Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| 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 |
| 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 |
| functional analysis of genes in the rfb locus of leptospira borgpetersenii serovar hardjo subtype hardjobovis. | lipopolysaccharide (lps) is a key antigen in immunity to leptospirosis. its biosynthesis requires enzymes for the biosynthesis and polymerization of nucleotide sugars and the transport through and attachment to the bacterial membrane. the genes encoding these functions are commonly clustered into loci; for leptospira borgpetersenii serovar hardjo subtype hardjobovis, this locus, named rfb, spans 36.7 kb and contains 31 open reading frames, of which 28 have been assigned putative functions on the ... | 2000 | 10858186 |
| the lipopolysaccharide structures of salmonella enterica serovar typhimurium and neisseria gonorrhoeae determine the attachment of human mannose-binding lectin to intact organisms. | mannose-binding lectin (mbl) is an important component of the innate immune system. it binds to the arrays of sugars commonly presented by microorganisms and activates the complement system independently of antibody. despite detailed knowledge of the stereochemical basis of mbl binding, relatively little is known about how bacterial surface structures influence binding of the lectin. using flow cytometry, we have measured the binding of mbl to a range of mutants of salmonella enterica serovar ty ... | 2000 | 10858200 |
| adjuvant activity of a nontoxic mutant of escherichia coli heat-labile enterotoxin on systemic and mucosal immune responses elicited against a heterologous antigen carried by a live salmonella enterica serovar typhimurium vaccine strain. | systemic and mucosal antibody responses against both the major subunit of colonization factor antigen i (cfa/i) of enterotoxigenic escherichia coli (etec) and the somatic lipopolysaccharide expressed by recombinant bivalent salmonella vaccine strains were significantly enhanced by coadministration of a detoxified derivative with preserved adjuvant effects of the etec heat-labile toxin, lt((r192g)). the results further support the adjuvant effects of lt((r192g)) and represent a simple alternative ... | 2000 | 10858258 |
| long-term immunological memory induced by recombinant oral salmonella vaccine vectors. | we have previously shown that salmonella enterica serovar typhimurium expressing the hagb hemagglutinin gene from porphyromonas gingivalis can induce primary and recall immune responses in serum and secretions in mice; however, the longevity of memory induced by oral salmonella carriers has not been adequately demonstrated. in this study, we examined the capacity of mice to mount a recall response 52 weeks after primary immunization. recall responses were seen in serum immunoglobulin g (igg) and ... | 2000 | 10858264 |
| a randomized controlled comparison of azithromycin and ofloxacin for treatment of multidrug-resistant or nalidixic acid-resistant enteric fever. | to examine the efficacy and safety of short courses of azithromycin and ofloxacin for treating multidrug-resistant (mdr, i.e., resistant to chloramphenicol, ampicillin, and cotrimoxazole) and nalidixic acid-resistant enteric fever, azithromycin (1 g once daily for 5 days at 20 mg/kg/day) and ofloxacin (200 mg orally twice a day for 5 days at 8 mg/kg/day) were compared in an open randomized study in adults admitted to a hospital with uncomplicated enteric fever. a total of 88 blood culture-confir ... | 2000 | 10858343 |
| characterisation of streptomycin resistance determinants in danish isolates of salmonella typhimurium. | fifty six danish streptomycin (sm) resistant isolates of salmonella enterica serotype typhimurium from pigs (n=34), calves (n=3) and humans (n=19) were characterised with respect to co-resistances (14 drugs), transferability of sm-resistance by conjugation, genetic determinants encoding sm-resistance and diversity with respect to localisation of genes in the genome and dna-sequences. forty-six strains carried resistance(s) other than sm-resistance. nineteen different co-resistance patterns were ... | 2000 | 10865153 |
| virulence characterization of a strain of salmonella enterica subspecies houten (subspecies iv) with chromosomal integrated salmonella plasmid virulence (spv) genes. | the salmonella plasmid virulence genes (spv) are commonly found on plasmids contained in a small number of serotypes of salmonella belonging to subspecies i, where they are important for survival within macrophages and the establishment of successful systemic infection. however, in this study, spv genes were detected by the polymerase chain reaction in the chromosome of a plasmid-free strain of s. iv 16:z4, z32:- (salmonella subspecies iv). the full range of spv genes (spvr, spva, spvb, spvc and ... | 2000 | 10865945 |
| growth of salmonella choleraesuis subspecies diarizonae serovar 61:k:1,5,(7) in broth and fresh mutton. | three serovars of salmonella choleraesuis (iiib 61:k:1,5,(7), enteritidis and dublin) were grown in broths of ph 5.5 and 6.2 and incubated at 4, 6, 8 or 12 degrees c. growth in the broth, measured by means of an increase of absorbance, was not observed below 8 degrees c. at 8 and 12 degrees c, the maximum growth rate (mu(max)), lag period and maximum absorbance level (max(abs)) varied according to serovar and ph. in general, serovar iiib 61:k:1,5,(7) and serovar enteritidis grew better than sero ... | 2000 | 10868677 |
| quinolone resistance among salmonella enterica from cattle, broilers, and swine in denmark. | this study was conducted to determine the susceptibility to nalidixic acid and fluoroquinolones of salmonella dublin, s. enteritidis, and s. typhimurium isolates from cattle, broilers, and pigs over time in denmark and to characterise the gyra, gyrb, and parc genes in quinolone-resistant isolates. a total of 584 s. typhimiurium and 573 s. dublin isolates from cattle during 1984 through 1999, and 241 s. enteritidis and 131 s. typhimurium from broilers and 452 s. typhimurium from pigs isolated dur ... | 2000 | 10868803 |
| metabolic defects caused by mutations in the isc gene cluster in salmonella enterica serovar typhimurium: implications for thiamine synthesis. | the metabolic consequences of two insertions, iscr1::mudj and isca2::mudj, in the isc gene cluster of salmonella enterica serovar typhimurium were studied. each of these insertions had polar effects and caused a nutritional requirement for the thiazole moiety of thiamine. data showed that iscs was required for the synthesis of nicotinic acid and the thiazole moiety of thiamine and that one or more additional isc gene products were required for a distinct step in the thiazole biosynthetic pathway ... | 2000 | 10869064 |
| the flagellar hook protein, flge, of salmonella enterica serovar typhimurium is posttranscriptionally regulated in response to the stage of flagellar assembly. | we investigated the posttranscriptional regulation of flge, a class 2 gene that encodes the hook subunit protein of the flagella. rnase protection assays demonstrated that the flge gene was transcribed at comparable levels in numerous strains defective in known steps of flagellar assembly. however, western analyses of these strains demonstrated substantial differences in flge protein levels. although wild-type flge levels were observed in strains with deletions of genes encoding components of th ... | 2000 | 10869084 |
| a phop-regulated outer membrane protease of salmonella enterica serovar typhimurium promotes resistance to alpha-helical antimicrobial peptides. | the outer membrane protein contents of salmonella enterica serovar typhimurium strains with phop/phoq regulon mutations were compared by two-dimensional gel electrophoresis. at least 26 species of outer membrane proteins (omps) were identified as being regulated by phop/phoq activation. one phop/phoq-activated omp was identified by semiautomated tandem mass spectrometry coupled with electronic database searching as pgte, a member of the escherichia coli ompt and yersinia pestis pla family of out ... | 2000 | 10869088 |
| a comparison of immunogenicity and in vivo distribution of salmonella enterica serovar typhi and typhimurium live vector vaccines delivered by mucosal routes in the murine model. | we evaluated the immune responses elicited by attenuated salmonella enterica serovar typhi vaccine strain cvd 908-htra and serovar typhimurium strain sl3261 alone or as live vectors carrying a plasmid encoding fragment c of tetanus toxin (ptetnir15) in mice immunized intranasally and orogastrically, as well as the in vivo distribution of vaccine organisms following immunization. higher serologic and proliferative responses against both vector and the foreign antigen were elicited when vaccines w ... | 2000 | 10869765 |
| gammadelta t cells may dichotomously modulate infection with avirulent salmonella choleraesuis via ifn-gamma and il-13 in mice. | to investigate the roles of gammadelta t cells in salmonella infection, we examined the resolution of an intraperitoneal infection with avirulent salmonella choleraesuis 31n-1 in mice lacking t-cell-receptor (tcr) alphabeta t cells by disruption of the tcrbeta chain gene (tcrbeta(-/-)). the bacteria in tcrbeta(-/-) mice decreased with kinetics similar to that seen in control mice (tcrbeta(+/+)) after infection. the number of natural killer (nk) cells in the peritoneal cavity increased on day 6 a ... | 2000 | 10873307 |
| acetyl phosphate-dependent activation of a mutant phop response regulator that functions independently of its cognate sensor kinase. | the two-component system is a signal communication network generally consisting of a sensor kinase that receives inputs from the environment and modifies the phosphorylated state of a response regulator that executes an adaptive behavior. phop is a response regulator that controls virulence gene expression in salmonella enterica. transcription of phop-regulated genes is modulated by the mg(2+) levels detected by the sensor phoq. here, we describe a phop mutant protein, phop*, that functions in t ... | 2000 | 10873466 |
| interaction of salmonella serotypes with porcine macrophages in vitro does not correlate with virulence. | the interaction between salmonella serotypes and macrophages is potentially instrumental in determining the outcome of infection. the nature of this interaction was characterized with respect to virulence and serotype-host specificity using pigs as the infection model. experimental infection with salmonella typhimurium, salmonella choleraesuis or salmonella dublin resulted in enteric, systemic or asymptomatic infection, respectively, which correlates well with the association of s. choleraesuis ... | 2000 | 10878128 |
| enhancement by ampicillin of antibody responses induced by a protein antigen and a dna vaccine carried by live-attenuated salmonella enterica serovar typhi. | live-attenuated salmonella species are effective carriers of microbial antigens and dna vaccines. in a mouse model, the immunoglobulin m (igm) and total antibody levels directed toward the lipopolysaccharide of salmonella enterica serovar typhi were significantly enhanced at day 21 after oral immunization with live-attenuated serovar typhi (strain ty21a) when ampicillin was concomitantly administered (p < 0.05 and p < 0.005, respectively). the heat-killed ty21a-stimulated lymphocyte proliferatio ... | 2000 | 10882658 |
| genotypic characterisation by pfge of salmonella enterica serotype enteritidis phage types 1, 4, 6, and 8 isolated from animal and human sources in three european countries. | a total of 101 strains of salmonella enteritidis phage types (pt) 1, 4, 6, and 8 from denmark, england and spain were studied by pfge to elucidate genetic relationships among strains isolated from animal, human and environmental sources between 1983 and 1997. analysis with xba i, bln i and spe i enzymes showed that the power of discrimination of this method was increased by the combination of the three enzymes (d=0.802), subdividing the strains into 28 genomic groups or genotypes. many of the pt ... | 2000 | 10889406 |
| parallel evolution of virulence in pathogenic escherichia coli. | the mechanisms underlying the evolution and emergence of new bacterial pathogens are not well understood. to elucidate the evolution of pathogenic escherichia coli strains, here we sequenced seven housekeeping genes to build a phylogenetic tree and trace the history of the acquisition of virulence genes. compatibility analysis indicates that more than 70% of the informative sites agree with a single phylogeny, suggesting that recombination has not completely obscured the remnants of ancestral ch ... | 2000 | 10894541 |
| identification of an alternative nucleoside triphosphate: 5'-deoxyadenosylcobinamide phosphate nucleotidyltransferase in methanobacterium thermoautotrophicum delta h. | computer analysis of the archaeal genome databases failed to identify orthologues of all of the bacterial cobamide biosynthetic enzymes. of particular interest was the lack of an orthologue of the bifunctional nucleoside triphosphate (ntp):5'-deoxyadenosylcobinamide kinase/gtp:adenosylcobinamide-phosphate guanylyltransferase enzyme (cobu in salmonella enterica). this paper reports the identification of an archaeal gene encoding a new nucleotidyltransferase, which is proposed to be the nonortholo ... | 2000 | 10894731 |
| reduction of cob(iii)alamin to cob(ii)alamin in salmonella enterica serovar typhimurium lt2. | reduction of the cobalt ion of cobalamin from the co(iii) to the co(i) oxidation state is essential for the synthesis of adenosylcobalamin, the coenzymic form of this cofactor. a cob(ii)alamin reductase activity in salmonella enterica serovar typhimurium lt2 was isolated to homogeneity. n-terminal analysis of the homogeneous protein identified nad(p)h:flavin oxidoreductase (fre) (ec 1.6.8.1) as the enzyme responsible for this activity. the fre gene was cloned, and the overexpressed protein, with ... | 2000 | 10894741 |
| antibiotic susceptibility and genotypes of non-typhi salmonella isolates from children in kilifi on the kenya coast. | a 4-year retrospective study was undertaken at the kilifi district hospital on the coast of kenya to determine the antibiotic-susceptibility patterns and genotypes of non-typhi salmonella (nts) isolates from children. overall, during the period 1994-97, positive cultures were obtained from 543 (14%) of 3885 blood samples, 364 (30%) of 1210 stool samples and 143 (11%) of 1283 cerebrospinal fluid (csf) samples. nts were isolated from 151 (27.8%), 72 (19.8%), and 11 (7.7%) of these positive culture ... | 2000 | 10897371 |
| antimicrobial resistance and spread of class 1 integrons among salmonella serotypes. | the resistance profiles, for 15 antimicrobial agents, of 333 salmonella strains representing the most frequent nontyphoidal serotypes, isolated between 1989 and 1998 in a spanish region, and 9 reference strains were analyzed. all strains were susceptible to amikacin, ceftazidime, ciprofloxacin, and imipenem, and 31% were susceptible to all antimicrobials tested. the most frequent types of resistance were to sulfadiazine, tetracycline, streptomycin, spectinomycin, ampicillin, and chloramphenicol ... | 2000 | 10898692 |
| salmonella enterica serovar typhimurium waap mutants show increased susceptibility to polymyxin and loss of virulence in vivo. | in escherichia coli, the waap (rfap) gene product was recently shown to be responsible for phosphorylation of the first heptose residue of the lipopolysaccharide (lps) inner core region. waap was also shown to be necessary for the formation of a stable outer membrane. these earlier studies were performed with an avirulent rough strain of e. coli (to facilitate the structural chemistry required to properly define waap function); therefore, we undertook the creation of a waap mutant of salmonella ... | 2000 | 10899846 |
| constitutive expression of the vi polysaccharide capsular antigen in attenuated salmonella enterica serovar typhi oral vaccine strain cvd 909. | live oral ty21a and parenteral vi polysaccharide vaccines provide significant protection against typhoid fever, albeit by distinct immune mechanisms. vi stimulates serum immunoglobulin g vi antibodies, whereas ty21a, which does not express vi, elicits humoral and cell-mediated immune responses other than vi antibodies. protection may be enhanced if serum vi antibody as well as cell-mediated and humoral responses can be stimulated. disappointingly, several new attenuated salmonella enterica serov ... | 2000 | 10899868 |
| salmonella enterica serovars gallinarum and pullorum expressing salmonella enterica serovar typhimurium type 1 fimbriae exhibit increased invasiveness for mammalian cells. | salmonella enterica serovars gallinarum and pullorum are s. enterica biotypes that exhibit host specificity for poultry and aquatic birds and are not normally capable of causing disease in mammalian hosts. during their evolution toward host restriction serovars gallinarum and pullorum lost their ability to mediate mannose-sensitive hemagglutination (msha), a phenotype correlated with adherence to certain cell types. because adherence is an essential requirement for invasion of cells by bacterial ... | 2000 | 10899888 |
| drug-resistant salmonella enterica serotype paratyphi a in india. | the incidence of enteric fever caused by salmonella enterica serotype paratyphi a has been increasing in india since 1996. in 1998, the incidence of enteric fever caused by drug- resistant s. paratyphi a abruptly increased in the new delhi region. in the first 6 months of 1999, 32% of isolates were resistant to both chloramphenicol and cotrimoxazole and another 13% were resistant to more than two antibiotics. | 2000 | 10905982 |
| changes in antimicrobial resistance in salmonella enterica serovar typhimurium. | 2000 | 10905990 | |
| rpos mutants in archival cultures of salmonella enterica serovar typhimurium. | long-term survival under limited growth conditions presents bacterial populations with unique environmental challenges. the existence of salmonella enterica serovar typhimurium cultures undisturbed in sealed nutrient agar stab vials for 34 to 45 years offered a unique opportunity to examine genetic variability under natural conditions. we have initiated a study of genetic changes in these archival cultures. we chose to start with examination of the rpos gene since, among gram-negative bacteria, ... | 2000 | 10913067 |
| trfa-dependent inner membrane-associated plasmid rk2 dna synthesis and association of trfa with membranes of different gram-negative hosts. | trfa, the replication initiator protein of broad-host-range plasmid rk2, was tested for its ability to bind to the membrane of four different gram-negative hosts in addition to escherichia coli: pseudomonas aeruginosa, pseudomonas putida, salmonella enterica serovar typhimurium, and rhodobacter sphaeroides. cells harboring trfa-encoding plasmids were fractionated into soluble, inner membrane, and outer membrane fractions. the fractions were subjected to western blotting, and the blots were probe ... | 2000 | 10913068 |
| tissue-specific gene expression identifies a gene in the lysogenic phage gifsy-1 that affects salmonella enterica serovar typhimurium survival in peyer's patches. | in vivo expression technology was used to identify salmonella enterica serovar typhimurium genes that are transcriptionally induced when the bacteria colonize the small intestines of mice. these genes were subsequently screened for those that are transcriptionally inactive during the systemic stages of disease. this procedure identified gipa, a gene that is specifically induced in the small intestine of the animal. the gipa gene is carried on the lambdoid phage gifsy-1. consistent with the expre ... | 2000 | 10913072 |
| a variation of the amplified-fragment length polymorphism (aflp) technique using three restriction endonucleases, and assessment of the enzyme combination bglii-mfei for aflp analysis of salmonella enterica subsp. enterica isolates. | we have performed amplified-fragment length polymorphism (aflp) fingerprinting on a collection of salmonella enterica subsp. enterica serovar typhimurium strains with a restriction endonuclease combination (bglii and mfei) that has previously been used successfully for typing campylobacter jejuni isolates with high resolution. additionally, a variation of the aflp assay in which two rare cutting restriction enzymes (xbai and bsrgi) in combination with the frequent cutter (hinp1i) was examined. t ... | 2000 | 10913860 |
| role of the cystic fibrosis transmembrane conductance regulator in innate immunity to pseudomonas aeruginosa infections. | chronic pseudomonas aeruginosa infection occurs in 75-90% of patients with cystic fibrosis (cf). it is the foremost factor in pulmonary function decline and early mortality. a connection has been made between mutant or missing cf transmembrane conductance regulator (cftr) in lung epithelial cell membranes and a failure in innate immunity leading to initiation of p. aeruginosa infection. epithelial cells use cftr as a receptor for internalization of p. aeruginosa via endocytosis and subsequent re ... | 2000 | 10922041 |
| isolation and characterization of salmonella gallinarum cytotoxic factors. | two distinct cytotoxic factors isolated from a salmonella gallinarum strain recovered from a bird died during an outbreak of fowl typhoid were purified to homogeneity through ciprofloxacin extraction, salt precipitation, dialysis, gelfiltration, ionexchange chromatography and chromatofocusing. these were designated as salmonella gallinarum cytotoxin i (gct-i) and ii (gct-ii). gct-i was a glycoprotein having mol.wt and pi of ca 70 kda and 8.8, respectively. it was lethal to birds (ld50, 150 micro ... | 2000 | 11395962 |
| antimicrobial drug resistance in non-typhoidal salmonellas from humans in england and wales in 1999: decrease in multiple resistance in salmonella enterica serotypes typhimurium, virchow, and hadar. | in 1999 the incidence of multiple drug resistance (to four or more antimicrobials) in non-typhoidal salmonellas from humans in england and wales fell in isolations of salmonella enterica serotypes typhimurium, virchow, and hadar. this fall has been most noticeable in s. typhimurium, where 59% of isolates were multiresistant compared to 81% in 1996. the main reason for this has been a 75% decline in isolations of multiply-resistant s. typhimurium definitive phage type (dt) 104 (mr dt104) since 19 ... | 2000 | 11272261 |
| studies of the phenomenon of host adaptation in salmonella. | to study the phenomenon of host adaptation in salmonella, a mathematical model has been developed which permits a definition and experimental investigation of the specific interaction between the adapted serovar and the adequate host. after experimental infection using a mixture of equal parts of two salmonella strains, a and b, the bacterial concentrations ca and cb were determined in the organs of the animals infected. if an animal of species a and an animal of species b are infected with the ... | 2000 | 11244872 |
| multidrug-resistant strains of salmonella enterica serotype typhi are genetically homogenous and coexist with antibiotic-sensitive strains as distinct, independent clones. | the goal of this study was to report the molecular analysis of antibiotic-sensitive and multidrug-resistant (mdr) strains of salmonella typhi, using pulsed-field gel electrophoresis (pfge), with a particular emphasis on the coexistence of these strains in a typhoid-endemic region of karachi, pakistan. | 2000 | 11231181 |
| first human case of salmonella enterica serotype landwasser recovered from breast fluid. | 2000 | 11185066 | |
| [antibiotics for uncomplicated salmonella enteritis: are they useful? a critical consideration of the literature]. | this article, a version of an earlier publication (6), reviews the human and veterinary literature on the effect of anti-microbials on uncomplicated salmonella enteritis. the main conclusion is that there is no evidence for the widely held belief that anti-microbials prolong the time that salmonellae are shed. | 2000 | 11189906 |
| prevalence and polymorphism of genes encoding translocated effector proteins among clinical isolates of salmonella enterica. | pathogenic salmonella enterica strains are capable of causing local and/or systemic infections. they employ two type iii secretion systems to translocate an array of virulence-associated proteins (effector proteins) directly into the cytosol of target cells of the host. earlier data had shown that changes in the repertoire of translocated effector proteins may contribute to the adaptation of salmonella strains to new hosts and to the emergence of epidemic strains. using pcr and southern blot tec ... | 2000 | 11200542 |
| sequence analysis and distribution in salmonella enterica serovars of is3-like elements. | the genome of salmonella enterica serovar enteritidis was shown to possess three is3-like insertion elements, designated is1230a, b and c, and each was cloned and their respective deoxynucleotide sequences determined. mutations in elements is1230a and b resulted in frameshifts in the open reading frames that encoded a putative transposase to be inactive. is1230c was truncated at nucleotide 774 relative to is1230b and therefore did not possess the 3' terminal inverted repeat. the three is1230 der ... | 2000 | 11200543 |
| epidemiology and characterization of animal salmonella enterica subspecies enterica serotype typhimurium dt104 in hungary. | reports on the internationally emerging significance of multiresistant zoonotic salmonella in animals and man prompted studies to estimate the significance of multiresistant salmonella enterica subspecies enterica serotype typhimurium (s. typhimurium) phage type dt104 of animal origin in hungary. a collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrof ... | 2000 | 11402658 |
| the fliu and fliv genes are expressed as a single orf in salmonella choleraesuis. | a dna fragment carrying flagellar genes was cloned from salmonella choleraesuis. compared to the corresponding dna fragment of salmonella muenchen, this fragment contained three orfs instead of four shown in s. muenchen. the dna sequence data showed that there was an insertion of nucleotide c in the orf of the s. choleraesuis fliu gene, which resulted in the disappearance of a termination codon downstream. the recombinant plasmid pfu11 containing the coding region of the fliu gene made by pcr on ... | 2000 | 11142406 |
| induction of early immunopotentiation to fimbriae of salmonella enteritidis (se) by administering thymulin and zinc to se-vaccinated chicken breeders: relationship to protection. | the purpose of this study is to attempt the induction of early immunopotentiation of antibodies specific to fimbriae of salmonella enterica serovar enteritidis (se), by administering thymulin and zinc to se-vaccinated chicken breeders, and the improvement of protection against a controlled-live challenge by se. the first two groups of breeders were administered subcutaneously at 15 and 19 weeks of age a killed se vaccine. breeders of the third and fourth groups were left unvaccinated. breeders o ... | 2000 | 11129855 |
| a cdna encoding 3-deoxy-d-manno-oct-2-ulosonate-8-phosphate synthase of pisum sativum l. (pea) functionally complements a kdsa mutant of the gram-negative bacterium salmonella enterica. | recombinant plasmids encoding 3-deoxy-d-manno-oct-2-ulosonate-8-phosphate (kdo-8-p) synthase (kdsa; ec 4.1.2.16) were identified from a cdna library of pisum sativum l. (pea) by complementing a temperature-sensitive kdsa(ts) mutant of the gram-negative bacterium salmonella enterica. sequence analysis of several inserts revealed a central open reading frame encoding a protein of 290 amino acids with a high degree of amino acid sequence similarity to bacterial kdsa. the cdna was confirmed by ampli ... | 2000 | 11219578 |
| a novel integron in salmonella enterica serovar enteritidis, carrying the bla(dha-1) gene and its regulator gene ampr, originated from morganella morganii. | the genetic organization of the gene coding for dha-1 and the corresponding ampr gene was determined by pcr mapping. these genes have been mobilized from the morganella morganii chromosome and inserted into a complex suli-type integron, similar to in6 and in7. however, they are not themselves mobile cassettes. this integron probably includes a specific site for recombination allowing the mobilization of diverse resistance genes, as observed for bla(cmy-1) and bla(mox-1). | 2000 | 10602756 |
| igh-6(-/-) (b-cell-deficient) mice fail to mount solid acquired resistance to oral challenge with virulent salmonella enterica serovar typhimurium and show impaired th1 t-cell responses to salmonella antigens. | in the present study we evaluated the role of b cells in acquired immunity to salmonella infection by using gene-targeted b-cell-deficient innately susceptible mice on a c57bl/6 background (igh-6(-/-)). igh-6(-/-) mice immunized with a live, attenuated aroa salmonella enterica serovar typhimurium vaccine strain showed impaired long-term acquired resistance against the virulent serovar typhimurium strain c5. igh-6(-/-) mice were able to control a primary infection and to clear the inoculum from t ... | 2000 | 10603367 |
| in vivo characterization of the murine intranasal model for assessing the immunogenicity of attenuated salmonella enterica serovar typhi strains as live mucosal vaccines and as live vectors. | attenuated salmonella enterica serovar typhi live vector vaccine strains are highly immunogenic in mice following intranasal but not orogastric inoculation. to elucidate the relationship between organs within which vaccine organisms are found and the induction of specific serum immunoglobulin g (igg) antibodies, we examined the in vivo distribution of serovar typhi vaccine strain cvd 908-htra following intranasal administration. vaccine organisms were cultured from the nasal lymphoid tissue (nal ... | 2000 | 10603389 |
| protection against experimental fowl typhoid by parenteral administration of live sl5828, an aroa-serc (aromatic dependent) mutant of a wild-type salmonella gallinarum strain made lysogenic for p22 sie. | a wild-type strain of salmonella enterica serotype gallinarum, lysogenized with p22 sie (superinfection-exclusion defective) was greatly attenuated for newly hatched or 21-day-old chickens. an aroa transductant of the lysogenic strain and an aroa-serc tetracycline-sensitive deletion or deletioninversion mutant of the latter were equally attenuated. intramuscular administration of the aroa-serc strain to 21-day-old chickens protected them against oral challenge with 10(6) colony forming units of ... | 2000 | 19184834 |
| evaluation of the effect of mannan-oligosaccharides on the competitive exclusion of salmonella enteritidis colonization in broiler chicks. | this study evaluated the protection against colonization by salmonella enterica serovar enteritidis in the chick's caecum when dosed with caecal contents from hens fed dietary carbohydrates based on mannose. protection was investigated by comparing the effects of four suspensions of hen caecal contents (hcc) fed diets supplemented with 2.5% d -mannose (man-hcc), 2.5% mannoseoligosaccharide (mos-hcc), 2.5% palm kernel meal (pkm-hcc) or unsupplemented mash (mashhcc). four trials to quantify and co ... | 2000 | 19184854 |
| pathogenicity of salmonella enteritidis phage types 4, 8 and 23 in specific pathogen free chicks. | the pathogenicity of two isolates of salmonella enterica serovar enteritidis (se) phage type (pt) 4, three of pt8 and one of pt23 was investigated in groups of 1-day-old specific pathogen free white leghorn chicks. two groups were crop gavaged with each culture but at two different doses. two additional groups were given salmonella enterica serovar pullorum (sp) at similar doses and one further group served as uninoculated controls. body weights were recorded at 14, 21, and 28 days postinoculati ... | 2000 | 19184855 |
| salmonella derby cross-protection study. | an avirulent live (avl), salmonella choleraesuis vaccine (salmo shield live [grand laboratories, inc.]) was administered to pigs at weaning or 3 weeks of age. two weeks after vaccination the vaccinated pigs as well as unvaccinated control pigs were challenged intranasally with a commonly isolated environmental salmonella serotype, s. derby. at 2, 4, and 6 weeks after challenge, pigs were euthanized and cultured for s. derby. although the number of pigs in this study was too small to draw any def ... | 2000 | 19757566 |
| clonal relationship of salmonella enterica serovar typhimurium phage type dt104 in germany and austria. | a new epidemic clone of salmonella enterica serovar typhimurium designated definitive phage type (dt) 104 has been emerging since 1990 to become most common type among s. typhimurium isolates in germany and austria. molecular fingerprinting (pfge-pattern, plasmid profiles, is200 pattern, ribotype, eric-type, omp and mle patterns) revealed the majority of the dt104 isolates to have clonal identity; they were designated as type 1 (about 95%). moreover, clonal type 1 of dt104 was found to occur in ... | 1999 | 10603659 |
| mucosal competitive exclusion to reduce salmonella in swine. | a mucosal competitive exclusion culture has been shown to reduce or eliminate salmonella spp. in poultry. using similar techniques, a mucosal competitive exclusion culture from swine (mces) was produced from the cecum of a 6-week-old pig. suckling pigs were inoculated with 5 ml of mces by oral gavage within 6 h postfarrowing (pf) and again at 24 h pe all pigs were challenged with 10(3) cfu of salmonella choleraesuis at 48 h pf by intranasal instillation, including pigs from two sows that had not ... | 1999 | 10606140 |
| changes in antimicrobial resistance among salmonella enterica serovar typhimurium isolates from humans and cattle in the northwestern united states, 1982-1997. | we compared antimicrobial resistance patterns of salmonella enterica serovar typhimurium (st) of isolates from humans (n = 715) and cattle (n = 378) in the pacific northwest from 1982 through 1997. the major changes in antimicrobial resistance can be attributed to the widespread clonal dissemination of multidrug-resistant definitive phage type 104 st. | 1999 | 10603215 |
| multinational outbreak of salmonella enterica serotype newport infections due to contaminated alfalfa sprouts. | in december 1995, reported salmonella enterica serotype newport (sn) infections increased sharply in oregon and british columbia but not elsewhere in north america. similar unexplained increases had been noted in 6 other states in the fall of 1995. | 1999 | 9917119 |
| transduction of multiple drug resistance of salmonella enterica serovar typhimurium dt104. | epidemic strain salmonella typhimurium dt104 is characterized by various multiresistance patterns. at least some of the resistance genes are organized as integrons. resistance genes of dt104 isolates can be efficiently transduced by p22-like phage es18 and by phage pdt17 which is released by all dt104 isolates so far analyzed. cotransduction tests demonstrate that the resistance genes, although not organized in a unique integron, are tightly clustered on the salmonella chromosome. the spread of ... | 1999 | 9919675 |
| the spi-3 pathogenicity island of salmonella enterica. | pathogenicity islands are chromosomal clusters of pathogen-specific virulence genes often found at trna loci. we have determined the molecular genetic structure of spi-3, a 17-kb pathogenicity island located at the selc trna locus of salmonella enterica serovar typhimurium. the g+c content of spi-3 (47.5%) differs from that of the salmonella genome (52%), consistent with the notion that these sequences have been horizontally acquired. spi-3 harbors 10 open reading frames organized in six transcr ... | 1999 | 9922266 |
| complement activation by bacterial surface glycolipids: a study with planar bilayer membranes. | planar asymmetric glycolipid/phospholipid bilayer membranes were used as a reconstitution model of the lipid matrix of the outer membrane of gram-negative bacteria to study complement (c) activation by various bacterial surface glycolipids with the aim of defining the c activation pathway. as glycolipids the lipopolysaccharides of salmonella enterica serovar minnesota r mutant strains r595 (re lps) and r4 (rd2 lps), pentaacyl lipid a from the lps of the escherichia coli re mutant f515, and glyco ... | 1999 | 9929374 |
| the virulence plasmid of salmonella typhimurium is self-transmissible. | most isolates of salmonella enterica serovar typhimurium contain a 90-kb virulence plasmid. this plasmid is reported to be mobilizable but nonconjugative. however, we have determined that the virulence plasmid of strains lt2, 14028, and sr-11 is indeed self-transmissible. the plasmid of strain sl1344 is not. optimal conjugation frequency requires filter matings on m9 minimal glucose plates with a recipient strain lacking the virulence plasmid. these conditions result in a frequency of 2.9 x 10(- ... | 1999 | 9973370 |
| mhc class ii-dependent nk1.1+ gammadelta t cells are induced in mice by salmonella infection. | we observed the emergence of a novel population of gammadelta t cells expressing nk1.1 ag in the peritoneal cavity of mice infected with salmonella choleraesuis. the nk1.1+gammadelta t cells accounted for approximately 20% of all gammadelta t cells emerging in the peritoneal cavity of c57bl/6 mice and expressed preferentially rearranged vgamma4-jgamma1 and vdelta6.3-ddelta1-ddelta2-jdelta1 genes with n diversity. the gammadelta t cells proliferated vigorously in response to pha-treated spleen ce ... | 1999 | 9973415 |