| 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 |
| [antimicrobial susceptibility of a selection of salmonella enterica strains of various origins isolated in spain]. | the widespread use of antimicrobials in human and veterinary practice is increasingly causing the emergence of different multidrug-resistant human pathogens. this situation makes treating infections caused by these microorganisms difficult. salmonella enterica is an ubiquitous organism and may be a good indicator of the influence of the use and abuse of antimicrobials on the appearance of multiresistant strains. one hundred and ninety s. enterica strains of different origins isolated in spain in ... | 1999 | 10878517 |
| [evolution of resistance to quinolonesin salmonella enterica in our environment] | 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 | 10878530 |
| 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 |
| incidence of new salmonella serovar (s. ratchaburi) in thailand. | eighteen strains of salmonella group e from stool samples were confirmed as salmonella new serovar. 3, 10 : z35 : 1, 6 by centre international des salmonella, institut pasteur, paris, who collaborating center for salmonella, atlanta, usa and salmonella-zentrale hygienischen institut, hamburg, germany. the name of this new serovar was proposed as s. ratchaburi according to the place of its first isolation in ratchaburi province. the new serovar of salmonella was sensitive to many antimicrobial ag ... | 1999 | 10928375 |
| partial characterization of a genomic island associated with the multidrug resistance region of salmonella enterica typhymurium dt104. | this study describes the identification of the insertion site and partial characterization of a 43-kb region harboring the genes associated with the penta-resistant phenotype of a canadian isolate of salmonella enterica typhymurium dt104 labelled 96-5227. the 43-kb fragment, here referred to as salmonella genomic island i (sgii), was found in the genome of s. enterica typhymurium between the thdf and a prophage cp-4-like integrase (int2) gene and is flanked by an imperfect 18-bp direct repeat. a ... | 2000 | 10930753 |
| the cis requirements for transcriptional activation by hila, a virulence determinant encoded on spi-1. | in several models of pathogenesis, salmonella requires genes encoded on salmonella pathogenicity island 1 (spi-1) for virulence. in salmonella enterica serovar typhimurium (s. typhimurium), most spi-1 genes are arranged in operons and are co-ordinately regulated in response to environmental signals via the spi-1-encoded protein hila. in order to understand how hila controls the transcription of spi-1 genes, we have analysed the invf and prgh promoters. we have reconstituted hila-dependent activa ... | 2000 | 10931326 |
| mechanisms of action of rabbit cap18 on monolayers and liposomes made from endotoxins or phospholipids. | we have investigated the mechanism of action of the cationic antimicrobial protein (18 kda) cap18 on liposomes and monolayers made from phospholipids and enterobacterial lipopolysaccharides (lps). cap18 intercalates into lipid matrices composed of lps from sensitive strains, weaker into those made of lps from a resistant strain (proteus mirabilis strain r45) or negatively charged phospholipids, but not into those composed of neutral phosphatidylcholine. from the combination of data obtained with ... | 2000 | 10931974 |
| adhesion of salmonella enterica var enteritidis strains lacking fimbriae and flagella to rat ileal explants cultured at the air interface or submerged in tissue culture medium. | rat ileal air interface and submerged explant models were developed and used to compare the adhesion of salmonella enterica var enteritidis wild-type strains with that of their isogenic single and multiple deletion mutants. the modified strains studied were defective for fimbriae, flagella, motility or chemotaxis and binding was assessed on tissues with and without an intact mucus layer. a multiple afimbriate/aflagellate (fim-/fla-) strain, a fimbriate but aflagellate (fla-) strain and a fimbria ... | 2000 | 10933252 |
| the paratyphoid salmonellae. | the paratyphoid salmonella bacteria, comprising more than 2,000 serovars or serotypes, are a major problem to the poultry industry. this is largely the result of entry of the bacteria into the human food chain. human infection takes the form of a gastroenteritis, which in highly susceptible individuals can result in death. some strains of certain serotypes have the capacity to produce morbidity and mortality in very young chickens. in adult birds, some serovars become localised in the reproducti ... | 2000 | 10935268 |
| regulation of sigma s degradation in salmonella enterica var typhimurium: in vivo interactions between sigma s, the response regulator mvia(rssb) and clpx. | the alternate sigma factor sigmas plays an important role in the survival of salmonella typhimurium following sudden encounters with a variety of stress conditions. the level of sigmas is very low in rapidly growing cells but dramatically increases as those cells encounter environmental stress or enter into stationary phase. this increase is due in large measure to the stabilization of sigmas protein against degradation by the clpxp protease. the mvia protein, also known as rssb or spre in esche ... | 2000 | 10939250 |
| arguments against the replacement of type species of the genus salmonella from salmonella choleraesuis to 'salmonella enterica' and the creation of the term 'neotype species', and for conservation of salmonella choleraesuis. | the proposals of le minor and popoff in 1987 and again of euzéby in 1999 on the type species of the genus salmonella are in violation of rule 20a of the bacteriological code (1990 revision) and should be rejected. the introduction of the term 'neotype species' should be rejected. the specific epithet choleraesuis in the binary combination salmonella choleraesuis should be conserved. the serovar name choleraesuis should be changed to hogcholera. | 2000 | 10939679 |
| [salmonella enterica infections]. | | 2000 | 10941252 |
| constitutively expressed phop inhibits mouse-virulence of salmonella typhimurium in an spv-dependent manner. | in salmonella typhimurium, the transcription of several virulence genes including spvb is regulated by the phop/phoq regulatory system. to further examine the relationship between the phop/phoq and spv systems for virulence in mice, we examined a non-polar phop mutation combined with different virulence plasmid genotypes for effects on virulence of s. typhimurium in the mouse model. phop-/spv+ and phop-/spv- mutants were not detectably recovered from the spleens of subcutaneously or orally inocu ... | 2000 | 10941927 |
| salmonella infantis osteomyelitis in sickle cell disease. | | 2000 | 10942649 |
| the virulence plasmids of salmonella. | certain salmonella serovars belonging to subspecies i carry a large, low-copy-number plasmid that contains virulence genes. virulence plasmids are required to trigger systemic disease; their involvement in the enteric stage of the infection is unclear. salmonella virulence plasmids are heterogeneous in size (50-90 kb), but all share a 7.8 kb region, spv, required for bacterial multiplication in the reticuloendothelial system. other loci of the plasmid, such as the fimbrial operon pef, the conjug ... | 1999 | 10943411 |
| 16s to 23s rrna spacer fragment length polymorphism of salmonella enterica at subspecies and serotype levels. | the variation in the lengths of the internal transcribed spacer (its) between 16s and 23s rrna genes of 101 strains representing 58 serotypes of salmonella enterica (used for salm. choleraesuis) subsp. enterica (i), salamae (ii), arizonae (iiia), diarizonae (iiib), houtenae (iv) and indica (vi) was used for typing by pcr amplification. ten fragment lengths were observed by denaturing polyacrylamide gel electrophoresis on an automatic dna sequencer resulting in 21 unique fragment patterns. ten ou ... | 2000 | 10945789 |
| invasion genes are not required for salmonella enterica serovar typhimurium to breach the intestinal epithelium: evidence that salmonella pathogenicity island 1 has alternative functions during infection. | salmonella enterica serovar typhimurium invasion genes are necessary for bacterial invasion of intestinal epithelial cells and are thought to allow salmonellae to enter and cross the intestinal epithelium during infection. many invasion genes are encoded on salmonella pathogenicity island 1 (spi1), and their expression is activated by hila, a transcription factor also encoded on spi1. we have studied the role of salmonella invasion genes during infection of mice following intragastric inoculatio ... | 2000 | 10948124 |
| vacuole acidification is not required for survival of salmonella enterica serovar typhimurium within cultured macrophages and epithelial cells. | phagosome acidification is an important component of the microbicidal response by infected eukaryotic cells. thus, intracellular pathogens that reside within phagosomes must either block phagosome acidification or be able to survive at low ph. in this work, we studied the effect of phagosomal acidification on the survival of intracellular salmonella enterica serovar typhimurium in different cell types. bafilomycin a1, a specific inhibitor of the vacuolar proton-atpases, was used to block acidifi ... | 2000 | 10948170 |
| a hydrogen peroxide-forming nadh oxidase that functions as an alkyl hydroperoxide reductase in amphibacillus xylanus. | the amphibacillus xylanus nadh oxidase, which catalyzes the reduction of oxygen to hydrogen peroxide with beta-nadh, can also reduce hydrogen peroxide to water in the presence of free flavin adenine dinucleotide (fad) or the small disulfide-containing salmonella enterica ahpc protein. the enzyme has two disulfide bonds, cys128-cys131 and cys337-cys340, which can act as redox centers in addition to the enzyme-bound fad (k. ohnishi, y. niimura, m. hidaka, h. masaki, h. suzuki, t. uozumi, and t. ni ... | 2000 | 10960086 |
| lesions in gsha (encoding gamma-l-glutamyl-l-cysteine synthetase) prevent aerobic synthesis of thiamine in salmonella enterica serovar typhimurium lt2. | thiamine pyrophosphate is an essential cofactor that is synthesized de novo in salmonella enterica serovar typhimurium and other bacteria. in addition to genes encoding enzymes in the biosynthetic pathway, mutations in other metabolic loci have been shown to prevent thiamine synthesis. the latter loci identify the integration of the thiamine biosynthetic pathway with other metabolic processes and can be uncovered when thiamine biosynthesis is challenged. mutations in gsha, encoding gamma-l-gluta ... | 2000 | 10960103 |
| phosphorylation-induced signal propagation in the response regulator ntrc. | the bacterial enhancer-binding protein ntrc is a well-studied response regulator in a two-component regulatory system. the amino (n)-terminal receiver domain of ntrc modulates the function of its adjacent output domain, which activates transcription by the sigma(54) holoenzyme. when a specific aspartate residue in the receiver domain of ntrc is phosphorylated, the dimeric protein forms an oligomer that is capable of atp hydrolysis and transcriptional activation. a chemical protein cleavage metho ... | 2000 | 10960104 |
| the flagellar filament of rhodobacter sphaeroides: ph-induced polymorphic transitions and analysis of the flic gene. | flagellar motility in rhodobacter sphaeroides is notably different from that in other bacteria. r. sphaeroides moves in a series of runs and stops produced by the intermittent rotation of the flagellar motor. r. sphaeroides has a single, plain filament whose conformation changes according to flagellar motor activity. conformations adopted during swimming include coiled, helical, and apparently straight forms. this range of morphological transitions is larger than that in other bacteria, where fi ... | 2000 | 10960108 |
| the escherichia coli o111 and salmonella enterica o35 gene clusters: gene clusters encoding the same colitose-containing o antigen are highly conserved. | o antigen is part of the lipopolysaccharide present in the outer membrane of gram-negative bacteria. escherichia coli and salmonella enterica each have many forms of o antigen, but only three are common to the two species. it has been found that, in general, o-antigen genes are of low gc content. this deviation in gc content from that of typical s. enterica or e. coli genes (51%) is thought to indicate that the o-antigen dna originated in species other than s. enterica or e. coli and was capture ... | 2000 | 10960113 |
| mutational analysis of genes encoding the early flagellar components of helicobacter pylori: evidence for transcriptional regulation of flagellin a biosynthesis. | we investigated the roles of flif, flis, flhb, fliq, flig, and flii of helicobacter pylori, predicted by homology to encode structural components of the flagellar basal body and export apparatus. mutation of these genes resulted in nonmotile, nonflagellate strains. western blot analysis showed that all the mutants had considerably reduced levels of both flagellin subunits and of flge, the flagellar hook protein. rna slot blot hybridization showed reduced levels of flaa mrna, indicating that tran ... | 2000 | 10960117 |
| prevalence of intestinal pathogens in danish finishing pig herds. | our aim was to determine the prevalence of the intestinal bacteria: lawsonia intracellularis, brachyspira hyodysenteriae, serpulina intermedia, brachyspira innocens, brachyspira pilosicoli, pathogenic escherichia coli (serogroups o138, o139, o141 and o149) and salmonella enterica in danish finishing pig herds. a total of 79 herds was randomly selected and visited during 1998. from each herd, 20 faecal samples were collected from individual pigs weighing 30-50kg. furthermore, 10 pooled pen sample ... | 2000 | 10960714 |
| rapid identification of salmonella typhimurium, s. enteritidis and s. virchow isolates by polymerase chain reaction based fingerprinting methods. | in this study we used and evaluated three rapid molecular typing methods for the identification of three frequent, clinically significant salmonella serovars on the basis of the ease, simplicity and reproducibility of the chosen methods. we determined the genetic diversity among several isolates of salmonella enteritidis, s. typhimiurium and s. virchow, and compared them with other enterobacteria by using the repetitive extragenic palindromic (rep) sequences, the enterobacterial repetitive inter ... | 2000 | 10963331 |
| engineering hydrogen sulfide production and cadmium removal by expression of the thiosulfate reductase gene (phsabc) from salmonella enterica serovar typhimurium in escherichia coli. | the thiosulfate reductase gene (phsabc) from salmonella enterica serovar typhimurium was expressed in escherichia coli to overproduce hydrogen sulfide from thiosulfate for heavy metal removal (or precipitation). a 5.1-kb dna fragment containing phsabc was inserted into the pmb1-based, high-copy, isopropyl-beta-d-thiogalactopyranoside-inducible expression vector ptrc99a and the rk2-based, medium-copy, m-toluate-inducible expression vector pjb866, resulting in plasmids psb74 and psb77. a 3. 7-kb d ... | 2000 | 10966412 |
| resuscitation by ferrioxamine e of stressed salmonella enterica serovar typhimurium from soil and water microcosms. | storage of salmonella enterica serovar typhimurium strains in soil and water microcosms resulted in loss of culturability on standard plating media. prior incubation in buffered peptone water supplemented with ferrioxamine e markedly extended the time that bacteria were recoverable by plating, except in the case of mutants deficient in ferrioxamine e uptake. | 2000 | 10966440 |
| genotypes of multidrug-resistant salmonella enterica serotype typhimurium from two regions of kenya. | a combination of phage typing and pulsed-field gel electrophoresis of xbal-digested chromosomal dna has been used to study the epidemiological relationships of multidrug-resistant salmonella enterica serotype typhimurium from nairobi (64 isolates) and kilifi (40 isolates) collected over the period 1994-1997. isolates from nairobi belonged to 11 definitive phage types (dts) encompassing eight different pfge patterns. in contrast, isolates from kilifi were mainly dt 56 (60%) and all fell into a si ... | 2000 | 10967254 |
| automated 5' nuclease pcr assay for identification of salmonella enterica. | a simple and ready-to-go test based on a 5' nuclease (taqman) pcr technique was developed for identification of presumptive salmonella enterica isolates. the results were compared with those of conventional methods. the taqman assay was evaluated for its ability to accurately detect 210 s. enterica isolates, including 100 problematic "rough" isolates. an internal positive control was designed to use the same salmonella primers for amplification of a spiked nonrelevant template (116 bp) in the sa ... | 2000 | 10970396 |
| identification of dt104 and u302 phage types among salmonella enterica serotype typhimurium isolates by pcr. | a dna sequence was identified in isolates of salmonella enterica serotype typhimurium definitive type 104 (dt104). the pcr amplification of an internal segment of this sequence identified dt104 and the closely related u302 phage type among 146 isolates of s. enterica serotype typhimurium tested, thus providing a tool for rapid identification of dt104 and related isolates. | 2000 | 10970411 |
| fecal excretion of salmonella enterica serovar typhimurium following a food-borne outbreak. | fecal excretion of salmonella enterica serovar typhimurium organisms was observed in patients and in people not showing symptoms who were involved in an outbreak of food-borne infection with this organism. excretion of organisms was prolonged in the patients who were given antimicrobial drugs compared with those who were not. the isolates were indistinguishable by their pulsed-field gel electrophoresis patterns and biotyping from the strain recovered from the roast pork that had been consumed by ... | 2000 | 10970414 |
| the spvb gene-product of the salmonella enterica virulence plasmid is a mono(adp-ribosyl)transferase. | a number of well-known bacterial toxins adp-ribosylate and thereby inactivate target proteins in their animal hosts. recently, several vertebrate ecto-enzymes (art1-art7) with activities similar to bacterial toxins have also been cloned. we show here that psiblast, a position-specific-iterative database search program, faithfully connects all known vertebrate ecto-mono(adp-ribosyl)transferases (madprts) with most of the known bacterial madprts. intriguingly, no matches were found in the availabl ... | 2000 | 10972829 |
| genetic variation of dtdp-l-rhamnose pathway genes in salmonella enterica. | the genetic variation in the dtdp-l-rhamnose pathway gene set (rmlb, rmld, rmla, rmlc) in salmonella enterica was examined after sequencing the four genes from 11 rml-containing gene clusters encoding seven o antigens, and a 903 bp rmlb segment from another 23 strains representing the seven subspecies. there was considerable sequence variation and strong polarity in the nature and level of variation among rml genes. the 5' end of the rml gene set, including rmlb, rmld and most of rmla, is in gen ... | 2000 | 10974117 |
| [extra-intestinal infections caused by non-typhi salmonella serotypes. 9 yrs' experience]. | the most characteristic finding in non typhoid salmonella serotype infection is acute gastroenteritis which is usually benign and self-limiting. however, more serious extraintestinal findings, such as bacteraemia and focal infections localized to any organ may appear. | 2000 | 10974765 |
| [construction of an expression plasmid vector for accomplishing in vivo delivery of recombinant biologically active proteins. 2. synthesis of hbcag in a vaccine strain of salmonella choleraesuis]. | the capacity of a previously described plasmid vector paz to deliver bioactive proteins to targets in vivo has been studied. this vector molecule has a strong constitutive promoter, is extremely stable in cells of vaccinal s. choleraesuis strain, and encodes the synthesis of marker protein beta-galactosidase which helps monitor the vector's fate in the host. the gene encoding hepatitis b virus core antigen (hbcag) has been inserted into paz under its constitutive promoter. the resultant recombin ... | 2000 | 10975075 |
| activation of akt/protein kinase b in epithelial cells by the salmonella typhimurium effector sigd. | the serine-threonine kinase akt is a protooncogene involved in the regulation of cell proliferation and survival. activation of akt is initiated by binding to the phospholipid products of phosphoinositide 3-kinase at the inner leaflet of the plasma membranes followed by phosphorylation at ser(473) and thr(308). we have found that akt is activated by salmonella enterica serovar typhimurium in epithelial cells. a bacterial effector protein, sigd, which is translocated into host cells via the speci ... | 2000 | 10978351 |
| grouping of salmonella enterica serotype montevideo strains by ribotyping and is200 profiling. | one-hundred and twenty-one isolates of salmonella enterica serotype montevideo, representing different biotypes and incidents of infection detected in the uk between 1977 and 1995, were analysed by ecori ribotyping, pvuii ribotyping and is200 fingerprinting. among the isolates examined, 7 ecori ribotypes, 5 pvuii ribotypes and 55 is200 profile types were recognized and 4 arbitrary groups defined. all 33 isolates of biotype 2d belonged to ecori/pvuii ribotype 1/1 and is200 lineage a and comprised ... | 2000 | 10982060 |
| serovar specific risk factors and clinical features of salmonella enterica ssp. enterica serovar enteritidis: a study in south-west germany. | human salmonellosis in germany has been an increasing problem since the 1980s, with a peak of 195,000 reported cases in 1992. during the peak years, isolates of salmonella enteritidis (se) predominated by far over other salmonella serovars (nse) (80 vs. 20%). in a comparison of the clinical characteristics of 790 persons infected with se to 175 persons infected with nse, watery diarrhoea (or 1.7) and high grade (> 39 degrees c) fever (or 1.8) were independently associated with se infection. when ... | 2000 | 10982061 |
| web-based visualization tools for bacterial genome alignments. | with the increase in the flow of sequence data, both in contigs and whole genomes, visual aids for comparison and analysis studies are becoming imperative. we describe three web-based tools for visualizing alignments of bacterial genomes. the first, called enteric, produces a graphical, hypertext view of pairwise alignments between a reference genome and sequences from each of several related organisms, covering 20 kb around a user-specified position. insertions, deletions and rearrangements rel ... | 2000 | 10982867 |
| action of the thiamine antagonist bacimethrin on thiamine biosynthesis. | bacimethrin is an analog of the 4-amino-5-hydroxymethyl-2-methylpyrimidine (hmp) moiety of thiamine and inhibits the growth of salmonella enterica serovar typhimurium on a defined medium. two classes of mutants that had increased bacimethrin resistance were isolated and characterized. results showed that overexpression of the thi operon or specific lesions in thid resulted in a bacimethrin-resistant phenotype. phenotypic analyses of the thid mutants suggested that they had a specific defect in o ... | 2000 | 10986269 |
| new technology for regiospecific covalent coupling of polysaccharide antigens in elisa for serological detection. | in this study we demonstrate a new uv irradiation technique for covalent coupling of bacterial polysaccharides derived from lipopolysaccharides to microtiter plates and the use of such plates in an enzyme linked immunosorbent assay (elisa). lipopolysaccharides were cleaved by mild acid hydrolysis into the lipid a part and the polysaccharide part. the polysaccharide was conjugated regiospecifically to a photochemically active compound, anthraquinone, resulting in a polysaccharide-anthraquinone co ... | 2000 | 10986396 |
| susceptibility to secondary bacterial infections in growing pigs as an early response in ochratoxicosis. | mycotoxic nephropathy was induced in twelve 14 kg pigs fed a dietary component, moulded by aspergillus ochraceus and contributing ochratoxin a at 1 or 3 ppm for up to 3 weeks. concurrently, salmonellosis arose spontaneously in all six animals treated at 3 ppm and all died between days 15 and 17. two of the six pigs in the 1 ppm group died similarly but the rest, and all of six control animals, were unaffected. clinical biochemistry and histology revealed changes typical of renal ochratoxicosis i ... | 2000 | 10987179 |
| risk factors for the occurrence of sporadic salmonella enterica serotype typhimurium infections in children in france: a national case-control study. | to determine risk factors for the occurrence of sporadic salmonella typhimurium infections among children in france, we conducted a matched case-control study. cases were identified between 15 june and 30 september 1996. we interviewed 101 pairs of case patients and control subjects, matched for age and place of residence. the risk of illness was greater for children who ate undercooked ground beef than for those who did not (odds ratio [or], 5.0; 95% confidence interval [ci], 1.9-13.1). case pa ... | 2000 | 10987710 |
| plasmid-mediated florfenicol resistance encoded by the flor gene in escherichia coli isolated from cattle. | a florfenicol resistance gene almost identical to flor of salmonella enterica serovar typhimurium dt104 was detected on 110- to 125-kb plasmids in escherichia coli isolates of animal origin. analysis of the flor gene flanking regions of one of the plasmids showed that they were different from those encountered in s. enterica serovar typhimurium dt104. | 2000 | 10991873 |
| multiple-antibiotic resistance mediated by structurally related incl/m plasmids carrying an extended-spectrum beta-lactamase gene and a class 1 integron. | a conjugative incl/m plasmid (psem) conferring resistance to gentamicin, amikacin, kanamycin, sulfonamides, and expanded-spectrum cephalosporins was found in pathogenic strains of salmonella enterica serotype typhimurium. resistance to aminoglycosides was encoded by a sul1-type class 1 integron (in-t3). an extended-spectrum beta-lactamase gene, bla(shv-5), was identified 3. 5 kb downstream of the integrase (inti1) gene of in-t3. nucleotide sequence analysis of the 5.3-kb bla(shv-5)-in-t3 region ... | 2000 | 10991889 |
| high-affinity interaction between gram-negative flagellin and a cell surface polypeptide results in human monocyte activation. | flagella from diverse gram-negative bacteria induce tumor necrosis factor alpha (tnf-alpha) and interleukin-1beta (il-1beta) synthesis by human monocytes (f. ciacci-woolwine, p. f. mcdermott, and s. b. mizel, infect. immun. 67:5176-5185, 1999). in this study, we establish that purified flagellin (flic or fljb), the major filament protein from salmonella enterica serovar enteritidis, s. enterica serovar typhimurium, and pseudomonas aeruginosa, is an extremely potent inducer of tnf-alpha productio ... | 2000 | 10992449 |
| regulation of cathelicidin gene expression: induction by lipopolysaccharide, interleukin-6, retinoic acid, and salmonella enterica serovar typhimurium infection. | cathelicidins are a family of antimicrobial peptides prominent in the host defense mechanisms of several mammalian species. in addition to their antimicrobial activities, these peptides have been implicated in wound healing, angiogenesis, and other innate immune mechanisms. to investigate the regulatory mechanisms of cathelicidin gene expression, we conducted in vitro experiments evaluating the bone marrow cell expression of two porcine cathelicidins, pr-39 and protegrin, and cloned and evaluate ... | 2000 | 10992453 |
| salmonella enterica serovar typhimurium-dependent regulation of inducible nitric oxide synthase expression in macrophages by invasins sipb, sipc, and sipd and effector sope2. | when salmonella enterica invades mammalian cells, it activates signals leading to increased expression of inflammatory mediators. one such mediator is nitric oxide (no), which is produced under control of the enzyme inducible no synthase (inos). induction of inos in response to salmonella infection has been demonstrated, but the bacterial effector molecules that regulate expression of the enzyme have not been identified. in the study reported here, an analysis of salmonella-dependent inos expres ... | 2000 | 10992455 |
| human c-reactive protein is protective against fatal salmonella enterica serovar typhimurium infection in transgenic mice. | c-reactive protein (crp) is an acute-phase protein with a well-known association with infection and other inflammatory conditions. we have shown that expression of human crp by crp transgenic (crptg) mice is protective against lethal infection by streptococcus pneumoniae, an effect likely mediated by crp's ability to bind to this gram-positive pathogen. in the present study we tested whether crptg mice are resistant to infection with salmonella enterica serovar typhimurium, a gram-negative patho ... | 2000 | 10992466 |
| salmonella pathogenicity island 1-independent induction of apoptosis in infected macrophages by salmonella enterica serotype typhimurium. | the enteric pathogen salmonella enterica serotype typhimurium induces apoptosis in infected macrophages. this process is rapid, specific, and depends on the type iii protein secretion system encoded within salmonella pathogenicity island 1 (spi1). here, we demonstrate that serotype typhimurium can activate programmed macrophage cell death independently of spi1. spi1 independent induction of apoptosis in infected macrophages is observed as early as 12 to 13 h postinfection, even in the absence of ... | 2000 | 10992474 |
| comparison of abilities of salmonella enterica serovar typhimurium aroa arod and aroa htra mutants to act as live vectors. | we compared the ability of salmonella enterica serovar typhimurium sl1344 aroa arod (brd509) and aroa htra (brd807) mutants to act as live vectors for delivery of fragment c of tetanus toxin (frgc). frgc was expressed in these strains from either ptetnir15 or ptethtra1. brd509frgc(+) strains elicited approximately 2-log-higher serum anti-frgc antibody titers than brd807frgc(+) strains. all mice immunized with brd807ptethtra1, brd509ptethtra1, and brd509ptetnir15 (but not brd807ptetnir15) were pr ... | 2000 | 10992518 |
| identification of rpos (sigma(s))-regulated genes in salmonella enterica serovar typhimurium. | the rpos gene encodes the alternative sigma factor sigma(s) (rpos) and is required for survival of bacteria under starvation and stress conditions. it is also essential for salmonella virulence in mice. most work on the rpos regulon has been in the closely related enterobacterial species escherichia coli. to characterize the rpos regulon in salmonella, we isolated 38 unique rpos-activated lacz gene fusions from a bank of salmonella enterica serovar typhimurium mutants harboring random tn5b21 mut ... | 2000 | 11004173 |
| sigma(54) promoters control expression of genes encoding the hook and basal body complex in rhodobacter sphaeroides. | gene expression of the flagellar system is tightly controlled by external stimuli or intracellular signals. a general picture of this regulation has been obtained from studies of salmonella enterica serovar typhimurium. however, these regulatory mechanisms do not apply to all bacterial groups. in this study, we have investigated regulation of the flagellar genetic system in rhodobacter sphaeroides. deletion analysis, site-directed mutagenesis, and 5'-end mapping were conducted in order to identi ... | 2000 | 11004178 |
| identification of a copper-responsive two-component system on the chromosome of escherichia coli k-12. | using a genetic screen we have identified two chromosomal genes, cusrs (ylca ybcz), from escherichia coli k-12 that encode a two-component, signal transduction system that is responsive to copper ions. this regulatory system is required for copper-induced expression of pcoe, a plasmid-borne gene from the e. coli copper resistance operon pco. the closest homologs of cusr and cuss are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: pcor and pcos from ... | 2000 | 11004187 |
| no genetic barriers between salmonella enterica serovar typhimurium and escherichia coli in sos-induced mismatch repair-deficient cells. | conjugational crosses trigger sos induction in escherichia coli f(-) cells mated with salmonella enterica serovar typhimurium hfr donors. using an epigenetic indicator of sos induction, we showed that a strong sos response occurring in a subpopulation of mated mismatch repair-deficient cells totally abolishes genetic barriers between these two genera. | 2000 | 11004198 |
| the colanic acid gene cluster of salmonella enterica has a complex history. | the colanic acid gene cluster of salmonella enterica lt2 was sequenced and compared with that of escherichia coli k-12. the two clusters are similar with divergence slightly higher than average for genes of the two species. the cluster was divided into four blocks by gc content and seems likely to have transferred from a higher gc content species to the ancestor of e. coli and s. enterica. all 19 genes of k-12 and 13 genes of lt2 appear to have undergone random genetic drift with amelioration of ... | 2000 | 11004393 |
| detection and characterisation of integrons in salmonella enterica serotype enteritidis. | integrons have been widely described among the enterobacteriaceae including strains of multi-resistant salmonella enterica serotype typhimurium dt104; however, information with respect to the presence of integrons among s. enterica serotype enteritidis strains is limited. multi-resistant isolates of enteritidis were screened for the presence of integrons using a pcr protocol. one integron was detected in all isolates that were resistant to sulfonamide and streptomycin. characterisation of these ... | 2000 | 11004412 |
| vesicle-mediated transfer of virulence genes from escherichia coli o157:h7 to other enteric bacteria. | membrane vesicles are released from the surfaces of many gram-negative bacteria during growth. vesicles consist of proteins, lipopolysaccharide, phospholipids, rna, and dna. results of the present study demonstrate that membrane vesicles isolated from the food-borne pathogen escherichia coli o157:h7 facilitate the transfer of genes, which are then expressed by recipient salmonella enterica serovar enteritidis or e. coli jm109. electron micrographs of purified dna from e. coli o157:h7 vesicles sh ... | 2000 | 11010892 |
| improved template preparation for pcr-based assays for detection of food-borne bacterial pathogens. | shigella flexneri, salmonella enterica serotype typhimurium, and listeria monocytogenes were applied to fta filters, and the filters were used directly as templates to demonstrate their sensitivity and applicability in pcr-based detection assays. with pure cultures, the sensitivities of detection by fta filter-based pcr were 30 to 50 and 200 cfu for the gram-negative enterics and listeria, respectively. different numbers of s. flexneri cells were used in controlled contamination experiments with ... | 2000 | 11010913 |
| the lipid a region of lipopolysaccharides from rhizobiaceae activates bone marrow granulocytes from lipopolysaccharide-hyporesponsive c3h/hej and c57bl/10sccr mice. | we established in previous studies that the binding of salmonella lipopolysaccharide (lps) to constitutive receptors of low affinity triggers the expression of the inducible lps-binding molecule cd14 in bone marrow cells (bmc) of c3h/heou mice, but not in bmc from c3h/hej mice. we show in this study that bmc from c3h/hej and c57bl/10sccr mice do not express cd14 after exposure to lpss from salmonella enterica and bordetella pertussis, but do express this marker when treated with several lpss fro ... | 2000 | 11012780 |
| comparison of danish isolates of salmonella enterica serovar enteritidis pt9a and pt11 from hedgehogs (erinaceus europaeus) and humans by plasmid profiling and pulsed-field gel electrophoresis. | during the years 1994 to 1998, 10 strains of salmonella enterica serovar enteritidis phage type 11 (pt11) and 6 pt9a strains were isolated from danish hedgehogs, together with 7 strains that did not yield phage susceptibility patterns conforming with any known phage type (routine dilution no conformity [rdnc]). from 1995 to 1998, five danish patients were reported infected with serovar enteritidis pt11 and two with pt9a. all serovar enteritidis pt11, pt9a, and rdnc isolates from hedgehogs and hu ... | 2000 | 11015375 |
| permeability barrier of the gram-negative bacterial outer membrane with special reference to nisin. | the effect of nisin pretreatment on organic acid-induced permeability increase in strains of escherichia coli, pseudomonas aeruginosa, p. marginalis, and salmonella enterica sv. typhimurium was investigated, using assays based on the uptake of a fluorescent dye 1-n-phenylnaphthylamine (npn) and on the bacterial susceptibility to detergent-induced bacteriolysis. the outer membrane of bacteria which had been pretreated with nisin was shown to be less stable against 1 mm edta, as indicated by their ... | 2000 | 11016605 |
| regulation of septation: a novel role for serc/pdxf in salmonella? | the sfiw locus of salmonella enterica, previously identified by mutations that suppress the cell division defect of his-constitutive (his(c)) strains, corresponds to serc, the bifunctional gene for phosphoserine-oxoglutarate aminotransferase (serc) and 2-ketoerythroic acid 4-phosphate transaminase (pdxf). serc- mutants form small, nearly spherical cells in a wild-type (his+) background, suggesting that the serc/pdxf product acts as a septation antagonist. suppression of his(c) filamentation by s ... | 2000 | 11016848 |
| bacterial virulence gene regulation: an evolutionary perspective. | coevolution between bacteria and their plant or animal hosts determines characteristics of the interaction, the bacterial virulence genes involved, and the regulatory systems controlling expression of virulence genes. the long-standing association between salmonellae and their animal hosts has resulted in the acquisition by salmonella subspecies of a variety of virulence genes and the evolution of complex regulatory networks. the particular repertoire of virulence genes acquired by different sal ... | 2000 | 11018137 |
| biophysical characterization of sipa, an actin-binding protein from salmonella enterica. | an essential step in the pathogenesis of salmonella enterica infections is bacterial entry into non-phagocytic cells of the intestinal epithelium. proteins injected by salmonella into host cells stimulate cellular responses that lead to extensive actin cytoskeleton reorganization and subsequent bacterial uptake. one of these proteins, sipa, modulates actin dynamics by directly binding to f-actin. we have biophysically characterized a c-terminal fragment, sipa(446-684), which has previously been ... | 2000 | 11018527 |
| application of the agar gel precipitin test to detect antibodies to salmonella enterica serovar enteritidis in serum and egg yolks from infected hens. | serological surveillance can be an important component for egg quality assurance programs geared toward controlling problems with salmonella enterica serovar enteritidis (s. enteritidis) within a flock. serum is the primary sample source for the procedures, although egg yolk antibody assays have become popularity in recent years. however, these assays tend to be labor intensive, requiring procedures for extracting antibodies from the yolk followed by assaying the samples. we describe an adaptati ... | 2000 | 11020067 |
| the effect of fecal sample weight on detection of salmonella enterica in swine feces. | the effect of different fecal sample weights on the detection of salmonella enterica in swine feces was examined. sample weights evaluated were rectal swabs and fecal samples weighing 1 g, 10 g, and 25 g. comparisons were made on matched fecal samples obtained from individual pigs housed on 2 commercial swine farms in north carolina. relative sensitivity (number of positive pigs per fecal weight category/number positive in all weight categories) increased (p < 0.001) with fecal sample weight, an ... | 2000 | 11021427 |