or in combination with PRRSV. Nine days after the bacterial challenge, Salmonella was isolated from ileocecal lymph nodes of all challenged pigs regardless of DFM treatment. Compared to the single bacterial challenge, the dual challenge with Salmonella and PRRSV resulted in a pathogenic synergy exhibited by a higher rate of Salmonella colonization in the lung and a more extensive and severe interstitial pneumonia. Provision of DFM to dually challenged pigs reduced the rate of lung colonization by Salmonella, eliminated or reduced the presence of PRRSV in the lung, and reduced the extent and severity of gross lung pathology. Dually challenged pigs that received DFM had increased concentrations of interleukin 1 (IL-1) and IL-8 in lung lavage fluids, accompanied by increased expression in their blood cells of nucleotide-binding oligomerization domain receptor 2 (NOD2) and triggering receptor expressed in myeloid cells 1 (TREM-1) molecules. These changes in pulmonary inflammatory cytokine production and increased expression of NOD2 and TREM-1 suggest that the DFM exerted a systemic modulating effect on innate immunity. These observations are consistent with the notion that tonic stimulation by gut-derived microbial products can poise innate immunity to fight infections in the respiratory tract.
Topics: Animals; Bacillus; Coinfection; Pneumonia; Porcine respiratory and reproductive syndrome virus; Salmonella; Salmonella enterica; Serogroup; Swine; Triggering Receptor Expressed on Myeloid Cells-1
PubMed: 35254092
DOI: 10.1128/iai.00574-21 -
Frontiers in Cellular and Infection... 2014The human-pathogenic bacterium Salmonella enterica adjusts and adapts to different environments while attempting colonization. In the course of infection nutrient... (Review)
Review
The human-pathogenic bacterium Salmonella enterica adjusts and adapts to different environments while attempting colonization. In the course of infection nutrient availabilities change drastically. New techniques, "-omics" data and subsequent integration by systems biology improve our understanding of these changes. We review changes in metabolism focusing on amino acid and carbohydrate metabolism. Furthermore, the adaptation process is associated with the activation of genes of the Salmonella pathogenicity islands (SPIs). Anti-infective strategies have to take these insights into account and include metabolic and other strategies. Salmonella infections will remain a challenge for infection biology.
Topics: Animals; Bacterial Proteins; Humans; Salmonella Infections; Salmonella enterica; Virulence
PubMed: 25688337
DOI: 10.3389/fcimb.2014.00191 -
Applied and Environmental Microbiology Jul 2011Fresh and processed poultry have been frequently implicated in cases of human salmonellosis. Furthermore, increased consumption of meat and poultry has increased the... (Review)
Review
Fresh and processed poultry have been frequently implicated in cases of human salmonellosis. Furthermore, increased consumption of meat and poultry has increased the potential for exposure to Salmonella enterica. While advances have been made in reducing the prevalence and frequency of Salmonella contamination in processed poultry, there is mounting pressure on commercial growers to prevent and/or eliminate these human pathogens in preharvest production facilities. Several factors contribute to Salmonella colonization in commercial poultry, including the serovar and the infectious dose. In the early 1900s, Salmonella enterica serovars Pullorum and Gallinarum caused widespread diseases in poultry, but vaccination and other voluntary programs helped eradicate pullorum disease and fowl typhoid from commercial flocks. However, the niche created by the eradication of these serovars was likely filled by S. Enteritidis, which proliferated in the bird populations. While this pathogen remains a significant problem in commercial egg and poultry production, its prevalence among poultry has been declining since the 1990s. Coinciding with the decrease of S. Enteritidis, S. Heidelberg and S. Kentucky have emerged as the predominant serovars in commercial broilers. In this review, we have highlighted bacterial genetic and host-related factors that may contribute to such shifts in Salmonella populations in commercial poultry and intervention strategies that could limit their colonization.
Topics: Animals; Ovum; Population Dynamics; Poultry; Salmonella Infections, Animal; Salmonella enterica; Serotyping
PubMed: 21571882
DOI: 10.1128/AEM.00598-11 -
Clinical Microbiology Reviews Apr 2004Nontyphoid Salmonella strains are important causes of reportable food-borne infection. Among more than 2,000 serotypes, Salmonella enterica serotype Choleraesuis shows... (Review)
Review
Nontyphoid Salmonella strains are important causes of reportable food-borne infection. Among more than 2,000 serotypes, Salmonella enterica serotype Choleraesuis shows the highest predilection to cause systemic infections in humans. The most feared complication of serotype Cholearesuis bacteremia in adults is the development of mycotic aneurysm, which previously was almost uniformally fatal. The advances in diagnostic techniques, surgical care, and antimicrobial therapy have greatly improved the survival of these patients. However, the recent emergence of serotype Choleraesuis that is resistant to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, and, notably, fluoroquinolone antibiotics has aroused concern about the use of these agents for the empirical treatment of systemic infection caused by this organism. In view of the serious implications of the situation, the chain of transmission and mechanism of resistance should be carefully studied to reduce the spread of infection and threat to human health. To date, there are no vaccines available to prevent serotype Choleraesuis infections in humans. The availability, in the near future, of the genome sequence of serotype Cholearesuis will facilitate the development of effective vaccines as well as the discovery of new targets for novel antimicrobial agents.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Humans; Salmonella Infections; Salmonella Vaccines; Salmonella enterica; Serotyping; Virulence
PubMed: 15084503
DOI: 10.1128/CMR.17.2.311-322.2004