Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
effect of chemical denaturants on the conformational stability of gyrb subunit of dna gyrase from salmonella enterica serovar typhi.dna gyrase, a type ii topoisomerase maintains the topology of dna by introducing negative supercoils using energy generated by atp hydrolysis. it is composed of two subunits, gyra and gyrb (gyra2gyrb2 hetero-tetramer). gyrb comprises two domains, a 43kda amino n-terminus (gbntd) and 47kda carboxyl c- terminus (gbctd). till now no study has been reported in terms of stability of gyrase b and its domains using chemical denaturants related to its function. to understand the role of each domain in g ...201728499947
a novel approach for construction of an inactivated typhoid vaccine candidate that effectively augments both humoral and cellular immune responses.salmonella enterica serovar typhi ghost was constructed as a vaccine candidate against typhoid fever. an asd(+) plasmid pjhl187 harboring a ghost cassette comprised of phix 174 e lysis gene stringently controlled under the convergent promotor components and was transformed into the asd gene-deleted mutant s. typhi ty21a strain (stg). twenty female balb/c mice randomly assigned into two groups were subcutaneously vaccinated at 5weeks of age to assess immunogenic characteristics of the constructed ...201728495314
waning immunity and microbial vaccines-workshop of the national institute of allergy and infectious diseases.since the middle of the 20th century, vaccines have made a significant public health impact by controlling infectious diseases globally. although long-term protection has been achieved with some vaccines, immunity wanes over time with others, resulting in outbreaks or epidemics of infectious diseases. long-term protection against infectious agents that have a complex life cycle and antigenic variation remains a key challenge. novel strategies to characterize the short- and long-term immune respo ...201728490424
vi capsular polysaccharide produced by recombinant salmonella enterica serovar paratyphi a confers immunoprotection against infection by salmonella enterica serovar typhi.enteric fever is predominantly caused by salmonella enterica serovar typhi and salmonella enterica serovar paratyphi a, and accounts for an annual global incidence of 26.9 millions. in recent years, the rate of s. paratyphi a infection has progressively increased. currently licensed vaccines for typhoid fever, live ty21a vaccine, vi subunit vaccine, and vi-conjugate vaccine, confer inadequate cross immunoprotection against enteric fever caused by s. paratyphi a. therefore, development of bivalen ...201728484685
biosynthesis of silver nanoparticles using myristica fragrans seed (nutmeg) extract and its antibacterial activity against multidrug-resistant (mdr) salmonella enterica serovar typhi isolates.biosynthesis of nanoparticles has received increasing attention due its effective mode of action, eco-friendly preparation methodology, and less cytotoxicity. in the present study, silver nanoparticles (agnps) from aqueous seed extract of myristica fragrans (nutmeg) were characterized. gas chromatography-mass spectrometry (gc-ms) analysis revealed the presence of bioactive components acts as effective in reducing and capping agents for converting agno3 to agnps. the uv-vis absorption spectrum of ...201728470497
simultaneous molecular detection of salmonella enterica serovars typhi, enteritidis, infantis, and typhimurium.salmonella enterica serovar typhi, as causative agent of typhoid fever, is one of the most important endemic pathogens. non-typhoidal salmonella serovars, including typhimurium, infantis, and enteritidis are amongst the most prevalent serotypes worldwide and in developing areas such as iran. the aim of this study was to apply a uniplex pcr for rapid detection of salmonella spp., and a multiplex pcr for the simultaneous detection of the four most common salmonella serovars in iran.201728451535
enteric fever in children in western sydney, australia, 2003-2015.enteric fever is a vaccine-preventable disease with cases in australia predominantly acquired overseas. the aim of this study was to define the burden of enteric fever in children presenting to a pediatric hospital in western sydney between 2003 and 2015.201728445250
rhabdomyolysis complicating typhoid fever in a child and review of the literature.typhoid fever is an important cause of morbidity and mortality in the developing world, particularly in children, but is infrequently observed in the developed world and can occur in patients without a significant travel history. rhabdomyolysis as a complication has rarely been reported, and never in a child. a child with salmonella enterica serovar typhi septicemia, complicated by rhabdomyolysis, encephalopathy and pancreatitis is described and all 15 reported cases to date are summarized.201728430751
challenge of humans with wild-type salmonella enterica serovar typhi elicits changes in the activation and homing characteristics of mucosal-associated invariant t cells.gastrointestinal infections by salmonella enterica serovar typhi (s. typhi) are rare in industrialized countries. however, they remain a major public health problem in the developing world with an estimated 26.9 million new cases annually and significant mortality when untreated. recently, we provided the first direct evidence that cd8(+) mait cells are activated and have the potential to kill cells exposed to s. typhi, and that these responses are dependent on bacterial load. however, mait cell ...201728428786
antibacterial effects of lactobacillus isolates of curd and human milk origin against food-borne and human pathogens.this study was undertaken to assess the antibacterial efficacy of lactobacilli isolated from curd and human milk samples. identities of thirty-one different lactobacilli (20 from curd and 11 from human milk) were confirmed by genus-specific pcr and 16s rrna-based sequencing. these strains belonged to five species, lactobacillus casei, l. delbrueckii, l. fermentum, l. plantarum, and l. pentosus. antibacterial activities of cell-free supernatants (cfss) of all the lactobacillus isolates were estim ...201728401466
gut microbiota-mediated protection against diarrheal infections.the mammalian gut microbiota is a highly abundant and diverse microbial community that resides in the gastrointestinal tract. one major benefit that the gut microbiota provides to its host is colonization resistance-the ability to prevent colonization by foreign microbes, including diarrheal pathogens such as clostridium difficile , salmonella enterica serovar typhimurium and diarrheagenic escherichia coli .201728520994
antibacterial activity of crude extracts of some south african medicinal plants against multidrug resistant etiological agents of diarrhoea.this study evaluated the antibacterial activity of some plants used in folklore medicine to treat diarrhoea in the eastern cape province, south africa.201728629407
direct and inverted repeat stimulated excision (direx): simple, single-step, and scar-free mutagenesis of bacterial genes.the need for generating precisely designed mutations is common in genetics, biochemistry, and molecular biology. here, i describe a new λ red recombineering method (direct and inverted repeat stimulated excision; direx) for fast and easy generation of single point mutations, small insertions or replacements as well as deletions of any size, in bacterial genes. the method does not leave any resistance marker or scar sequence and requires only one transformation to generate a semi-stable intermedi ...201728854250
anti-aging activities of extracts from tunisian medicinal halophytes and their aromatic constituents.six medicinal halophytes widely represented in north africa and commonly used in traditional medicine were screened for pharmacological properties to set out new promising sources of natural ingredients for cosmetic or nutraceutical applications. thus, citrullus colocynthis, cleome arabica, daemia cordata, haloxylon articulatum, pituranthos scoparius and scorzonera undulata were examined for their in vitro antioxidant (dpph scavenging and superoxide anion-scavenging, β-carotene bleaching inhibit ...201728827992
comparative sequence analysis of multidrug-resistant inca/c plasmids from salmonella enterica.determinants of multidrug resistance (mdr) are often encoded on mobile elements, such as plasmids, transposons, and integrons, which have the potential to transfer among foodborne pathogens, as well as to other virulent pathogens, increasing the threats these traits pose to human and veterinary health. our understanding of mdr among salmonella has been limited by the lack of closed plasmid genomes for comparisons across resistance phenotypes, due to difficulties in effectively separating the dna ...201728824587
functional analysis of genes encoded by the locus of heat resistance (lhr) in escherichia coli.the locus of heat resistance (lhr) is a 15 - 19 kb genomic island conferring exceptional heat resistance to organisms in the family enterobacteriaceae including pathogenic strains of salmonella enterica and escherichia coli the complement of lhr-encoded genes that is necessary for heat resistance and the stress- or growth-phase induced expression of lhr-encoded genes are unknown. this study determined the contribution of the 7 lhr-encoded genes yfdx1gi, yfdx2, hdedgi, orf11, trxgi, kefb, and psi ...201728802266
novel plasmid-mediated colistin resistance mcr-4 gene in salmonella and escherichia coli, italy 2013, spain and belgium, 2015 to 2016.a novel mcr colistin resistance gene was identified in a strain of salmonella enterica, monophasic variant of serovar typhimurium (4,5,12:i:- ), isolated from a pig at slaughter in italy in 2013, and in escherichia coli strains collected during routine diagnostic of post-weaning diarrhoea in pigs from spain and belgium in 2015 and 2016. immediate implementation of mcr-screening including this novel gene variant is required for salmonella and e. coli from humans and food-producing animals in euro ...201728797329
construction of an inactivated typhoid vaccine candidate expressing escherichia coli heat-labile enterotoxin b subunit and evaluation of its immunogenicity in a murine model.typhoid fever caused by salmonella enterica serovar typhi has contributed to the global public health burden, particularly in developing countries. in this study, an s. typhi ghost was developed and its capacity as a vaccine candidate against typhoid fever was assessed.201728792376
rho protein: roles and mechanisms.at the end of the multistep transcription process, the elongating rna polymerase (rnap) is dislodged from the dna template either at specific dna sequences, called the terminators, or by a nascent rna-dependent helicase, rho. in escherichia coli, about half of the transcription events are terminated by the rho protein. rho utilizes its rna-dependent atpase activities to translocate along the mrna and eventually dislodges the rnap via an unknown mechanism. the transcription elongation factor nusg ...201728731845
serum albumin and osmolality inhibit bdellovibrio bacteriovorus predation in human serum.we evaluated the bactericidal activity of bdellovibrio bacteriovorus, strain hd100, within blood sera against bacterial strains commonly associated with bacteremic infections, including e. coli, klebsiella pneumoniae and salmonella enterica. tests show that b. bacteriovorus hd100 is not susceptible to serum complement or its bactericidal activity. after a two hour exposure to human sera, the prey populations decreased 15- to 7,300-fold due to the serum complement activity while, in contrast, the ...201728725056
role of the inner-membrane histidine kinase rcsc and outer-membrane lipoprotein rcsf in the activation of the rcs phosphorelay signal transduction system in escherichia coli.the rcs phosphorelay signal transduction system of escherichia coli controls genes for capsule production and many other envelope-related functions and is implicated in biofilm formation. the outer-membrane lipoprotein rcsf is an essential component of the rcs system. mislocalization of rcsf to the periplasm or the cytoplasmic membrane leads to high activation of the rcs system, suggesting that rcsf functions by interacting with the cytoplasmic membrane component(s) of the system in activating t ...201728691662
purification and characterization of an atpase gsia from salmonella enterica.the coding sequence of salmonella enterica gsia was cloned and expressed in e. coli. the protein was purified and atpase activity was characterized by nadh oxidation method. gsia exhibited optimum activity at 30°c and at ph 8 in tris/hcl buffer. gsia protein was stable at 20°c. 66% and 44% activity remained after incubation at 30°c and 40°c for 30 min. ph 7 and ph 9 incubation would obviously reduce the atpase activity. in vivo functionality of gsia was determined by constructing gene deletion s ...201728691022
super-cationic carbon quantum dots synthesized from spermidine as an eye drop formulation for topical treatment of bacterial keratitis.we have developed a one-step method to synthesize carbon quantum dots (cqdpas) from biogenic polyamines (pas) as an antibacterial agent for topical treatment of bacterial keratitis (bk). cqds synthesized by direct pyrolysis of spermidine (spd) powder through a simple dry heating treatment exhibit a solubility and yield much higher than those from putrescine and spermine. we demonstrate that cqds obtained from spds (cqdspds) possess effective antibacterial activities against non-multidrug-resista ...201728677399
host and pathogen copper-transporting p-type atpases function antagonistically during salmonella infection.copper is an essential yet potentially toxic trace element that is required by all aerobic organisms. a key regulator of copper homeostasis in mammalian cells is the copper-transporting p-type atpase atp7a, which mediates copper transport from the cytoplasm into the secretory pathway, as well as copper export across the plasma membrane. previous studies have shown that atp7a-dependent copper transport is required for killing phagocytosed escherichia coli in a cultured macrophage cell line. in th ...201728652309
emergence of drug resistant bacteria at the hajj: a systematic review.hajj is the annual mass gathering of muslims, and is a reservoir and potential source of bacterial transmission. the emergence of bacterial transmission, including multi-drug resistance (mdr) bacteria, during hajj has not been systematically assessed.201728652197
epigallocatechin gallate inhibits the type iii secretion system of gram-negative enteropathogenic bacteria under model conditions.epigallocatechin gallate (egcg), a major polyphenol in green tea, inhibits the type iii secretion system (t3ss) of enteropathogenic and enterohemorrhagic escherichia coli (epec and ehec, respectively), salmonella enterica serovar typhimurium, and yersinia pseudotuberculosis. the inhibitory effect causes the inhibition of hemolysis, cell invasion, cell adhesion and apoptosis, which are functions of the type iii secretion device. in the case of epec, espb accumulates in the cells. rt-pcr showed th ...201728651361
gut microbiota, nitric oxide, and microglia as prerequisites for neurodegenerative disorders.regulating fluctuating endogenous nitric oxide (no) levels is necessary for proper physiological functions. aberrant no pathways are implicated in a number of neurological disorders, including alzheimer's disease (ad) and parkinson's disease. the mechanism of no in oxidative and nitrosative stress with pathological consequences involves reactions with reactive oxygen species (e.g., superoxide) to form the highly reactive peroxynitrite, hydrogen peroxide, hypochloride ions and hydroxyl radical. n ...201728640632
atp-synthesis capacity of pulsed light-exposed bacteria.the ability of four different bacteria to synthesize new atp upon exposure to different doses of pulsed-light (pl) irradiation was investigated. the bacterial cells were pl treated on a gel surface, resuspended in phosphate buffered saline (pbs) and subsequently incubated in tryptic soy broth (tsb) at 37°c. cellular atp levels were monitored during a 2h incubation period and compared to the respective colony count data. although pl affected atp production in a dose dependent manner, the results ...201728629639
anaerobic cysteine degradation and potential metabolic coordination in salmonella enterica and escherichia coli.salmonella enterica has two cyur-activated enzymes that degrade cysteine, i.e., the aerobic cdsh and an unidentified anaerobic enzyme; escherichia coli has only the latter. to identify the anaerobic enzyme, transcript profiling was performed for e. coli without cyur and with overexpressed cyur thirty-seven genes showed at least 5-fold changes in expression, and the cyupa (formerly yhaom) operon showed the greatest difference. homology suggested that cyup and cyua represent a cysteine transporter ...201728607157
comparison of methods for detection of plasmid-mediated and chromosomally encoded colistin resistance in enterobacteriaceae.because of the emergence of plasmid-mediated (mcr-1 and mcr-2 genes) and chromosomally encoded colistin resistance, reliable methods for detecting colistin resistance/susceptibility in routine laboratories are required. we evaluated the respective performances of the bd phoenix automated system, the newly developed rapid polymyxin np test and the broth microdilution (bmd) reference method to detect colistin resistance in enterobacteriaceae, and particularly those producing mcr-1 and mcr-2.201728606644
oxidation of phosphorothioate dna modifications leads to lethal genomic instability.genomic modification by sulfur in the form of phosphorothioate (pt) is widespread among prokaryotes, including human pathogens. apart from its physiological functions, pt sulfur has redox and nucleophilic properties that suggest effects on bacterial fitness in stressful environments. here we show that pts are dynamic and labile dna modifications that cause genomic instability during oxidative stress. in experiments involving isotopic labeling coupled with mass spectrometry, we observed sulfur re ...201728604692
bdm-mediated regulation of flagellar biogenesis in escherichia coli and salmonella enterica serovar typhimurium.synthesis of the flagellar apparatus in escherichia coli is mediated via complex regulatory pathways. a previous study indicated that the protein encoded by the biofilm-dependent modulation (bdm) gene is linked closely with a regulatory pathway for flagellar assembly. however, the specific role of bdm in flagellar biogenesis remains unknown. herein, we showed that bdm interacts with flgm and inhibits its function as an anti-σ28 factor, which induces the transcription of flagellar late-class gene ...201728603807
a functional metagenomic analysis of tetracycline resistance in cheese bacteria.metagenomic techniques have been successfully used to monitor antibiotic resistance genes in environmental, animal and human ecosystems. however, despite the claim that the food chain plays a key role in the spread of antibiotic resistance, metagenomic analysis has scarcely been used to investigate food systems. the present work reports a functional metagenomic analysis of the prevalence and evolution of tetracycline resistance determinants in a raw-milk, blue-veined cheese during manufacturing ...201728596758
a versatile toolbox for the control of protein levels using n(ε)-acetyl-l-lysine dependent amber suppression.the analysis of the function of essential genes in vivo depends on the ability to experimentally modulate levels of their protein products. current methods to address this are based on transcriptional or post-transcriptional regulation of mrnas, but approaches based on the exploitation of translation regulation have so far been neglected. here we describe a toolbox, based on amber suppression in the presence of n(ε)-acetyl-l-lysine (ack), for translational tuning of protein output. we chose the ...201728594177
the rcs-regulated colanic acid capsule maintains membrane potential in salmonella enterica serovar typhimurium.the rcs phosphorelay and psp (phage shock protein) systems are envelope stress responses that are highly conserved in gammaproteobacteria. the rcs regulon was found to be strongly induced during metal deprivation of salmonella enterica serovar typhimurium lacking the psp response. nineteen genes activated by the rcsa-rcsb response regulator make up an operon responsible for the production of colanic acid capsular polysaccharide, which promotes biofilm development. despite more than half a centur ...201728588134
the ubik protein is an accessory factor necessary for bacterial ubiquinone (uq) biosynthesis and forms a complex with the uq biogenesis factor ubij.ubiquinone (uq), also referred to as coenzyme q, is a widespread lipophilic molecule in both prokaryotes and eukaryotes in which it primarily acts as an electron carrier. eleven proteins are known to participate in uq biosynthesis in escherichia coli, and we recently demonstrated that uq biosynthesis requires additional, nonenzymatic factors, some of which are still unknown. here, we report on the identification of a bacterial gene, yqic, which is required for efficient uq biosynthesis, and whic ...201728559279
phage applications for improving food safety and infection control in egypt.the study investigated the use of bacteriophages to control bacterial contamination of chicken skin, eggs, tomatoes and meat.201728557189
inhibitor-assisted high-pressure inactivation of bacteria in skim milk.the combined inactivation effects of high hydrostatic pressure (hhp) and antimicrobial compounds (potassium sorbate and ε-polylysine [ε-pl]) on 4 different bacterial strains present in skim milk and the effect of these treatments on milk quality were investigated in this study. hhp treatment at 500 mpa for 5 min reduced the populations of escherichia coli, salmonella enterica typhimurium, listeria monocytogenes, and staphylococcus aureus from 6.5 log colony-forming units (cfus) or higher to less ...201728556370
label-free biosensing of salmonella enterica serovars at single-cell level.the emerging nanotechnologies have greatly facilitated the development of label-free biosensors. the atomic force microscopy (afm) has been used to study the molecular mechanism of the reactions for protein and aptamers. the surface plasmon resonance (spr) have been used in fast detections of various pathogens such as bacteria. this study used both afm and spr to investigate the complex reactions between aptamers and outer membrane proteins (omps) on the surface of s. typhimurium.201728514955
anco3, a new member of the emerging family of phage-like plasmids.a phage-like plasmid isolated from a clinical isolate of salmonella enterica serovar derby has strong nucleotide sequence identity to the phage-like plasmids pstm_phi isolated from salmonella enterica serovar typhimurium l495, anco1 and anco2 from escherichia coli 243 and escherichia coli 244, and the virulent salmonella-specific ssu5 bacteriophage.201728495760
identification of the potentiating mutations and synergistic epistasis that enabled the evolution of inter-species cooperation.microbes often engage in cooperation through releasing biosynthetic compounds required by other species to grow. given that production of costly biosynthetic metabolites is generally subjected to multiple layers of negative feedback, single mutations may frequently be insufficient to generate cooperative phenotypes. synergistic epistatic interactions between multiple coordinated changes may thus often underlie the evolution of cooperation through overproduction of metabolites. to test the import ...201728493869
attachment and biofilm formation by selected strains of salmonella enterica and entrohemorrhagic escherichia coli of fresh produce origin.this study compared the abilities of selected salmonella enterica and enterohemorrhagic escherichia coli (ehec) strains of fresh produce origin to form biofilms on polystyrene surface and to attach to alfalfa and bean sprouts. each of the 7 s. enterica and 4 ehec inocula (2 ml; 10(7) cfu/ml) was placed in 6 different broths in 24-well polystyrene tissue culture plates at 28 °c for 1 to 7 d. developed biofilms were quantified using the crystal violet binding assay. in a separate experiment, alfal ...201728493317
the c-terminus of ribosomal protein us4 contributes to small ribosomal subunit biogenesis and the fidelity of translation.ribosomal protein us4 is an essential ribosomal component involved in multiple functions, including mrna decoding. structural analyses indicate that during decoding, the interface between the c-terminus of us4 and protein us5 is disrupted and in agreement with this, c-terminal us4 truncation mutants are readily isolated on the basis of their increased miscoding phenotypes. the same mutants can also display defects in small subunit assembly and 16s rrna processing and some are temperature sensiti ...201728483689
the response to 2-aminoacrylate differs in escherichia coli and salmonella enterica, despite shared metabolic components.the metabolic network of an organism includes the sum total of the biochemical reactions present. in microbes, this network has an impeccable ability to sense and respond to perturbations caused by internal or external stimuli. the metabolic potential (i.e., network structure) of an organism is often drawn from the genome sequence, based on the presence of enzymes deemed to indicate specific pathways. escherichia coli and salmonella enterica are members of the enterobacteriaceae family of gram-n ...201728461448
prevalence and pathogen load of campylobacter spp., salmonella enterica and escherichia coli o157/o145 serogroup in sheep faeces collected at sale yards and in abattoir effluent in western australia.develop a multiplex quantitative pcr assay to investigate the prevalence and shedding of escherichia coli o157/o145, salmonella spp. and campylobacter spp. in sheep at sale yards and abattoirs.201728444752
the legacy of genetic analysis advances contemporary research with escherichia coli k-12 and salmonella enterica serovar typhimurium lt2.escherichia coli k-12 and salmonella enterica serovar typhimurium lt2 became standard organisms for genetic analysis during the truman administration. half a century later, genetic analysis with these strains had become an art form, interpreted through 23 articles in the ambitious two-volume masterpiece edited by the late fred neidhardt and colleagues. these legacy articles now are available through ecosal plus, so as to inform and inspire contemporary genetic analyses in these standard organism ...201728443537
transport and attenuation of salmonella enterica, fecal indicator bacteria and a poultry litter marker gene are correlated in soil columns.millions of tons of fecal-contaminated poultry litter are applied to u.s. agricultural fields annually. precipitation and irrigation facilitate transport of fecal-derived pathogens and fecal indicator bacteria (fib) to groundwater. the goal of this study was to compare transport of pathogens, fib, and a microbial source tracking marker gene for poultry litter (la35) in a simulated soil-to-groundwater system. nine laboratory soil columns containing four different soil types were used to evaluate ...201728441599
genomic analysis of factors associated with low prevalence of antibiotic resistance in extraintestinal pathogenic escherichia coli sequence type 95 strains.extraintestinal pathogenic escherichia coli (expec) strains belonging to multilocus sequence type 95 (st95) are globally distributed and a common cause of infections in humans and domestic fowl. st95 isolates generally show a lower prevalence of acquired antimicrobial resistance than other pandemic expec lineages. we took a genomic approach to identify factors that may underlie reduced resistance. we fully assembled genomes for four st95 isolates representing the four major fimh-based lineages w ...201728405633
convergence of dna methylation and phosphorothioation epigenetics in bacterial genomes.explosive growth in the study of microbial epigenetics has revealed a diversity of chemical structures and biological functions of dna modifications in restriction-modification (r-m) and basic genetic processes. here, we describe the discovery of shared consensus sequences for two seemingly unrelated dna modification systems, (6m)a methylation and phosphorothioation (pt), in which sulfur replaces a nonbridging oxygen in the dna backbone. mass spectrometric analysis of dna from escherichia coli b ...201728400512
natural product discovery from the human microbiome.human-associated microorganisms have the potential to biosynthesize numerous secondary metabolites that may mediate important host-microbe and microbe-microbe interactions. however, there is currently a limited understanding of microbiome-derived natural products. a variety of complementary discovery approaches have begun to illuminate this microbial "dark matter," which will in turn allow detailed mechanistic studies of the effects of these molecules on microbiome and host. herein, we review re ...201728389564
lack of acrb efflux function confers loss of virulence on salmonella enterica serovar typhimurium.acrab-tolc is the paradigm resistance-nodulation-division (rnd) multidrug resistance efflux system in gram-negative bacteria, with acrb being the pump protein in this complex. we constructed a nonfunctional acrb mutant by replacing d408, a highly conserved residue essential for proton translocation. western blotting confirmed that the acrb d408a mutant had the same native level of expression of acrb as the parental strain. the mutant had no growth deficiencies in rich or minimal medium. however, ...201728720734
intestinal epithelial ecto-5' -nucleotidase (cd73) regulates intestinal colonization and infection by nontyphoidal salmonella.ecto-5' -nucleotidase (cd73) is expressed abundantly on the apical surface of intestinal epithelial cells (iec) and functions as the terminal enzyme in the generation of extracellular adenosine. previous work has demonstrated that adenosine signaling in iecs results in a number of tissue-protective effects during inflammation; however, a rationale for its apical expression has been lacking. we hypothesized that the highly polarized expression of cd73 is indicative of an important role for extrac ...201728717030
phenotypic characteristics and genetic diversity of salmonella enterica serotype derby isolated from human patients and foods of animal origin.salmonella enterica serotype derby is among the three most common serotypes of nontyphoidal salmonella isolated from patients with diarrhea in china. in this study, 133 salmonella derby isolates from human patients (n = 74) and foods of animal origin (n = 59) in shanghai, china, between september 2013 and december 2014, were selected to study its phenotypic characteristics and genetic diversity. the isolates were subjected to antimicrobial susceptibility testing, plasmid replicon typing, virulen ...201728708426
salmonella typhimurium infection in total knee arthroplasty: a case report with review of literature.salmonella enterica serotype typhimurium is a rare cause of prosthetic joint infection (pji). the recognized predisposing risk factors for salmonella septic arthritis include diabetes mellitus, renal failure, human immunodeficiency virus infection and chronic corticosteroid use. we describe a case of pji of the knee in a 74-year-old lady who was on antitubercular treatment. the patient presented with discharging sinus and raised inflammatory markers. she was successfully treated by the removal o ...201728706395
quinolones and fluroquinolones metabolism and resistance in salmonella typhimurium: a mini review.salmonella enterica serovars causes substantial morbidity and mortality worldwide. more than 2500 different serotypes of salmonella were identified to date. in particular, salmonella enterica serovar typhimurium is the most important serotype of salmonella transmitted from animals to humans in most parts of the world. they are associated with an estimated 1 million deaths annually. quinolones are an important class of broad-spectrum antimicrobials has been utilized in the treatment option for ov ...201728699507
salmonella enterica serovar typhimurium st34 co-expressing blandm-5 and blactx-m-55 isolated in china. 201728698668
development of a novel, rapid multiplex polymerase chain reaction assay for the detection and differentiation of salmonella enterica serovars enteritidis and typhimurium using ultra-fast convection polymerase chain reaction.salmonella enterica serovars enteritidis and typhimurium are the most common causative agents of human nontyphoidal salmonellosis. the rapid detection and timely treatment of salmonellosis are important to increase the curative ratio and prevent spreading of the disease. in this study, we developed a rapid multiplex convection polymerase chain reaction (pcr) method to detect salmonella spp. and differentiate salmonella enteritidis and salmonella typhimurium. we used the inva gene for salmonella ...201728696782
diversity of antimicrobial resistance phenotypes in salmonella isolated from commercial poultry farms.salmonella remains the leading cause of foodborne illness in the united states, and the dissemination of drug-resistant salmonellae through the food chain has important implications for treatment failure of salmonellosis. we investigated the ecology of salmonella in integrated broiler production in order to understand the flow of antibiotic susceptible and resistant strains within this system. data were analyzed from a retrospective study focused on antimicrobial resistant salmonella recovered f ...201728691011
genomic characterization of a large plasmid containing a bla ndm-1 gene carried on salmonella enterica serovar indiana c629 isolate from china.the bla ndm-1 gene in salmonella species is mostly reported in clinical cases, but is rarely isolated from red and white meat in china.201728687066
combination of antimicrobials and essential oils as an alternative for the control of salmonella enterica multiresistant strains related to foodborne disease.due to the increase in bacterial resistance to antimicrobials (ambs) commonly used in veterinary and human medicine, the new strategies for controlling zoonoses focus on the study of natural products with demonstrated amb activity, such as essential oils (eos). the aim of this study was to evaluate the in vitro effect of the combination of enrofloxacin (enr), ceftiofur (cef), and trimethoprim-sulfamethoxazole (sxt) with cinnamon, clove, oregano, and red thyme eos against multiple drug-resistant ...201728683217
serotype distribution, antimicrobial resistance, and class 1 integrons profiles of salmonella from animals in slaughterhouses in shandong province, china.the current study aimed to analyze the prevalence and characterization of salmonella enterica isolated from animals in slaughterhouses before slaughter. a total of 143 non-duplicate salmonella were recovered from 1,000 fresh fecal swabs collected from four major pig slaughterhouses (49/600, 8.2%) and four major chicken slaughterhouses (94/400, 23.5%) between march and july 2016. among salmonella isolates from pigs, the predominant serovars were salmonella rissen (28/49, 57.1%) and typhimurium (1 ...201728680418
role of sapa and yfga in susceptibility to antibody-mediated complement-dependent killing and virulence of salmonella enterica serovar typhimurium.the st313 pathovar of salmonella enterica serovar typhimurium contributes to a high burden of invasive disease among african infants and hiv-infected adults. it is characterized by genome degradation (loss of coding capacity) and has increased resistance to antibody-dependent complement-mediated killing compared with enterocolitis-causing strains of s typhimurium. vaccination is an attractive disease-prevention strategy, and leading candidates focus on the induction of bactericidal antibodies. a ...201728674031
differences in expression of genes in the myd88 and trif signalling pathways and methylation of tlr4 and trif in tibetan chickens and daheng s03 chickens infected with salmonella enterica serovar enteritidis.salmonella enterica serovar (s. enteritidis) is a pathogenic bacterium that can cause symptoms of food poisoning, leading to death of poultry, resulting in serious economic losses. the myd88 and trif signalling pathways play important roles in activating innate and adaptive immunity in chickens infected with s. enteritidis. the objective of the present study was to characterize in vivo mrna expressions, protein levels and methylation levels of genes in the above two pathways in both tibetan chic ...201728669384
spv locus aggravates salmonella infection of zebrafish adult by inducing th1/th2 shift to th2 polarization.salmonella enterica serovar typhimurium (s. typhimurium) are facultative intracellular enteric pathogens causing disease with a broad range of hosts. it was known that th1-type cytokines such as ifn-γ, il-12, and tnf-α etc. could induce protective immunity against intracellular pathogens, while th2-type cytokines such as il-4, il-10, and il-13 etc. are proved to help pathogens survive inside hosts and cause severe infection. one of the critical virulence factor attributes to the pathogenesis of ...201728666864
microbial community profiling of fresh basil and pitfalls in taxonomic assignment of enterobacterial pathogenic species based upon 16s rrna amplicon sequencing.application of 16s rrna (gene) amplicon sequencing on food samples is increasingly applied for assessing microbial diversity but may as unintended advantage also enable simultaneous detection of any human pathogens without a priori definition. in the present study high-throughput next-generation sequencing (ngs) of the v1-v2-v3 regions of the 16s rrna gene was applied to identify the bacteria present on fresh basil leaves. however, results were strongly impacted by variations in the bioinformati ...201728666129
sopb-mediated recruitment of snx18 facilitates salmonella typhimurium internalization by the host cell.to invade epithelial cells, salmonella enterica serovar typhimurium (s. typhimurium) induces macropinocytosis through the action of virulence proteins delivered across the host cell membrane via a type iii secretion system. we show that after docking at the plasma membrane s. typhimurium triggers rapid recruitment of cytosolic snx18, a sh3-px-bar domain sorting nexin protein, to the bacteria-induced membrane ruffles and to the nascent salmonella-containing vacuole. snx18 recruitment required the ...201728664153
bacterial autophagy: offense and defense at the host-pathogen interface.autophagy is a fundamental cellular process used for the turnover and recycling of cytosolic components and damaged organelles. originally characterized as a response to cellular stress, it now is well established that autophagy also is used as a defensive mechanism to combat the infection of host cells by intracellular pathogens. however, although this defensive strategy does limit the proliferation of most pathogens within their host cells, successful pathogens have evolved countermeasures tha ...201728660242
coordinated expression of acrab-tolc and eight other functional efflux pumps through activating rama and mara in salmonella enterica serovar typhimurium.the aim of this study was to determine the expression of eight other functional transporter genes upon acrab inactivation and also the expression of acrab when the function of eight other transporters are impaired in salmonella enterica. we used single- or multigene deletion mutants (i.e., δacra, δacrb, δtolc, δacrab, δacref, δacrd, δmdsabc, δmdtabc, δemrab, δmacab, δmdfa, δmdtk, δacrabrama, δacrabmara, and δacrabsoxs) and real time (rt)-pcr to quantify the expression of different pump and regul ...201728650690
three-dimensional organotypic co-culture model of intestinal epithelial cells and macrophages to study salmonella enterica colonization patterns.three-dimensional models of human intestinal epithelium mimic the differentiated form and function of parental tissues often not exhibited by two-dimensional monolayers and respond to salmonella in key ways that reflect in vivo infections. to further enhance the physiological relevance of three-dimensional models to more closely approximate in vivo intestinal microenvironments encountered by salmonella, we developed and validated a novel three-dimensional co-culture infection model of colonic ep ...201728649632
the validation and implications of using whole genome sequencing as a replacement for traditional serotyping for a national salmonella reference laboratory.salmonella serotyping remains the gold-standard tool for the classification of salmonella isolates and forms the basis of canada's national surveillance program for this priority foodborne pathogen. public health officials have been increasingly looking toward whole genome sequencing (wgs) to provide a large set of data from which all the relevant information about an isolate can be mined. however, rigorous validation and careful consideration of potential implications in the replacement of trad ...201728649236
immunogenicity and protective efficacy of a salmonella enteritidis sptp mutant as a live attenuated vaccine candidate.salmonella enterica serovar enteritidis (s. enteritidis) is a highly adaptive pathogen in both humans and animals. as a salmonella type iii secretion system (t3ss) effector, salmonella protein tyrosine phosphatase (sptp) is critical for virulence in this genus. to investigate the feasibility of using c50336δsptp as a live attenuated oral vaccine in mice, we generated the sptp gene deletion mutant c50336δsptp in s. enteritidis strain c50336 by λ-red mediated recombination and evaluated the protec ...201728646853
a novel antimicrobial approach based on the inhibition of zinc uptake in salmonella enterica.in this review we discuss evidences suggesting that bacterial zinc homeostasis represents a promising target for new antimicrobial strategies. the ability of the gut pathogen salmonella enterica sv typhimurium to withstand the host responses aimed at controlling growth of the pathogen critically depends on the zinc importer znuabc. strains lacking a functional znuabc or its soluble component znua display a dramatic loss of pathogenicity, due to a reduced ability to express virulence factors; wit ...201728636417
molecular characterization of salmonella from human and animal origins in uganda.sporadic salmonella outbreaks with varying clinical presentations have been on the rise in various parts of uganda. the sources of outbreaks and factors underlying the different clinical manifestation are curtailed by paucity of information on salmonella genotypes and the associated virulence genes. this study reports molecular diversity of salmonella enterica and their genetic virulence profiles among human and animal isolates. characterization was done using kauffman-white classification schem ...201728634597
control of virulence gene transcription by indirect readout in vibrio cholerae and salmonella enterica serovar typhimurium.indirect readout mechanisms of transcription control rely on the recognition of dna shape by transcription factors (tfs). tfs may also employ a direct readout mechanism that involves the reading of the base sequence in the dna major groove at the binding site. tfs with winged helix-turn-helix (whth) motifs use an alpha helix to read the base sequence in the major groove while inserting a beta sheet 'wing' into the adjacent minor groove. such whth proteins are important regulators of virulence ge ...201728631437
sipa activation of caspase-3 is a decisive mediator of host cell survival at early stages of salmonella enterica serovar typhimurium infection.salmonella invasion protein a (sipa) is a dual-function effector protein that plays roles in both actin polymerization and caspase-3 activation in intestinal epithelial cells. to date its function in other cell types has remained largely unknown despite its expression in multiple cell types and its extracellular secretion during infection. here we show that in macrophages sipa induces increased caspase-3 activation early in infection. this activation required a threshold level of sipa linked to ...201728630067
elimination of persistent vaccine bacteria of salmonella enterica serovar typhimurium in the guts of immunized mice by inducible expression of truncated ynce.orally administered vaccine bacteria usually persist for a period of time in the intestinal tracts of immunized individuals, and are excreted in feces to the environment resulting in a potential biosafety issue. the releasing risk can be minimized by immediate elimination of the persistent vaccine bacteria once adequate protective immune responses have been elicited by the vaccine bacteria. in a previous study, inducible expression of truncated ynce gene (ynce*) was found lethal to host bacteria ...201728628661
characterization of a blandm‑1‑harboring plasmid from a salmonella enterica clinical isolate in china.the plasmid-mediated transmission of antibiotic resistance genes has been reported to be involved in the development of antibiotic resistance in bacteria, and poses a serious threat for the success of bacterial infection treatment and human health worldwide. the present study used a 454 gs‑flx pyrosequencing system to determine the ~140 kb nucleotide sequence of plasmid phs36‑ndm, which was identified in a salmonella stanley isolate from the stool sample of an 11‑month‑old girl at lishui central ...201728627648
coupling killing to neutralization: combined therapy with ceftriaxone/pep19-2.5 counteracts sepsis in rabbits.sepsis, which is induced by severe bacterial infections, is a major cause of death worldwide, and therapies combating the disease are urgently needed. because many drugs have failed in clinical trials despite their efficacy in mouse models, the development of reliable animal models of sepsis is in great demand. several studies have suggested that rabbits reflect sepsis-related symptoms more accurately than mice. in this study, we evaluated a rabbit model of acute sepsis caused by the intravenous ...201728620220
vaccination against salmonella infection: the mucosal way.salmonella enterica subspecies enterica includes several serovars infecting both humans and other animals and leading to typhoid fever or gastroenteritis. the high prevalence of associated morbidity and mortality, together with an increased emergence of multidrug-resistant strains, is a current global health issue that has prompted the development of vaccination strategies that confer protection against most serovars. currently available systemic vaccine approaches have major limitations, includ ...201728615285
rna target profiles direct the discovery of virulence functions for the cold-shock proteins cspc and cspe.the functions of many bacterial rna-binding proteins remain obscure because of a lack of knowledge of their cellular ligands. although well-studied cold-shock protein a (cspa) family members are induced and function at low temperature, others are highly expressed in infection-relevant conditions. here, we have profiled transcripts bound in vivo by the cspa family members of salmonella enterica serovar typhimurium to link the constitutively expressed cspc and cspe proteins with virulence pathways ...201728611217
resistance to the cyclotide cycloviolacin o2 in salmonella enterica caused by different mutations that often confer cross-resistance or collateral sensitivity to other antimicrobial peptides.antimicrobial peptides (amps) are essential components of innate immunity in all living organisms, and these potent broad-spectrum antimicrobials have inspired several antibacterial development programs in the past 2 decades. in this study, the development of resistance to the gram-negative bacterium-specific peptide cycloviolacin o2 (cyo2), a member of the cyclotide family of plant miniproteins, was characterized in salmonella enterica serovar typhimurium lt2. mutants isolated from serial passa ...201728607015
the snake raiser lung: an unusual cause of salmonella enterica subspecies arizonae pneumonia. 201728602385
schmallenberg virus infection confirmed in scotland.schmallenberg virus infection in malformed lambsfood chain issues after lead poisoning incidentsuspected ragwort poisoning in heifersewe abortions due to salmonella enterica serovar urbanacoxiella burnetii detected in aborted lambsthese are among matters discussed in the disease surveillance report for february 2017 from sac consulting: veterinary services (sac c vs).201728600415
non-typhi salmonella enterica urinary tract infections.non-typhi salmonella enterica urinary tract infections (utis) are not frequent and rarely reported in the literature. we aimed to characterize clinical presentations and risk factors for the infection.201728600113
draft genome sequences of salmonella lysozyme gene knockout mutants.lysozyme enzymes hydrolyze the β-1,4-glycosidic bond in oligosaccharides. these enzymes are part of a broad group of glucoside hydrolases that are poorly characterized; however, they are important for growth and are being recognized as emerging virulence factors. this is the release of four lysozyme-encoding-gene-deletion mutants in salmonella enterica serovar typhimurium lt2.201728596411
transcriptomic analysis of the swarm motility phenotype of salmonella enterica serovar typhimurium mutant defective in periplasmic glucan synthesis.movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. salmonella enterica serovar typhimurium mutants defective in osmoregulated periplasmic glucans (opg) synthesis are unable to exhibit motility on moist surfaces (swarming); however, their mobility in liquid (swim motility) remains unaffected. in order to understand the role of opg in swarm motility, transcriptomic analysis was perform ...201728593349
borrelidins c-e: new antibacterial macrolides from a saltern-derived halophilic nocardiopsis sp.chemical investigation of a halophilic actinomycete strain belonging to the genus nocardiopsis inhabiting a hypersaline saltern led to the discovery of new 18-membered macrolides with nitrile functionality, borrelidins c-e (1-3), along with a previously reported borrelidin (4). the planar structures of borrelidins c-e, which are new members of the rare borrelidin class of antibiotics, were elucidated by nmr, mass, ir, and uv spectroscopic analyses. the configurations of borrelidines c-e were det ...201728587270
evidence for improved encapsulated pathway behavior in a bacterial microcompartment through shell protein engineering.bacterial microcompartments are a class of proteinaceous organelles comprising a characteristic protein shell enclosing a set of enzymes. compartmentalization can prevent escape of volatile or toxic intermediates, prevent off-pathway reactions, and create private cofactor pools. encapsulation in synthetic microcompartment organelles will enhance the function of heterologous pathways, but to do so, it is critical to understand how to control diffusion in and out of the microcompartment organelle. ...201728585808
factors influencing the salmonella internalization into seedpods and whole plants of arachis hypogaea (l.).here we investigated whether salmonella enterica serovar typhimurium atcc 14028 was capable of internalizing in peanut seedpods and plants when exposed to inoculated soil and the edaphic factors that influenced uptake. intact dry virginia (dv) and fresh green virginia (gv) seedpods were exposed to soil containing 6.5 log (cfu/g) salmonella under different soil moisture conditions. internalization of s. typhimurium into peanut plants germinated in inoculated soil was also examined with and withou ...201728576367
signal transduction pathway mediated by the novel regulator loia for low oxygen tension induced salmonella typhimurium invasion.salmonella enterica serovar typhimurium (s. typhimurium) is a major intestinal pathogen of both humans and animals. salmonella pathogenicity island 1 (spi-1)-encoded virulence genes are required for s. typhimurium invasion. while oxygen (o2) limitation is an important signal for spi-1 induction under host conditions, how the signal is received and integrated to the central spi-1 regulatory system in s. typhimurium is not clear. here, we report a signal transduction pathway that activates spi-1 e ...201728575106
patterns in antimicrobial susceptibility of salmonellae isolated at a tertiary care hospital in northern india.multidrug-resistant salmonellae have emerged worldwide as also in india. the aim of this study was to study the antimicrobial susceptibility pattern of salmonella enterica serovars isolated at a tertiary care hospital in northern india.201728574025
recovery of salmonella enterica from australian layer and processing environments following outbreaks linked to eggs. 201728570831
a toxin involved in salmonella persistence regulates its activity by acetylating its cognate antitoxin, a modification reversed by cobb sirtuin deacetylase.bacterial toxin-antitoxin systems trigger the onset of a persister state by inhibiting essential cellular processes. the tact toxin of salmonella enterica is known to induce a persister state in macrophages through the acetylation of aminoacyl-trnas. here, we show that the tact toxin and the taca antitoxin work as a complex that modulates tact activity via the acetylation state of taca. tact acetylates taca at residue k44, a modification that is removed by the nad(+)-dependent cobb sirtuin deace ...201728559487
sugar sulfates are not hydrolyzed by the acid-inducible sulfatase asla from salmonella enterica enteritidis nal(r) and kentucky 3795 at ph 5.5.the open reading frames sen0085 and seka_a4361, from salmonella enterica serovar enteritidis nal(r) and serovar kentucky 3795, respectively, corresponding to the acid-inducible sulfatase gene asla from salmonella enterica serovar typhimurium, were previously suggested by microarray analysis to be differentially expressed under acid conditions. however, growth and enzyme activity tests in the present study demonstrated that both wild-type strains exhibited sulfatase activity with 4-nitrophenyl su ...201728558253
structural and functional dissection reveals distinct roles of ca2+-binding sites in the giant adhesin siie of salmonella enterica.the giant non-fimbrial adhesin siie of salmonella enterica mediates the first contact to the apical site of epithelial cells and enables subsequent invasion. siie is a 595 kda protein composed of 53 repetitive bacterial immunoglobulin (big) domains and the only known substrate of the spi4-encoded type 1 secretion system (t1ss). the crystal structure of big50-52 of siie revealed two distinct ca2+-binding sites per big domain formed by conserved aspartate or glutamate residues. in a mutational ana ...201728558023
global gene-expression analysis of the response of salmonella enteritidis to egg white exposure reveals multiple egg white-imposed stress responses.chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. the key features of the egg white anti-bacterial system are iron restriction, high ph, antibacterial peptides and proteins, and viscosity. salmonella enterica serovar enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the har ...201728553268
the in vitro and in vivo protective effects of tannin derivatives against salmonella enterica serovar typhimurium infection.in this study, we investigated the protective effects of tannin-derived components, gallic acid (ga) and tannic acid (ta), in vitro and in vivo against salmonella infection in mice. both ga and ta showed antibacterial effects against salmonella (s.) typhimurium as well as inhibitory effects on the adherence, invasion, and intracellular growth of the pathogens in macrophages. following a lethal dose of salmonella infection in mice, reduced virulence in both ga- and ta-treated groups was observed ...201728552635
evaluation of radio-frequency heating in controlling salmonella enterica in raw shelled almonds.this study was conducted to investigate the efficacy of radio-frequency (rf) heating to reduce salmonella enterica serovars enteritidis, typhimurium, and senftenberg in raw shelled almonds compared to conventional convective heating, and the effect of rf heating on quality by measuring changes in the color and degree of lipid oxidation. agar-grown cells of three pathogens were inoculated onto the surface or inside of raw shelled almonds using surface inoculation or the vacuum perfusion method, r ...201728551280
quantitative proteomic analysis of host epithelial cells infected by salmonella enterica serovar typhimurium.systems-level analyses have the capability to offer new insight into host-pathogen interactions on the molecular level. using salmonella infection of host epithelial cells as a model system, we previously analyzed intracellular bacterial proteome as a window into pathogens' adaptations to their host environment [infect. immun. 2015; j. proteome res. 2017]. herein we extended our efforts to quantitatively examine protein expression of host cells during infection. in total, we identified more than ...201728544771
first detection of a fosfomycin resistance gene, fosa7, in salmonella enterica serovar heidelberg isolated from broiler chickens.we previously described salmonella enterica serovar heidelberg isolates harboring a chromosomal gene cluster similar to the glutathione s-transferase gene, a putative fosa gene conferring resistance to fosfomycin. here, we show that this new gene, named fosa7, confers resistance to fosfomycin. the introduction of fosa7 into the fosfomycin-susceptible salmonella enterica serovar enteritidis resulted in a substantial increase in the fosfomycin mic. this finding increases the awareness of antibioti ...201728533247
Refresh
firstprev
12345678910...
nextlast
Displaying items 301 - 400 of 11731