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enhancement of reactive oxygen species production and chlamydial infection by the mitochondrial nod-like family member nlrx1.chlamydia trachomatis infections cause severe and irreversible damage that can lead to infertility and blindness in both males and females. following infection of epithelial cells, chlamydia induces production of reactive oxygen species (ros). unconventionally, chlamydiae use ros to their advantage by activating caspase-1, which contributes to chlamydial growth. nlrx1, a member of the nod-like receptor family that translocates to the mitochondria, can augment ros production from the mitochondria ...201020959452
surveillance of shigellosis by real-time pcr suggests underestimation of shigellosis prevalence by culture-based methods in a population of rural china.shigellosis is a leading public health issue in china, especially in children under 5 years of age. the disease burden of shigellosis is usually underestimated by conventional culture. in this study, real-time pcr was applied to detect shigella infection in parallel with routine culture, to investigate the true burden of disease caused by shigella spp.201020951728
expression of bacterial virulence factors and cytokines during in vitro macrophage infection by enteroinvasive escherichia coli and shigella flexneri: a comparative study.enteroinvasive escherichia coli (eiec) and shigella spp cause bacillary dysentery in humans by invading and multiplying within epithelial cells of the colonic mucosa. although eiec and shigella share many genetic and biochemical similarities, the illness caused by shigella is more severe. thus, genomic and structure-function molecular studies on the biological interactions of these invasive enterobacteria with eukaryotic cells have focused on shigella rather than eiec. here we comparatively stud ...201020944993
combination of two separate binding domains defines stoichiometry between type iii secretion system chaperone ipgc and translocator protein ipab.type iii secretion systems (ttsss) utilized by enteropathogenic bacteria require the presence of small, acidic virulence-associated chaperones for effective host cell infection. we adopted a combination of biochemical and cellular techniques to define the chaperone binding domains (cbds) in the translocators ipab and ipac associated with the chaperone ipgc from shigella flexneri. we identified a novel cbd in ipab and furthermore precisely mapped the boundaries of the cbds in both translocator pr ...201020937829
domains of the shigella flexneri type iii secretion system ipab protein involved in secretion regulation.type iii secretion systems (t3sss) are key determinants of virulence in many gram-negative bacterial pathogens. upon cell contact, they inject effector proteins directly into eukaryotic cells through a needle protruding from the bacterial surface. host cell sensing occurs through a distal needle "tip complex," but how this occurs is not understood. the tip complex of quiescent needles is composed of ipad, which is topped by ipab. physical contact with host cells initiates secretion and leads to ...201020937761
viable but nonculturable state of foodborne pathogens in grapefruit juice: a study of laboratory.several foodborne human pathogens, when exposed to harsh conditions, enter viable but nonculturable (vbnc) state; however, still open is the question whether vbnc pathogens could be a risk for public health, because, potentially, they can resuscitate. moreover, cultural methods for food safety control were not able to detect vbnc forms of foodborne bacteria. particularly, it has not been established whether food chemophysical characteristics can induce vbnc state in contaminating pathogen bacter ...201020932087
defensins play a crucial role in protecting mice against oral shigella flexneri infection.an earlier study revealed that 4-day-old mice, but not older mice, were infected with invasive shigella strains. here we attempted to determine the underlying mechanism that induces inflammation in the intestines of neonate mice after oral shigella infection. wild-type balb/c mice of different ages (7, 14, and 35 days old) were orally administered gfp-expressing shigella flexneri 5a m90t strain (5 x 10⁹ cfu) and analyzed for colonization 6h following infection. we found that shigella localized i ...201020888321
dysbiosis of fecal microbiota in crohn's disease patients as revealed by a custom phylogenetic microarray.a custom phylogenetic microarray composed of small subunit ribosomal rna probes, representing ≈500 bacterial species from the human and animal gut, was developed and evaluated for analysis of gut microbial diversity using fecal samples from healthy subjects and crohn's disease (cd) patients.201020848492
formulation and immunogenicity of a potential multivalent type iii secretion system-based protein vaccine.the virulence of many pathogenic gram-negative bacteria is dependent upon their type iii secretion (tts) systems. here, we discuss initial formulation studies of five tts needle tip proteins ipad (shigella flexneri), bipd (burkholderia pseudomallei), sipd (salmonella spp.), lcrv (yersinia spp.), and pcrv (pseudomonas aeruginosa) as targets for subunit vaccines. excipient screening and subsequent assays lead to the selection of 10% sucrose and 5% dextrose as an optimal stabilizer combination for ...201020845449
formulation and immunogenicity studies of type iii secretion system needle antigens as vaccine candidates.bacterial infections caused by shigella flexneri, salmonella typhimurium, and burkholderia pseudomallei are currently difficult to prevent due to the lack of a licensed vaccine. here we present formulation and immunogenicity studies for the three type iii secretion system (ttss) needle proteins mxih(δ5), prgi(δ5), and bsal(δ5) (each truncated by five residues at its c terminus) as potential candidates for vaccine development. these antigens are found to be thermally stabilized by the presence of ...201020845448
the effects of x-ray radiation on escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri inoculated on whole roma tomatoes.in the last two decades several foodborne disease outbreaks associated with produce were reported. tomatoes, in particular, have been associated with several multi-state salmonella outbreaks. inactivation of inoculated escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri on whole roma tomato surfaces by x-ray at 0.1, 0.5, 0.75, 1.0, and 1.5 kgy was studied. the main purpose of this study was to achieve a 5 log reduction in consistent with the recommendation ...201020832685
a disulfide driven domain swap switches off the activity of shigella ipah9.8 e3 ligase.we show that the monomeric form of shigella ipah9.8 e3 ligase catalyses the ubiquitination of human u2af35 in vitro, providing a molecular mechanism for the observed in vivo effect. we further discover that under non-reducing conditions ipah9.8 undergoes a domain swap driven by the formation of a disulfide bridge involving the catalytic cysteine and that this dimer is unable to catalyse the ubiquitination of u2af35. the crystal structure of the domain-swapped dimer is presented. the redox inacti ...201020831869
molecular mechanisms of necroptosis: an ordered cellular explosion.for a long time, apoptosis was considered the sole form of programmed cell death during development, homeostasis and disease, whereas necrosis was regarded as an unregulated and uncontrollable process. evidence now reveals that necrosis can also occur in a regulated manner. the initiation of programmed necrosis, 'necroptosis', by death receptors (such as tumour necrosis factor receptor 1) requires the kinase activity of receptor-interacting protein 1 (rip1; also known as ripk1) and rip3 (also kn ...201020823910
a disposable immunosensor for shigella flexneri based on multiwalled carbon nanotube/sodium alginate composite electrode.a novel shigella flexneri immunosensor based on horseradish peroxidase-labeled antibodies to s. flexneri (hrp-anti-s. flexneri) immobilized by physical adsorption on the multiwalled carbon nanotube (mwcnt)/sodium alginate (sa) composite modified screen-printed electrode surface was successfully fabricated. in this strategy, mwcnt/sa biocomposite acted as the matrix to adsorb and immobilize hrp-anti-s. flexneri. the modified electrodes were characterized with an atomic force microscope and cyclic ...201120816661
an outbreak of shigellosis due to shigella flexneri serotype 3a in a prison in iran.on june 16 and 17, 2007, the medical clinic of a prison in isfahan, iran received multiple reports of gastrointestinal illness among prisoners. a cross-sectional study was therefore undertaken to determine the extent, causative agent and possible source of the outbreak.201020804308
[the evolution of the etiological structure of shigellosis]. 201020734730
pad4 is essential for antibacterial innate immunity mediated by neutrophil extracellular traps.neutrophils trap and kill bacteria by forming highly decondensed chromatin structures, termed neutrophil extracellular traps (nets). we previously reported that histone hypercitrullination catalyzed by peptidylarginine deiminase 4 (pad4) correlates with chromatin decondensation during net formation. however, the role of pad4 in net-mediated bacterial trapping and killing has not been tested. here, we use pad4 knockout mice to show that pad4 is essential for net-mediated antibacterial function. u ...201020733033
medicinal potions used against infectious bowel diseases in mayan traditional medicine.since one of the main health problems of the indigenous population are infectious bowel diseases, we decided to test mayan medicinal potions used to treat these conditions against some of the causal agents.201020728517
detection of airborne bacteria in a german turkey house by cultivation-based and molecular methods.today's large-scale poultry production with densely stocked and enclosed production buildings is often accompanied by very high concentrations of airborne microorganisms leading to a clear health hazard for employees working in such environments. depending on the expected exposure to microorganisms, work has to be performed under occupational safety conditions. in this study, turkey houses bioaerosols were investigated by cultivation-based and molecular methods in parallel to determine the conce ...201020720091
csra and cra influence shigella flexneri pathogenesis.shigella flexneri is a facultative intracellular pathogen that invades and disrupts the colonic epithelium. in order to thrive in the host, s. flexneri must adapt to environmental conditions in the gut and within the eukaryotic cytosol, including variability in the available carbon sources and other nutrients. we examined the roles of the carbon consumption regulators csra and cra in a cell culture model of s. flexneri virulence. csra is an activator of glycolysis and a repressor of gluconeogene ...201020713625
pic, an autotransporter protein secreted by different pathogens in the enterobacteriaceae family, is a potent mucus secretagogue.a hallmark of enteroaggregative escherichia coli (eaec) infection is a formation of biofilm, which comprises a mucus layer with immersed bacteria in the intestines of patients. while studying the mucinolytic activity of pic in an in vivo system, rat ileal loops, we surprisingly found that eaec induced hypersecretion of mucus, which was accompanied by an increase in the number of mucus-containing goblet cells. interestingly, an isogenic pic mutant (eaec δpic) was unable to cause this mucus hypers ...201020696826
crystal structures of phd-doc, higa, and yeeu establish multiple evolutionary links between microbial growth-regulating toxin-antitoxin systems.bacterial toxin-antitoxin (ta) systems serve a variety of physiological functions including regulation of cell growth and maintenance of foreign genetic elements. sequence analyses suggest that ta families are linked by complex evolutionary relationships reflecting likely swapping of functional domains between different ta families. our crystal structures of phd-doc from bacteriophage p1, the higa antitoxin from escherichia coli cft073, and yeeu of the yeeuwv systems from e. coli k12 and shigell ...201020696400
hemolysin e (hlye, clya, shea) and related toxins.certain strains of escherichia coli, salmonella enterica and shigella flexneri produce a pore-forming toxin hemolysin e (hlye), also known as cytolysin a (clya) and silent hemolysin, locus a (shea). hlye lyses erythrocytes and mammalian cells, forming transmembrane pores with a minimum internal diameter of-25 a. we review the current knowledge of hlye structure and function in its solution and pore forms, models for membrane insertion, its potential use in biotechnology applications and its rela ...201020687485
plasmid-mediated streptomycin and sulfamethoxazole resistance in shigella flexneri 3a.shigellosis is a major cause of diarrhoea-related morbidity and mortality, especially in children in developing countries such as india. recently, it was estimated that 91 million individuals worldwide contract shigellosis each year. the emergence and dissemination of multidrug-resistant strains of shigella is now an emerging global health problem. during the past two decades, much attention was given to re-evaluation of treatment recommendations. in the present study, we investigated a clinical ...201020685089
facile glycosylation strategy with two-stage activation of allyl glycosyl donors. application to concise synthesis of shigella flexneri serotype y o-antigen.a practical, useful glycosylation method employing only allyl glycoside building blocks has been developed. the donor's glycosylation reactivity is turned on via isomerization of its anomeric allyl protecting group into the corresponding prop-1-enyl moiety. subsequent chemoselective activation with nis/tfoh achieves high yields in glycosidic bond construction at room temperature. the efficacy and efficiency of this approach in carbohydrate synthesis is demonstrated in the concise synthesis of th ...201020683518
in silico characterization of shikimate kinase of shigella flexneri: a potential drug target.shigella flexneri is a major pathogen responsible for shigellosis causing massive morbidity among young population and imposes huge socio-economic burden. in this study, shikimate kinase (sk) from s. flexneri was characterized in silico and disordered regions were predicted. motifs and domains were calculated using computational tools. a three dimensional model of shikimate kinase of s.flexneri was constructed using shikimate kinase of e.coli (pdbid: 1kag_a) as template by comparative modeling a ...201020658341
enteropathogenic escherichia coli, samonella, shigella and yersinia: cellular aspects of host-bacteria interactions in enteric diseases.abstract: a successful infection of the human intestine by enteropathogenic bacteria depends on the ability of bacteria to attach and colonize the intestinal epithelium and, in some cases, to invade the host cell, survive intracellularly and disseminate from cell to cell. to accomplish these processes bacteria have evolved an arsenal of molecules that are mostly secreted by dedicated type iii secretion systems, and that interact with the host, subverting normal cellular functions. here we overvi ...201020649986
[structure of the oligosaccharide region (core) of the lipopolysaccharides of shigella flexneri types 2a and 5b].the full structure of the lipopolysaccharide core of bacteria shigella flexneri types 2a and 5b, the causative agents of bacillary dysentery (shigellosis), was established by chemical methods, high-resolution electrospray ionization mass spectrometry, and two-dimensional nmr spectroscopy. the structure of the o-antigen repeating unit and the configuration and position of the linkage between the o-antigen and the core were determined in the lipopolysaccharide of s. flexneri type 2a.201020644600
photodynamic antimicrobial chemotherapy by liposome-encapsulated water-soluble photosensitizers.photodynamic antimicrobial chemotherapy is an alternative method for killing bacterial cells in view of the increasing problem of multi-antibiotic resistance. we examined the effect of three water-soluble photosensitizers (phs): methylene blue (mb), neutral red (nr) and rose bengal (rb) on gram-positive and gram-negative bacteria. we compared the efficacy of phs in their free form and encapsulated in liposomal formulations against various bacterial strains, and determined conditions for the effe ...201020644595
the omptins of yersinia pestis and salmonella enterica cleave the reactive center loop of plasminogen activator inhibitor 1.plasminogen activator inhibitor 1 (pai-1) is a serine protease inhibitor (serpin) and a key molecule that regulates fibrinolysis by inactivating human plasminogen activators. here we show that two important human pathogens, the plague bacterium yersinia pestis and the enteropathogen salmonella enterica serovar typhimurium, inactivate pai-1 by cleaving the r346-m347 bait peptide bond in the reactive center loop. no cleavage of pai-1 was detected with yersinia pseudotuberculosis, an oral/fecal pat ...201020639337
evidence for alternative quaternary structure in a bacterial type iii secretion system chaperone.type iii secretion systems are a common virulence mechanism in many gram-negative bacterial pathogens. these systems use a nanomachine resembling a molecular needle and syringe to provide an energized conduit for the translocation of effector proteins from the bacterial cytoplasm to the host cell cytoplasm for the benefit of the pathogen. prior to translocation specialized chaperones maintain proper effector protein conformation. the class ii chaperone, invasion plasmid gene (ipg) c, stabilizes ...201020633281
safety and immunogenicity of a shigella flexneri 2a invaplex 50 intranasal vaccine in adult volunteers.shigellosis is a leading cause of diarrhea worldwide prompting vaccine development. the shigella flexneri invaplex 50 is a macromolecular complex containing ipab, ipac, and lps, formulated from an aqueous extract of virulent shigella delivered via nasal administration. preclinical vaccine testing demonstrated safety, immunogenicity and efficacy. an open-label dose-escalating phase 1 study evaluated a 3-dose (2-week intervals) regimen via nasal pipette delivery. thirty-two subjects were enrolled ...201020619378
escape of intracellular shigella from autophagy requires binding to cholesterol through the type iii effector, icsb.type iii secretion systems are present in many pathogenic bacteria and mediate the translocation of bacterial effectors into host cells. identification of host targets of these effectors is crucial for understanding bacterial virulence. icsb, a type iii secretion effector, helps shigella to evade the host autophagy defense system by binding to the autophagy protein, atg5. here, we show that icsb is able to interact specifically with cholesterol. the cholesterol binding domain (cbd) of icsb is lo ...201020599519
newer insights into the mechanism of action of psidium guajava l. leaves in infectious diarrhoea.psidium guajava l., myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. however, the effect of the leaf extract of p. guajava on the pathogenesis of infectious diarrhoea has not been studied. the present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of p. guajava on parameters associated with pathogenicity of infectious diarrhoea. the aim was to understand its possible mecha ...201020584265
generation of chitin-derived oligosaccharides toxic to pathogenic bacteria using chia74, an endochitinase native to bacillus thuringiensis.to demonstrate that an endochitinase (chia74) native to bacillus thuringiensis can be used to generate chitin-derived oligosaccharides (ogs) with antibacterial activity against a number of aetiological agents of disease, including bacteria that cause diarrhoeal and emetic syndromes in humans.201020557451
structures of the o-antigens of escherichia coli o13, o129, and o135 related to the o-antigens of shigella flexneri.o-polysaccharides (o-antigens) were isolated from escherichia coli o13, o129, and o135 and studied by chemical analyses along with 2d (1)h and (13)c nmr spectroscopy. they were found to possess a common -->2)-l-rha-(alpha1-->2)-l-rha-(alpha1-->3)-l-rha-(alpha1-->3)-d-glcnac-(beta1--> backbone, which is a characteristic structural motif of the o-polysaccharides of shigella flexneri types 1-5. in both the bacterial species, the backbone is decorated with lateral glucose residues or/and o-acetyl gr ...201020546712
protein refolding is required for assembly of the type three secretion needle.pathogenic gram-negative bacteria use a type three secretion system (ttss) to deliver virulence factors into host cells. although the order in which proteins incorporate into the growing ttss is well described, the underlying assembly mechanisms are still unclear. here we show that the ttss needle protomer refolds spontaneously to extend the needle from the distal end. we developed a functional mutant of the needle protomer from shigella flexneri and salmonella typhimurium to study its assembly ...201020543831
immunochemical studies of shigella flexneri 2a and 6, and shigella dysenteriae type 1 o-specific polysaccharide-core fragments and their protein conjugates as vaccine candidates.there is no licensed vaccine for the prevention of shigellosis. our approach to the development of a shigella vaccines is based on inducing serum igg antibodies to the o-specific polysaccharide (o-sp) domain of their lipopolysaccharides (lps). we have shown that low molecular mass o-sp-core (o-spc) fragments isolated from shigella sonnei lps conjugated to proteins induced significantly higher antibody levels in mice than the full length o-sp conjugates. this finding is now extended to the o-spc ...201020542498
a novel anti-virulence gene revealed by proteomic analysis in shigella flexneri 2a.abstract:201020540790
crystallization and preliminary crystallographic studies of corc, a magnesium-ion transporter.corc is a magnesium transporter that is involved in the mg(2+)-efflux function of the cora transporter system, an mg(2+) channel, from shigella flexneri. native corc was purified and crystallized in the native form and in a ligand-free form and diffraction data sets were collected to 2.9 and 3.4 a resolution, respectively. the native corc crystals belonged to space group p2(1)2(1)2(1), with unit-cell parameters a = 64.31, b = 74.44, c = 132.78 a. the ligand-free corc crystals belonged to space g ...201020516599
["autophagy and microorganisms": hotspots of a mini-symposium]. 201020510155
[analysis on bacillary dysentery surveillance data collected from the national surveillance system in 2007.].to improve the national surveillance plan on bacillary dysentery and to increase the sensitivity of the surveillance system on the disease.201020510059
the 33 carboxyl-terminal residues of spa40 orchestrate the multi-step assembly process of the type iii secretion needle complex in shigella flexneri.the type iii secretion apparatus (t3sa) is a central virulence factor of many gram-negative bacteria. its overall morphology consists of a cytoplasmic region, inner- and outer-membrane sections and an extracellular needle. in shigella, the length of the needle is regulated by spa32. to understand better the role of spa32 we searched for its interacting partners using a two-hybrid screen in yeast. we found that spa32 interacts with the 33 c-terminal residues (cc*) of spa40, a member of the conser ...201020507885
[antibacterial activity of recombinant thanatin expressed by e.coli er2566].to express antibacterial peptide thanatin in the prokaryotic expression system and test its antibacterial activity.201020501392
regulation of high-affinity iron acquisition homologues in the tsetse fly symbiont sodalis glossinidius.sodalis glossinidius is a facultative intracellular bacterium that is a secondary symbiont of the tsetse fly (diptera: glossinidae). since studies with other facultative intracellular bacteria have shown that high-affinity iron acquisition genes are upregulated in vivo, we investigated the regulation of several sodalis genes that encode putative iron acquisition systems. these genes, sg1538 (hemt) and sg1516 (sita), are homologous to genes encoding periplasmic heme and iron/manganese transporter ...201020494987
the type iii effectors nlee and nleb from enteropathogenic e. coli and ospz from shigella block nuclear translocation of nf-kappab p65.many bacterial pathogens utilize a type iii secretion system to deliver multiple effector proteins into host cells. here we found that the type iii effectors, nlee from enteropathogenic e. coli (epec) and ospz from shigella, blocked translocation of the p65 subunit of the transcription factor, nf-kappab, to the host cell nucleus. nf-kappab inhibition by nlee was associated with decreased il-8 expression in epec-infected intestinal epithelial cells. ectopically expressed nlee also blocked nuclear ...201020485572
changing species distribution and antimicrobial susceptibility pattern of shigella over a 29-year period (1980-2008).we studied changes in species distribution and antimicrobial resistance patterns of shigella during 1980-2008, using the diarrhoeal diseases surveillance system of dhaka hospital of icddr,b. in hospitalized patients shigella prevalence decreased steadily from 8-12% in the 1980s to 3% in 2008. endemic s. flexneri was the most commonly isolated species (54%). epidemic s. dysenteriae type 1 had two peaks in 1984 and 1993, but was not found after 2000, except for one case in 2004. the therapeutic op ...201120478088
acid stress response in enteropathogenic gammaproteobacteria: an aptitude for survival.enteric bacteria such as escherichia coli have acquired a wide array of acid stress response systems to counteract the extreme acidity encountered when invading the host's digestive or urinary tracts. these acid stress response systems are both enzyme and chaperone based. the 3 main enzyme-based acid resistance pathways are glutamate-, arginine-, and lysine-decarboxylase pathways. they are under a complex regulatory network allowing the bacteria to fine tune its response to the external environm ...201020453931
carbon metabolism of intracellular bacterial pathogens and possible links to virulence.new technologies such as high-throughput methods and 13c-isotopologue-profiling analysis are beginning to provide us with insight into the in vivo metabolism of microorganisms, especially in the host cell compartments that are colonized by intracellular bacterial pathogens. in this review, we discuss the recent progress made in determining the major carbon sources and metabolic pathways used by model intracellular bacterial pathogens that replicate either in the cytosol or in vacuoles of infecte ...201020453875
mutagenesis and chemical cross-linking suggest that wzz dimer stability and oligomerization affect lipopolysaccharide o-antigen modal chain length control.in shigella flexneri, the polysaccharide copolymerase (pcp) protein wzz(sf) confers a modal length of 10 to 17 repeat units (rus) to the o-antigen (oag) component of lipopolysaccharide (lps). pcps form oligomeric structures believed to be related to their function. to identify functionally important regions within wzz(sf), random in-frame linker mutagenesis was used to create mutants with 5-amino-acid insertions (termed wzz(i) proteins), and dna sequencing was used to locate the insertions. anal ...201020453100
screening of antibacterial potentials of some medicinal plants from melghat forest in india.cyperus rotundus, caesalpinia bonducella, tinospora cordifolia, gardenia gummifera, ailanthus excelsa, acacia arabica, embelia ribes and ventilago maderspatana from melghat forest were screened for their antibacterial potential against escherichia coli, staphylococcus aureus, klebsiella pneumoniae, proteus vulgaris, salmonella typhi, shigella flexneri, salmonella paratyphi, salmonella typhimurium, pseudomonas aeruginosa, enterobacter aerogenes by disc diffusion method. out of these medicinal pla ...200920448847
genome-wide analysis of the h-ns and sfh regulatory networks in salmonella typhimurium identifies a plasmid-encoded transcription silencing mechanism.the conjugative inchi1 plasmid psfr27 from shigella flexneri 2a strain 2457t encodes the sfh protein, a paralogue of the global transcriptional repressor h-ns. sfh allows psfr27 to be transmitted to new bacterial hosts with minimal impact on host fitness, providing a 'stealth' function whose molecular mechanism has yet to be determined. the impact of the sfh protein on the salmonella enterica serovar typhimurium transcriptome was assessed and binding sites for sfh in the salmonella typhimurium g ...201020444106
antimicrobial resistance trends of shigella serotypes in new york city, 2006-2009.shigellosis is the third most common enteric bacterial infection in the united states. although infection is typically self-limiting, empiric treatment is often prescribed. because of increasing antimicrobial resistance to shigella, empiric treatment options are decreasing. identifying resistance patterns can inform empiric treatment recommendations. the goals of our study were to examine risk factors associated with antimicrobial resistance of shigella and examine issues related to empiric trea ...201020438349
phenotypic characterization and genomic analysis of the shigella sonnei bacteriophage sp18.a novel bacteriophage that infects shigella sonnei was isolated from the gap river in korea, and its phenotypic and genomic characteristics were investigated. the virus, called sp18, showed morphology characteristic of the family myoviridae, and phylogenetic analysis of major capsid gene (gp23) sequences classified it as a t4-like phage. based on host spectrum analysis, it is lytic to s. sonnei, but not to shigella flexneri, shigella boydii or members of the genera escherichia and salmonella. py ...201020437154
modulation of shigella virulence in response to available oxygen in vivo.bacteria coordinate expression of virulence determinants in response to localized microenvironments in their hosts. here we show that shigella flexneri, which causes dysentery, encounters varying oxygen concentrations in the gastrointestinal tract, which govern activity of its type three secretion system (t3ss). the t3ss is essential for cell invasion and virulence. in anaerobic environments (for example, the gastrointestinal tract lumen), shigella is primed for invasion and expresses extended t ...201020436458
microarray analysis of shigella flexneri-infected epithelial cells identifies host factors important for apoptosis inhibition.shigella flexneri inhibits apoptosis in infected epithelial cells. in order to understand the pro-survival effects induced by the bacteria, we utilized apoptosis-specific microarrays to analyze the changes in eukaryotic gene expression in both infected and uninfected cells in the presence and absence of staurosporine, a chemical inducer of the intrinsic pathway of apoptosis. the goal of this research was to identify host factors that contribute to apoptosis inhibition in infected cells.201020429941
production and characterisation of monoclonal antibodies specific for escherichia coli o157:h7.seven monoclonal antibodies (mabs) specific for escherichia coli o157:h7, one of the major causes of haemorrhagic colitis in humans, were produced by immunising balb/c mice with the strain e. coli o157:h7. these monoclonal antibodies do not cross-react with other bacteria such as salmonella enterica serovar typhimurium, e. coli o14, e. coli jm109, s. enterica serovar enteritidis, s. panama, s. saintpaul, s. derby, s. muenchen, s. bredeney, s. hadar, yersinia enterocolitica, proteus vulgaris, shi ...200620429059
tracking the secretion of fluorescently labeled type iii effectors from single bacteria in real time.a large number of gram negative pathogens use a specialized needle-like molecular machine known as type iii secretion (t3s) system. this highly sophisticated molecular device consists of a basal body spanning the two bacterial membranes and a protruding needle structure that is connected to a distal translocator complex. the main features of the t3s system are (i) activation after host cellular membrane contact and (ii) the ability to "inject" effectors into host cells through the needle apparat ...201020419414
production and immunogenicity of recombinant ferric enterobactin protein (fepa).ferric siderophore complexes are produced by most bacteria to acquire iron, a vital element. these complexes are transported across the outer membrane by receptor proteins commonly known as fepa (ferric enterobactin protein). in this study we attempted to evaluate the immunogenicity of the membrane protein fepa, aiming at inhibition of iron uptake to protect invasion of the host by the bacterium.201020418143
innate ifn-gamma production by subsets of natural killer cells, natural killer t cells and gammadelta t cells in response to dying bacterial-infected macrophages.interferon-gamma (ifn-gamma) activation of macrophages is a crucial step in the early innate defence against bacterial infection. this innate ifn-gamma is thought to be produced mainly by natural killer (nk) cells through activation with interleukin (il)-12p70 secreted by macrophages and dendritic cells (dcs) that have sensed bacterial products. however, a number of reports have shown that bacterial stimuli are unable to induce macrophages and/or dcs to produce sufficient amounts of il-12p70 unl ...201020415785
structure of shigella ipgb2 in complex with human rhoa: implications for the mechanism of bacterial guanine nucleotide exchange factor mimicry.a common theme in bacterial pathogenesis is the manipulation of eukaryotic cells by targeting the cytoskeleton. this is in most cases achieved either by modifying actin, or indirectly via activation of key regulators controlling actin dynamics such as rho-gtpases. a novel group of bacterial virulence factors termed the wxxxe family has emerged as guanine nucleotide exchange factors (gefs) for these gtpases. the precise mechanism of nucleotide exchange, however, has remained unclear. here we repo ...201020363740
long-term downregulation of protease-activated receptor-2 expression in distal colon in rats following bacillary dysentery.the aim of this study was to determine changes of par-2 expression in distal colon and the sensitivity of colonic muscle to sligrl-nh2, the par-2-activating peptide (par-2-ap) following bacillary dysentery. shigella flexneri was administrated intragastrically in healthy male rats to induce bacillary dysentery. the effect of sligrl-nh2 on the motility of colonic muscle strips were examined. the expression of par-2 was determined by immunohistochemistry and western blotting. intragastric administr ...201020347884
34 kda momp of shigella flexneri promotes tlr2 mediated macrophage activation with the engagement of nf-kappab and p38 map kinase signaling.the 34 kda major outer membrane protein (momp) of shigella flexneri 2a induces combinatorial expression of tlr2 and tlr6 on peritoneal macrophages of balb/c mice. between the two best-characterized tlrs, to date, tlr2 and tlr4, which are chiefly responsible for recognizing majority of bacterial products, tlr2 alone participates in recognition of 34 kda momp. in addition to tlrs, momp enhances the mrna expression of myd88 and traf6 and induces the nuclear translocation of nf-kappab as well as act ...201020347487
a soluble form of the pilus protein fima targets the vdac-hexokinase complex at mitochondria to suppress host cell apoptosis.inhibition of apoptotic response of host cells during an early phase of infection is a strategy used by many enteroinvasive bacterial pathogens to enhance their survival. here, we report the identification of a soluble form of the pilus protein fima from the culture supernatants of e. coli k1, salmonella, and shigella that can potently inhibit bax-mediated release of cytochrome c from isolated mitochondria. similar to the infected cells, hct116 cells stably expressing fima display a delay in the ...201020347420
identification of active site residues in the shigella flexneri glucosyltransferase gtrv.the serotype-specific glucosyltransferase, gtrv, is responsible for glucosylation of the o-antigen repeating unit of shigella flexneri serotype 5a strains. gtrv is an integral inner membrane protein with two essential periplasmic loops: the large loop 2 and the c-terminal loop 10. in this study, the full length of the loop 2 was shown to be necessary for gtrv function. site-directed mutagenesis within this loop revealed that conserved aromatic and charged amino acids have a critical role in the ...201020334579
an urban, water-borne outbreak of diarrhoea and shigellosis in a district town in eastern india.in september 2007, the gayeshpur municipality reported a cluster of cases with diarrhoea. we aimed to identify the causative agent and the source of the disease.200920334044
neutrophil antimicrobial proteins enhance shigella flexneri adhesion and invasion.shigella flexneri is an enteric pathogen that causes massive inflammation and destruction of the human intestinal epithelium. neutrophils are the first cells of the innate immune system recruited to the site of infection. these cells can attack microbes by phagocytosis, neutrophil extracellular trap (net) formation and degranulation. here, we investigated how neutrophil degranulation affects virulence and show that exposure of shigella to granular proteins enhances infection of epithelial cells. ...201020331641
non-mannitol-fermenting shigella flexneri, type 103. 194720266374
the effect of temperature on the survival of shigella sonnei and shigella flexneri in faeces. 194620258501
high-throughput screening of the virulence regulator virf: a novel antibacterial target for shigellosis.shigella flexneri is a human enteropathogen that infects about 165 million people and claims more than 1 million lives per year worldwide. although shigellosis has been considered a disease of the "third world," like many other contagious diseases, it does occur in developed countries. the emergence of drug and multidrug-resistant strains of shigella emphasizes the need for novel antibiotic development. virf, an arac-type transcriptional regulator, is responsible for the expression of all downst ...201020237205
shigella mediated depletion of macrophages in a murine breast cancer model is associated with tumor regression.a tumor promoting role of macrophages has been described for a transgenic murine breast cancer model. in this model tumor-associated macrophages (tams) represent a major component of the leukocytic infiltrate and are associated with tumor progression. shigella flexneri is a bacterial pathogen known to specificly induce apotosis in macrophages. to evaluate whether shigella-induced removal of macrophages may be sufficient for achieving tumor regression we have developed an attenuated strain of s. ...201020221397
[rectal prolapse in a neonate with shigella diarrhea].a case of neonatal rectal prolapse during shigella diarrhea is described. a 10 days neonate exclusively breast fed, whose 2 years old brother has had the same process 2 weeks ago. medical treatment with intravenous ceftriaxone resolved rectal prolapse in 48 hours. stool cultures showed the presence of shigella flexneri ii resistant to amoxicillin; blood and cerebrospinal fluid, cultures were negative. conclusion: rectal prolapse is an uncommon complication seen in infants with shigella diarrhea. ...201020204227
prevalence of plasmid-mediated quinolone-resistance determinants in shigella flexneri isolates from anhui province, china.quinolones are used extensively to treat shigella flexneri infection, and plasmid-mediated quinolone resistance (pmqr) determinants were recently reported. a total of 26 s. flexneri isolates collected from anhui province, china, in 2005 were screened for pmqr determinants, bla gene, gyra and parc genes, by pcr and sequencing. pmqr determinants were present in 53.8% (14 of 26) of isolates and qnra(1), qnrs(1), qnrs(2), aac(6')-ib-cr and qepa were present in 30.8, 11.5, 3.8, 19.2 and 11.5% of thos ...201020203702
the proteome of shigella flexneri 2a 2457t grown at 30 and 37 degrees c.to upgrade the proteome reference map of shigella flexneri 2a 2457t, the protein expression profiles of log phase and stationary phase cells grown at 30 and 37 degrees c were thoroughly analyzed using multiple overlapping narrow ph range (between ph 4.0 and 11.0) two-dimensional gel electrophoresis. a total of 723 spots representing 574 protein entries were identified by maldi-tof/tof ms, including the majority of known key virulence factors. 64 hypothetical proteins and six misannotated protein ...201020164057
evaluation of antimicrobial activity of the stem bark of cylicodiscus gabunensis (mimosaceae).ethyl acetate (ea) extract of the stem bark of cylicodiscus gabunensis (cg) was analysed phytochemically and evaluated for its antimicrobial activity against 17 pathogenic species isolated from patient: escherichia coli, klebsiella pneumoniae, shigella dysenteriae, shigella flexneri, morganella morganii, proteus vulgaris, proteus mirabilis, salmonella typhi, citrobacter freundii, enterobacter cloacae, enterobacter agglomerans, staphylococcus aureus, streptococcus feacalis, pseudomonas aeruginosa ...200620162076
in vitro antimicrobial activity of crude extracts from plants bryophyllum pinnatum and kalanchoe crenata.extracts from the leaves of bryophyllum pinnatum and kalanchoe crenata were screened for their antimicrobial activities. solvents used included water, methanol, and local solvents such as palmwine, local gin (seaman's schnapps 40% alcoholic drink,) and "omi ekan-ogi" (sour water from 3 days fermented milled maize). leaves were dried and powdered before being soaked in solvents for 3 days. another traditional method of extraction by squeezing raw juice from the leaves was also employed. all extra ...200720161897
a repulsive electrostatic mechanism for protein export through the type iii secretion apparatus.many gram-negative bacteria initiate infections by injecting effector proteins into host cells through the type iii secretion apparatus, which is comprised of a basal body, a needle, and a tip. the needle channel is formed by the assembly of a single needle protein. to explore the export mechanisms of mxih needle protein through the needle of shigella flexneri, an essential step during needle assembly, we have performed steered molecular dynamics simulations in implicit solvent. the trajectories ...201020141759
crystal structure of the dna-recognition component of the bacterial virus sf6 genome-packaging machine.in herpesviruses and many bacterial viruses, genome-packaging is a precisely mediated process fulfilled by a virally encoded molecular machine called terminase that consists of two protein components: a dna-recognition component that defines the specificity for packaged dna, and a catalytic component that provides energy for the packaging reaction by hydrolyzing atp. the terminase docks onto the portal protein complex embedded in a single vertex of a preformed viral protein shell called procapsi ...201020133842
innate immune detection of the type iii secretion apparatus through the nlrc4 inflammasome.the mammalian innate immune system uses toll-like receptors (tlrs) and nod-lrrs (nlrs) to detect microbial components during infection. often these molecules work in concert; for example, the tlrs can stimulate the production of the proforms of the cytokines il-1beta and il-18, whereas certain nlrs trigger their subsequent proteolytic processing via caspase 1. gram-negative bacteria use type iii secretion systems (t3ss) to deliver virulence factors to the cytosol of host cells, where they modula ...201020133635
a novel antisense rna regulates at transcriptional level the virulence gene icsa of shigella flexneri.the virulence gene icsa of shigella flexneri encodes an invasion protein crucial for host colonization by pathogenic bacteria. within the intergenic region vira-icsa, we have discovered a new gene that encodes a non-translated antisense rna (named rnag), transcribed in cis on the complementary strand of icsa. in vitro transcription assays show that rnag promotes premature termination of transcription of icsa mrna. transcriptional inhibition is also observed in vivo by monitoring the expression p ...201020129941
highly sensitive detection of shigella flexneri using fluorescent silica nanoparticles.robust signal amplification tactic is a good solution for improving detection sensitivity. unprocessed fluorophores have many limitations. here we describe an effective strategy for highly sensitive detection of bacteria by using fluorescent conjugated nanoparticles. the nanoparticles were synthesized using silica as matrix. fluorescein isothiocyanate distributed in the matrix. s. flexneri specific antibody was coated on the surface of the nanoparticles. compared to the traditional fluorescent a ...200920128444
bacterial guanine nucleotide exchange factors sope-like and wxxxe effectors.subversion of rho family small gtpases, which control actin dynamics, is a common infection strategy used by bacterial pathogens. in particular, salmonella enterica serovar typhimurium, shigella flexneri, enteropathogenic escherichia coli (epec), and enterohemorrhagic escherichia coli (ehec) translocate type iii secretion system (t3ss) effector proteins to modulate the rho gtpases rhoa, cdc42, and rac1, which trigger formation of stress fibers, filopodia, and lamellipodia/ruffles, respectively. ...201020123714
structural and functional divergence of the newly identified gtric from its gtr family of conserved shigella flexneri serotype-converting glucosyltransferases.glucosyltransferases (gtrs) and o-acetyltransferase (oac) are integral membrane proteins embedded within the cytoplasmic membrane of shigella flexneri. gtrs and oac are responsible for unidirectional host serotype conversion by altering the epitopic properties of the bacterial surface lipopolysaccharide (lps) o-antigen. in this study, we present the membrane topology of a recently recognized gtr, gtric, which is known to mediate s. flenxeri serotype switching from 1a to 1c. the gtric topology is ...201020095950
[characteristics of dysentery-causing strains isolated from patients and carriers in republic of south ossetia during period of humanitarian disaster]. 200920095424
th17 cells are the dominant t cell subtype primed by shigella flexneri mediating protective immunity.the t cell response to shigella, the causative agent of bacillary dysentery, remains poorly understood. using a murine model of infection, we report that shigella flexneri primes predominately il-17a- and il-22-producing th17 cells. shigella-specific th1 cells are only significantly induced on secondary infection, whereas specific th2 and cd8(+) t cells are undetectable. apart from th17 cells that are primed in a mhc class ii- and il-6-dependent, but il12/23p40-independent manner, we identified ...201020089698
the extreme c terminus of shigella flexneri ipab is required for regulation of type iii secretion, needle tip composition, and binding.type iii secretion systems (t3sss) are widely distributed virulence determinants of gram-negative bacteria. they translocate bacterial proteins into host cells to manipulate them during infection. the shigella t3ss consists of a cytoplasmic bulb, a transmembrane region, and a hollow needle protruding from the bacterial surface. the distal tip of mature, quiescent needles is composed of ipad, which is topped by ipab. physical contact with host cells initiates secretion and leads to assembly of a ...201020086081
tracking the dynamic interplay between bacterial and host factors during pathogen-induced vacuole rupture in real time.escape into the host cell cytosol following invasion of mammalian cells is a common strategy used by invasive pathogens. this requires membrane rupture of the vesicular or vacuolar compartment formed around the bacteria after uptake into the host cell. the mechanism of pathogen-induced disassembly of the vacuolar membrane is poorly understood. we established a novel, robust and sensitive fluorescence microscopy method that tracks the precise time point of vacuole rupture upon uptake of gram-nega ...201020070313
osmoregulated periplasmic glucans synthesis gene family of shigella flexneri.osmoregulated periplasmic glucans (opgs) of food- and water-borne enteropathogen shigella flexneri were characterized. opgs were composed of 100% glucose with 2-linked glucose as the most abundant residue with terminal glucose, 2-linked and 2,6-linked glucose also present in high quantities. most dominant backbone polymer chain length was seven glucose residues. individual genes from the opg gene family comprising of a bicistronic operon opggh, opgb, opgc and opgd were mutagenized to study their ...201020062978
the structure of the salmonella typhimurium type iii secretion system needle shows divergence from the flagellar system.the type iii secretion system (t3ss) is essential for the infectivity of many pathogenic gram-negative bacteria. the t3ss contains proteins that form a channel in the inner and outer bacterial membranes, as well as an extracellular needle that is used for transporting and injecting effector proteins into a host cell. the homology between the t3ss and the bacterial flagellar system has been firmly established, based upon both sequence similarities between respective proteins in the two systems an ...201020060835
age-related efficacy of shigella o-specific polysaccharide conjugates in 1-4-year-old israeli children.despite its high worldwide morbidity and mortality, there is yet no licensed vaccine for shigellosis. we reported the safety and immunogenicity of shigella o-specific polysaccharide-protein conjugates in adults and young children and efficacy of shigella sonnei conjugate in young adults.201020056180
multilocus variable-number tandem repeat analysis for molecular typing and phylogenetic analysis of shigella flexneri.shigella flexneri is one of the causative agents of shigellosis, a major cause of childhood mortality in developing countries. multilocus variable-number tandem repeat (vntr) analysis (mlva) is a prominent subtyping method to resolve closely related bacterial isolates for investigation of disease outbreaks and provide information for establishing phylogenetic patterns among isolates. the present study aimed to develop an mlva method for s. flexneri and the vntr loci identified were tested on 242 ...200920042119
antibacterial and antifungal activities of some mexican medicinal plants.in mexico about 4,000 plant species have some medicinal use. the aim of this work was to evaluate the antimicrobial activity of six mexican medicinal plants against fungi and gram-positive and gram-negative bacteria. methanolic extracts were prepared from the mexican medicinal plants amphypteringium adstrigens, castella tortuosa, coutarea latiflora, ibervillea sonorae, jatropha cuneata, and selaginella lepidophylla. the antibacterial and antifungal activities of the plants were determined by the ...200920041800
transcriptional profile of the shigella flexneri response to an alkaloid: berberine.berberine, a natural isoquinoline alkaloid found in many medicinal herbs, has been shown to be active against a variety of microbial infections. to examine the potential effects of berberine on shigella flexneri, a whole-genome dna microarray was constructed and a transcriptome analysis of the cellular responses of s. flexneri when exposed to berberine chloride (bc) was performed. our data revealed that bc upregulated a group of genes involved in dna replication, repair and division. intriguingl ...201020030725
the immunogenic siga enterotoxin of shigella flexneri 2a binds to hep-2 cells and induces fodrin redistribution in intoxicated epithelial cells.we have previously shown that the enterotoxin siga which resides on the she pathogenicity island (pai) of s. flexneri 2a is an autonomously secreted serine protease capable of degrading casein. we have also demonstrated that siga is cytopathic for hep-2 cells and plays a role in the intestinal fluid accumulation associated with s. flexneri infections.200920011051
a bacterial e3 ubiquitin ligase ipah9.8 targets nemo/ikkgamma to dampen the host nf-kappab-mediated inflammatory response.nf-kappab (nuclear factor kappab) has a pivotal role in many cellular processes, including the inflammatory and immune responses and, therefore, its activation is tightly regulated by the ikk (ikappab kinase) complex and by ikappabalpha degradation. when shigella bacteria multiply within epithelial cells they release peptidoglycans, which are recognized by nod1 and stimulate the nf-kappab pathway, thus leading to a severe inflammatory response. here, we show that ipah9.8, a shigella effector pos ...201020010814
helicobacter pylori induces mapk phosphorylation and ap-1 activation via a nod1-dependent mechanism.helicobacter pylori rapidly activates mapks and transcription factors, nf-kappab and ap-1, in gastric epithelial cells following host attachment. activation of these signal transducers is largely dependent on the cag pathogenicity island (cagpai)-encoded type iv secretion system. h. pylori was shown to translocate peptidoglycan through the type iv secretion system, which is recognized by the pathogen recognition molecule, nod1, thus resulting in nf-kappab activation. the mechanisms of h. pylori- ...200920007577
identification of antibacterial and antifungal pharmacophore sites for potent bacteria and fungi inhibition: indolenyl sulfonamide derivatives.synthesis of seven new indolenyl sulfonamides, have been prepared by the condensation reaction of indole-3-carboxaldehyde with different sulfonamides such as, sulphanilamide, sulfaguanidine, sulfathiazole, sulfamethoxazole, sulfisoxazole, sulfadiazine and sulfamethazine. these synthesized compounds have been used as potential ligands for complexation with some selective divalent transition metal ions (cobalt, copper, nickel & zinc). structure of the synthesized ligands has been deduced from thei ...201020005022
a changing picture of shigellosis in southern vietnam: shifting species dominance, antimicrobial susceptibility and clinical presentation.shigellosis remains considerable public health problem in some developing countries. the nature of shigellae suggests that they are highly adaptable when placed under selective pressure in a human population. this is demonstrated by variation and fluctuations in serotypes and antimicrobial resistance profile of organisms circulating in differing setting in endemic locations. antimicrobial resistance in the genus shigella is a constant threat, with reports of organisms in asia being resistant to ...200920003464
global analysis of a plasmid-cured shigella flexneri strain: new insights into the interaction between the chromosome and a virulence plasmid.shigella flexneri is an important human pathogen that causes dysentery, and remains a significant threat to public health, particularly in developing countries. the virulence of this pathogen is dependent on an acquired virulence plasmid. to investigate the crosstalk between the bacterial chromosome and the exogenous virulence plasmid, a virulence plasmid-cured strain was constructed using plasmid incompatibility. the global patterns of gene expression of this strain compared with the wild-type ...201020000779
emergence of a new multidrug-resistant serotype x variant in an epidemic clone of shigella flexneri.shigella spp. are the causative agent of shigellosis with shigella flexneri serotype 2a being the most prevalent in developing countries. epidemiological surveillance in china found that a new serotype of s. flexneri appeared in 2001 and replaced serotype 2a in 2003 as the most prevalent serotype in henan province. the new serotype also became the dominant serotype in 7 of the 10 other provinces under surveillance in china by 2007. the serotype was identified as a variant of serotype x. it diffe ...201019955273
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