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synthesis and characterization of bactericidal silver nanoparticles using cultural filtrate of simulated microgravity grown klebsiella pneumoniae.silver nanoparticles were synthesized by biological method using cultural filtrate of klebsiella pneumoniae cultured under simulated microgravity and silver nitrate solution as precursor. the nanoparticles exhibited typical plasmon absorption maximum of silver nanoparticles between 405 and 407 nm. spherical silver nanoparticles were found to have size between 15 and 37 nm by tem analysis. xrd pattern corresponding to planes (111), (200), (220) (311) revealed the crystalline nature of the biosynt ...201323410925
novel methods for expression of foreign antigens in live vector vaccines.bacterial live vector vaccines represent a vaccine development strategy that offers exceptional flexibility. in this approach, genes encoding protective antigens of unrelated bacterial, viral or parasitic pathogens are expressed in an attenuated bacterial vaccine strain that delivers these foreign antigens to the immune system, thereby eliciting relevant immune responses. rather than expressing these antigens using low copy expression plasmids, here we pursue expression of foreign proteins from ...201323406777
genome sequences of salmonella enterica serovar heidelberg isolates isolated in the united states from a multistate outbreak of human salmonella infections.salmonella enterica is recognized as one of the most common bacterial agents of foodborne illness. we report draft genomes of four salmonella serovar heidelberg isolates associated with the recent multistate outbreak of human salmonella heidelberg infections linked to kosher broiled chicken livers in the united states in 2011. isolates 2011k-1259 and 2011k-1232 were recovered from humans, whereas 2011k-1724 and 2011k-1726 were isolated from chicken liver. whole genome sequence analysis of these ...201323405335
cellular distribution of lipid a and lps r595 after in vitro application to isolated human monocytes by freeze-fracture replica immunogold-labelling.we have performed freeze-fracture replica immunogold labelling of endotoxin preparations (lipid a and deep rough mutant lps re from salmonella enterica sv. minnesota), i.e. adding the endotoxins to human monocytes, labelling with monoclonal abs recognizing either lipid a or lps re (a6 and a20 respectively), and fixing with immunogold secondary ab. we have found that the endotoxins intercalated into the cell membranes with subsequent internalization by the cells. surprisingly, membrane uptake too ...201323405031
salmonella enterica suppresses pectobacterium carotovorum subsp. carotovorum population and soft rot progression by acidifying the microaerophilic environment.although enteric human pathogens are usually studied in the context of their animal hosts, a significant portion of their life cycle occurs on plants. plant disease alters the phyllosphere, leading to enhanced growth of human pathogens; however, the impact of human pathogens on phytopathogen biology and plant health is largely unknown. to characterize the interaction between human pathogens and phytobacterial pathogens in the phyllosphere, we examined the interactions between pectobacterium caro ...201323404399
insights into the evolution of gene organization and multidrug resistance from klebsiella pneumoniae plasmid pkf3-140.plasmid-mediated transfer of drug-resistance genes among various bacterial species is considered one of the most important mechanisms for the spread of multidrug resistance. to gain insights into the evolution of gene organization and antimicrobial resistance in clinical bacterial samples, a complete plasmid genome of klebsiella pneumoniae pkf3-140 is determined, which has a circular chromosome of 147,416bp in length. among the 203 predicted genes, 142 have function assignment and about 50 appea ...201323402892
impact of disinfectant-filled foot mats on mechanical transmission of bacteria in a veterinary teaching hospital.to evaluate the efficacy of disinfectant-filled foot mats at reducing tracking of salmonella enterica and overall bacterial contamination on floors in a veterinary teaching hospital.201323402417
estimation of the rate of egg contamination from salmonella-infected chickens.salmonella enterica serovar enteritidis (s. enteritidis) is one of the most prevalent causes for human gastroenteritis and is by far the predominant salmonella serovar among human cases, followed by salmonella typhimurium. contaminated eggs produced by infected laying hens are thought to be the main source of human infection with s. enteritidis throughout the world. although previous studies have looked at the proportion of infected eggs from infected flocks, there is still uncertainty over the ...201423398774
inactivation of salmonella enterica serovar typhimurium and quality maintenance of cherry tomatoes treated with gaseous essential oils.the antimicrobial activity of the essential oils (eos) from cinnamon bark, oregano, mustard, and of their major components cinnamaldehyde, carvacrol, and allyl isothiocyanate (ait) was evaluated as a gaseous treatment to reduce salmonella enterica serovar typhimurium in vitro and on tomatoes. in vitro tests showed that mustard eo and ait had the greatest inhibition of salmonella, followed by cinnamon eo and cinnamaldehyde, while oregano and carvacrol showed the least inhibition. scanning electro ...201323398191
salmonella promotes asc oligomerization-dependent caspase-1 activation.innate immune cells sense and respond to the cytoplasmic infection of bacterial pathogens through nlrp3, nlrc4 or aim2 inflammasome depending on the unique molecular pattern of invading pathogens. the infection of flagellin- or type iii secretion system (t3ss)-containing gram-negative bacteria such as salmonella enterica serovar typhimurium (s. typhimurium) or pseudomonas aeruginosa (p. aeruginosa) triggers nlrc4-dependent caspase-1 activation leading to the secretion of proinflammatory cytokine ...201223396959
ompw is cooperatively upregulated by mara and soxs in response to menadione.ompw is a minor porin whose biological function has not been clearly defined. evidence obtained in our laboratory indicates that in salmonella enterica serovar typhimurium the expression of ompw is activated by soxs upon exposure to paraquat and it is required for resistance. soxs belongs to the arac family of transcriptional regulators, like mara and rob. due to their high structural similarity, the genes under their control have been grouped in the mar/sox/rob regulon, which presents a dna-bin ...201323393149
use of real-time pcr on faecal samples for detection of sub-clinical salmonella infection in cattle did not improve the detection sensitivity compared to conventional bacteriology.there is a need for more sensitive detection methods to improve effectiveness of control programmes of salmonella enterica subsp. enterica serotypes (salmonella) in cattle. we assessed the performance of a rapid, molecular-based, real-time pcr (rt-pcr) method against the conventional bacteriological culture-reference method (bcrm) on cattle faecal samples for detection of sub-clinical salmonella infections in cattle. thirty faecal samples were artificially contaminated with either 10 or 50 cfu o ...201323391438
lactic acid bacteria and bifidobacteria attenuate the proinflammatory response in intestinal epithelial cells induced by salmonella enterica serovar typhimurium.inflammation is a physiological response to infections and tissue injury; however, abnormal immune responses can give rise to chronic inflammation and contribute to disease progression. various dietary components, including probiotic lactic acid bacteria and prebiotics, have the potential to modulate intestinal inflammatory responses. one factor in particular, the chemokine interleukin-8 (il-8, cxcl-8), is one of the major mediators of the inflammatory response. the purpose of this study was to ...201223391223
identification and typing of salmonella enterica serotypes isolated from guinea fowl (numida meleagris) farms in benin during four laying seasons (2007 to 2010).the main problem for the local guinea fowl (numida meleagris) traditional farming and raising system in north-east benin is the high mortality rate of the keets (up to 70%) due to a combination of climatic, nutritional, hygienic and infectious causes. the present study was carried out to identify and compare the isolates of salmonella enterica from necropsied keets, laying guinea fowl, surrogate hen mothers, other contact animal species and farmers during four laying seasons (2007 to 2010). s. e ...201323391175
decline in ciprofloxacin-resistant salmonella enterica serovar choleraesuis in taiwan, 2001-2011. 201323390070
rida proteins prevent metabolic damage inflicted by plp-dependent dehydratases in all domains of life.pyridoxal 5'-phosphate (plp) is a coenzyme synthesized by all forms of life. relevant to the work reported here is the mechanism of the plp-dependent threonine/serine dehydratases, which generate reactive enamine/imine intermediates that are converted to keto acids by members of the rida family of enzymes. the rida protein of salmonella enterica serovar typhimurium lt2 is the founding member of this broadly conserved family of proteins (formerly known as yjgf/yer057c/uk114). rida proteins were r ...201323386433
rac and rab gtpases dual effector nischarin regulates vesicle maturation to facilitate survival of intracellular bacteria.the intracellular pathogenic bacterium salmonella enterica serovar typhimurium (salmonella) relies on acidification of the salmonella-containing vacuole (scv) for survival inside host cells. the transport and fusion of membrane-bound compartments in a cell is regulated by small gtpases, including rac and members of the rab gtpase family, and their effector proteins. however, the role of these components in survival of intracellular pathogens is not completely understood. here, we identify nischa ...201323386062
deletion in the c-terminal domain of clpx delayed entry of salmonella enterica into a viable but non-culturable state.under stressful conditions, bacteria enter a viable but non-culturable (vbnc) state in which they are alive but fail to grow on conventional media. the molecular basis underlying this state is unknown. to identify the key gene responsible for the vbnc state in salmonella spp., we examined a s. typhimurium lt2 vbnc mutant, which shows a characteristic delay in entering the vbnc state. the mutant showed a higher level of expression of general stress sigma factor rpos than wild-type lt2. the mutant ...201323385142
on the evolutionary history, population genetics and diversity among isolates of salmonella enteritidis pfge pattern jegx01.0004.facile laboratory tools are needed to augment identification in contamination events to trace the contamination back to the source (traceback) of salmonella enterica subsp. enterica serovar enteritidis (s. enteritidis). understanding the evolution and diversity within and among outbreak strains is the first step towards this goal. to this end, we collected 106 new s. enteriditis isolates within s. enteriditis pulsed-field gel electrophoresis (pfge) pattern jegx01.0004 and close relatives, and de ...201323383127
cooperation of the multidrug efflux pump and lipopolysaccharides in the intrinsic antibiotic resistance of salmonella enterica serovar typhimurium.in gram-negative bacteria, drug susceptibility is associated with multidrug efflux systems and an outer membrane (om) barrier. previous studies revealed that salmonella enterica serovar typhimurium has 10 functional drug efflux pumps. among them, acrb is a major factor to maintain the intrinsic drug resistance in this organism. the lipopolysaccharide (lps) content of om is also important for resistance to lipophilic drugs; however, the interplay between the multidrug efflux pump and lps in the i ...201323378414
pathogenicity of dodecyltrimethylammonium chloride-resistant salmonella enterica.salmonella infection causes a self-limiting gastroenteritis in humans but can also result in a life-threatening invasive disease, especially in old, young, and/or immunocompromised patients. the prevalence of antimicrobial and multidrug-resistant salmonella has increased worldwide since the 1980s. however, the impact of antimicrobial resistance on the pathogenicity of salmonella strains is not well described. in our study, a microarray was used to screen for differences in gene expression betwee ...201323377943
colonization and internalization of salmonella enterica in tomato plants.the consumption of fresh tomatoes has been linked to numerous food-borne outbreaks involving various serovars of salmonella enterica. recent advances in our understanding of plant-microbe interactions have shown that human enteric pathogenic bacteria, including s. enterica, are adapted to survive in the plant environment. in this study, tomato plants (solanum lycopersicum cv. micro-tom) grown in sandy loam soil from virginia's eastern shore (ves) were inoculated with s. enterica serovars to eval ...201323377940
differential protein expression patterns between planktonic and biofilm cells of salmonella enterica serovar enteritidis pt4 on stainless steel surface.in the present study, the proteome of a strain of s. enterica serovar enteritidis pt4, grown either as biofilm on stainless steel surface or as free-floating (planktonic) in brain heart (bh) broth, was investigated in order to detect the strong differences in whole-cell protein expression patterns between the two growth styles. the proteins extracted from both types of cells were subjected to 2-d page, followed by in-gel tryptic digestion, extraction, subsequent maldi-tof mass spectrometry (ms) ...201323376784
evaluation of silver-infused polylactide films for inactivation of salmonella and feline calicivirus in vitro and on fresh-cut vegetables.there is a growing trend to develop packaging materials with an active role in guarantying that the quality and safety characteristics of packaged products will remain or improve from preparation throughout shelf-life. in the present study, 0.001-1.0 wt.% silver ions were satisfactorily incorporated into polylactide (pla) films by a solvent casting technique. silver migration from the films was measured by voltamperometry and then correlated with its antimicrobial efficacy against salmonella ent ...201323376782
novel antibody/gold nanoparticle/magnetic nanoparticle nanocomposites for immunomagnetic separation and rapid colorimetric detection of staphylococcus aureus in milk.we demonstrated the new antibody/gold nanoparticle/magnetic nanoparticle nanocomposites (antibody/aunp/mnps) and their application in the detection of the foodborne pathogen, staphylococcus aureus (s. aureus), in milk. the nanocomposites were synthesized by coating the mnps with bovine serum albumin (bsa) then adsorbing the aunps and anti-s. aureus antibodies on their surface. using the completed immunomagnetic nanostructures, s. aureus inoculated in the milk sample was captured and isolated fro ...201323370174
effect of wheat distillers dried grains with solubles or sugar beet pulp on prevalence of salmonella enterica typhimurium in weaned pigs.salmonella enterica typhimurium (st) is of concern in the swine industry with relevance for animal health and consumer safety. nutritional strategies might help to reduce st infection and transmission. this study examined the potential of wheat (triticum aestivum) distillers dried grains with solubles (ddgs) and sugar beet (beta vulgaris) pulp (sbp) to alter intestinal microbial communities and st shedding using a trojan model. weaned pigs (n = 105; 28.5 ± 3.5 d of age) were separated into 3 tre ...201223365269
pmdt1, a small cole1-like plasmid mobilizing a new variant of the aac(6')-ib-cr gene in salmonella enterica serovar typhimurium.to characterize a 5.9 kb aac(6')-ib-cr-harbouring plasmid that was detected in a clinical salmonella typhimurium dt104b strain.201323361643
aminopurine derivatives as putative sope inhibitors.abstract salmonella outer protein e, sope, is a virulence factor that is secreted from gram-negative salmonella enterica, which is pathogenic to humans and is responsible for gastroenteritis and typhoid fever. sope targets the rho gtpase family proteins of the host cell and manipulates them by mimicking gtpase regulatory protein guanine nucleotide exchange factor. the aim of this work is the investigation of novel inhibitors against sope. structure-based pharmacophore modeling was used to identi ...201423360503
recombinant salmonella vaccination technology and its application to human bacterial pathogens.salmonella enterica is a gram-negative intracellular bacterial pathogen which causes salmonellosis in humans and animals. during the past several decades, extensive studies have shown that the attenuated salmonella vaccine vector is an optimal vehicle for delivering passenger antigens to mucosal sites to induce humoral, cellular, and mucosal immunity. this immunity leads to protection against challenges with the wild-type pathogens from which the passenger antigens were derived. a myriad of stud ...201323360265
growth of salmonella enterica in foliar pesticide solutions and its survival during field production and postharvest handling of fresh market tomato.to evaluate in vitro the growth kinetics of salmonella enterica in pesticide solutions labelled for fresh market tomato and the effect of ag-chemical application with contaminated water to tomatoes during field production.201323360242
dissemination of antimicrobial-resistant clones of salmonella enterica among domestic animals, wild animals, and humans.non-typhoidal salmonellosis is an important zoonotic disease caused by salmonella enterica. this work focuses on the identification of salmonella enterica clonal strains which, presenting a wide distribution potential, express resistance determinants that compromise effectiveness of the antimicrobial therapy. the screening was performed on 506 salmonella enterica isolates from animals and humans, which were characterized by serovar and phage typing, genome macrorestriction and pulsed-field gel e ...201323360170
iron induces bimodal population development by escherichia coli.bacterial biofilm formation is a complex developmental process involving cellular differentiation and the formation of intricate 3d structures. here we demonstrate that exposure to ferric chloride triggers rugose biofilm formation by the uropathogenic escherichia coli strain uti89 and by enteric bacteria citrobacter koseri and salmonella enterica serovar typhimurium. two unique and separable cellular populations emerge in iron-triggered, rugose biofilms. bacteria at the air-biofilm interface exp ...201323359678
bacterial colonization of host cells in the absence of cholesterol.reports implicating important roles for cholesterol and cholesterol-rich lipid rafts in host-pathogen interactions have largely employed sterol sequestering agents and biosynthesis inhibitors. because the pleiotropic effects of these compounds can complicate experimental interpretation, we developed a new model system to investigate cholesterol requirements in pathogen infection utilizing dhcr24(-/-) mouse embryonic fibroblasts (mefs). dhcr24(-/-) mefs lack the δ24 sterol reductase required for ...201323358892
pathogenicity of yersinia pestis synthesis of 1-dephosphorylated lipid a.synthesis of escherichia coli lpxl, which transfers a secondary laurate chain to the 2' position of lipid a, in yersinia pestis produced bisphosphoryl hexa-acylated lipid a at 37°c, leading to significant attenuation of virulence. our previous observations also indicated that strain χ10015(pcd1ap) (δlpxp32::p(lpxl) lpxl) stimulated a strong inflammatory reaction but sickened mice before recovery and retained virulence via intranasal (i.n.) infection. the development of live, attenuated y. pestis ...201323357387
the type vi secretion system encoded in salmonella pathogenicity island 19 is required for salmonella enterica serotype gallinarum survival within infected macrophages.salmonella enterica serotype gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity and mortality that causes major economic losses in poultry production. we have reported that s. gallinarum harbors a type vi secretion system (t6ss) encoded in salmonella pathogenicity island 19 (spi-19) that is required for efficient colonization of chicks. in the present study, we aimed to characterize the spi-19 t6ss functionality and to investigate the mechanisms behind t ...201323357385
stochasticity in colonial growth dynamics of individual bacterial cells.conventional bacterial growth studies rely on large bacterial populations without considering the individual cells. individual cells, however, can exhibit marked behavioral heterogeneity. here, we present experimental observations on the colonial growth of 220 individual cells of salmonella enterica serotype typhimurium using time-lapse microscopy videos. we found a highly heterogeneous behavior. some cells did not grow, showing filamentation or lysis before division. cells that were able to gro ...201323354712
microfluidic chip-based detection and intraspecies strain discrimination of salmonella serovars derived from whole blood of septic mice.salmonella is a zoonotic pathogen that poses a considerable public health and economic burden in the united states and worldwide. resultant human diseases range from enterocolitis to bacteremia to sepsis and are acutely dependent on the particular serovar of salmonella enterica subsp. enterica, which comprises over 99% of human-pathogenic s. enterica isolates. point-of-care methods for detection and strain discrimination of salmonella serovars would thus have considerable benefit to medical, vet ...201323354710
the molecular adjuvant mc3d enhances the immunogenicity of fima from type i fimbriae of salmonella enterica serovar enteritidis.the fimbriae of salmonella enterica serovar enteritidis are used for colonization and invasion into host cells, and have drawn considerable interest because fimbriae can serve as potential immunogens against many pathogenic bacteria that colonize on epithelial surfaces. the purpose of the study is to use a molecular adjuvant, c3d, to enhance the immunogenicity of fima proteins against salmonella enterica serovar enteritidis.201423352331
systemic administration of lipopolysaccharide in laying hens stimulates antimicrobial properties of egg white against staphylococcus aureus.the natural protective system of eggs relies on egg yolk immunoglobulins and on antimicrobial proteins/peptides mainly concentrated in the egg white. there is much evidence concerning the specific stimulation of immunoglobulins by antigens but to date, the influence of the hen milieu on the regulation of the egg innate molecular immunity has not been established. to explore the hypothesis of modulation in egg antimicrobial molecules, laying hens were immune-challenged with intravenous injections ...201323351641
antimicrobial resistance genes in multidrug-resistant salmonella enterica isolated from animals, retail meats, and humans in the united states and canada.salmonella enterica is a prevalent foodborne pathogen that can carry multidrug resistance (mdr) and pose a threat to human health. identifying the genetics associated with mdr in salmonella isolated from animals, foods, and humans can help determine sources of mdr in food animals and their impact on humans. s. enterica serovars most frequently carrying mdr from healthy animals, retail meats, and human infections in the united states and canada were identified and isolates resistant to the larges ...201323350745
contribution of thy1+ nk cells to protective ifn-γ production during salmonella typhimurium infections.ifn-γ is critical for immunity against infections with intracellular pathogens, such as salmonella enterica. however, which of the many cell types capable of producing ifn-γ controls salmonella infections remains unclear. using a mouse model of systemic salmonella infection, we observed that only a lack of all lymphocytes or cd90 (thy1)(+) cells, but not the absence of t cells, retinoic acid-related orphan receptor (ror)-γt-dependent lymphocytes, (nk)1.1(+) cells, natural killer t (nkt), and/or ...201323345426
reassessing the type i dehydroquinate dehydratase catalytic triad: kinetic and structural studies of glu86 mutants.dehydroquinate dehydratase (dhqd) catalyzes the third reaction in the biosynthetic shikimate pathway. type i dhqds are members of the greater aldolase superfamily, a group of enzymes that contain an active site lysine that forms a schiff base intermediate. three residues (glu86, his143, and lys170 in the salmonella enterica dhqd) have previously been proposed to form a triad vital for catalysis. while the roles of lys170 and his143 are well defined-lys170 forms the schiff base with the substrate ...201323341204
outbreak of salmonella typhi enteric fever in sub-urban area of north india: a public health perspective.outbreaks of enteric fever are a major health concern not only due to significant human morbidity and mortality but also fear of spread of multidrug resistant strains. we report an outbreak of enteric fever caused by salmonella enterica serotype typhi in a suburban area, in city chandigarh of north india. twenty-seven strains of s. typhi were isolated from blood cultures over a period of two weeks with 18 of these 27 patients residing in the same area. maximum cases were in the age group 5-14 ye ...201323339924
wksl3, a new biocontrol agent for salmonella enterica serovars enteritidis and typhimurium in foods: characterization, application, sequence analysis, and oral acute toxicity study.of the salmonella enterica serovars, s. enteritidis and s. typhimurium are responsible for most of the salmonella outbreaks implicated in the consumption of contaminated foods in the republic of korea. because of the widespread occurrence of antimicrobial-resistant salmonella in foods and food processing environments, bacteriophages have recently surfaced as an alternative biocontrol tool. in this study, we isolated a virulent bacteriophage (wksl3) that could specifically infect s. enteritidis, ...201323335772
inactivation of pathogens in feces by desiccation and urea treatment for application in urine-diverting dry toilets.ecological sanitation technologies can be effective in providing health and environmental pollution control if they can efficiently reduce the pathogenicity of microorganisms carried in fecal material to safe levels. this study evaluated the sanitizing effects of different additives for dry treatment of feces from urine-diverting dry toilets, based on inactivation of enterococcus faecalis, salmonella enterica serovar typhimurium, bacteriophages ms2 and φx, and ascaris suum. the additives, ash (a ...201323335764
a t-bet gradient controls the fate and function of ccr6-rorγt+ innate lymphoid cells.at mucosal surfaces, the immune system should not initiate inflammatory immune responses to the plethora of antigens constantly present in the environment, but should remain poised to unleash a potent assault on intestinal pathogens. the transcriptional programs and regulatory factors required for immune cells to switch from homeostatic (often tissue-protective) function to potent antimicrobial immunity are poorly defined. mucosal retinoic-acid-receptor-related orphan receptor-γt-positive (rorγt ...201323334414
long-term survival of escherichia coli o157:h7 and salmonella enterica on butterhead lettuce seeds, and their subsequent survival and growth on the seedlings.the long-term survival of enteric pathogens on butterhead lettuce seeds, and their subsequent survival and growth on seedlings were investigated. lettuce seeds were inoculated at a high level with two salmonella enterica and two escherichia coli o157:h7 strains each (±8 log₁₀ cfu/g seed) and the survival of the pathogens was monitored over two years using standard plating techniques on selective medium. the salmonella strains (serovars typhimurium and thompson) survived significantly better on t ...201323334101
survival of food-borne pathogens on natural black table olives after post-processing contamination.the aim of this study was to evaluate the survival of salmonella, escherichia coli o157:h7, listeria monocytogenes, and staphylococcus aureus on natural black olives during aerobic storage without brine and to conclude about the safety of this fermented food. fermented black olives (ph 3.95; nacl 6.02%) were artificially inoculated with 4 strains of salmonella enterica ser. enteritidis, 4 strains of s. enterica ser. typhimurium, 3 strains of e. coli o157:h7, 3 strains of l. monocytogenes, and 3 ...201323334099
active modification of host inflammation by salmonella.the dampening of host immune responses is a critical aspect of pathogenesis for the enteropathogen salmonella enterica. our laboratory has recently described a role for the secreted effector gogb in disruption of nfκb activation and limitation of the host inflammatory response to infection. gogb alters the nfκb pathway by preventing iκb degradation by the host scf e3 ubiquitin ligase, through an interaction with skp1 and fbxo22. the prevention of nfκb activation through this interaction dampens ...201323333857
the plasmidome of a salmonella enterica serovar derby isolated from pork meat.the complete nucleotide sequences of four plasmids hosted by a salmonella enterica serovar. derby strain 6mk1 isolated from pork were determined by shotgun sanger sequencing. a 107,637 base pairs (bp) conjugative plasmid psd107 containing 150 putative coding sequences (cds) could be assigned to the narrow host range incompatibility group inci1. a detailed annotation of all cds was carried out, revealing the presence of genes needed for plasmid replication, conjugal transfer, plasmid partitioning ...201323333216
current antibiogram and clonal relatedness among drug-resistant salmonella enterica serovar typhi in northern india.in view of the changing sensitivity pattern of salmonella, this study was carried out to investigate the current antibiogram and clonal relatedness among the drug-resistant salmonella enterica serovar typhi in northern india.201323330551
genetic types, gene repertoire, and evolution of isolates of the salmonella enterica serovar 4,5,12:i:- spanish clone assigned to different phage types.salmonella enterica subsp. enterica 4,[5],12:i:- is one of the most prevalent serovars associated with human infections worldwide. two multidrug-resistant clones, designated spanish and european clones, are recognized as having importance for public health and are subject to control measures in the european union. in this study, 23 clinical isolates belonging to the spanish clone were characterized by multilocus sequence typing, multiple-locus variable number tandem repeat analysis (mlva), pcr a ...201323325816
characterization of salmonella food isolates with concurrent resistance to ceftriaxone and ciprofloxacin.foodborne salmonellosis is an important public health problem worldwide. most human salmonella infections occur through the consumption of contaminated food of animal origin. the study reported the first isolation of two salmonella enterica serovar oranienburg strains from pork in china with concurrent resistance to ciprofloxacin and ceftriaxone. both isolates also showed resistance to norfloxacin, trimethoprim-sulfamethoxazole, and chloramphenicol, and an elevated minimal inhibitory concentrato ...201323320422
development of ceftriaxone resistance affects the virulence properties of salmonella enterica serotype typhimurium strains.development of antibiotic resistance may alter the virulence properties of bacterial organisms. in this study, nine clinical ceftriaxone-susceptible salmonella enterica serotype typhimurium strains were subjected to stepwise selection with increasing concentrations of ceftriaxone in culture media. mutations in virulence-associated genes and antibiotic efflux genes were analyzed by polymerase chain reaction (pcr) and dna sequencing. the expression levels of virulence genes inva and stn as well as ...201323320420
ingress of salmonella enterica typhimurium into tomato leaves through hydathodes.internal contamination of salmonella in plants is attracting increasing attention for food safety reasons. in this study, three different tomato cultivars "florida lanai", "crown jewel", "ailsa craig" and the transgenic line sp5 of "ailsa craig" were inoculated with 1 µl gfp-labeled salmonella typhimurium through guttation droplets at concentrations of 10(9) or 10(7) cfu/ml. survival of salmonella on/in tomato leaves was detected by both direct plating and enrichment methods. salmonella cells su ...201323320087
salmonella polarises peptide-mhc-ii presentation towards an unconventional type b cd4+ t-cell response.distinct peptide-mhc-ii complexes, recognised by type a and b cd4(+) t-cell subsets, are generated when antigen is loaded in different intracellular compartments. conventional type a t cells recognize their peptide epitope regardless of the route of processing, whereas unconventional type b t cells only recognise exogenously supplied peptide. type b t cells are implicated in autoimmune conditions and may break tolerance by escaping negative selection. here we show that salmonella differentially ...201323319341
intratumoral injection of attenuated salmonella vaccine can induce tumor microenvironmental shift from immune suppressive to immunogenic.attenuated salmonella vaccines show therapeutic anti-cancer effects, but the underlying mechanism has not been well investigated. in the current study, intratumoral (i.t.) injection of recombinant attenuated salmonella enterica serovar typhimurium vaccine (rasv) significantly inhibited her-2/neu-expressing tumor growth. although depletion of cd8(+) cells in rasv-treated mice significantly restored tumor growth, the induction of her-2/neu-specific cytotoxic t lymphocytes (ctls) was not well corre ...201323318147
inhibitory effect of cinnamon powder on pathogen growth in laboratory media and oriental-style rice cakes (sulgidduk).there has been an increasing interest in the use of natural plant materials as alternative food preservatives. we examined the antimicrobial effects of natural plant materials used as additives against foodborne pathogens in laboratory media and sulgidduk, oriental-style rice cakes. cinnamon, mugwort, and garlic powder solutions (3%) were tested for their antimicrobial activities against pathogens in laboratory media. sulgidduk prepared with different amounts of cinnamon powder (1, 3, and 6%) wa ...201323317869
initial contamination of chicken parts with salmonella at retail and cross-contamination of cooked chicken with salmonella from raw chicken during meal preparation.the current study was undertaken to acquire data on contamination of chicken parts with salmonella at retail and to acquire data on cross-contamination of cooked chicken with salmonella from raw chicken during meal preparation. whole raw chickens (n = 31) were obtained from local retail stores and cut into two wings, two breasts without skin or bones, two thighs, and two drumsticks. data for cross-contamination were obtained by cutting up a sterile, cooked chicken breast with the same board and ...201323317854
thermal inactivation of salmonella enteritidis pt 30 in almond kernels as influenced by water activity.salmonellosis outbreaks related to consumption of raw almonds have encouraged the scientific community to study the inactivation kinetics of pathogens in this dry commodity. however, the low moisture content of the product presents a challenge for thermal control, because the time required to achieve the desired thermal inactivation of microorganisms increases sharply with reduced moisture content and water activity. in this study, we explored and modeled the heat inactivation of salmonella ente ...201323317853
antimicrobial resistance of salmonella enterica isolates from bulk tank milk and milk filters in the united states.salmonella isolates were recovered from bulk tank milk as part of the national animal health monitoring system (nahms) dairy 2002 and 2007 surveys. in-line milk filters were also tested in the 2007 survey. the objective of this study was to determine the prevalence of antimicrobial resistance among salmonella enterica isolates from bulk milk and milk filters in the nahms dairy 2002 and 2007 surveys and to further characterize resistant isolates. susceptibilities to 15 antibiotics were determined ...201323317852
bactericidal activities of health-promoting, food-derived powders against the foodborne pathogens escherichia coli, listeria monocytogenes, salmonella enterica, and staphylococcus aureus.we evaluated the relative bactericidal activities (ba(50) ) of 10 presumed health-promoting food-based powders (nutraceuticals) and, for comparison, selected known components against the following foodborne pathogens: escherichia coli o157:h7, salmonella enterica, listeria monocytogenes, and staphylococcus aureus. the relative activities were evaluated using quantitative bactericidal activity [(ba(50) value, defined as the percentage of the sample in the assay mixture that resulted in a 50% decr ...201323317422
a genomewide mutagenesis screen identifies multiple genes contributing to vi capsular expression in salmonella enterica serovar typhi.a transposon-based, genomewide mutagenesis screen exploiting the killing activity of a lytic viii bacteriophage was used to identify salmonella enterica serovar typhi genes that contribute to vi polysaccharide capsule expression. genes enriched in the screen included those within the viab locus (tviabcde and vexabcde) as well as oxyr, bara/sira, and yrff, which have not previously been associated with vi expression. the role of these genes in vi expression was confirmed by constructing defined n ...201323316043
characterization of an acid-inducible sulfatase in salmonella enterica serovar typhimurium.sulfatases of enteric bacteria can provide access to heavily sulfated mucosal glycans. in this study, we show that asla (stm0084) of salmonella enterica serovar typhimurium lt2 encodes a sulfatase that requires mildly acidic ph for its expression and activity. asla is not regulated by sulfur compounds or tyramine but requires the envz-ompr and phopq regulatory systems, which play an important role in pathogenesis.201323315743
reactive arthritis following salmonella infection: a population-based study.to study the incidence and clinical picture of salmonella-associated reactive arthritis (rea), as well as other reactive musculoskeletal symptoms and the arthritogenicity of various salmonella enterica ssp. enterica serotypes in the population.201323311895
lack of effect of the salmonella deubiquitinase ssel on the nf-κb pathway.intracellular replication of salmonella enterica requires effector proteins translocated across the salmonella-containing vacuolar membrane by salmonella pathogenicity island-2 (spi-2) encoded type iii secretion system (t3ss). the spi-2 t3ss effector ssel is a deubiquitinase that contributes to virulence in mice. previous work has produced conflicting evidence as to the involvement of ssel in interference with the nf-κb pathway. to attempt to clarify these discrepancies, we compared mrna levels ...201323308136
role of the salmonella enterica serovar typhi fur regulator and small rnas rfra and rfrb in iron homeostasis and interaction with host cells.iron is an essential element but can be toxic at high concentrations. therefore, its acquisition and storage require tight control. salmonella encodes the global regulator fur (ferric uptake regulator) and the small regulatory non-coding rnas (srnas) rfra and rfrb, homologues of ryhb. the role of these iron homeostasis regulators was investigated in salmonella enterica serovar typhi (s. typhi). strains containing either single or combined deletions of these regulators were obtained. the mutants ...201323306672
antioxidant and antimicrobial properties of monofloral bee pollen.the main aim of this study was to determine antioxidant properties and antibacterial activity of monofloral bee pollen samples to pathogenic bacteria. these samples were collected in different localities in slovakia. the antioxidant properties of examined plant species were different and decreasing in the following order: brassica napus subsp. napus l > papaver somniferum l. > helianthus annuus l. the antimicrobial effect of the bee product samples were tested by using the agar well diffusion me ...201323305281
hunanamycin a, an antibiotic from a marine-derived bacillus hunanensis.hunanamycin a, the first natural product with a pyrido[1,2,3-de]quinoxaline-2,3-dione core, was isolated from a marine-derived bacillus hunanensis. hunanamycin a is related to a degradation product of riboflavin but has undergone an n-prenylation and subsequent cyclization. the structure, including stereochemistry, was determined by nmr and ms methods. hunanamycin a exhibits a minimum inhibitory concentration (mic) of 12.4 μm against the bacterial pathogen salmonella enterica.201323305153
immune profiling with a salmonella typhi antigen microarray identifies new diagnostic biomarkers of human typhoid.current serological diagnostic assays for typhoid fever are based on detecting antibodies against salmonella lps or flagellum, resulting in a high false-positive rate. here we used a protein microarray containing 2,724 salmonella enterica serovar typhi antigens (>63% of proteome) and identified antibodies against 16 igg antigens and 77 igm antigens that were differentially reactive among acute typhoid patients and healthy controls. the igg target antigens produced a sensitivity of 97% and specif ...201323304434
virulence and stress-related periplasmic protein (visp) in bacterial/host associations.gram-negative bacteria have an outer membrane containing lps. lps is constituted of an oligosaccharide portion and a lipid-a moiety that embeds this molecule within the outer membrane. lps is a pathogen-associated molecular pattern, and several pathogens modify their lipid-a as a stealth strategy to avoid recognition by the innate immune system and gain resistance to host factors that disrupt the bacterial cell envelope. an essential feature of salmonella enterica typhimurium pathogenesis is its ...201323302685
escherichia coli o157:h7 induces stronger plant immunity than salmonella enterica typhimurium sl1344.consumption of fresh produce contaminated with bacterial human pathogens has resulted in various, sometimes deadly, disease outbreaks. in this study, we assessed plant defense responses induced by the fully pathogenic bacteria escherichia coli o157:h7 and salmonella enterica serovar typhimurium sl1344 in both arabidopsis thaliana and lettuce (lactuca sativa). unlike sl1344, o157:h7 induced strong plant immunity at both pre-invasion and post-invasion steps of infection. for instance, o157:h7 trig ...201323301812
evaluation antibacterial activity of quaternary-based chitin/chitosan derivatives in vitro.total of 3 water-soluble quaternary-based chitin/chitosan derivatives, which have an identical molecular weight and anion, were synthesized and characterized. their antibacterial activities against salmonella cholerae-suis and bacillus subtilis were evaluated in vitro. the polysaccharides exhibited the antibacterial efficiency. their minimum inhibitory concentration (mic) values vary from 0.02 to 20.48 mg/ml, and their minimum bactericidal concentration (mbc) values vary from 0.08 to 40.96 mg/ml ...201323301607
isolation of salmonella mutants resistant to the inhibitory effect of salicylidene acylhydrazides on flagella-mediated motility.salicylidene acylhydrazides identified as inhibitors of virulence-mediating type iii secretion systems (t3sss) potentially target their inner membrane export apparatus. they also lead to inhibition of flagellar t3ss-mediated swimming motility in salmonella enterica serovar. typhimurium. we show that inp0404 and inp0405 act by reducing the number of flagella/cell. these molecules still inhibit motility of a salmonella δflih-flii-flij/flhb((p28t)) strain, which lacks three soluble components of th ...201323300965
an allele of an ancestral transcription factor dependent on a horizontally acquired gene product.changes in gene regulatory circuits often give rise to phenotypic differences among closely related organisms. in bacteria, these changes can result from alterations in the ancestral genome and/or be brought about by genes acquired by horizontal transfer. here, we identify an allele of the ancestral transcription factor pmra that requires the horizontally acquired pmrd gene product to promote gene expression. we determined that a single amino acid difference between the pmra proteins from the hu ...201223300460
colonization of internal organs by salmonella enteritidis in experimentally infected laying hens housed in conventional or enriched cages.more human illnesses caused by salmonella enterica subspecies enterica serovar enteritidis throughout the world have been linked to the consumption of contaminated eggs than to any other food vehicle. deposition of this pathogen in the edible contents of eggs occurs when systemic infections of laying hens involve colonization of reproductive organs. in recent years, the consequences of different housing systems for laying flocks have become the focus of international attention from both animal w ...201323300315
[genetic determinants of secreted lysozyme inhibitors and enterobacteria anti-lysozyme phenotype].determination of interconnection of genetic determinants of secreted lysozyme inhibitors with enterobacteria anti-lysozyme phenotype.201323297624
an essential serotype recognition pocket on phage p22 tailspike protein forces salmonella enterica serovar paratyphi a o-antigen fragments to bind as nonsolution conformers.bacteriophage p22 recognizes o-antigen polysaccharides of salmonella enterica subsp. enterica (s.) with its tailspike protein (tsp). in the serovars s. typhimurium, s. enteritidis, and s. paratyphi a, the tetrasaccharide repeat units of the respective o-antigens consist of an identical main chain trisaccharide but different 3,6-dideoxyhexose substituents. here, the epimers abequose, tyvelose and paratose determine the specific serotype. p22 tsp recognizes o-antigen octasaccharides in an extended ...201323292517
occurrence of β-lactamase genes among non-typhi salmonella enterica isolated from humans, food animals, and retail meats in the united states and canada.non-typhi salmonella cause over 1.7 million cases of gastroenteritis in north america each year, and food-animal products are commonly implicated in human infections. for invasive infections, antimicrobial therapy is indicated. in north america, the antimicrobial susceptibility of salmonella is monitored by the u.s. national antimicrobial resistance monitoring system (narms) and the canadian integrated program for antimicrobial resistance surveillance (cipars). in this study, we determined the s ...201323289438
molecular characterization of the inve regulator in the secretion of type iii secretion translocases in salmonella enterica serovar typhimurium.the type iii secretion systems (t3sss) are exploited by many gram-negative pathogenic bacteria to deliver a set of effector proteins into the host cytosol during cell entry. the t3ss of salmonella enterica serovar typhimurium is composed of more than 20 proteins that constitute the membrane-associated base, the needle and the tip complex at the distal end of the t3ss needle. membrane docking and piercing between the t3ss and host cells is followed by the secretion of effector proteins. therefore ...201323288540
pitfalls of interpreting ciprofloxacin minimum inhibitory concentrations in salmonella enterica serovar typhi. 201223287141
early diagnosis of typhoid fever by nested pcr for flagellin gene of salmonella enterica serotype typhi.typhoid fever caused by salmonella typhi continues to be a major health problem in spite of the use of antibiotics and the development of newer antibacterial drugs. inability to make an early laboratory diagnosis and resort to empirical therapy, often lead to increased morbidity and mortality in cases of typhoid fever. this study was aimed to optimize a nested pcr for early diagnosis of typhoid fever and using it as a diagnostic tool in culture negative cases of suspected typhoid fever.201223287134
evaluation of salmonella enterica serovar typhimurium ttss-2 deficient fur mutant as safe live-attenuated vaccine candidate for immunocompromised mice.salmonella enterica serovar typhimurium has been extensively exploited as live attenuated vaccines (lav) which generally confers better protection than killed or subunit vaccines. however, many lav are limited by their inherent ability to access systemic organs in many of the vaccinated hosts, especially those which are immunocompromised. we evaluated the efficacy of a live-attenuated spi2-deficient (δssav) s. typhimurium vaccine candidate (mt13) that additionally devoids the ferric uptake regul ...201223284865
salmonella typhimurium's transthyretin-like protein is a host-specific factor important in fecal survival in chickens.the transthyretin-like protein (tlp) from salmonella enterica subspecies i is a periplasmic protein with high level structural similarity to a protein found in mammals and fish. in humans, the protein homologue, transthyretin, binds and carries retinol and thyroxine, and a series of other, unrelated aromatic compounds. here we show that the amino acid sequence of the tlp from different species, subspecies and serovars of the salmonella genus is highly conserved and demonstrate that the tlp gene ...201223284609
human isolates of salmonella enterica serovar typhimurium from taiwan displayed significantly higher levels of antimicrobial resistance than those from denmark.salmonella enterica serovar typhimurium is a major zoonotic pathogen with a high prevalence of antimicrobial resistance. this pathogen can disseminate across borders and spread far distances via the food trade and international travel. in this study, we compared the genotypes and antimicrobial resistance of 378 s. typhimurium isolates collected in taiwan and denmark between 2009 and 2010. genotyping revealed that many s. typhimurium strains were concurrently circulating in taiwan, denmark and ot ...201323279815
characterization of citrobacter sp. line 328 as a source of vi for a vi-crm(197) glycoconjugate vaccine against salmonella typhi.salmonella enterica serovar typhi is the causative agent of typhoid fever with over 22 million cases and over 200,000 deaths reported annually. a vaccine is much needed for use in young children and the novartis vaccines institute for global health (nvgh) is developing a conjugate vaccine which targets s. typhi vi capsular polysaccharide.201223277501
[role of pathogen surveillance and subtyping in outbreak recognition of food-borne bacterial infections. microbiological perspective - aims, methods and prospects of pathogen subtyping].the recognition of infection clusters via determination of clonal relationships between pathogen isolates represents the major aim of pathogen subtyping during outbreaks. in addition, a continuing and comprehensive subtyping of pathogen isolates is a prerequisite for early recognition of changes within pathogen populations, especially of new pathogen types and variants. here, in an exemplary manner, we outline the current practice in germany for three important agents of food-borne infections, s ...201323275955
mobile effector proteins on phage genomes.bacteriophage genomes found in a range of bacterial pathogens encode a diverse array of virulence factors ranging from superantigens or pore forming lysins to numerous exotoxins. recent studies have uncovered an entirely new class of bacterial virulence factors, called effector proteins or effector toxins, which are encoded within phage genomes that reside among several pathovars of escherichia coli and salmonella enterica. these effector proteins have multiple domains resulting in proteins that ...201223275865
molecular serotyping of salmonella enterica by complete rpob gene sequencing.serotyping has been the gold standard for identifying salmonella, but it requires large amounts of standard antisera. multilocus sequence typing (mlst) has been applied to identify salmonella serovars, but the recombination of 4-7 housekeeping genes and multiple analytic steps diminish its applicability. in the present study, we determined the complete sequences of the rna polymerase beta subunit gene (rpob) and 7 housekeeping genes (aroc, dnan, hemd, hisd, pure, suca, and thra) for 76 strains o ...201223274983
exploring the immune response of porcine mesenteric lymph nodes to salmonella enterica serovar typhimurium: an analysis of transcriptional changes, morphological alterations and pathogen burden.infections caused by salmonella enterica serovar typhimurium (s. typhimurium) cause important economic problems in the swine industry and threaten the integrity of a safe and healthy food supply. controlling the prevalence of salmonella in pig production requires a thorough knowledge of the response processes that occurs in the gut associated immune tissues. to explore the in vivo porcine response to s. typhimurium, mln samples from four control pigs and twelve infected animals at 1, 2 and 6 day ...201323274115
β-lactamases, transferable quinolone resistance determinants, and class 1 integron-mediated antimicrobial resistance in human clinical salmonella enterica isolates of non-typhimurium serotypes.this work investigates the occurrence and features of class 1 integrons and the presence of transferable quinolone resistance determinants (tqrd) among 382 clinical salmonella enterica isolates of non-typhimurium serotypes as well as the β-lactamases produced by amoxicillin-resistant isolates. these isolates were recovered in 2001 and from 2004 to 2009 from patients from the health region of terres de l'ebre (catalonia, spain) and comprised 41 different serotypes, mostly of serovar enteritidis ( ...201323273534
a weibull model to describe antimicrobial kinetics of oregano and lemongrass essential oils against salmonella enteritidis in ground beef during refrigerated storage.the antimicrobial effect of oregano (origanum vulgare l.) and lemongrass (cymbopogon citratus (dc.) stapf.) essential oils (eos) against salmonella enterica serotype enteritidis in in vitro experiments, and inoculated in ground bovine meat during refrigerated storage (4±2 °c) for 6 days was evaluated. the weibull model was tested to fit survival/inactivation bacterial curves (estimating of p and δ parameters). the minimum inhibitory concentration (mic) value for both eos on s. enteritidis was 3. ...201323273476
systemic exposure, tissue distribution, and disease evolution of a high solubility ciprofloxacin-aluminum complex in a murine model of septicemia induced by salmonella enterica serotype enteritidis.a new pharmaceutical derivative obtained by stoichiometric complexation of ciprofloxacin (cip) with aluminum (cip-complex) has been investigated and reported in this study. such product has high solubility in the gastrointestinal ph range and was successful in the development of optimized formulations while maintaining its antimicrobial potency. the systemic exposure, tissue distribution, and the disease evolution after given cip-complex were assessed. the systemic exposure and distribution in i ...201323273286
optimized microbial dna extraction from diarrheic stools.the detection of enteropathogens in stool specimens increasingly relies on the detection of specific nucleic acid sequences. we observed that such detection was hampered in diarrheic stool specimens and we set-up an improved protocol combining lyophilization of stools prior to a semi-automated dna extraction.201223273000
azithromycin and ciprofloxacin resistance in salmonella bloodstream infections in cambodian adults.salmonella enterica is a frequent cause of bloodstream infection (bsi) in asia but few data are available from cambodia. we describe salmonella bsi isolates recovered from patients presenting at sihanouk hospital centre of hope, phnom penh, cambodia (july 2007-december 2010).201223272255
antimicrobial susceptibility and multi-drug resistance of salmonella enterica subspecies enterica serovars in sudan.this study was undertaken to determine the antimicrobial resistance patterns of salmonella enterica subspecies enterica recovered from human, food, water, and animal samples collected in khartoum state, sudan. a total of 64 salmonella isolates belonging to 28 different serovars were tested for their susceptibility to 13 antimicrobial agents. the majority of isolates (98.4 %) were resistant to at least one antimicrobial agent. isolates were frequently resistant to ampicillin (90.6 %), cephalexin ...201323271416
sesbania grandiflora leaf extract mediated green synthesis of antibacterial silver nanoparticles against selected human pathogens.simple, effective and rapid approach for the green synthesis of silver nanoparticles (agnps) using leaf extract of sesbania grandiflora and their in vitro antibacterial activity against selected human pathogens has been demonstrated in the study. various instrumental techniques were adopted to characterize the synthesized agnps viz. uv-vis, ftir, xrd, tem, edx and afm. surface plasmon spectra for agnps are centered at 422 nm with dark brown color. the synthesized agnps were found to be spherical ...201223270884
microbiological study of biofilm formation in isolates of salmonella enterica typhimurium dt104 and dt104b cultured from the modern pork chain.the purpose of this study was to characterise 172 salmonella typhimurium isolates taken from the pork chain for their biofilm forming abilities and to analyse their potential to survive on food processing surfaces. many salmonella have the ability to form biofilms. these natural structures, elaborated by bacteria are important in food production because their formation contributes to bacterial survival. adherent bacterial cells are more resilient to displacement strategies including physical and ...201323266499
salmonella infection in a remote, isolated wild pig population.although wild pig populations are known to sometimes be infected by salmonella, the situation in australia has received little attention and few population-based, planned studies have been conducted. understanding the distribution of salmonella infections within wild pig populations allows the potential hazard posed to co-grazing livestock to be assessed. we sampled a remote and isolated wild pig population in northwestern australia. faecal and mesenteric lymph node samples were collected from 6 ...201323266110
critical role of type i interferon-induced macrophage necroptosis during infection with salmonella enterica serovar typhimurium. 201323262973
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