| construction and characterization of a salmonella enterica serovar typhimurium clone expressing a salivary adhesin of streptococcus mutans under control of the anaerobically inducible nirb promoter. | attenuated salmonella enterica serovar typhimurium has been used for targeted delivery of recombinant antigens to the gut-associated lymphoid tissues. one potential problem associated with this vaccine approach is the likelihood of in vivo instability of the plasmid constructs caused by constitutive hyperexpression of the heterologous immunogen. the aim of this study was to generate and characterize an expression system encoding the saliva-binding region (sbr) of streptococcus mutans antigen i/i ... | 2000 | 10678973 |
| antibacterial efficacy of gentamicin encapsulated in ph-sensitive liposomes against an in vivo salmonella enterica serovar typhimurium intracellular infection model. | encapsulation of gentamicin in liposomes can be used to achieve intracellular delivery and broaden the clinical utility of this drug. we have previously described a novel, rationally designed, ph-sensitive liposomal carrier for gentamicin that has superior in vitro efficacy against intracellular infections compared to the efficacies of both free gentamicin and non-ph-sensitive liposomal controls. this liposomal carrier demonstrated ph-sensitive fusion that was dependent on the presence of unsatu ... | 2000 | 10681314 |
| antibacterial activity of diospyrin, isodiospyrin and bisisodiospyrin from the root of diospyros piscatoria (gurke) (ebenaceae). | two dimeric naphthoquinones, diospyrin and isodiospyrin, isolated from the root of diospyros piscatoria (gurke), a common ingredient in several folk medicines, have been shown to have a broad spectrum of antibacterial activity. the minimum inhibitory concentrations (mics) of diospyrin against streptococcus pyogenes atcc 12344 and streptococcus pneumoniae atcc 33400 ranged from 1.56 to 50 microg/ml. while those against salmonella choleraesuis serotype typhi (s. typhi), atcc 6539 and mycobacterium ... | 2000 | 10685108 |
| ssra (tmrna) plays a role in salmonella enterica serovar typhimurium pathogenesis. | escherichia coli ssra encodes a small stable rna molecule, tmrna, that has many diverse functions, including tagging abnormal proteins for degradation, supporting phage growth, and modulating the activity of dna binding proteins. here we show that ssra plays a role in salmonella enterica serovar typhimurium pathogenesis and in the expression of several genes known to be induced during infection. moreover, the phage-like attachment site, attl, encoded within ssra, serves as the site of integratio ... | 2000 | 10692360 |
| specificity mutants of the binding protein of the oligopeptide transport system of lactococcus lactis. | the kinetic properties of wild-type and mutant oligopeptide binding proteins of lactococcus lactis were determined. to observe the properties of the mutant proteins in vivo, the oppa gene was deleted from the chromosome of l. lactis to produce a strain that was totally defective in oligopeptide transport. amplified expression of the oppa gene resulted in an 8- to 12-fold increase in oppa protein relative to the wild-type level. the amplified expression was paralleled by increased bradykinin bind ... | 2000 | 10692365 |
| levels of virulence are not determined by genomic lineage of salmonella enterica serotype enteritidis strains. | mouse virulence and the ability to adhere to, and invade cultured mdck cells were investigated in 38 phage type reference strains of salmonella enterica serotype enteritidis and correlated with genomic lineage. the genomic lineage of 11 of the strains was determined in the present study; one is200 and one ribotype pattern that had not been reported previously were observed. log c.f.u. in the spleen 10 days post intraperitoneal (i.p.) infection with 3x10(3) bacteria (logvc10) varied between 2.9 a ... | 1999 | 10694152 |
| antagonistic activity of lactobacillus acidophilus lb against intracellular salmonella enterica serovar typhimurium infecting human enterocyte-like caco-2/tc-7 cells. | to gain further insight into the mechanism by which lactobacilli develop antimicrobial activity, we have examined how lactobacillus acidophilus lb inhibits the promoted cellular injuries and intracellular lifestyle of salmonella enterica serovar typhimurium sl1344 infecting the cultured, fully differentiated human intestinal cell line caco-2/tc-7. we showed that the spent culture supernatant of strain lb (lb-scs) decreases the number of apical serovar typhimurium-induced f-actin rearrangements i ... | 2000 | 10698785 |
| development of a nonantibiotic dominant marker for positively selecting expression plasmids in multivalent salmonella vaccines. | we report the novel application of a herbicide-resistance-based dominant marker for the positive selection of expression plasmids in salmonella serovar vaccines. the beta-lactamase gene of the plasmid ptetnir15, which expresses fragment c of tetanus toxin (tetc), has been replaced with the bar gene marker. the new plasmid pbat1 can be positively selected in vitro within salmonella serovars in the presence of the herbicide dl-phosphinothricin. the expression of tetc remains unaltered, and the sal ... | 2000 | 10698796 |
| diagnostic and public health dilemma of lactose-fermenting salmonella enterica serotype typhimurium in cattle in the northeastern united states. | the presence of lactose-fermenting salmonella strains in clinical case materials presented to microbiology laboratories presents problems in detection and identification. failure to detect these strains also presents a public health problem. the laboratory methods used in detecting lactose-fermenting salmonella enterica serotype typhimurium from six outbreaks of salmonellosis in veal calves are described. each outbreak was caused by a multiply-resistant and lactose-fermenting strain of s. enteri ... | 2000 | 10699026 |
| multiple clones within multidrug-resistant salmonella enterica serotype typhimurium phage type dt104. the greek nontyphoidal salmonella study group. | six distinct clones were present among greek multidrug-resistant salmonella enterica serotype typhimurium phage type dt104, since isolates belonging to resistance phenotypes including the acssut (ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline) core could be distinguished with respect to their pulsed-field gel electrophoresis patterns, int1 integron structures, and presence or absence of antibiotic resistance genes ant(3'')-ia, pse-1, and tem-1. | 2000 | 10699039 |
| multidrug-resistant salmonella enterica serotype typhimurium dt104. | | 2000 | 10702060 |
| improved repetitive-element pcr fingerprinting of salmonella enterica with the use of extremely elevated annealing temperatures. | modified thermal cycling conditions were explored in an effort to improve the reproducibility and resolving power of repetitive-element pcr (rep-pcr) fingerprinting. assay performance was rigorously evaluated under standard and modified cycling conditions, using as a test set 12 strains putatively representing 12 serovars of salmonella enterica. for all three fingerprint types (eric2, boxa1r, and composite fingerprints), the use of extremely elevated annealing temperatures plus an initial "touch ... | 2000 | 10702502 |
| clinical application of a dot blot test for diagnosis of enteric fever due to salmonella enterica serovar typhi in patients with typhoid fever from colombia and peru. | clinical application of a dot blot test to detect immunoglobulin g (igg) (88% sensitivity and specificity) and igm (12.1% sensitivity and 97% specificity) against flagellar antigen from salmonella enterica serovar typhi was performed in peruvian and colombian patients with typhoid fever. this test can be used as a good predictor of serovar typhi infection in regions lacking laboratory facilities and in field studies. | 2000 | 10702512 |
| synergism between porcine reproductive and respiratory syndrome virus (prrsv) and salmonella choleraesuis in swine. | porcine reproductive and respiratory syndrome virus (prrsv) and salmonella choleraesuis are two leading causes of economic loss in the swine industry. while respiratory disease is common in both s. choleraesuis and prrsv infections, the factors that contribute to its development remain largely undefined. we investigated the interaction of prrsv, s. choleraesuis, and stress in 5-week-old swine. all combinations of three factors (inoculation with s. choleraesuis on day 0, prrsv on day 3, and treat ... | 2000 | 10703702 |
| prevalence of enteric zoonotic organisms in cats. | to determine prevalence of enteric zoonotic organisms in cats in north-central colorado. | 2000 | 10707683 |
| infections and intoxications associated with animal feed and forage which may present a hazard to human health. | animal feed or forage may be the source of a limited number of infections for farm animals that could lead to human illness. likely organisms include salmonella enterica, toxoplasma gondii, trichinella spiralis and possibly the agent of bovine spongiform encephalopathy. the risk to human health from other infectious agents which may contaminate either feed or forage appear to be either negligible, e.g. bacillus anthracis and mycobacterium bovis, or non-existent, e.g. clostridium botulinum toxin ... | 2000 | 10712800 |
| multiple factors independently regulate hila and invasion gene expression in salmonella enterica serovar typhimurium. | hila activates the expression of salmonella enterica serovar typhimurium invasion genes. to learn more about regulation of hila, we isolated tn5 mutants exhibiting reduced hila and/or invasion gene expression. in addition to expected mutations, we identified tn5 insertions in psts, fadd, flhd, flhc, and flia. analysis of the psts mutant indicates that hila and invasion genes are repressed by the response regulator phob in the absence of the pst high-affinity inorganic phosphate uptake system. th ... | 2000 | 10714991 |
| isolation and characterization of vich, encoding a new pleiotropic regulator in vibrio cholerae. | during the last decade, the hns gene and its product, the h-ns protein, have been extensively studied in escherichia coli. h-ns-like proteins seem to be widespread in gram-negative bacteria. however, unlike in e. coli and in salmonella enterica serovar typhimurium, little is known about their role in the physiology of those organisms. in this report, we describe the isolation of vich, an hns-like gene in vibrio cholerae, the etiological agent of cholera. this gene was isolated from a v. cholerae ... | 2000 | 10715012 |
| a community--wide outbreak of salmonella enterica serotype typhimurium infection associated with eating a raw milk soft cheese in france. | in 1997, a community-wide outbreak of salmonella enterica serotype typhimurium (s. typhimurium) infection occurred in france. the investigation included case searching and a case-control study. a case was defined as a resident of the jura district with fever or diarrhoea between 12 may and 8 july 1997, from whom s. typhimurium was isolated in stool or blood. one hundred and thirteen cases were identified. thirty-three (83 %) of 40 cases but only 23 (55 %) of 42 community controls, matched for ag ... | 2000 | 10722123 |
| serum amyloid p component bound to gram-negative bacteria prevents lipopolysaccharide-mediated classical pathway complement activation. | although serum amyloid p component (sap) is known to bind many ligands, its biological function is not yet clear. recently, it was demonstrated that sap binds to lipopolysaccharide (lps). in the present study, sap was shown to bind to gram-negative bacteria expressing short types of lps or lipo-oligosaccharide (los), such as salmonella enterica serovar copenhagen re and escherichia coli j5, and also to clinical isolates of haemophilus influenzae. it was hypothesized that sap binds to the bacteri ... | 2000 | 10722560 |
| pilot study of phop/phoq-deleted salmonella enterica serovar typhimurium expressing helicobacter pylori urease in adult volunteers. | attenuated salmonella enterica serovar typhi has been studied as an oral vaccine vector. despite success with attenuated s. enterica serovar typhimurium vectors in animals, early clinical trials of s. enterica serovar typhi expressing heterologous antigens have shown that few subjects have detectable immune responses to vectored antigens. a previous clinical study of phop/phoq-deleted s. enterica serovar typhi expressing helicobacter pylori urease from a multicopy plasmid showed that none of eig ... | 2000 | 10722611 |
| sequence variation of the 16s to 23s rrna spacer region in salmonella enterica. | the possibility for identification of salmonella enterica serotypes by sequence analysis of the 16s to 23s rrna internal transcribed spacer was investigated by direct sequencing of polymerase chain reaction-amplified dna from all operons simultaneously in a collection of 25 strains of 18 different serotypes of s. enterica, and by sequencing individual cloned operons from a single strain. it was only possible to determine the first 117 bases upstream from the 23s rrna gene by direct sequencing be ... | 2000 | 10724482 |
| supplement 1998 (no. 42) to the kauffmann-white scheme. | this supplement reports the characterization of 14 new salmonella serovars recognized in 1998 by the who collaborating centre for reference and research on salmonella: 11 were assigned to s. enterica subsp. enterica, one to subspecies salamae, one to subspecies diarizonae, and one to subsp. indica. in addition, the antigenic factor h:z88 is described. | 2000 | 10724485 |
| kinetics of the mucosal antibody secreting cell response and evidence of specific lymphocyte migration to the lung after oral immunisation with attenuated s. enterica var. typhimurium. | the kinetic of mucosal secretory responses elicited by the vaccine vector salmonella enterica var. typhimurium (s. typhimurium) was examined by enzyme linked immunospot (elispot) and compared with serum responses. mice immunised orally with brd509, the aroa, arod mutant of virulent s. typhimurium sl1344 expressing the c fragment of tetanus toxin (tt), simultaneously developed an iga antibody secreting cells (asc) response in the gastrointestinal lamina propria, the spleen and the lung, against b ... | 2000 | 10727882 |
| the structure of the linkage between the o-specific polysaccharide and the core region of the lipopolysaccharide from salmonella enterica serovar typhimurium revisited. | salmonella enterica sv. typhimurium strain 1135 possesses smooth(s)-form lipopolysaccharide (lps). although the structures of the core region and the o-specific polysaccharide were investigated intensively between the 1960s and the 1980s, the structure of the linkage region between the o-chain and the core was not elucidated unequivocally. by using modern ms and high-field nmr spectroscopy for analysis of the isolated carbohydrate backbone of the lps, it has been shown that it is a beta-d-galp r ... | 2000 | 10727941 |
| an rna transcription-based amplification technique (nasba) for the detection of viable salmonella enterica. | possession of mrna is indicative of cell viability. rtpcr is not appropriate for mrna detection as it cannot unambiguously detect mrna in a dna background. the alternative amplification technique, nasba, avoids the disadvantages of rtpcr. we have devised a method for detection of viable salmonella enterica. this involves nasba amplification of mrna transcribed from the dnak gene. amplification of mrna extracted from viable and heat-killed cells from the same population produced consistent and hi ... | 2000 | 10728566 |
| evaluation of a novel enzyme-linked immunosorbent assay for detection of antibodies against salmonella, employing a stable coating of lipopolysaccharide-derived antigens covalently attached to polystyrene microwells. | polysaccharides derived from salmonella typhimurium lipopolysaccharide (lps) representing the o-antigen factors 1, 4, 5, and 12 and the o-antigen factors 6 and 7 from salmonella choleraesuis lps were derivatized with the photoreactive compound anthraquinone and subsequently covalently coupled to microtiter polystyrene plates by ultraviolet irradiation. both polysaccharide antigens could be coupled simultaneously to the same microtiter plate. the coated surface was used in indirect elisa for the ... | 2000 | 10730941 |
| the effects of dietary mannaoligosaccharides on cecal parameters and the concentrations of enteric bacteria in the ceca of salmonella-challenged broiler chicks. | the ability of different enteric pathogens and coliforms to trigger agglutination of yeast cells (saccharomyces cerevisiae, ncyc 1026) and a yeast cell wall preparation (mos) was examined. five of seven strains of escherichia coli and 7 of 10 strains of salmonella typhimurium and salmonella enteritidis agglutinated mos and sac. cerevisiae cells. strains of salmonella choleraesuis, salmonella pullorum, and campylobacter did not lead to agglutination. two strains that agglutinated mos (s. typhimur ... | 2000 | 10735748 |
| ompr regulates the stationary-phase acid tolerance response of salmonella enterica serovar typhimurium. | tolerance to acidic environments is an important property of free-living and pathogenic enteric bacteria. salmonella enterica serovar typhimurium possesses two general forms of inducible acid tolerance. one is evident in exponentially growing cells exposed to a sudden acid shock. the other is induced when stationary-phase cells are subjected to a similar shock. these log-phase and stationary-phase acid tolerance responses (atrs) are distinct in that genes identified as participating in log-phase ... | 2000 | 10735868 |
| complex function for sica, a salmonella enterica serovar typhimurium type iii secretion-associated chaperone. | salmonella enterica encodes a type iii secretion system within a pathogenicity island located at centisome 63 that is essential for virulence. all type iii secretion systems require the function of a family of low-molecular-weight proteins that aid the secretion process by acting as partitioning factors and/or secretion pilots. one such protein is sica, which is encoded immediately upstream of the type iii secreted proteins sipb and sipc. we found that the absence of sica results in the degradat ... | 2000 | 10735870 |
| identification of sope2, a salmonella secreted protein which is highly homologous to sope and involved in bacterial invasion of epithelial cells. | type iii secreted sop protein effectors are delivered into target eukaryotic cells and elicit cellular responses underlying salmonella pathogenicity. in this work, we have identified another secreted protein, sope2, and showed that sope2 is an important invasion-associated effector. sope2 is encoded by the sope2 gene which is present and conserved in pathogenic strains of salmonella. sope2 is highly homologous to sope, a protein encoded by a gene within a temperate bacteriophage and present in o ... | 2000 | 10735884 |
| differentiation of salmonella enterica serotype gallinarum biotype pullorum from biotype gallinarum by analysis of phase 1 flagellin c gene (flic). | salmonella enterica serotype gallinarum biotype gallinarum and biotype pullorum are non-motile and pathogenic avian strains. biotype gallinarum causes fowl typhoid and biotype pullorum is the cause of pullorum disease in chickens. the two biotypes could be differentiated based on biochemical characteristics. however, conventional culture and biochemical assays are time-consuming, laborious and need sterile laboratory practices. although the two biotypes, gallinarum and pullorum are non-motile, t ... | 2000 | 10739340 |
| dual role for macrophages in vivo in pathogenesis and control of murine salmonella enterica var. typhimurium infections. | salmonella spp. are regarded as facultative intracellular bacterial pathogens which are found inside macrophages (mphi) after i. v. infection. it is generally assumed that mphi restrict the replication of the bacteria during infection. in this study we examined the in vivo activities of mphi during experimental s. typhimurium infections, using a selective liposome-based mphi elimination technique. unexpectedly, elimination of mphi prior to infection with virulent s. typhimurium decreased morbidi ... | 2000 | 10741413 |
| survival and filamentation of salmonella enterica serovar enteritidis pt4 and salmonella enterica serovar typhimurium dt104 at low water activity. | in this study we investigated the long-term survival of and morphological changes in salmonella strains at low water activity (a(w)). salmonella enterica serovar enteritidis pt4 and salmonella enterica serovar typhimurium dt104 survived at low a(w) for long periods, but minimum humectant concentrations of 8% nacl (a(w), 0. 95), 96% sucrose (a(w), 0.94), and 32% glycerol (a(w), 0.92) were bactericidal under most conditions. salmonella rpos mutants were usually more sensitive to bactericidal level ... | 2000 | 10742199 |
| pathogenic role of sef14, sef17, and sef21 fimbriae in salmonella enterica serovar enteritidis infection of chickens. | very little is known about the contribution of surface appendages of salmonella enterica serovar enteritidis to pathogenesis in chickens. this study was designed to clarify the role of sef14, sef17, and sef21 fimbriae in serovar enteritidis pathogenesis. stable, single, defined sefa (sef14), agfa (sef17), and fima (sef21) insertionally inactivated fimbrial gene mutants of serovar enteritidis were constructed. all mutant strains invaded caco-2 and ht-29 enterocytes at levels similar to that of th ... | 2000 | 10742278 |
| salmonella perils of pet reptiles. | | 2000 | 10743310 |
| analysis of plasmid and chromosomal dna of multidrug-resistant salmonella enterica serovar typhi from asia. | molecular analysis of chromosomal dna from 193 multidrug-resistant (mdr) salmonella enterica serovar typhi isolates from 1990 to 1995 from pakistan, kuwait, malaysia, bangladesh, and india produced a total of five major different pulsed-field gel electrophoresis (pfge) patterns. even within a particular country mdr s. enterica serovar typhi dna was found to be in different pfge groups. similar self-transferable 98-mda plasmids belonging to either incompatibility group inchi1 or inchi1/fiia were ... | 2000 | 10747124 |
| characterization of salmonella enterica serovar typhimurium dt104 isolated from denmark and comparison with isolates from europe and the united states. | a total of 136 isolates of salmonella enterica serovar typhimurium dt104 from denmark (n = 93), germany (n = 10), italy (n = 4), spain (n = 5), and the united kingdom (n = 9) were characterized by antimicrobial resistance analysis, plasmid profiling, pulsed-field gel electrophoresis (pfge) with the restriction enzymes xbai and blni, and analysis for the presence of integrons and antibiotic resistance genes. the isolates from denmark were from nine pig herds, while the isolates from other countri ... | 2000 | 10747147 |
| fluorescent amplified-fragment length polymorphism genotyping of salmonella enterica subsp. enterica serovars and comparison with pulsed-field gel electrophoresis typing. | we have performed the fluorescently labeled amplified-fragment length polymorphism (faflp) method on 97 strains of the food-borne pathogen salmonella enterica subsp. enterica comprising seven different serovars using the restriction enzymes ecori and msei. from the total faflp fingerprinted strains, 81 were compared with pulsed-field gel electrophoresis (pfge) typing of the same strains. the faflp method showed a discriminatory power equal to that of pfge. we report a fast, robust, and high-reso ... | 2000 | 10747153 |
| inactivation of the flagellin gene of salmonella enterica serotype enteritidis strongly reduces invasion into differentiated caco-2 cells. | a nonflagellated mutant of salmonella enterica serotype enteritidis was constructed by disrupting the flagellin gene (flic). northern blot analysis indicated that the mutation did not affect expression of the downstream fliu gene. infection experiments with differentiated caco-2 cells revealed that the mutant was about 50-fold less invasive than the wild-type strain, while bacterial adherence was unaffected. complementation of the mutant with an intact flic copy restored flagella formation and e ... | 2000 | 10754244 |
| proposal of salmonella paratyphi sp. nov., nom. rev. and request for an opinion to conserve the specific epithet paratyphi in the binary combination salmonella paratyphi as nomen epitheton conservandum. | we propose salmonella paratyphi sp. nov., nom. rev., by raising salmonella choleraesuis subsp. choleraesuis serovar paratyphi a to species status and request an opinion to include the specific epithet paratyphi in the binary combination of salmonella paratyphi in the list of epitheta specifica conservanda. | 2000 | 10758909 |
| recognition of nomenclatural standing of salmonella typhi (approved lists 1980), salmonella enteritidis (approved lists 1980) and salmonella typhimurium (approved lists 1980), and conservation of the specific epithets enteritidis and typhimurium. request for an opinion. | in 1994, the judicial commission of the icsb announced that le minor and popoff's request for an opinion in 1987 to designate salmonella enterica sp. nov., nom. rev. as the type and only species of the genus salmonella was denied. thus, the current species of the genus salmonella are salmonella typhimurium, salmonella enteritidis, salmonella typhi, salmonella choleraesuis (including six subspecies) and salmonella bongori, with the type species, s. choleraesuis (smith 1894) weldin 1927 (approved ... | 2000 | 10758910 |
| a parallel intraphagosomal survival strategy shared by mycobacterium tuberculosis and salmonella enterica. | mycobacterium tuberculosis and salmonella enterica cause very different diseases and are only distantly related. however, growth within macrophages is crucial for virulence in both of these intracellular pathogens. here, we demonstrate that in spite of the phylogenetic distance, m. tuberculosis and salmonella employ a parallel survival strategy for growth within macrophage phagosomes. previous studies established that the salmonella mgtc gene is required for growth within macrophages and for vir ... | 2000 | 10760138 |
| prevalence of subclinical salmonella enterica infection in danish finishing pig herds. | our aim was to determine the salmonella enterica prevalence in 96 randomly selected danish pig herds, based on serological examination of blood samples and bacteriological examination of faecal samples (collected simultaneously from the same pens). for comparison, 39 high-seroprevalence herds were included in the study. the representativeness of the selected herds was assessed, based on descriptive statistics of herd size and type. totals of 1330 pen samples and 6814 blood samples were examined. ... | 2000 | 10760401 |
| peptidase e, a peptidase specific for n-terminal aspartic dipeptides, is a serine hydrolase. | salmonella enterica serovar typhimurium peptidase e (pepe) is an n-terminal asp-specific dipeptidase. pepe is not inhibited by any of the classical peptidase inhibitors, and its amino acid sequence does not place it in any of the known peptidase structural classes. a comparison of the amino acid sequence of pepe with a number of related sequences has allowed us to define the amino acid residues that are strongly conserved in this family. to ensure the validity of this comparison, we have express ... | 2000 | 10762256 |
| lipopolysaccharide-binding protein and phospholipid transfer protein release lipopolysaccharides from gram-negative bacterial membranes. | although animals mobilize their innate defenses against gram-negative bacteria when they sense the lipid a moiety of bacterial lipopolysaccharide (lps), excessive responses to this conserved bacterial molecule can be harmful. of the known ways for decreasing the stimulatory potency of lps in blood, the binding and neutralization of lps by plasma lipoproteins is most prominent. the mechanisms by which host lipoproteins take up the native lps that is found in bacterial membranes are poorly underst ... | 2000 | 10768924 |
| tetanus toxin fragment c expressed in live salmonella vaccines enhances antibody responses to its fusion partner schistosoma haematobium glutathione s-transferase. | tetanus toxoid has been used widely as an adjuvant. the atoxic fragment c from tetanus toxin (tetc) is potently immunogenic when expressed in salmonella vaccine strains and has been used as a fusion partner for antigens (ag). however, there has been no formal comparison of the immunomodulatory impact of tetc on its fusion partners. in this study, we have addressed this important issue. the protective 28-kda glutathione s-transferase (gst) from schistosoma haematobium (sh28gst) was expressed eith ... | 2000 | 10768937 |
| the shda gene is restricted to serotypes of salmonella enterica subspecies i and contributes to efficient and prolonged fecal shedding. | little is known about factors which enable salmonella serotypes to circulate within populations of livestock and domestic fowl. we have identified a dna region which is present in salmonella serotypes commonly isolated from livestock and domestic fowl (s. enterica subspecies i) but absent from reptile-associated salmonella serotypes (s. bongori and s. enterica subspecies ii to vii). this dna region was cloned from salmonella serotype typhimurium and sequence analysis revealed the presence of a 6 ... | 2000 | 10768965 |
| the flagellar sigma factor flia (sigma(28)) regulates the expression of salmonella genes associated with the centisome 63 type iii secretion system. | one of the essential features of all pathogenic strains of salmonella enterica is the ability to enter into nonphagocytic cells. this pathogenic property is mediated by the salmonella pathogenicity island 1 (spi-1)-encoded type iii secretion system. expression of components and substrates of this system is subject to complex regulatory mechanisms. these mechanisms include a number of specific and global transcriptional regulatory proteins. in this study we have compared in s. enterica serovars t ... | 2000 | 10768967 |
| interaction of salmonella enterica serotype typhimurium with dendritic cells is defined by targeting to compartments lacking lysosomal membrane glycoproteins. | dendritic cells (dcs) play a central role in the generation of acquired immunity to infections by pathogenic microorganisms. salmonella enterica serotype typhimurium is known to survive and proliferate intracellularly within macrophages and nonphagocytic cells, but no data exist on how this pathogen interacts with dcs. in this report, we show the capacity of serotype typhimurium to survive within the established mouse dc line cb1. in contrast to the case for the macrophage model, the compartment ... | 2000 | 10768999 |
| evidence for active efflux as the primary mechanism of resistance to ciprofloxacin in salmonella enterica serovar typhimurium. | the occurrence of active efflux and cell wall modifications were studied in salmonella enterica serovar typhimurium mutants that were selected with enrofloxacin and whose phenotypes of resistance to fluoroquinolones could not be explained only by mutations in the genes coding for gyrase or topoisomerase iv. mutant bn18/21 exhibited a decreased susceptibility to ciprofloxacin (mic = 0.125 microg/ml) but did not have a mutation in the gyra gene. mutants bn18/41 and bn18/71 had the same substitutio ... | 2000 | 10770755 |
| occurrence of a salmonella enterica serovar typhimurium dt104-like antibiotic resistance gene cluster including the flor gene in s. enterica serovar agona. | recently a chromosomal locus possibly specific for salmonella enterica serovar typhimurium dt104 has been reported that contains a multiple antibiotic resistance gene cluster. evidence is provided that salmonella enterica serovar agona strains isolated from poultry harbor a similar gene cluster including the newly described flor gene, conferring cross-resistance to chloramphenicol and florfenicol. | 2000 | 10770778 |
| hospital outbreak of salmonella virchow possibly associated with a food handler. | a foodborne outbreak of salmonella infection at a private hospital in london in 1994 was found to be associated with eating turkey sandwiches prepared by a food handler. one patient, nine staff, and a foodhandler's baby were confirmed to have salmonella enterica serotype virchow, phage type 26 infection. the attack rate was estimated to be 5% among the approximately 200 patients and staff at risk. a food handler reportedly became ill days after, but her baby days before, the first hospital case. ... | 2000 | 10772833 |
| a small protein that mediates the activation of a two-component system by another two-component system. | the pmra-pmrb two-component system of salmonella enterica controls resistance to the peptide antibiotic polymyxin b and to several antimicrobial proteins from human neutrophils. transcription of pmra-activated genes is induced by high iron, but can also be promoted by growth in low magnesium in a process that requires another two-component system, phop-phoq. here, we define the genetic basis for the interaction between the phop-phoq and pmra-pmrb systems. we have identified pmrd as a phop-activa ... | 2000 | 10775270 |
| salmonella typhimurium dt104 from livestock in japan. | we examined the distribution of multidrug-resistant salmonella enterica serotype typhimurium definitive phage type 104 (dt104) among japanese livestock from 1973 to 1998. the 144 s. typhimurium field isolates were tested for susceptibility to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline, kanamycin, trimethoprim, nalidixic acid, and norfloxacin. thirty-six of 68 strains which exhibited resistance to five or more antimicrobials (acssut+) were identified as dt104. resul ... | 2000 | 10777852 |
| pcr typing of tetracycline resistance determinants (tet a-e) in salmonella enterica serotype hadar and in the microbial community of activated sludges from hospital and urban wastewater treatment facilities in belgium. | the distribution of tetracycline resistance determinants tet a-e was studied by pcr in 40 tetracycline-resistant salmonella enterica serotype hadar (s. hadar) isolates collected from human patients in 1996 and 1997, as well as in the microbial community originating from activated sludges of hospital and urban wastewater treatment facilities. a fast dna extraction and purification method from activated sludges was used to provide amplifiable dna. the method is based on the direct lysis of bacteri ... | 2000 | 10779622 |
| ceftriaxone-resistant salmonella infection acquired by a child from cattle. | the emergence of resistance to antimicrobial agents within the salmonellae is a worldwide problem that has been associated with the use of antibiotics in livestock. resistance to ceftriaxone and the fluoroquinolones, which are used to treat invasive salmonella infections, is rare in the united states. we analyzed the molecular characteristics of a ceftriaxone-resistant strain of salmonella enterica serotype typhimurium isolated from a 12-year-old boy with fever, abdominal pain, and diarrhea. | 2000 | 10781620 |
| induction of salmonella enterotoxin (stn) gene expression by epithelial cells (iec-6). | prevalence of salmonella enterotoxin (stn) gene among salmonella enterica and s. bongori was investigated by polymerase chain reaction (pcr) and gene probe and its status of phenotypic expression was examined on chinese hamster ovary cells by cultivating the strains with conventional method for enterotoxin production and by cultivating the organisms in contact with intestinal epithelial cells of rats (iec-6). all the 19 strains and serovars of s. enterica such as typhimurium, enteritidis, newpor ... | 1999 | 10783743 |
| immobilization with metal hydroxides as a means to concentrate food-borne bacteria for detection by cultural and molecular methods. | the application of nucleic acid amplification methods to the detection of food-borne pathogens could be facilitated by concentrating the organisms from the food matrix before detection. this study evaluated the utility of metal hydroxide immobilization for the concentration of bacterial cells from dairy foods prior to detection by cultural and molecular methods. using reconstituted nonfat dry milk (nfdm) as a model, two food-borne pathogens (listeria monocytogenes and salmonella enterica serovar ... | 2000 | 10788338 |
| lactic acid permeabilizes gram-negative bacteria by disrupting the outer membrane. | the effect of lactic acid on the outer membrane permeability of escherichia coli o157:h7, pseudomonas aeruginosa, and salmonella enterica serovar typhimurium was studied utilizing a fluorescent-probe uptake assay and sensitization to bacteriolysis. for control purposes, similar assays were performed with edta (a permeabilizer acting by chelation) and with hydrochloric acid, the latter at ph values corresponding to those yielded by lactic acid, and also in the presence of kcn. already 5 mm (ph 4. ... | 2000 | 10788373 |
| genetic relatedness of salmonella isolates from nondomestic birds in southeastern united states. | salmonella infections have been implicated in large-scale die-offs of wild birds in the united states. although we know quite a bit about the epidemiology of salmonella infection among domestic fowl, we know little about the incidence, epidemiology, and genetic relatedness of salmonellae in nondomestic birds. to gain further insight into salmonellae in these hosts, 22 salmonella isolates from diseased nondomestic birds were screened for the presence of virulence and antibiotic resistance-associa ... | 2000 | 10790113 |
| effects of the antimicrobial growth promoter tylosin on subclinical infection of pigs with salmonella enterica serotype typhimurium. | to determine whether feeding tylosin, an antimicrobial growth promoter, to pigs was associated with increased risk of infection with and excretion of salmonella enterica serotype typhimurium. | 1999 | 10791930 |
| the role of sef14 and sef17 fimbriae in the adherence of salmonella enterica serotype enteritidis to inanimate surfaces. | to gain an understanding of the role of fimbriae and flagella in the adherence of salmonella enterica serotype enteritidis to inanimate surfaces, the extent of adherence of viable wild-type strains to a polystyrene microtitration plate was determined by a crystal violet staining assay. elaboration of surface antigens by adherent bacteria was assayed by fimbriae- and flagella-specific elisas. wild-type enteritidis strains adhered well at 37 degrees c and 25 degrees c when grown in microtitration ... | 2000 | 10798562 |
| rmlc, the third enzyme of dtdp-l-rhamnose pathway, is a new class of epimerase. | deoxythymidine diphosphate (dtdp)-l-rhamnose is the precursor of l-rhamnose, a saccharide required for the virulence of some pathogenic bacteria. dtdp-l-rhamnose is synthesized from glucose-1-phosphate and deoxythymidine triphosphate (dttp) via a pathway involving four distinct enzymes. this pathway does not exist in humans and the enzymes involved in dtdp-l-rhamnose synthesis are potential targets for the design of new therapeutic agents. here, the crystal structure of dtdp-6-deoxy-d-xylo-4-hex ... | 2000 | 10802738 |
| the phosphatase activity is the target for mg2+ regulation of the sensor protein phoq in salmonella. | the phop/phoq two-component system controls the expression of essential virulence traits in the pathogenic bacterium salmonella enterica serovar typhimurium. environmental deprivation of mg(2+) activates the phop/phoq signal transduction cascade, which results in an increased expression of genes necessary for survival inside the host. it was previously demonstrated that the interaction of mg(2+) with the periplasmic domain of phoq promotes a conformational change in the sensor protein that leads ... | 2000 | 10807931 |
| subdivision of salmonella enterica serovar enteritidis phage types pt14b and pt21 by plasmid profiling. | we have shown that plasmid profiling is a sensitive method for further identification of strains of salmonella enterica serovar enteritidis (s. enteritidis) phage type pt21 and to a lesser extent the strains of phage type pt14b. five and three plasmid types were identified within 33 strains of phage type pt21 and 19 strains of phage type pt14b, respectively. plasmid types in strains of phage type pt21 showed significant correlation with geographical origin of the strain. in strains of phage type ... | 2000 | 10808090 |
| molecular epidemiology of an outbreak caused by salmonella enterica serovar newport in finland and the united kingdom. | between december 1997 and january 1998 an increase in the number of isolates of salmonella enterica serovar newport, a serotype rarely causing indigenous infections in finland, was detected. this included two clusters of gastroenteritis following funeral meals. an inquiry via enter-net revealed a concomitant increase in cases of s. newport in the united kingdom. to investigate the finnish outbreak, a total of 56 s. newport strains (22 from the outbreak period, 27 from pre- and post-outbreak peri ... | 2000 | 10813141 |
| salmonella enterica serovar typhi uses type ivb pili to enter human intestinal epithelial cells. | dna sequencing upstream of the salmonella enterica serovar typhi pilv and rci genes previously identified in the ca. 118-kb major pathogenicity island (x.-l. zhang, c. morris, and j. hackett, gene 202:139-146, 1997) identified a further 10 pil genes apparently forming a pil operon. the product of the pils gene, prepils protein (a putative type ivb structural prepilin) was purified, and an anti-prepils antiserum was raised in mice. mutants of serovar typhi either lacking the whole pil operon or w ... | 2000 | 10816445 |
| extending the cd4(+) t-cell epitope specificity of the th1 immune response to an antigen using a salmonella enterica serovar typhimurium delivery vehicle. | we analyzed the cd4 t-cell immunodominance of the response to a model antigen (ag), male, when delivered by an attenuated strain of salmonella enterica serovar typhimurium (sl3261*pmale). compared to purified male ag administered with adjuvant, the mapping of the peptide-specific proliferative responses showed qualitative differences when we used the salmonella vehicle. we observed the disappearance of one out of eight male peptides' t-cell reactivity upon sl3261*pmale immunization, but this phe ... | 2000 | 10816447 |
| effect of preexisting immunity to salmonella on the immune response to recombinant salmonella enterica serovar typhimurium expressing a porphyromonas gingivalis hemagglutinin. | recombinant salmonella strains expressing foreign heterologous genes have been extensively studied as live oral vaccine delivery vectors. we have investigated the mucosal and systemic immune responses following oral immunization with a recombinant salmonella enterica serovar typhimurium expressing the hemagglutinin hagb from porphyromonas gingivalis, a suspected etiological agent of adult periodontal disease. we have previously shown a primary mucosal and systemic response following oral immuniz ... | 2000 | 10816452 |
| mucosal and systemic immune responses to chimeric fimbriae expressed by salmonella enterica serovar typhimurium vaccine strains. | recombinant live oral vaccines expressing pathogen-derived antigens offer a unique set of attractive properties. among these are the simplicity of administration, the capacity to induce mucosal and systemic immunity, and the advantage of permitting genetic manipulation for optimal antigen presentation. in this study, the benefit of having a heterologous antigen expressed on the surface of a live vector rather than intracellularly was evaluated. accordingly, the immune response of mice immunized ... | 2000 | 10816454 |
| microgravity as a novel environmental signal affecting salmonella enterica serovar typhimurium virulence. | the effects of spaceflight on the infectious disease process have only been studied at the level of the host immune response and indicate a blunting of the immune mechanism in humans and animals. accordingly, it is necessary to assess potential changes in microbial virulence associated with spaceflight which may impact the probability of in-flight infectious disease. in this study, we investigated the effect of altered gravitational vectors on salmonella virulence in mice. salmonella enterica se ... | 2000 | 10816456 |
| sspa is required for lethal salmonella enterica serovar typhimurium infections in calves but is not essential for diarrhea. | salmonella pathogenicity island 1 (spi-1) encodes virulence determinants, which are important for enteropathogenicity in calves. to determine whether the salmonella enterica serovar typhimurium spi-1 effector proteins sspa and sptp are important for enteropathogenicity, strains lacking these proteins were tested during oral infection of calves. calves infected with a sptp mutant or its isogenic parent developed diarrhea and lethal morbidity. in contrast, calves infected with an sspa mutant devel ... | 2000 | 10816458 |
| cs22, a novel human enterotoxigenic escherichia coli adhesin, is related to cs15. | enterotoxigenic escherichia coli (etec) expresses a broad spectrum of o:h antigens. serogroup o20 is one of the most prevalent among the etec strains lacking any of the defined colonization factors (cfs), in argentina. an o20:h- strain, arg-3, adhered to caco-2 cells and exhibited a thermoregulated 15.7-kda protein band upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page). an antiserum against this protein inhibited arg-3 adhesion to caco-2 cells and bound to very thin fibri ... | 2000 | 10816474 |
| characterization of fimy as a coactivator of type 1 fimbrial expression in salmonella enterica serovar typhimurium. | type 1 fimbriae of salmonella enterica serovar typhimurium are surface appendages that carry adhesins specific for mannosylated host glycoconjugates. regulation of the major fimbrial subunit is thought to be controlled by a number of ancillary fim genes, including fimz, fimy, fimw, and fimu. previous studies using a fimz mutant have indicated that this protein is necessary for fima expression, and in vitro dna binding assays determined that fimz is a transcriptional activator that binds directly ... | 2000 | 10816478 |
| antibody is required for protection against virulent but not attenuated salmonella enterica serovar typhimurium. | resolution of infection with attenuated salmonella is an active process that requires cd4(+) t cells. here, we demonstrate that costimulation via the surface molecule cd28, but not antibody production by b cells, is required for clearance of attenuated aroa salmonella enterica serovar typhimurium. in contrast, specific antibody is critical for vaccine-induced protection against virulent bacteria. therefore, cd28(+) cd4(+) t cells are sufficient for clearance of avirulent salmonella in naive host ... | 2000 | 10816483 |
| transcriptional organization and function of invasion genes within salmonella enterica serovar typhimurium pathogenicity island 1, including the prgh, prgi, prgj, prgk, orga, orgb, and orgc genes. | salmonella enterica serovar typhimurium initiates infection of a host by inducing its own uptake into specialized m cells which reside within the epithelium overlaying peyer's patches. entry of salmonella into intestinal epithelial cells is dependent upon invasion genes that are clustered together in salmonella pathogenicity island 1 (spi-1). upon contact between serovar typhimurium and epithelial cells targeted for bacterial internalization, bacterial proteins are injected into the host cell th ... | 2000 | 10816487 |
| salmonella enterica serovars typhimurium and dublin can lyse macrophages by a mechanism distinct from apoptosis. | salmonella enterica serovars typhimurium and dublin lysed primary bovine alveolar macrophages and immortalized j774.2 macrophage-like cells in the absence of either the morphological changes or dna fragmentation characteristic of apoptosis. macrophage lysis was dependent on a subset of caspases and an intact sipb gene. | 2000 | 10816540 |
| constitutive mutations of the salmonella enterica serovar typhimurium transcriptional virulence regulator phop. | the phop-phoq two-component system is necessary for the virulence of salmonella spp. and is responsible for regulating several modifications of the lipopolysaccharide (lps). mutagenesis of the transcriptional regulator phop resulted in the identification of a mutant able to activate transcription of regulated genes approximately 100-fold in the absence of phoq. sequence analysis showed two single-base alterations resulting in amino acid changes at positions 93 (s93n) and 203 (q203r). these mutat ... | 2000 | 10816543 |
| mutation of waan reduces salmonella enterica serovar typhimurium-induced enteritis and net secretion of type iii secretion system 1-dependent proteins. | mutation of waan, a gene involved in lipid a biosynthesis, reduced enteropathogenic responses induced by salmonella enterica serovar typhimurium in bovine ligated ileal loops. however, the secretion of key virulence determinants was also reduced, and therefore the reduction in enteropathogenicity cannot be solely attributed to a reduction in biological activity of lipid a. | 2000 | 10816545 |
| a functional cra gene is required for salmonella enterica serovar typhimurium virulence in balb/c mice. | a minitransposon mutant of salmonella enterica serovar typhimurium sr-11, sr-11 fad(-), is unable to utilize gluconeogenic substrates as carbon sources and is avirulent and immunogenic when administered perorally to balb/c mice (m. j. utley et al., fems microbiol. lett., 163:129-134, 1998). here, evidence is presented that the mutation in sr-11 fad(-) that renders the strain avirulent is in the cra gene, which encodes the cra protein, a regulator of central carbon metabolism. | 2000 | 10816546 |
| curli loci of shigella spp. | an unstable chromosomal element encoding multiple antibiotic resistance in shigella flexneri serotype 2a was found to include sequences homologous to the csg genes encoding curli in escherichia coli and salmonella enterica serovar typhimurium. as curli have been implicated in the virulence of serovar typhimurium, we investigated the csg loci in all four species of shigella. dna sequencing and pcr analysis showed that the csg loci of a wide range of shigella strains, of diverse serotypes and diff ... | 2000 | 10816548 |
| matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of lipopolysaccharides. | | 2000 | 10820729 |
| structure of the sialic acid-containing o-specific polysaccharide from salmonella enterica serovar toucra o48 lipopolysaccharide. | lipopolysaccharide was extracted from cells of salmonella enterica serovar toucra o48 and, after mild acid hydrolysis (1% acoh, 1 h, 100 degrees c or 0.1 m naoh-acoh, ph 4.5, 5 h, 100 degrees c), the o-specific polysaccharide was isolated and characterized. the core and an oligosaccharide containing a fragment of the repeating unit linked to the core region were also obtained, depending on hydrolysis conditions. on the basis of sugar and methylation analyses and nmr spectroscopy of the hydrolysi ... | 2000 | 10824100 |
| occurrence of sef & pef genes among different serovars of salmonella. | a total of 29 strains of salmonella enterica belonging to seven serovars isolated from human, animals and birds were used to study the occurrence of salmonella fimbriae genes (sef and pef) by pcr amplification technique using their specific primers. all the strains (15) of s. enteritidis were found to carry both sef and pef genes irrespective of the source of isolation. s. typhimurium strains were found to harbour only pef genes, while s. gallinarum strains harboured only sef genes. other serova ... | 2000 | 10824465 |
| persistence of a salmonella enterica serotype typhimurium clone in danish pig production units and farmhouse environment studied by pulsed field gel electrophoresis (pfge) | the clonal relationship among salmonella enterica serotype typhimurium isolates from selected pig production units in denmark was investigated by the pulsed field gel electrophoresis (pfge) typing method to determine environmental survival and spread of salmonella in different herds. thirty-four typhimurium isolated during 1996-1998 from porcine faeces and environmental samples from three pig farms designated 1, 3 and 5 were characterised by pfge using two restriction enzymes. farm 5 supplied pi ... | 2000 | 10828394 |
| evaluation of is200-pcr and comparison with other molecular markers to trace salmonella enterica subsp. enterica serotype typhimurium bovine isolates from farm to meat. | a procedure that uses an original molecular marker (is200-pcr) and that is based on the amplification of dna with outward-facing primers complementary to each end of is200 has been evaluated with a collection of 85 salmonella enterica subsp. enterica serotype typhimurium isolates. these strains were isolated from a group of 10 cows at different stages: during transportation between the farm and the slaughterhouse, on the slaughter line, from the environment, and from the final product (ground be ... | 2000 | 10834977 |
| epidemiologic typing of salmonella enterica serotype enteritidis in a canada-wide outbreak of gastroenteritis due to contaminated cheese. | a major canada-wide outbreak of gastroenteritis due to salmonella enterica serotype enteritidis phage type (pt) 8 occurred in 1998, and this was traced to contaminated cheese in a commercial lunch pack product. phage typing and pulsed-field gel electrophoresis linked the clinical and cheese isolates of serotype enteritidis but failed to differentiate outbreak from nonoutbreak pt 8 strains. further differentiation was made by biotyping based on melibiose fermentation. | 2000 | 10835016 |
| salmonella ssrb activates a global regulon of horizontally acquired genes. | salmonella enterica is a bacterial pathogen of humans that can proliferate within epithelial cells as well as professional phagocytes of the immune system. this ability requires an s. enterica specific locus termed salmonella pathogenicity island 2 (spi-2). spi-2 encodes a type iii secretion system that injects effectors encoded within the island into host cell cytosol to promote virulence. ssrab is a two-component regulator encoded within spi-2 that was assumed to activate spi-2 genes exclusive ... | 2000 | 10844662 |
| host adaptation and the emergence of infectious disease: the salmonella paradigm. | the recent emergence of food-borne pathogens, such as salmonella enterica serotype enteritidis (s. enteritidis) and escherichia coli o157:h7, has generated increasing interest in how infectious diseases can invade, persist and spread within new host populations. to alter their host range pathogens require adaptations, which ensure their circulation in a new animal population. adaptations for circulation in different populations of vertebrate hosts seem to have been acquired multiple times within ... | 2000 | 10844686 |
| salmonella pathogenicity island 2. | systemic infections by salmonella enterica, such as typhoid fever, are a significant threat to human health. recent studies indicate that the function of a type iii secretion system encoded by salmonella pathogenicity island 2 (spi2) is central for the ability of s. enterica to cause systemic infections and for intracellular pathogenesis. this review summarizes approaches leading to the identification of spi2, the molecular genetics and evolution of spi2, and the current understanding of the reg ... | 2000 | 10844687 |
| the nramp proteins of salmonella typhimurium and escherichia coli are selective manganese transporters involved in the response to reactive oxygen. | nramps (natural resistance-associated macrophage proteins) have been characterized in mammals as divalent transition metal transporters involved in iron metabolism and host resistance to certain pathogens. the mechanism of pathogen resistance is proposed to involve sequestration of fe2+ and mn2+, cofactors of both prokaryotic and eukaryotic catalases and superoxide dismutases, not only to protect the macrophage against its own generation of reactive oxygen species, but to deny the cations to the ... | 2000 | 10844693 |
| surveillance of multidrug-resistant strains of salmonella enterica serotype typhimurium in southern italy in the years 1992-1997. | spread of multidrug-resistant strains of salmonella enterica serotype typhimurium (s. typhimurium) is increasingly reported worldwide. the presence of a pattern of resistance to ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracycline (acssut), in some cases associated to trimethoprim and infrequently to quinolones, is of particular concern. this resistance pattern appears to be chromosomally encoded and, in most epidemiological studies, closely related to definitive type 104 (dt ... | 2000 | 10845262 |
| evidence for a signaling system in helicobacter pylori: detection of a luxs-encoded autoinducer. | helicobacter pylori possesses a homolog of the luxs gene, initially identified by its role in autoinducer production for the quorum-sensing system 2 in vibrio harveyi. the genomes of several other species of bacteria, notably escherichia coli, salmonella enterica serovar typhimurium, and vibrio cholerae, also include luxs homologs. all of these bacteria have been shown to produce active autoinducers capable of stimulating the expression of the luciferase operon in v. harveyi. in this report, we ... | 2000 | 10850976 |
| phosphorylated pmra interacts with the promoter region of ugd in salmonella enterica serovar typhimurium. | the salmonella pmra-pmrb system controls the expression of genes necessary for polymyxin b resistance. four loci were previously identified as part of the regulon, and interaction of pmra with the promoter region of three of them was observed. here we characterized the interaction of pmra with the promoter region of ugd, previously suggested to be regulated indirectly by pmra. our results indicate that pmra controls the expression of ugd by interacting with a specific sequence in the promoter re ... | 2000 | 10851011 |
| review of studies on the thermal resistance of salmonellae. | heat resistance data for different serotypes of salmonella enterica in different food products and laboratory media are reviewed. from all d-values reported, the highest heat resistance of salmonella was in liquid eggs and liquid egg yolks. the equation from a line drawn through the highest d-values, and above all values reported, was log d-value = 11.7 - 0.188t degrees c. from this equation, the calculated z-value was 5.3 degrees c (9.5 degrees f), and a process at 71degrees c (160 degrees f) w ... | 2000 | 10852574 |
| hypersensitivity of escherichia coli delta(uvrb-bio) mutants to 6-hydroxylaminopurine and other base analogs is due to a defect in molybdenum cofactor biosynthesis. | we have shown previously that escherichia coli and salmonella enterica serovar typhimurium strains carrying a deletion of the uvrb-bio region are hypersensitive to the mutagenic and toxic action of 6-hydroxylaminopurine (hap) and related base analogs. this sensitivity is not due to the uvrb excision repair defect associated with this deletion because a uvrb point mutation or a uvra deficiency does not cause hypersensitivity. in the present work, we have investigated which gene(s) within the dele ... | 2000 | 10852865 |
| salmonella enterica serovar typhimurium peptidase b is a leucyl aminopeptidase with specificity for acidic amino acids. | peptidase b (pepb) of salmonella enterica serovar typhimurium is one of three broad-specificity aminopeptidases found in this organism. we have sequenced the pepb gene and found that it encodes a 427-amino-acid (46.36-kda) protein, which can be unambiguously assigned to the leucyl aminopeptidase (lap) structural family. pepb has been overexpressed and purified. the active enzyme shows many similarities to other members of the lap family: it is a heat-stable (70 degrees c; 20 min) hexameric ( app ... | 2000 | 10852868 |
| analysis of the sos response in salmonella enterica serovar typhimurium using rna fingerprinting by arbitrarily primed pcr. | we report an analysis of a sample of the sos response of salmonella enterica serovar typhimurium using the differential display of rna fingerprinting gels of arbitrarily primed pcr products. the sos response was induced by the addition of mitomycin c to an exponentially growing culture of serovar typhimurium, and the rna population was sampled during the following 2 h. these experiments revealed 21 differentially expressed pcr fragments representing mrna transcripts. these 21 fragments correspon ... | 2000 | 10852882 |
| [evolution of resistance to quinolones in salmonella enterica in our setting]. | salmonella enterica is mainly associated with acute gastroenteritis; however, it is also associated with other more severe disease processes, for which quinolones are the treatment of choice. we retrospectively studied the evolution of resistance to nalidixic acid and ciprofloxacin of all the clinical isolates of s. enterica from 1992 to 1998 in our hospital environment. a total of 848 strains from feces, blood and other locations were studied. we detected an increase in the resistance to nalidi ... | 1999 | 10855017 |