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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 -
Clinical Microbiology Reviews Jan 2019The ability of pathogenic bacteria to affect higher organisms and cause disease is one of the most dramatic properties of microorganisms. Some pathogens can establish... (Review)
Review
The ability of pathogenic bacteria to affect higher organisms and cause disease is one of the most dramatic properties of microorganisms. Some pathogens can establish transient colonization only, but others are capable of infecting their host for many years or even for a lifetime. Long-term infection is called persistence, and this phenotype is fundamental for the biology of important human pathogens, including , , and Both typhoidal and nontyphoidal serovars of the species can cause persistent infection in humans; however, as these two groups cause clinically distinct diseases, the characteristics of their persistent infections in humans differ significantly. Here, following a general summary of pathogenicity, host specificity, epidemiology, and laboratory diagnosis, I review the current knowledge about persistence and discuss the relevant epidemiology of persistence (including carrier rate, duration of shedding, and host and pathogen risk factors), the host response to persistence, genes involved in this lifestyle, as well as genetic and phenotypic changes acquired during prolonged infection within the host. Additionally, I highlight differences between the persistence of typhoidal and nontyphoidal strains in humans and summarize the current gaps and limitations in our understanding, diagnosis, and curing of persistent infections.
Topics: Carrier State; Humans; Risk Factors; Salmonella Infections; Salmonella enterica; Serogroup
PubMed: 30487167
DOI: 10.1128/CMR.00088-18 -
Microbiological Research Jan 2018Salmonella is a major foodborne pathogen with a complex nomenclature. This genus is composed of two species, S. enterica and S. bongori. S. enterica is divided into six... (Review)
Review
Salmonella is a major foodborne pathogen with a complex nomenclature. This genus is composed of two species, S. enterica and S. bongori. S. enterica is divided into six subspecies. S. enterica subspecies enterica is composed of more than 1500 serotypes with some of great importance, such as S. Typhimurium and S. Enteritidis. S. enterica subsp. enterica is responsible of more than 99% of human salmonellosis and therefore it is widely studied. However, the non-enterica subspecies of S. enterica have been little studied. These subspecies are considered to be related to cold-blooded animals and their pathogenicity is very limited. Phenotype and genotype information generated from different studies of non-enterica subspecies reveal poor ability to invade host cells and the absence or modification of important virulence factors. Also, the great majority of human infections due to non-enterica subspecies are related to a previous depressed immune system. Therefore, we propose to treat these subspecies only as opportunistic pathogens. For establish this premise, the present review evaluated, among other things, the genomic characteristics, prevalence, antimicrobial resistance and reported human cases of the non-enterica subspecies.
Topics: Animals; Biofilms; Drug Resistance, Bacterial; Ecology; Genes, Bacterial; Genetic Speciation; Genotype; Humans; Phylogeny; Prevalence; Public Health; Salmonella Infections; Salmonella Infections, Animal; Salmonella enterica; Serogroup; Virulence; Virulence Factors
PubMed: 29146261
DOI: 10.1016/j.micres.2017.09.010 -
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 -
Infection and Immunity Sep 2019In recent years nontyphoidal has emerged as one of the pathogens most frequently isolated from the bloodstream in humans. Only a small group of serovars cause this... (Review)
Review
In recent years nontyphoidal has emerged as one of the pathogens most frequently isolated from the bloodstream in humans. Only a small group of serovars cause this systemic infection, known as invasive nontyphoidal salmonellosis. Here, we present a focused minireview on serovar Panama, a serovar responsible for invasive salmonellosis worldwide. Panama has been linked with infection of extraintestinal sites in humans, causing septicemia, meningitis, and osteomyelitis. The clinical picture is often complicated by antimicrobial resistance and has been associated with a large repertoire of transmission vehicles, including human feces and breast milk. Nonhuman sources of Panama involve reptiles and environmental reservoirs, as well as food animals, such as pigs. The tendency of Panama to cause invasive disease may be linked to certain serovar-specific genetic factors.
Topics: Drug Resistance, Multiple, Bacterial; Global Health; Humans; Salmonella Infections; Salmonella enterica; Virulence
PubMed: 31262982
DOI: 10.1128/IAI.00273-19 -
BioMed Research International 2017The coding sequence of was cloned and expressed in . The protein was purified and ATPase activity was characterized by NADH oxidation method. GsiA exhibited optimum...
The coding sequence of was cloned and expressed in . The protein was purified and ATPase activity was characterized by NADH oxidation method. GsiA exhibited optimum activity at 30°C and at pH 8 in Tris/HCl buffer. GsiA protein was stable at 20°C. 66% and 44% activity remained after incubation at 30°C and 40°C for 30 min. pH 7 and pH 9 incubation would obviously reduce the ATPase activity. In vivo functionality of was determined by constructing gene deletion strains. was shown to be essential for GSI mediated glutathione uptake and deletion could decrease the virulence of . Interactions of glutathione import proteins GsiA, GsiB, GsiC, and GsiD were investigated by using bacterial two-hybrid system. GsiA could interact with itself and inner membrane proteins GsiC and GsiD. This report provides the first description of functions in . The results could help elucidating the glutathione uptake mechanism and glutathione functions in bacteria.
Topics: Adenosine Triphosphatases; Animals; Bacterial Proteins; Glutathione; Male; Mice; NAD; Oxidation-Reduction; Protein Binding; Salmonella enterica
PubMed: 28691022
DOI: 10.1155/2017/3076091 -
MBio Jan 2021Enterobacterial pathogens infect the gut by a multistep process, resulting in colonization of both the lumen and the mucosal epithelium. Due to experimental constraints,...
Enterobacterial pathogens infect the gut by a multistep process, resulting in colonization of both the lumen and the mucosal epithelium. Due to experimental constraints, it remains challenging to address how luminal and epithelium-lodged pathogen populations cross-feed each other Enteroids are cultured three-dimensional miniature intestinal organs with a single layer of primary intestinal epithelial cells (IECs) surrounding a central lumen. They offer new opportunities to study enterobacterial infection under near-physiological conditions, at a temporal and spatial resolution not attainable in animal models, but remain poorly explored in this context. We employed microinjection, time-lapse microscopy, bacterial genetics, and barcoded consortium infections to describe the complete infection cycle of serovar Typhimurium in both human and murine enteroids. Flagellar motility and type III secretion system 1 (TTSS-1) promoted Typhimurium targeting of the intraepithelial compartment and breaching of the epithelial barrier. Strikingly, however, TTSS-1 also potently boosted colonization of the enteroid lumen. By tracing the infection over time, we identified a cycle(s) of TTSS-1-driven IEC invasion, intraepithelial replication, and reemergence through infected IEC expulsion as a key mechanism for Typhimurium luminal colonization. These findings suggest a positive feed-forward loop, through which IEC invasion by planktonic bacteria fuels further luminal population expansion, thereby ensuring efficient colonization of both the intraepithelial and luminal niches. Pathogenic gut bacteria are common causes of intestinal disease. Enteroids-cultured three-dimensional replicas of the mammalian gut-offer an emerging model system to study disease mechanisms under conditions that recapitulate key features of the intestinal tract. In this study, we describe the full life cycle of the prototype gut pathogen serovar Typhimurium within human and mouse enteroids. We map the consecutive steps and define the bacterial virulence factors that drive colonization of luminal and epithelial compartments, as well as breaching of the epithelial barrier. Strikingly, our work reveals how bacterial colonization of the epithelium potently fuels expansion also in the luminal compartment, through a mechanism involving the death and expulsion of bacterium-infected epithelial cells. These findings have repercussions for our understanding of the infection cycle. Moreover, our work provides a comprehensive foundation for the use of microinjected enteroids to model gut bacterial diseases.
Topics: Animals; Disease Models, Animal; Epithelial Cells; Epithelium; Humans; Intestinal Mucosa; Mice; Salmonella Infections; Salmonella Infections, Animal; Salmonella enterica; Salmonella typhimurium; Serogroup; Type III Secretion Systems; Virulence Factors
PubMed: 33436434
DOI: 10.1128/mBio.02684-20 -
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 -
Microbiology Spectrum Dec 2022Salmonella bacteria pose a significant threat to animal husbandry and human health due to their virulence and multidrug resistance. The lasso peptide MccY is a recently...
Salmonella bacteria pose a significant threat to animal husbandry and human health due to their virulence and multidrug resistance. The lasso peptide MccY is a recently discovered antimicrobial peptide that acts against various serotypes of Salmonella. In this study, we further explore the resistance mechanism and activity of MccY. Mutants of Ton system genes, including , , and , in Salmonella enterica subsp. serovar Typhimurium were constructed, and the MICs to MccY exhibited significant increases in these deletion mutants compared to the MIC of the parent strain. Subsequently, MccY resistance was quantitatively analyzed, and these mutants also showed greatly reduced rates of killing, even with a high concentration of MccY. In addition, a minimal medium with low iron environment enhanced the sensitivity of these mutants to MccY. Measurements of a series of physiological indicators, including iron utilization, biofilm formation, and motility, demonstrated that MccY may decrease the virulence of Typhimurium. Transcriptomic analysis showed that iron utilization, biofilm formation, flagellar assembly, and virulence-related genes were downregulated to varying degrees when Typhimurium was treated with MccY. In conclusion, deletion of Ton system genes resulted in resistance to MccY and the susceptibility of these mutants to MccY was increased and differed under a low-iron condition. This lasso peptide can alter multiple physiological properties of Typhimurium. Our study will contribute to improve the knowledge and understanding of the mechanism of MccY resistance in Salmonella strains. The resistance of Salmonella to traditional antibiotics remains a serious challenge. Novel anti-Salmonella drugs are urgently needed to address the looming crisis. The newly identified antimicrobial peptide MccY shows broad prospects for development and application because of its obvious antagonistic effect on various serotypes of Salmonella. However, our previous study showed that the peptide could confer resistance to Salmonella by disrupting the receptor gene . In this study, we further explored the potential resistance mechanism of MccY and demonstrated the importance of the Salmonella Ton complex for MccY transport. Disruption in Ton system genes resulted in Typhimurium resistance to this peptide, and MccY could alter multiple bacterial physiological properties. In summary, this study further explored the resistance mechanism and antibacterial effect of MccY in Typhimurium and provided a scientific basis for its development and application.
Topics: Anti-Bacterial Agents; Salmonella enterica; Salmonella typhimurium; Serogroup; Bacteriocins
PubMed: 36453909
DOI: 10.1128/spectrum.01859-22 -
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