Publications

the salmonella enterica sv. typhimurium smva, yddg and ompd (porin) genes are required for the efficient efflux of methyl viologen.	in gram-negative bacteria, a subset of inner membrane proteins in the major facilitator superfamily (mfs) acts as efflux pumps to decrease the intracellular concentrations of multiple toxic substrates and confers multidrug resistance. the salmonella enterica sv. typhimurium smva gene encodes a product predicted to be an mfs protein most similar to qaca of staphylococcus aureus. like mutations in qaca, mutations in smva confer increased sensitivity to methyl viologen (mv). mutations in the adjace ...	2002	12410826
molecular and functional analysis of the type iii secretion signal of the salmonella enterica invj protein.	central to the pathogenicity of salmonella enterica is the function of a type iii secretion system (ttss) encoded within a pathogenicity island at centisome 63 (spi-1). an essential component of this system is a supramolecular structure termed the needle complex. proteins to be delivered into host cells possess specific signals that route them to the type iii secretion pathway. in addition, some bacterial proteins have signals that deliver them to the secretion complex to either become their str ...	2002	12410834
salmonella vaccines for use in humans: present and future perspectives.	in recent years there has been significant progress in the development of attenuated salmonella enterica serovar typhi strains as candidate typhoid fever vaccines. in clinical trials these vaccines have been shown to be well tolerated and immunogenic. for example, the attenuated s. enterica var. typhi strains cvd 908-htra (aroc arod htra), ty800 (phop phoq) and chi4073 (cya crp cdt) are all promising candidate typhoid vaccines. in addition, clinical trials have demonstrated that s. enterica var. ...	2002	12413664
potential salmonella transmission from ornamental fountains.	besides the usual food and drinking-water vehicles, there are other routes by which salmonella can be transmitted, especially at outdoor locations. public fountains containing salmonella offer models of exposure routes beyond those usually considered in the context of recreational use. the authors studied the bacteriological quality of water sampled from five ornamental fountains in guadalajara, mexico during two periods of six and of 10 months. coliform bacteria and escherichia coli were detect ...	2002	12415885
common themes among bacteriophage-encoded virulence factors and diversity among the bacteriophages involved.	there are common themes among bacteriophage-encoded virulence factors, which include the well-characterized bacterial toxins and proteins that alter antigenicity as well as several new classes of bacteriophage-encoded proteins such as superantigens, effectors translocated by a type iii secretion system, and proteins required for intracellular survival and host cell attachment. these virulence factors are encoded by a diversity of bacteriophages, members of the viral families siphoviridae, podovi ...	2002	12419617
identification of salmonella enterica serovar typhimurium genes associated with growth suppression in stationary-phase nutrient broth cultures and in the chicken intestine.	over 2,800 tn 5 insertion mutants of salmonella enterica sv. typhimurium were screened for the loss of ability to suppress the multiplication of a spectinomycin-resistant (spc(r)) but otherwise isogenic s. enterica sv. typhimurium strain, when the spc(r) mutant was added to 24-h lb broth cultures of the mutants. selected "growth non-suppressive" (gns) mutants were defective in respiration (insertions in arca and fnr), amino acid biosynthesis (aroa and arod), nutrient uptake and its regulation (t ...	2002	12420160
antimicrobial-resistant salmonella enterica serovars isolated from chickens in spain.	in order to analyze the antibiotic resistance of salmonella enterica serovars, a total of 112 salmonella strains were tested (54 s. enteritidis, 32 s. typhimurium, 11 s. heidelberg, 7 s. infantis, 4 s. virchow and 4 s. hadar). the bacteria were isolated from 691 samples of frozen and fresh chicken meat. identification of microorganisms and antimicrobial sensitivity testing were undertaken by means of the automated microscan autoscan 4 method (baxter in spain). 45.5% of 112 strains tested were su ...	2002	12420851
salmonella enterica serotype typhimurium dt104 isolated from humans, united states, 1985, 1990, and 1995.	first isolated from an ill person in 1985, multidrug-resistant salmonella enterica serotype typhimurium dt104 emerged in the mid-1990s as a strain of salmonella frequently isolated from humans in the united states. we compared the integron content, plasmid profile, and xbai pulsed-field gel electrophoresis (pfge) patterns of multidrug-resistant s. typhimurium dt104 (mr-dt104) isolated from humans in the united states in 1985, 1990, and 1995. all isolates contained a 60-mda plasmid and had indist ...	2002	11971772
salmonella enterica serotype typhimurium dt 104 antibiotic resistance genomic island i in serotype paratyphi b.	we have identified salmonella genomic island i (sgi1) in an isolate of salmonella enterica serotype paratyphi b. this antibiotic-resistance gene cluster, which confers multidrug resistance, has been previously identified in s. enterica serotype typhimurium phage types dt 104 and dt 120 and in s. enterica serotype agona.	2002	11971780
multiply resistant (mr) salmonella enterica serotype typhimurium dt 12 and dt 120: a case of mr dt 104 in disguise?	multiresistant salmonella enterica serotype typhimurium definitive phage type (dt) 12 and dt 120 are more closely related to dt 104 than to non-multiresistant strains of their respective phage types. multiresistant dt 12 and dt 120 appear to have arisen due to changes in phage susceptibility of dt 104 rather than horizontal transfer of resistance genes.	2002	11971781
salmonella enterica serotype enteritidis phage type 4b outbreak associated with bean sprouts.	in november 2000 in the netherlands, an outbreak of salmonella enterica serotype enteritidis phage type 4b was investigated. eating bean sprouts was the only exposure associated with s. enteritidis pt 4b infection (matched odds ratio 13.0, 95% confidence interval 2.0-552.5). contaminated seeds were the most likely cause of contamination of the sprouts. the sprout grower applied a concentration of hypochlorite solution that was too low for seed disinfection.	2002	11971783
insertions in the anticodon loop of trna1gln(sufg) and trna(lys) promote quadruplet decoding of caaa.	base insertion mutations in the anticodons of two different escherichia coli trnas have been isolated that allow suppression of a series of +1 frameshift mutations. insertion of a u between positions 34 and 35 of trnagln1 or addition of a g between positions 36 and 37 of trna(lys) expand the anticodons of both trnas similarly to 3'-guuu(-5') and allow decoding of complementary 5'-caaa(-3') quadruplets. analysis of the suppressed mrna sequences suggests that suppression occurs by pairing of the e ...	2002	11972336
mg2+ homeostasis and avoidance of metal toxicity.	because mg2+ is required for a wide variety of cellular functions, its intracellular levels must be tightly regulated. in the gram-negative bacterium salmonella enterica, three transporters mediate mg2+ uptake: the p-type atpases mgta and mgtb, whose expression is transcriptionally induced in low mg2+ by the mg2+-regulated phop/phoq two-component system; and cora, whose transcription is regulated neither by the levels of mg2+ nor by the phop/phoq system. we now report that mutants defective in p ...	2002	11972791
salmonella enterica infections in market swine with and without transport and holding.	the objective of this study was to compare, by using identical sample types, the salmonella enterica prevalences and serovar diversities between pigs necropsied on the farm and those necropsied at the abattoir after transport and holding. we necropsied 567 market weight pigs (>70 kg) from six herds. pigs were alternately assigned to be necropsied on the farm or at the abattoir. one-half of the group was sent in clean, disinfected trailers to slaughter at a commercial abattoir. after transport (m ...	2002	11976111
the evolving genome of salmonella enterica serovar pullorum.	salmonella enterica serovar pullorum is a fowl-adapted bacterial pathogen that causes dysentery (pullorum disease). host adaptation and special pathogenesis make s. enterica serovar pullorum an exceptionally good system for studies of bacterial evolution and speciation, especially regarding pathogen-host interactions and the acquisition of pathogenicity. we constructed a genome map of s. enterica serovar pullorum rks5078, using i-ceui, xbai, avrii, and spei and tn10 insertions. pulsed-field gel ...	2002	11976291
identification of two prpdbc gene clusters in corynebacterium glutamicum and their involvement in propionate degradation via the 2-methylcitrate cycle.	genome sequencing revealed that the corynebacterium glutamicum genome contained, besides glta, two additional citrate synthase homologous genes (prpc) located in two different prpdbc gene clusters, which were designated prpd1b1c1 and prpd2b2c2. the coding regions of the two gene clusters as well as the predicted gene products showed sequence identities of about 70 to 80%. significant sequence similarities were found also to the prpbcde operons of escherichia coli and salmonella enterica, which a ...	2002	11976302
elevated levels of ketopantoate hydroxymethyltransferase (panb) lead to a physiologically significant coenzyme a elevation in salmonella enterica serovar typhimurium.	pantothenate is the product of the atp-dependent condensation of pantoate and beta-alanine and is a direct precursor of coenzyme a. a connection exists between pantothenate biosynthesis and thiamine biosynthesis in salmonella enterica serovar typhimurium since derivatives of a purf mutant that can grow (on glucose medium) in the absence of thiamine excrete pantothenate. we show here that the causative mutation in three such mutants was the addition of a cg base pair upstream of the panb gene. th ...	2002	11976313
two class ii d-tagatose-bisphosphate aldolases from enteric bacteria.	escherichia coli, salmonella enterica, klebsiella pneumoniaeand klebsiella oxytocawere found to contain two d-tagatose 1,6-bisphosphate (tagbp)-specific aldolases involved in catabolism of galactitol (genes gaty gatz) and of n-acetyl-galactosamine and d-galactosamine (genes kbay kbaz,also called agay agaz). the two aldolases were closely related (> or = 53.8% identical amino acids) and could substitute for each other in vivo. the catalytic subunits gaty or kbay alone were sufficient to show aldo ...	2002	11976750
how do bacteria resist human antimicrobial peptides?	cationic antimicrobial peptides (camps), such as defensins, cathelicidins and thrombocidins, are an important human defense mechanism, protecting skin and epithelia against invading microorganisms and assisting neutrophils and platelets. staphylococcus aureus, salmonella enterica and other bacterial pathogens have evolved countermeasures to limit the effectiveness of camps, including the repulsion of camps by reducing the net negative charge of the bacterial cell envelope through covalent modifi ...	2002	11912025
bacterial superoxide dismutase and virulence.		2002	11912905
characterization of the campylobacter jejuni heptosyltransferase ii gene, waaf, provides genetic evidence that extracellular polysaccharide is lipid a core independent.	campylobacter jejuni produces both lipooligosaccharide (los) and a higher-molecular-weight polysaccharide that is believed to form a capsule. the role of these surface polysaccharides in c. jejuni-mediated enteric disease is unclear; however, epitopes associated with the los are linked to the development of neurological complications. in escherichia coli and salmonella enterica serovar typhimurium the waaf gene encodes a heptosyltransferase, which catalyzes the transfer of the second l-glycero-d ...	2002	11914340
gene transfer between salmonella enterica serovar typhimurium inside epithelial cells.	virulence and antibiotic resistance genes transfer between bacteria by bacterial conjugation. conjugation also mediates gene transfer from bacteria to eukaryotic organisms, including yeast and human cells. predicting when and where genes transfer by conjugation could enhance our understanding of the risks involved in the release of genetically modified organisms, including those being developed for use as vaccines. we report here that salmonella enterica serovar typhimurium conjugated inside cul ...	2002	11914355
salmonella effectors within a single pathogenicity island are differentially expressed and translocated by separate type iii secretion systems.	pathogenicity islands (pais) are large dna segments in the genomes of bacterial pathogens that encode virulence factors. five pais have been identified in the gram-negative bacterium salmonella enterica. two of these pais, salmonella pathogenicity island (spi)-1 and spi-2, encode type iii secretion systems (ttss), which are essential virulence determinants. these 'molecular syringes' inject effectors directly into the host cell, whereupon they manipulate host cell functions. these effectors are ...	2002	11918798
an evaluation of the performance of xld, dca, mlcb, and abc agars as direct plating media for the isolation of salmonella enterica from faeces.	to compare the performance of four media, singly and in combination, as direct plating media for the isolation of salmonella enterica from human faeces.	2002	11919214
salmonella enterica serovar enteritidis burden in broiler breeder chicks genetically associated with vaccine antibody response.	the relationship between antibody response to salmonella enteritidis vaccine and internal organ burden of s. enteritidis is not fully understood. the genetic relationship, therefore, between postchallenge s. enteritidis burden and antibody response to s. enteritidis vaccine was determined in broiler breeder chicks. sibling chicks from a broiler breeder male line were either inoculated with a pathogenic s. enteritidis or vaccinated with a commercial s. enteritidis vaccine. spleen, liver, cecal wa ...	2002	11922346
neutrophil phagocytosis following inoculation of salmonella choleraesuis into swine.	neutrophils are an important mediator of host defence, especially in early stages of infection. a major function of neutrophils is the uptake and killing of invading microbes. little is known about the effect of neutrophil activity on the pathogenesis and development of the carrier state in swine following infection with salmonella choleraesuis. a human whole-blood microassay using flow cytometry was modified to measure the effect of s. choleraesuis infection in vivo on the rate of ingestion, or ...	2002	11922481
comparison of gyra mutations, cyclohexane resistance, and the presence of class i integrons in salmonella enterica from farm animals in england and wales.	this study is focused on real-time detection of gyra mutations and of the presence of class i integrons in a panel of 100 veterinary isolates of salmonella enterica from farm animals. the isolates were selected on the basis of resistance to nalidixic acid, representing a variety of the most prevalent serotypes in england and wales. in addition, organic solvent (cyclohexane) resistance in these isolates was investigated in an attempt to elucidate the presence of efflux pump mechanisms. the most p ...	2002	11923377
identification of two phylogenetically related organisms from feces by pcr for detection of salmonella spp.	two previously reported pcr methods were evaluated to determine whether they are as sensitive and specific as conventional culture methods in detecting salmonella spp. from feces. bovine and equine feces were enriched overnight in brain heart infusion broth and assayed using pcr methods and primer sets described by other investigators. a total of 774 fecal specimens were tested using a primer set (inve-a primer set) that amplifies a region spanning the invasin e and a genes of salmonella enteric ...	2002	11923378
parotitis caused by salmonella choleraesuis varietas kunzendorf.		2002	11928112
salmonella enterica serotype typhimurium shda is an outer membrane fibronectin-binding protein that is expressed in the intestine.	the shda gene is the only determinant known to be required for persistence of salmonella enterica serotype typhimurium (s. typhimurium) in the murine caecum and for efficient and prolonged shedding of the organism with the faeces. to study the biological activity of the shda protein, we examined its expression and binding activity. shda was not detected with anti-shda antiserum in s. typhimurium strain atcc14028 grown in vitro, suggesting that this protein is not expressed under standard conditi ...	2002	11929540
envelope instability in dna adenine methylase mutants of salmonella enterica.	mutants of salmonella enterica serovar typhimurium lacking dna adenine (dam) methylase show reduced secretion of invasion effectors encoded in the salmonella-pathogenicity island 1 (spi-1). concomitant with this alteration, a high number and quantity of extracellular proteins are detected in cultures of dam(-) mutants. this study shows by subcellular fractionation analysis that the presence of numerous extracellular proteins in cultures of dam(-) mutants is linked to an exacerbated release of me ...	2002	11932461
antimicrobial susceptibility of actinobacillus pleuropneumoniae, escherichia coli, and salmonella choleraesuis recovered from taiwanese swine.	minimum inhibition concentrations (mics) were determined for ampicillin, ceftiofur, cephalothin, chloramphenicol, enrofloxacin, gentamicin, lincomycin, lincospectin (lincomycin/spectinomycin), neomycin, premafloxacin, spectinomycin, sulfamethoxazole/trimethoprim, and tetracycline against a total of 180 isolates of actinobacillus pleuropneumoniae, escherichia coli, and salmonella choleraesuis (60 each) clinically isolated from pigs on farms in taiwan from 1994 to 1996. no more than 3 isolates per ...	2002	11939337
three-dimensional structure of the l-threonine-o-3-phosphate decarboxylase (cobd) enzyme from salmonella enterica.	the three-dimensional structure of the pyridoxal 5'-phosphate (plp)-dependent l-threonine-o-3-phosphate decarboxylase (cobd) from salmonella enterica is described here. this enzyme is responsible for synthesizing (r)-1-amino-2-propanol phosphate which is the precursor for the linkage between the nucleotide loop and the corrin ring in cobalamin. the molecule is a molecular dimer where each subunit consists of a large and small domain. overall the protein is very similar to the members of the fami ...	2002	11939774
population heterogeneity of salmonella enterica serotype typhimurium resulting from phase variation of the lpf operon in vitro and in vivo.	the lpf fimbrial operon oscillates between phase on and phase off expression states, thereby generating heterogeneity within s. enterica serotype typhimurium populations with regard to expression of long polar fimbrial antigens. to determine whether the proportion of lpf phase variants changes with growth conditions, the lpf phase on content of cultures was determined after in vitro and in vivo passage. after passage in luria-bertani (lb) broth for 120 generations, 96% of cells in a serotype typ ...	2002	11948147
mobility of a restriction-modification system revealed by its genetic contexts in three hosts.	the flow of genes among prokaryotes plays a fundamental role in shaping bacterial evolution, and restriction-modification systems can modulate this flow. however, relatively little is known about the distribution and movement of restriction-modification systems themselves. we have isolated and characterized the genes for restriction-modification systems from two species of salmonella, s. enterica serovar paratyphi a and s. enterica serovar bareilly. both systems are closely related to the pvuii ...	2002	11948154
competitive exclusion of salmonella enterica serovar enteritidis by lactobacillus crispatus and clostridium lactatifermentans in a sequencing fed-batch culture.	competitive exclusion of salmonella enterica serovar enteritidis by a mixed culture of lactobacillus crispatus and clostridium lactatifermentans was studied in a sequencing fed-batch reactor mimicking the cecal ecophysiology of broiler chickens. growth of serovar enteritidis was inhibited by a mixed culture of l. crispatus and c. lactatifermentans at ph 5.8 but not by a monoculture of l. crispatus at the same ph. moreover, experiments performed at ph 7.0 did not show growth inhibition of serovar ...	2002	11823190
efficient insertion mutagenesis strategy for bacterial genomes involving electroporation of in vitro-assembled dna transposition complexes of bacteriophage mu.	an efficient insertion mutagenesis strategy for bacterial genomes based on the phage mu dna transposition reaction was developed. incubation of mua transposase protein with artificial mini-mu transposon dna in the absence of divalent cations in vitro resulted in stable but inactive mu dna transposition complexes, or transpososomes. following delivery into bacterial cells by electroporation, the complexes were activated for dna transposition chemistry after encountering divalent metal ions within ...	2002	11823210
selective amplification of tyv (rfbe), prt (rfbs), viab, and flic genes by multiplex pcr for identification of salmonella enterica serovars typhi and paratyphi a.	the pcr primers for o, h, and vi antigen genes, tyv (rfbe), prt (rfbs), flic-d, flic-a, and viab, were designed and used for the rapid identification of salmonella enterica serovars typhi and paratyphi a with multiplex pcr. the results showed that all the clinical isolates examined of salmonella serovars typhi and paratyphi a were accurately identified by this assay.	2002	11825983
[reactive arthritis after recent infection with group a beta-hemolytic streptococcus and group b salmonella].		2002	11827664
abomasitis associated with multiple antibiotic resistant salmonella enterica serotype typhimurium phagetype dt104.	salmonella enterica serotype typhimurium phagetype dt104 is a multiple antibiotic resistant pathogen that has been purported to be more pathogenic than other salmonella. in this study, we evaluated the possibility that dt104 is the causative agent of veal calf abomasitis observed in four independent outbreaks of salmonellosis. this study was undertaken to determine if the outbreaks might be due to hypervirulent s. enterica serotype typhimurium phagetype dt104 (dt104) since salmonella does not us ...	2002	11852190
type iii secretion of salmonella enterica serovar typhimurium translocated effectors and ssefg.	the type iii secretion system (ttss) encoded by salmonella enterica serovar typhimurium pathogenicity island 2 (spi2) is employed by salmonella enterica for interaction with host cells during the intracellular phase of pathogenesis. this ttss secretes a set of spi2-encoded proteins in vitro and translocates salmonella serovar typhimurium translocated effectors (ste) that are encoded by genes outside of spi2 into host cells. using an epitope-tagging approach, we analyzed secretion of proteins by ...	2002	11854226
extracellular antigens from salmonella enteritidis induce effective immune response in mice after oral vaccination.	we have studied polyacryl starch microparticles as an adjuvant in oral vaccination in mice. secreted antigens from salmonella enterica serovar enteritidis were administered covalently conjugated to microparticles, or as free antigens, orally or intramuscularly and evaluated for their immunogenicity and ability to elicit protective immune response against an oral challenge with live serovar enteritidis. the highest immunoglobulin m (igm)-plus-igg titers were obtained in the groups immunized with ...	2002	11854230
lipopolysaccharide-specific but not anti-flagellar immunoglobulin a monoclonal antibodies prevent salmonella enterica serotype enteritidis invasion and replication within hep-2 cell monolayers.	the protective potential of immunoglobulin a (iga) monoclonal antibodies (mabs) directed against o and h antigens of salmonella enterica serotype enteritidis to prevent bacterial adhesion to and invasion of hep-2 cells was evaluated. although anti-flagellar iga mabs showed strong agglutinating capacities, they did not protect cell monolayers. in contrast, iga mabs specific for the o:9 epitope of salmonella lipopolysaccharide antigen alone prevented s. enterica serotype enteritidis entry and repl ...	2002	11854252
analyses of the evolutionary distribution of salmonella translocated effectors.	the type iii secretion system encoded by salmonella pathogenicity island 2 (spi2) translocates salmonella translocated effectors (ste) into host cells. ste are encoded by genes outside of spi2. the distribution of ste loci within the salmonellae was investigated. in contrast to the spi2 locus that is conserved within salmonella enterica, ste loci show a variable distribution. in addition to other virulence determinants, the possession of various sets of ste loci may contribute to the different h ...	2002	11854253
salmonella enterica serotype typhimurium and its host-adapted variants.		2002	11953356
genome-based identification of chromosomal regions specific for salmonella spp.	acquisition of genomic elements by horizontal gene transfer represents an important mechanism in the evolution of bacterial species. pathogenicity islands are a subset of horizontally acquired elements present in various pathogens. these elements are frequently located adjacent to trna genes. we performed a comparative genome analysis of salmonella enterica serovars typhi and typhimurium and escherichia coli and scanned trna loci for the presence of species-specific, horizontally acquired genomi ...	2002	11953370
a superoxide-hypersusceptible salmonella enterica serovar typhimurium mutant is attenuated but regains virulence in p47(phox-/-) mice.	salmonella enterica serovar typhimurium is a gram-negative, facultative intracellular pathogen that predominantly invades mononuclear phagocytes and is able to establish persistent infections. one of the innate defense mechanisms of phagocytic cells is the production of reactive oxygen species, including superoxide. s. enterica serovar typhimurium has evolved mechanisms to resist such radicals, and these mechanisms could be decisive in its ability to survive and replicate within macrophages. rec ...	2002	11953403
biofilm formation and interaction with the surfaces of gallstones by salmonella spp.	salmonellae can exist in an asymptomatic carrier state in the human gallbladder. individuals with gallstones are more likely to become typhoid carriers, and antibiotic treatments are often ineffectual against salmonella enterica serovar typhi in carriers with gallstones. therefore, we hypothesized that salmonella spp. form biofilms on the surfaces of gallstones, where the bacteria are protected from high concentrations of bile and antibiotics. a number of methods were utilized to examine biofilm ...	2002	11953406
antimicrobial resistance in salmonella enterica serovars enteritidis and typhimurium isolated from animals in korea: comparison of phenotypic and genotypic resistance characterization.	fourteen and 22 each of salmonella enteritidis and salmonella typhimurium (s. typhimurium) were isolated from animals from 1983 to 1999 in korea and tested for their antibiotic resistance patterns, phage types and resistance gene patterns. s. typhimurium isolates were highly resistant to streptomycin, sulfisoxazole and tetracycline, 95, 95 and 86%, respectively. the incidence of multiple antibiotic resistance (resistant to more than two drugs tested) of s. typhimurium isolates was extremely high ...	2002	11955779
differences between national reference laboratories of the european community in their ability to serotype salmonella species.	the capacity of national reference laboratories of the european union member states to correctly serotype salmonella strains was assessed in four collaborative studies on serotyping in the period 1995-1999. participants were asked to identify 20 strains in studies i, ii and iii and 16 strains in study iv, using the typing method routinely performed in their laboratory. in the first study, the strains to be identified belonged to salmonella enterica subsp. enterica, salamae or houtenae, while in ...	2002	11957022
lack of interaction of fluoroquinolones with lipopolysaccharides.	fluoroquinolones are known to chelate with di- and trivalent cations, and it has accordingly been claimed that they perturb the integrity of the outer membrane (om) of gram-negative bacteria. so far, chelation has not been assessed in biologically relevant test systems. therefore, we investigated the interaction of ciprofloxacin and moxifloxacin in the absence and presence of mg2+ with whole bacteria and isolated lipopolysaccharide (lps) from various rough mutant strains of salmonella enterica c ...	2002	11959601
characterization of a laboratory-derived, high-level ampicillin-resistant salmonella enterica serovar typhimurium strain that caused meningitis in an infant.	a salmonella enterica serovar typhimurium strain that harbored a plasmid carrying a tem-1-type beta-lactamase gene was isolated from the blood and cerebrospinal fluid of an infant with meningitis. this 3.2-kb plasmid was further characterized to be a nonconjugative pgem series cloning vector containing a foreign insert. the strain was likely laboratory derived and contaminated the environment before it caused the infection.	2002	11959613
attenuated salmonella enterica serovar typhi live vector with inducible chromosomal expression of the t7 rna polymerase and its evaluation with reporter genes.	attenuated salmonella strains with defined gene deletions have been extensively evaluated as suitable live carriers of passenger antigens. a number of strategies for antigen delivery by these strains have been attempted, ranging from plasmid-based to chromosomal integration systems. we report here the chromosomal integration of the t7 rna polymerase gene (t7pol) in the attenuated strain salmonella enterica serovar typhi (salmonella typhi) cvd908 (aroc(-), arod(-)). the t7pol gene was amplified b ...	2002	11982332
invasive food poisoning caused by salmonella oranienburg.		2002	11982885
bromoperoxidase activity of vanadate-substituted acid phosphatases from shigella flexneri and salmonella enterica ser. typhimurium.	vanadium haloperoxidases and the bacterial class a nonspecific acid phosphatases have a conserved active site. it is shown that vanadate-substituted recombinant acid phosphatase from shigella flexneri (phon-sf) and salmonella enterica ser. typhimurium (phon-se) in the presence of h2o2 are able to oxidize bromide to hypobromous acid. vanadate is essential for this activity. the kinetic parameters for the artificial bromoperoxidases have been determined. the km value for h2o2 is about the same as ...	2002	11985594
increasing quinolone resistance in salmonella enterica serotype enteritidis.	until recently, salmonella enterica serotype enteritidis has remained sensitive to most antibiotics. however, national surveillance data from denmark show that quinolone resistance in s. enteritidis has increased from 0.8% in 1995 to 8.5% in 2000. these data support concerns that the current use of quinolone in food animals leads to increasing resistance in s. enteritidis and that action should be taken to limit such use.	2002	11996688
[will the effectiveness of the immunization of chicks with live salmonella vaccines be affected by maternal antibodies?].	in the progeny of breeder birds which had been vaccinated with live salmonella typhimurium and inactivated salmonella enteritidis vaccines, the caecal and systemic colonisation by a live salmonella enteritidis and a live salmonella typhimurium vaccine was studied. the efficacy of the oral immunisation of chicks from vaccinated and non-vaccinated breeders with a live salmonella enteritidis vaccine on day 1 of age was studied by an experimental challenge with salmonella enteritidis on day 30 of ag ...	2002	11998364
phage typing and pfge pattern analysis as tools for epidemiological surveillance of salmonella enterica serovar bovismorbificans infections.	some years ago, an increase in the number of sporadic cases and outbreaks of salmonellosis due to s. enterica serovar bovismorbificans was observed in several european countries including finland, sweden, england/wales, austria, and germany. in order to understand the recent spread of this serovar and to trace the route of infection back to its source, it was considered necessary to subtype s. bovismorbificans isolates. using phage typing (newly described here) and molecular fingerprinting (pfge ...	2002	12002528
is200 fingerprinting of salmonella enterica serotype abortusovis strains isolated in iran.	salmonella enterica serovar abortusovis is one of the most common pathogens responsible for abortion in sheep. in iran, the spread of abortusovis is highly dependent on the nomadic life style. in this study we performed is200 fingerprinting to identify the clonal lines circulating in iran. all the isolates contained 4 or 5 copies of the transposon and could be classified in 4 genotypes. a single genotype was highly prevalent and very likely it has circulated in iran since 1970. all the isolates ...	2002	12002552
composite integron array generated by insertion of an orf341-type integron within a tn21-like element.	two class 1 integrons, in-t1 and in-t2, were previously identified in incfi plasmids of salmonella enterica serotype typhimurium. molecular analysis revealed a close physical link between the two integrons. in-t1 is preceded by the transposase genes of tn21, whereas in-t2 is located downstream the 3'-conserved segment (3'-cs) of in-t1, in a head-to-tail configuration. in-t1 shows a peculiar sequence downstream the 3'-cs, containing an extended version of the open reading frame known as orf341 (r ...	2002	12002644
nucleotide and amino acid sequences of orit-tram-traj-tray-traa-tral regions and mobilization of virulence plasmids of salmonella enterica serovars enteritidis, gallinarum-pullorum, and typhimurium.	the virulence plasmid of salmonella enterica serovar gallinarum-pullorum (pspv) but not those of salmonella enterica serovars enteritidis (psev) and typhimurium (pstv) can be readily mobilized by an f or f-like conjugative plasmid. to investigate the reason for the difference, the orit-tram-traj-tray-traa-tral regions of the three salmonella virulence plasmids (psvs) were cloned and their nucleotide and deduced amino acid sequences were examined. the cloned fragments were generally mobilized mor ...	2002	12003924
argr-independent induction and argr-dependent superinduction of the astcadbe operon in escherichia coli.	for escherichia coli, growth in the absence of ammonia is termed nitrogen limited and results in the induction of genes that assimilate other nitrogen sources, a response mediated by sigma(54) and nitrogen regulator i (nr(i), also called ntrc). the astcadbe operon, which is required for growth with arginine as the sole nitrogen source, is moderately expressed during general nitrogen limitation and maximally expressed in the presence of arginine. the operon is also induced in stationary phase. pr ...	2002	12003934
fluoroquinolone resistance in salmonella serovars isolated from humans and food animals.	quinolone-resistant salmonella enterica usually contain a mutation in gyra within the region encoding the quinolone resistance determining region of the a subunit of dna gyrase. these mutations confer substitutions analogous to escherichia coli ser83-->phe and asp87-->gly or tyr, or a novel mutation resulting in ala119-->glu or val. mutations in gyrb are rare, and no mutations in parc or pare have been described. quinolone-resistant salmonella can also be cross-resistant to other agents includin ...	2002	12007640
characterisation of the diol dehydratase pdu operon of lactobacillus collinoides.	the three genes (pducde) encoding the diol dehydratase of lactobacillus collinoides were sequenced. they exhibited strong identities with the ddrabc and pducde genes of klebsiella oxytoca and salmonella enterica, respectively. these genes are part of a putative operon with at least four other genes. an eighth open reading frame was identified as homologous to the pocr gene (encoding the operon regulatory protein). although the enzyme was detected in exponential growth phase, pducde activity was ...	2002	12007656
development of a baculovirus expression system for soluble porcine tumor necrosis factor receptor type i and soluble porcine tumor necrosis factor receptor type i-igg fusion protein.	tumor necrosis factor-alpha (tnf-alpha) is a key mediator of inflammatory responses and gram-negative bacterial sepsis, but the role that it plays during salmonella enterica species bacterial infections in swine has not yet been elucidated. to facilitate studies on the role of tnf-alpha on the pathology associated with salmonella infections in pigs, recombinant soluble porcine tnf receptor type i (rsptnf-ri) and soluble tnf receptor type i fused to the fc region of porcine igg1 (rsptnf-ri-igg) w ...	2002	12007891
temperate phages in salmonella enterica serovar typhimurium: implications for epidemiology.	salmonella enterica serovar typhimurium is the most common salmonella serovar isolated from humans in australia. the most common definitive phage types (dt) include 9, 64 and 135. induction of lysogenic phages from dt 64 with mitomycin c followed by cesium chloride gradient purification, resulted in separation of two populations of phage particles. dna extracted from these particles that was digested with smai showed two distinct patterns of banding. transmission electron microscopy showed that ...	2002	12008917
modified pulsed-field gel electrophoresis method for dna degradation-sensitive salmonella enterica and escherichia coli strains.	a number of s. enterica and e. coli strains appeared sensitive to a rapid dna degradation during the course of pfge pattern analysis. this kind of dna degradation could not be stopped by intensive treatment with proteinase k, formalin treatment, or other modifications of the protocol for the isolation of intact chromosomal dna. however, the application of 100 microm thiourea into the running buffer gave rise to clear-cut pfge patterns and in turn to an overall typeability.	2002	12008918
cytokine expression by attenuated intracellular bacteria regulates the immune response to infection: the salmonella model.	attenuated salmonella strains have shown excellent efficacy as mucosal vaccine delivery systems. in the present report, several recombinant strains of salmonella enterica serovar typhimurium, engineered to express defined murine cytokines, were used to study their potential immunoregulatory capacity in the mouse model of typhoid fever. specifically, recombinant strains expressing il-2 (known as gidil2) or tnf-alpha (gidtnf) were compared with the parental, non-cytokine-secreting, strain (brd509) ...	2002	12009571
combination of pulsed-field gel electrophoresis (pfge) and single-enzyme amplified fragment length polymorphism (saflp) for differentiation of multiresistant salmonella enterica serotype typhimurium.	to assess the combined application of plasmid profile typing, pulsed-field gel electrophoresis (pfge) and pcr-based single-enzyme amplified fragment length polymorphism (saflp) for the differentiation of 18 multiresistant (mr) and one drug-sensitive strain of salmonella enterica serotype typhimurium from humans and food animals.	2002	12010170
sifa, a type iii secreted effector of salmonella typhimurium, directs salmonella-induced filament (sif) formation along microtubules.	a unique feature of salmonella enterica serovar typhimurium (s. typhimurium) is its ability to enter into (invade) epithelial cells and elongate the vacuole it occupies into tubular structures called salmonella-induced filaments (sifs). this phenotype is dependent on sifa, a salmonella virulence factor that requires the spi-2-encoded type iii secretion system for delivery into host cells. previous attempts to study sifa and other type iii secreted proteins have been limited by a lack of suitable ...	2002	12010459
the effect of genomic position on reversion of a lac frameshift mutation (laciz33) during non-lethal selection (adaptive mutation).	in a system described by cairns and foster, starvation of a particular leaky lac mutant (laciz33) in the presence of lactose appears to direct mutation in non-growing cells to sites that allow growth (adaptive mutation). this behaviour requires that the lac operon be located on an f' plasmid. this position effect was investigated by placing the mutant lac operon at many sites in the genome of salmonella enterica (typhimurium; lt2) and testing reversion behaviour. genomic position did not affect ...	2002	12010495
genetic diversity of salmonella enterica serovar paratyphi a from different geographical regions in asia.	subtyping of salmonella paratyphi a isolates from india, pakistan, indonesia and malaysia was carried out by pulsed-field gel electrophoresis (pfge) to assess the extent of genetic diversity of these isolates from different endemic countries.	2002	12010557
role of nitric oxide in host defense in murine salmonellosis as a function of its antibacterial and antiapoptotic activities.	host defense functions of nitric oxide (no) are known for many bacterial infections. in this study, we investigated the antimicrobial effect of no in murine salmonellosis by using inducible no synthase (inos)-deficient mice infected with an avirulent or virulent salmonella enterica serovar typhimurium strain. all inos-deficient mice died of severe septicemia within 6 days after intraperitoneal injection with an avirulent strain (lt2) to which wild-type mice were highly resistant; 50% lethal dose ...	2002	12011007
disruption of the salmonella-containing vacuole leads to increased replication of salmonella enterica serovar typhimurium in the cytosol of epithelial cells.	salmonella enterica serovar typhimurium is a facultative intracellular pathogen that inhabits a vacuolar compartment, called the salmonella-containing vacuole (scv), in infected host cells. maintenance of the scv is accomplished by sifa, and mutants of this salmonella pathogenicity island 2 type iii effector replicate more efficiently in epithelial cells. here we demonstrate that enhanced replication of sifa mutants occurs in the cytosol of these cells. increased replication of wild-type bacteri ...	2002	12011022
characterization of the spv locus in salmonella enterica serovar arizona.	salmonella enterica serovar arizona (s. enterica subspecies iiia) is a common salmonella isolate from reptiles and can cause serious systemic disease in humans. the spv virulence locus, found on large plasmids in salmonella subspecies i serovars associated with severe infections, was confirmed to be located on the chromosome of serovar arizona. sequence analysis revealed that the serovar arizona spv locus contains homologues of spvrabc but lacks the spvd gene and contains a frameshift in spva, r ...	2002	12011028
genomic organization of lps-specific loci.		2002	12014174
factors affecting haemolysin production and congo red binding in salmonella enterica serovar typhimurium dt 98.	differences in haemolysin expression were observed in a strain of salmonella enterica serovar typhimurium definitive phage type (dt) 98 cultured under various conditions. haemolysin expression was optimal in cultures grown micro-aerobically. the zones of haemolysis were wider after longer periods of incubation. haemolysin production varied after growth in the following media (greatest to least): brain heart infusion (bhi) broth > nutrient broth (nb)>trypticase soy broth (tsb)> m-9 glucose medium ...	2002	12018658
characterization of variant salmonella genomic island 1 multidrug resistance regions from serovars typhimurium dt104 and agona.	strains of multidrug-resistant salmonella enterica serovar typhimurium dt104 (dt104) and s. enterica serovar agona (agona) have been found to harbor salmonella genomic island 1 (sgi1), a 43-kb genomic region that contains many of the drug resistance genes. such strains are resistant to ampicillin (pse-1), chloramphenicol/florfenicol (flor), streptomycin/spectinomycin (aada2), sulfonamides (sul1), and tetracycline [tet(g)] (commonly called the acssut phenotype). all five resistance genes are foun ...	2002	12019080
reducing mortality in salmonella enterica serovar typhimurium-infected mice with a tripeptidic serum fraction.	salmonellosis-induced mortality in female swiss webster mice decreased significantly when tripeptidic immunostimulant (tpi) was administered prophylactically. prophylactic benefits developed in a dose-dependent manner wherein 15 mg of tpi given 1 day before challenge reduced mortality by 70%.	2002	12019117
specific gyra mutation at codon 83 in nalidixic acid-resistant salmonella enterica serovar typhi strains isolated from vietnamese patients.		2002	12019140
the sctr of salmonella enterica serova typhimurium encoding a homologue of merr protein is involved in the copper-responsive regulation of cuid.	we have identified the cuid gene in salmonella enterica serova typhimurium that codes for a putative multicopper oxidase. expression of cuid is induced by copper ion and its promoter/operator has sequence similarity to the promoters controlled by the transcriptional regulators of the merr family. we also identified and isolated a gene from s. enterica serova typhimurium that encodes a 138-amino acid residue protein, sctr, a new member of the merr family of transcriptional regulators. transposon- ...	2002	12023084
heterogeneity in expression of lipopolysaccharide by strains of salmonella enterica serotype typhimurium definitive phage type 104 and related phage types.	to investigate lipopolysaccharide (lps) expression in salmonella enterica serotype typhimurium definitive phage type 104 (salmonella typhimurium dt104) and related phage types.	2002	12028424
regulation of salmonella enterica serovar typhimurium mnth transcription by h(2)o(2), fe(2+), and mn(2+).	mnth, a bacterial homolog of mammalian natural resistance associated macrophage protein 1 (nramp1), is a primary transporter for mn(2+) influx in salmonella enterica serovar typhimurium and escherichia coli. s. enterica serovar typhimurium mnth contributes to h(2)o(2) resistance and is important for full virulence. consistent with its phenotype and function, mnth is regulated at the transcriptional level by both h(2)o(2) and substrate cation. we have now identified three trans-acting regulatory ...	2002	12029030
sitabcd is the alkaline mn(2+) transporter of salmonella enterica serovar typhimurium.	mnth, a bacterial homolog of the mammalian natural resistance-associated macrophage protein 1 (nramp1), is a primary mn(2+) transporter of salmonella enterica serovar typhimurium and escherichia coli. s. enterica serovar typhimurium mnth expression is important for full virulence; however, strains carrying an mnth deletion are only partially attenuated and display no obvious signs of mn(2+) deficiency. we noted that promoter sequences for mnth and for the putative fe(2+) transporter sitabcd appe ...	2002	12029031
mig-14 is a salmonella gene that plays a role in bacterial resistance to antimicrobial peptides.	it was previously demonstrated that the mig-14 gene of salmonella enterica serovar typhimurium is necessary for bacterial proliferation in the liver and spleen of mice following intragastric inoculation and that mig-14 expression, which is induced within macrophages, is under the control of the global regulator phop. here we demonstrate that the mig-14 promoter is induced by growth in minimal medium containing low magnesium or acidic ph, consistent with regulation by phop. in addition, mig-14 is ...	2002	12029036
substrate recognition properties of oligopeptidase b from salmonella enterica serovar typhimurium.	oligopeptidase b (opdb) is a serine peptidase broadly distributed among unicellular eukaryotes, gram-negative bacteria, and spirochetes which has emerged as an important virulence factor and potential therapeutic target in infectious diseases. we report here the cloning and expression of the opdb homologue from salmonella enterica serovar typhimurium and demonstrate that it exhibits amidolytic activity exclusively against substrates with basic residues in p(1). while similar to its eukaryotic ho ...	2002	12029050
genomewide identification of proteins secreted by the hrp type iii protein secretion system of pseudomonas syringae pv. tomato dc3000.	the ability of pseudomonas syringae pv. tomato dc3000 to be pathogenic on plants depends on the hrp (hypersensitive response and pathogenicity) type iii protein secretion system and the effector proteins it translocates into plant cells. through iterative application of experimental and computational techniques, the dc3000 effector inventory has been substantially enlarged. five homologs of known avirulence (avr) proteins and five effector candidates, encoded by genes with putative hrp promoters ...	2002	12032338
inorganic polyphosphate is essential for long-term survival and virulence factors in shigella and salmonella spp.	the importance of inorganic polyphosphate (poly p) and poly p kinase (ppk), the enzyme principally responsible for its synthesis, has been established previously for stationary-phase survival of escherichia coli and virulence in pseudomonas aeruginosa. the gene (ppk) that encodes ppk is highly conserved among many bacterial pathogens, including shigella and salmonella spp. in view of the phylogenetic similarity of the enteropathogens and the frequency with which virulence factors are expressed i ...	2002	12032342
microsatellites linked to salmonella enterica serovar enteritidis burden in spleen and cecal content of young f1 broiler-cross chicks.	contamination of poultry and poultry products by salmonella enterica serovar enteritidis (se) continues to be problematic even though biosafety management practices have aided in reduction of the se burden. identification of molecular markers linked to disease resistance loci would further reduce se burden by enabling selection for genetic resistance. the objectives of this study were therefore to evaluate specific genomic regions for resistance to se burden in young broiler-cross chicks and to ...	2002	12033415
profile of salmonella enterica subsp. enterica (subspecies i) serotype 4,5,12:i:- strains causing food-borne infections in new york city.	strains of newly emerging salmonella enterica subsp. enterica (subspecies i) serotype 4,5,12:i:- causing food-borne infections, including a large food poisoning outbreak (n = 86) characterized by persistent diarrhea (14% bloody), abdominal pain, fever, and headache, were examined. the organisms were found in the stool samples from the patients. the biochemical profile of the organisms is consistent with that of s. enterica subsp. i serotypes, except for decreased dulcitol (13%) and increased ino ...	2002	12037044
molecular subtyping methods for detection of salmonella enterica serovar oranienburg outbreaks.	this study involved 82 salmonella enterica serovar oranienburg isolates from patients with gastroenteritis and/or focal infections, healthy carriers, and cuttlefish chips which were epidemiologically linked to a major outbreak that had affected 1,505 people in japan between 1998 and 1999. we concurrently investigated four different molecular subtyping methods using human salmonellosis-associated salmonella serovars and their applicability in detection of serovar oranienburg in an outbreak. pulse ...	2002	12037064
dna microarray-based typing of an atypical monophasic salmonella enterica serovar.	a multidrug-resistant fljb-lacking salmonella enterica serovar [4,5,12:i:-] emerged in spain in 1997. we analyzed the genome from four strains of this serovar using a microarray containing almost all the predicted protein coding regions of serovar typhimurium strain lt2, including the pslt plasmid. only a few differences from serovar typhimurium lt2 were observed, suggesting the serovar to be typhimurium as well. six regions of interest were identified from the microarray data. cluster i was a d ...	2002	12037067
detection of plasmid-mediated ampc beta-lactamase genes in clinical isolates by using multiplex pcr.	therapeutic options for infections caused by gram-negative organisms expressing plasmid-mediated ampc beta-lactamases are limited because these organisms are usually resistant to all the beta-lactam antibiotics, except for cefepime, cefpirome, and the carbapenems. these organisms are a major concern in nosocomial infections and should therefore be monitored in surveillance studies. six families of plasmid-mediated ampc beta-lactamases have been identified, but no phenotypic test can differentiat ...	2002	12037080
salmonella enterica serovar typhimurium and escherichia coli contamination of root and leaf vegetables grown in soils with incorporated bovine manure.	bovine manure, with or without added salmonella enterica serovar typhimurium (three strains), was incorporated into silty clay loam (scl) and loamy sand (ls) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers. the s. enterica serovar typhimurium inoculum was 4 to 5 log cfu/g in manure-fertilized soil. the conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily ...	2002	12039728
differences in growth of salmonella enterica and escherichia coli o157:h7 on alfalfa sprouts.	sprout producers have recently been faced with several salmonella enterica and escherichia coli o157:h7 outbreaks. many of the outbreaks have been traced to sprout seeds contaminated with low levels of human pathogens. alfalfa seeds were inoculated with s. enterica and e. coli o157:h7 strains isolated from alfalfa seeds or other environmental sources and sprouted to examine growth of these human pathogens in association with sprouting seeds. s. enterica strains grew an average of 3.7 log(10) on ...	2002	12039774
unusual salmonella enterica serotype typhimurium isolate producing cmy-7, shv-9 and oxa-30 beta-lactamases.	beta-lactam resistance in salmonella isolates is increasing. this paper describes the combination of three different beta-lactamases, oxa-30, shv-9 and cmy-7, expressed by an isolate of salmonella enterica serotype typhimurium. this is the first report of an isolate of salmonella having both an extended-spectrum beta-lactamase and an ampc beta-lactamase.	2002	12039894
thermodynamics of aminoglycoside and acyl-coenzyme a binding to the salmonella enterica aac(6')-iy aminoglycoside n-acetyltransferase.	kinetic and mechanistic studies on the chromosomally encoded aminoglycoside 6'-n-acetyltransferase, aac(6')-iy, of salmonella enterica that confers resistance toward aminoglycosides have been previously reported [magnet et al. (2001) biochemistry 40, 3700-3709]. in the present study, equilibrium binding and the thermodynamic parameters of binding of aminoglycosides and acyl-coenzyme a derivatives to aac(6')-iy and of two mutants, c109a and the c109a/c70a double mutant, have been studied using fl ...	2002	12044186
enhanced antimicrobial effects of combination of lactate and diacetate on listeria monocytogenes and salmonella spp. in beef bologna.	the antimicrobial activities of salts of organic acids such as lactate and acetate are well documented, but there is limited information on their effect when used in combination. we previously reported enhanced inhibition of listeria monocvtogenes and salmonella enterica serovar enteritidis in sterile comminuted beef at 5 and 10 degrees c by combinations of sodium lactate (sl) (2.5%) and sodium diacetate (sda) (0.2%). the present study was undertaken to evaluate the inhibitory effect of these sa ...	2002	12051475
prevalence of escherichia coli o157:h7 prophage-like sequences among german salmonella enterica serotype typhimurium phage types and their use in detection of phage type dt104 by the polymerase chain reaction.	a 1.6kb dna fragment identified by random amplifiable polymorphic dna differentiation (rapd) from a salmonella enterica serotype typhimurium phage type dt104 isolate was used to investigate the prevalence of the region in 160 dt104 isolates, 83 other epidemiological important s. typhimurium phage types and 20 strains selected from 17 other salmonella serotypes. pcr screening tests using two different primer-sets derived from the rapd fragment's nucleotide sequence showed that 76% of the 160 dt10 ...	2002	12052335
effect of fermented feed on shedding of enterobacteriaceae by fattening pigs.	epidemiological studies showed that the use of fermented feed could significantly reduce salmonella prevalence in pigs compared to the use of normal feed. experimental challenge experiments with salmonella have however never been conducted to reveal the efficacy of fermented feed in reducing salmonella shedding and/or reducing the number of salmonella-positive pigs. a longitudinal study was conducted to measure the effect of fermented feed, in particular of its components lactic acid and lactoba ...	2002	12052336