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factors influencing in vitro killing of bacteria by hemocytes of the eastern oyster (crassostrea virginica).a tetrazolium dye reduction assay was used to study factors governing the killing of bacteria by oyster hemocytes. in vitro tests were performed on bacterial strains by using hemocytes from oysters collected from the same location in winter and summer. vibrio parahaemolyticus strains, altered in motility or colonial morphology (opaque and translucent), and listeria monocytogenes mutants lacking catalase, superoxide dismutase, hemolysin, and phospholipase activities were examined in winter and su ...199910388697
comparative efficacies of antibiotics in a rat model of meningoencephalitis due to listeria monocytogenes.the antibacterial activities of amoxicillin-gentamicin, trovafloxacin, trimethoprim-sulfamethoxazole (tmp-smx) and the combination of trovafloxacin with tmp-smx were compared in a model of meningoencephalitis due to listeria monocytogenes in infant rats. at 22 h after intracisternal infection, the cerebrospinal fluid was cultured to document meningitis, and the treatment was started. treatment was instituted for 48 h, and efficacy was evaluated 24 h after administration of the last dose. all tes ...199910390217
the development of bactericidal yeast strains by expressing the pediococcus acidilactici pediocin gene (peda) in saccharomyces cerevisiae.the excessive use of sulphur dioxide and other chemical preservatives in wine, beer and other fermented food and beverage products to prevent the growth of unwanted microbes holds various disadvantages for the quality of the end-products and is confronted by mounting consumer resistance. the objective of this study was to investigate the feasibility of controlling spoilage bacteria during yeast-based fermentations by engineering bactericidal strains of saccharomyces cerevisiae. to test this nove ...199910392443
megakaryocyte hyperplasia and enhanced agonist-induced platelet activation in vasodilator-stimulated phosphoprotein knockout mice.vasodilator-stimulated phosphoprotein (vasp), a substrate of camp- and cgmp-dependent protein kinases, is associated with focal adhesions, cell-cell contacts, microfilaments, and highly dynamic membrane regions. vasp, which is expressed in most cell types and in particularly high levels in human platelets, binds to profilin, zyxin, vinculin, f-actin, and the listeria monocytogenes surface protein acta. vasp is a member of the enabled (ena)/vasp protein family and is thought to be involved in act ...199910393958
high intake of milk fat inhibits intestinal colonization of listeria but not of salmonella in rats.during fat digestion, fatty acids and monoglycerides are liberated in the gastrointestinal tract. generally, these lipids are potent inhibitors of gram-positive bacteria in vitro but have less effect on gram-negative microbes. considering this, we hypothesized that increased intake of bovine milk fat would result in enhanced gastrointestinal killing of listeria monocytogenes (gram-positive) but have little effect on infection with salmonella enteritidis (gram-negative) in rats. to test this, rat ...199910395602
immune system development and function in prolactin receptor-deficient mice.prolactin (prl) is the primary lactogenic pituitary hormone that plays an essential role in many aspects of reproduction, from fertilization to mammary gland development and maternal behavior. prl has also been reported to play a role in immunoregulation. because initial observations indicated that hypophysectomized rats present abnormalities of the immune system, including increased thymic atrophy and lymphopenia, a number of studies have focused on the potential immunomodulatory roles of prl. ...199910395643
impaired cytokine signaling in mice lacking the il-1 receptor-associated kinase.stimulation of the type 1 il-1r (il-1r1) and the il-18r by their cognate ligands induces recruitment of the il-1r-associated kinase (irak). activation of irak leads in turn to nuclear translocation of nf-kappab, which directs expression of innate and adaptive immune response genes. to study irak function in cytokine signaling, we generated cells and mice lacking the irak protein. irak-deficient fibroblasts show diminished activation of nf-kappab when stimulated with il-1. immune effector cells w ...199910395695
inhibition of salmonella typhimurium in the chicken intestinal tract by a transformed avirulent avian escherichia coli.an avirulent, wild-type avian escherichia coli (e. coli av) was electrotransformed with a plasmid coding for the production of microcin 24 (pgob18) and was designated e. coli avgob18. the transformant inhibited the growth of seven serotypes of salmonella commonly associated with colonization and contamination of poultry products and seven strains of e. coli o157:h7 in the in vitro colicin/microcin assay. the transformant did not inhibit the replication of multiple isolates of listeria monocytoge ...199910396637
comparative study on the in vitro antibacterial activity of australian tea tree oil, cajuput oil, niaouli oil, manuka oil, kanuka oil, and eucalyptus oil.to compare the antibacterial activity of the australian tea tree oil (tto) with various other medicinally and commercially important essential myrtaceous oils (cajuput oil, niaouli oil, kanuka oil, manuka oil, and eucalyptus oil) the essential oils were first analysed by gc-ms and then tested against various bacteria using a broth microdilution method. the highest activity was obtained by tto, with mic values of 0.25% for enterobacter aerogenes, escherichia coli, klebsiella pneumoniae, proteus m ...199910399193
the use of dummy data points when fitting bacterial growth curves.we consider the problem of fitting mathematical models for bacterial growth and decline to experimental data. using models which represent the phases of the growth and decline cycle in a piecewise manner, we describe how least-squares fitting can lead to potentially misleading parameter estimates. we show how these difficulties can be overcome by extending a data set to include hypothetical observations (dummy data points) which reflect biological beliefs, and the resulting stabilization of para ...199910399311
the bacteriology of neonatal septicaemia in ile-ife, nigeria.the incidence of septicaemia among neonates categorized as being at high risk was 55 per cent in ile-ife, nigeria. gram-positive organisms, specifically staphylococcus aureus, were predominant (33.8 per cent) among bacteria cultured from proven cases of septicaemia. other coagulase-negative staphylococci also contributed 21 per cent, with staphylococcus epidermidis occurring in 5 per cent of the isolates. listeria monocytogenes was cultured from 8.4 per cent of septic neonates. pseudomonas aerug ...199910401192
in-vitro activity of levofloxacin, ofloxacin and d-ofloxacin against coryneform bacteria and listeria monocytogenes.the objective of this study was to evaluate the in-vitro activity of levofloxacin, ofloxacin and d-ofloxacin compared with ciprofloxacin, norfloxacin and sparfloxacin against coryneform bacteria and listeria monocytogenes isolated from clinical samples. the following organisms (and number of strains) were studied: corynebacterium jeikeium (20), corynebacterium urealyticum (20), corynebacterium minutissimum (20), corynebacterium striatum (20), corynebacterium amycolatum (30), brevibacterium spp. ...199910404334
antimicrobial activity of the essential oil of calamintha nepeta and its constituent pulegone against bacteria and fungi.the chemical composition of the essential oil of calamintha nepeta and its antimicrobial activity against listeria monocytogenes, bacillus cereus, salmonella veneziana, s. paratyphi b. s. typhimurium, fusarium moniliforme, botrytis cinerea, aspergillus niger and pyricularia oryzae have been studied. moreover the main constituents of the oil (limonene, menthone, pulegone, menthol) have been tested against the same microorganisms. only pulegone showed antimicrobial activity, particularly against a ...199910404547
repeated oral dosing with listeria monocytogenes in mice as a model of central nervous system listeriosis in man.human listeriosis is a food-borne disease of immunosuppressed or previously healthy adults. the repeated oral administration of a sublethal dose (5x10(9)colony-forming units) of listeria monocytogenes for 7 or 10 consecutive days led to the development of severe central nervous system (cns) lesions in 25% of experimental mice. histopathological examination of the brain revealed rhombencephalitis and ventriculitis as two distinct inflammatory patterns, resembling those seen in human listeriosis. ...199910405304
high-performance liquid chromatography determination of residue levels on chicken carcasses treated with cetylpyridinium chloride.cetylpyridinium chloride (cpc) has been found to be effective in reducing contamination of chicken carcasses from a variety of microorganisms, including escherichia coli o157:h7, salmonella typhimurium, campylobacter jejuni, aeromonas hydrophila, listeria monocytogenes, and staphylococcus aureus. a procedure has been developed to determine residue levels on chicken carcasses after cpc treatment. for the analysis, chicken carcasses were extracted with 95% ethanol. the cpc concentration in the ext ...199910406212
a single amino acid in e-cadherin responsible for host specificity towards the human pathogen listeria monocytogenes.human e-cadherin promotes entry of the bacterial pathogen listeria monocytogenes into mammalian cells by interacting with internalin (inla), a bacterial surface protein. here we show that mouse e-cadherin, although very similar to human e-cadherin (85% identity), is not a receptor for internalin. by a series of domain-swapping and mutagenesis experiments, we identify pro16 of e-cadherin as a residue critical for specificity: a pro-->glu substitution in human e-cadherin totally abrogates interact ...199910406800
oral administration of hot water extracts of chlorella vulgaris reduces ige production against milk casein in mice.hot water extract of chlorella vulgaris (cve) is a biological response modifier (brm) which enhances resistance to listeria monocytogenes through augmentation of helper t cell type 1 (thl) responses producing gamma-interferon (gammaifn). we show here that oral administration of cve in mice suppressed the production of immunoglobulin (ig)e against casein antigen accompanied by increased gammaifn and il-12 mrna expression. oral administration of cve enhanced thl response to casein in the spleen of ...199910408628
polar lipids of four listeria species containing l-lysylcardiolipin, a novel lipid structure, and other unique phospholipids.the membrane lipids of listeria innocua, listeria monocytogenes, listeria seeligeri and listeria welshimeri were fractionated on deae-cellulose and purified by chromatography on silica gel and/or preparative tlc. the lipid structures were elucidated by chemical and chromatographic means. the polar lipid composition of the four listeria species was similar. phospholipids predominated. they consisted of phosphatidylglycerol, l-lysylphosphatidylglycerol, cardiolipin [bis(phosphatidyl)glycerol] and ...199910408878
expression of l-selectin on th1 cells is regulated by il-12.l-selectin has become established as a key molecule in the recirculation of naïve t cells from the blood to peripheral lymph nodes, yet little is known about its role in the migration of effector or memory cells. while differentiating naïve cd4+ t cells into th1 and th2 subsets in vitro, it was noted that l-selectin levels were maintained on the th1 subset of cells. the expression of l-selectin on the th1 cells appeared to be dependent on the presence of il-12. th2 cells, differentiated in the a ...199910415016
th1 t cell responses to hiv-1 gag protein delivered by a listeria monocytogenes vaccine are similar to those induced by endogenous listerial antigens.listeria monocytogenes is a facultative intracellular bacterium that lives and grows in the cytoplasm of the host cell. the hallmark of a listerial infection is a cell-mediated immune response to its own secreted virulence factors. thus, l. monocytogenes vaccines engineered to secrete hiv proteins may be ideal vectors for boosting cellular immune responses against hiv. using strains of l. monocytogenes that stably express and secrete hiv gag (lm-gag) to deliver this ag to the immune system, we h ...199910415046
listeriosis in a holstein cow.bovine listeriosis is a sporadie bacterial infection most commonly manifested by encephalitis or meningoencephalitis in adult animals. cattle fed poorly fermented haylage or corn silage are at increased risk. mortality is high without early antibiotic and supportive therapy. listeria monocytogenes can affect many species and is a public health concern.199910416074
purification and properties of proline-rich antimicrobial peptides from sheep and goat leukocytes.we purified three proline-rich antimicrobial peptides from elastase-treated extracts of sheep and goat leukocytes and subjected two of them, oabac5alpha and chbac5, to detailed analysis. oabac5alpha and chbac5 were homologous to each other and to bovine bac5. both exhibited potent, broad-spectrum antimicrobial activity under low-concentration salt conditions. while the peptides remained active against escherichia coli, pseudomonas aeruginosa, bacillus subtilis, and listeria monocytogenes in 100 ...199910417180
plasma membrane expression of heat shock protein 60 in vivo in response to infection.heat shock protein 60 (hsp60) is constitutively expressed in the mitochondria of eukaryotic cells. however, it has been identified in other subcellular compartments in several disease states and in transformed cells, and it is an immunogenic molecule in various infectious and autoimmune diseases. to better understand the factors that influence expression of hsp60 in normal cells in vivo, we analyzed its cellular and subcellular distribution in mice infected with the intracellular bacterium liste ...199910417191
dynamics of actin-based movement by rickettsia rickettsii in vero cells.actin-based motility (abm) is a virulence mechanism exploited by invasive bacterial pathogens in the genera listeria, shigella, and rickettsia. due to experimental constraints imposed by the lack of genetic tools and their obligate intracellular nature, little is known about rickettsial abm relative to listeria and shigella abm systems. in this study, we directly compared the dynamics and behavior of abm of rickettsia rickettsii and listeria monocytogenes. a time-lapse video of moving intracellu ...199910417192
the smcl gene of listeria ivanovii encodes a sphingomyelinase c that mediates bacterial escape from the phagocytic vacuole.the ruminant pathogen listeria ivanovii differs from listeria monocytogenes in that it causes strong, bizonal haemolysis and a characteristic shovel-shaped co-operative haemolytic ('camp-like') reaction with rhodococcus equi. we cloned the gene responsible for the differential haemolytic properties of l. ivanovii, smcl. it encodes a sphingomyelinase c (smase) highly similar (> 50% identity) to the smases from staphylococcus aureus (beta-toxin), bacillus cereus and leptospira interrogans. smcl wa ...199910417642
the actin-based motility of intracellular listeria monocytogenes is not controlled by small gtp-binding proteins of the rho- and ras-subfamilies.in this study, we analyzed whether the actin-based motility of intracellular listeria monocytogenes is controlled by the small gtp-binding proteins of the rho- and ras-subfamilies. these signalling proteins are key regulatory elements in the control of actin dynamics and their activity is essential for the maintenance of most cellular microfilament structures. we used the clostridium difficile toxins tcdb-10463 and tcdb-1470 to specifically inactivate these gtp-binding proteins. treatment of euk ...199910418138
microbiological quality of retail imported unprepared whole lettuces: a phls food working group study. public health laboratory service.a study of imported unprepared whole lettuces sampled from supermarkets, greengrocers, shops, and market stalls found that all were of acceptable microbiological quality. twenty-seven out of 151 (18%) imported lettuce samples had enterobacteriaceae levels of 10(4) cfu/g or more. however, these bacteria that constitute part of the natural microflora of unprepared vegetables may also be derived from the soil and/or by poor handling. the pathogens, salmonella spp., shigella spp., campylobacter spp. ...199910419203
growth control of listeria monocytogenes on cold-smoked salmon using a competitive lactic acid bacteria flora.a lactobacillus sake strain lke5 and four strains of carnobacterium piscicola were evaluated as biopreservation cultures to control the growth of listeria monocytogenes on vacuum-packed, cold-smoked salmon stored at 5 degrees c. all five strains were antilisterial as live cultures in an agar diffusion assay. cell-free supernatants of two strains of c. piscicola and l. sake lke5 were also antilisterial because of the production of bacteriocins. the presence of high cell numbers of strains of c. p ...199910419205
influence of soft rot bacteria on growth of listeria monocytogenes on potato tuber slices.growth of listeria monocytogenes on potato tuber slices and its interaction with four representative species of soft rot bacteria (pseudomonas fluorescens, p. viridiflava, erwinia carotovora subsp. carotovora, and xanthomonas campestris) were investigated. when potato tuber slices were inoculated with one of two l. monocytogenes strains (scott a and atcc 15313), an increase in numbers of 3 to 4 logs per gram of tissue was observed with samples that were stored at 20 degrees c for 6 days. however ...199910419206
rapid detection of escherichia coli o157:h7 in ground beef using a fiber-optic biosensor.a portable fiber-optic biosensor was used to detect escherichia coli o157:h7 in seeded ground beef samples. the principle of the system is a sandwich immunoassay using cyanine 5 dye-labeled polyclonal anti-e. coli o157:h7 antibodies for generation of a specific fluorescent signal. signal acquisition is effected by launching light from a 635-nm diode laser into a dual tapered 600-microm silica fiber. fluorescent molecules within approximately 100 nm of the fiber surface are excited by the evanesc ...199910419260
incidence of salmonella, campylobacter jejuni, campylobacter coli, and listeria monocytogenes in poultry carcasses and different types of poultry products for sale on the belgian retail market.from january 1997 to may 1998, 772 samples of poultry carcasses and poultry products for sale on the retail market in belgium were analyzed for the presence of salmonella spp., salmonella enteritidis, campylobacter jejuni, c. coli, and listeria monocytogenes per 100 cm2 or 25 g. poultry samples were contaminated with salmonella (36.5%), c. jejuni and c. coli (28.5%), and l. monocytogenes (38.2%). in about 12.3% of the poultry samples, the l. monocytogenes contamination level exceeded 1 cfu per g ...199910419264
inactivation of listeria monocytogenes/pseudomonas biofilms by peracid sanitizers.the ability of peracetic acid and peroctanoic acid sanitizers to inactivate mixed-culture biofilms of a pseudomonas sp. and listeria monocytogenes on stainless steel was investigated. types of biofilms tested included a 4-h attachment of the mixed-cell suspension and a 48-h biofilm of mixed culture formed in skim milk or tryptic soy broth. biofilm-containing coupons were immersed in solutions of hypochlorite, peracetic acid, and peroctanoic acid either with or without organic challenge. organic ...199910419269
foodborne infections during pregnancy.the consequences of foodborne illness can be particularly devastating during pregnancy because both the woman and her fetus are at risk. escalated production of progesterone during pregnancy leads to down-regulation of cellular (cell-mediated) immune functions. many foodborne pathogens (and other pathogens) are intracellular pathogens, and infections caused by these pathogens are controlled by cell-mediated immunity. the pregnancy-induced decrease in cell-mediated immune functions leads to incre ...199910419281
the arp2/3 complex is essential for the actin-based motility of listeria monocytogenes.actin polymerisation is thought to drive the movement of eukaryotic cells and some intracellular pathogens such as listeria monocytogenes. the listeria surface protein acta synergises with recruited host proteins to induce actin polymerisation, propelling the bacterium through the host cytoplasm [1]. the arp2/3 complex is one recruited host factor [2] [3]; it is also believed to regulate actin dynamics in lamellipodia [4] [5]. the arp2/3 complex promotes actin filament nucleation in vitro, which ...199910421578
[a case of listeriosis revealed by voluminous cerebral abscesses]. 199910422151
listeriosis linked to retail outlets in hospitals--caution needed. 199910422368
codon optimization effect on translational efficiency of dna vaccine in mammalian cells: analysis of plasmid dna encoding a ctl epitope derived from microorganisms.interspecific difference of codon usage is one of the major obstacles for effective induction of specific immune responses against bacteria and protozoa by dna immunization. using genes encoding major histocompatibility complex class i-restricted cytotoxic t-lymphocyte (ctl) epitopes, derived from an intracellular bacterium, listeria monocytogenes and a mouse malaria parasite, plasmodium yoelii, we report here that the codon optimization level of the genes is not precisely proportional to, but d ...199910425204
actin-based motility of the intracellular pathogen listeria monocytogenes: assessing the inhibitory specificity of abm-1 peptide analogues.actin-based motility motifs [abm-1 sequence = (d/e)fppppx(d/e), where x = p or t, and abm-2 sequence = xppppp, where x denotes g, a, l, p, and s] facilitate assembly of an activated motility complex. potent inhibition of intracellular motility of pathogens by abm-1 and abm-2 peptide analogues has served as a criterion for investigating actin-based motility. to assess the specificity of abm-1 peptide inhibitors, we microinjected proline-rich peptides into listeria-infected ptk2 host cells. use of ...199910425223
production of listeriolysin o by listeria monocytogenes (scott a) under heat-shock conditions.early stationary phase cells of listeria monocytogenes (scott a) were examined to determine the effect of heat-shock on the production of listeriolysin o (llo) during and after resuscitation at 37 degrees c. cells were subjected to a heat-shock at 48 degrees c for 1 h. intracellular and extracellular proteins of the heat-shocked cells were assayed for llo using a microtiter plate hemolysis assay and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) and immunoblotti ...199910426449
a quantitative approach for studying the effect of heat treatment conditions on resistance and recovery of bacillus cereus spores.when a bacterial population undergoes an unfavourable transient increase in temperature, a death phase followed by a lag and growth phase are observed for the surviving and cultivable population. the lag phase is of great interest in regard to food safety, but for bacterial spores, very few studies have been carried out on the evolution of lag time versus heat treatment duration. the experiments monitored on spores of two strains of bacillus cereus showed a biphasic evolution of the lag time for ...199910426451
listeria monocytogenes reinfection in a pregnant woman. 199910430206
a comparison of t cell memory against the same antigen induced by virus versus intracellular bacteria.cytotoxic t cell (ctl) memory was analyzed after infection with lymphocytic choriomeningitis virus (lcmv) and recombinant listeria monocytogenes (rlm) expressing the complete nucleoprotein of lcmv (rlm-np(acta)) or only the immunodominant epitope of h-2(d) mice (rlm-np(118-126)). immunization with lcmv and rlm induced a long-lived increased ctl precursor (ctlp) frequency specific for the viral (np(118-126)) and for the bacterial (llo(91-99)) epitope, respectively. however, after infection with r ...199910430936
h2-m3-restricted t cells in bacterial infection: rapid primary but diminished memory responses.major histocompatibility complex (mhc) class ib molecules have been implicated in cd8(+) t cell-mediated defenses against intracellular bacterial infection, but the relative importance of mhc class ib-restricted t cells in antimicrobial immunity is unknown. in this report, we use mhc tetramers to characterize t cell responses restricted by h2-m3, an mhc class ib molecule that selectively presents n-formyl peptides. we find that sizeable h2-m3-restricted t cell responses, occurring earlier than m ...199910432283
the use of enterocin ccm 4231 in soy milk to control the growth of listeria monocytogenes and staphylococcus aureus.the inhibitory effect of enterocin ccm 4231 (concentration 3200 au ml-1) was used to control the growth of listeria monocytogenes ohio and staphylococcus aureus in soy milk. the growth and bacteriocin (enterocin) production of producer strain ccm 4231 in soy milk was also checked. bacteriocin production by ccm 4231 strain in soy milk was first detected after 2 h from the beginning of cultivation (100 au ml-1). the stationary phase for ccm 4231 was reached after 6 h reaching 10.38 cfu ml-1 (log10 ...199910432598
molecular investigation of a listeriosis outbreak in goats caused by an unusual strain of listeria monocytogenes.during a 16-month period, 10 goats with listeriosis were identified in 2 herds that shared 3 bucks, including 1 that died of listeriosis. using dna fingerprinting, we determined that a single genetically unique listeria monocytogenes strain had infected all goats from which isolates were available. all isolates were unable to metabolize rhamnose (rhamnose-negative), whereas as a species, l monocytogenes is considered to have a rhamnose-positive phenotype. therefore, these isolates would have bee ...199910434977
transposition of is1181 in the genomes of staphylococcus and listeria.the recombinant plasmid pip1713 was constructed to analyse the transpositional activity of the insertion sequence is1181 in staphylococcus aureus rn4220, staphylococcus carnosus tm300 and listeria monocytogenes egd. this 11.3-kb plasmid contains two genetically different elements: (i) a pe194ts-derived replicon, the ermc gene of which confers resistance to erythromycin in gram-positive bacteria of several species, and (ii) a copy of is1181, cloned from s. aureus bm3121, in which the tetracycline ...199910436926
the bvr locus of listeria monocytogenes mediates virulence gene repression by beta-glucosides.the beta-glucoside cellobiose has been reported to specifically repress the prfa-dependent virulence genes hly and plca in listeria monocytogenes nctc 7973. this led to the hypothesis that beta-glucosides, sugars of plant origin, may act as signal molecules, preventing the expression of virulence genes if l. monocytogenes is living in its natural habitat (soil). in three other laboratory strains (egd, l028, and 10403s), however, the effect of cellobiose was not unique, and all fermentable carboh ...199910438775
evaluation of an rdna listeria probe for listeria monocytogenes typing.a listeria monocytogenes dna fragment, identified as part of the 23s rrna gene and called b17, was used to type 266 l. monocytogenes strains and 43 strains of other listeria species. results were compared with those obtained: i) with pba2 (which consists of a 2.3 kb bacillus subtilis dna fragment encoding 16s rrna, inserted into the hindiii site of pbr322), a probe previously used for listeria and l. monocytogenes ribotyping, and ii) with dna macrorestriction profiles analysis. twenty profiles w ...199910440057
interleukin-15 production at the early stage after oral infection with listeria monocytogenes in mice.we previously reported that exogenous interleukin-15 (il-15) induces proliferation and activation of intestinal intraepithelial lymphocytes (i-iel) in naive mice. to investigate the ability of endogenous il-15 to stimulate i-iel in vivo, we monitored i-iel and intestinal epithelial cells (i-ec) in mice after an oral infection with listeria monocytogenes. although the populations of alphabeta and gammadelta i-iel were not significantly changed after the oral infection, the expression level of int ...199910447719
isolation of rifampin-resistant mutants of listeria monocytogenes and their characterization by rpob gene sequencing, temperature sensitivity for growth, and interaction with an epithelial cell line.the sequence of the rpob gene from listeria monocytogenes was determined. rifampin-resistant (rif(r)) mutants arising from l. monocytogenes cultures exposed to rifampin were isolated, and by partial sequencing of their rpob genes, seven different point mutations affecting five different amino acids (473asp-->asn or gly, 479gly-->asp, 483his-->tyr or leu, 528ile-->phe, and 530ser-->tyr), which led to mics of 0.5 to 100 microg/ml for the organisms, were determined. these mutants showed various def ...199910449475
role of il-10 in a neonatal mouse listeriosis model.this study was undertaken to test the hypothesis that altered il-10 production plays a role in the increased susceptibility of neonates to listeriosis. plasma il-10 levels were measured in neonatal and adult mice at various times after infection with listeria monocytogenes. relative to adults, neonatal mice had markedly increased il-10 levels early in the course of infection with listeria using a 90% lethal dose. higher neonatal il-10 responses were also observed after injecting adults and pups ...199910453021
inactivation of escherichia coli o157:h7 and listeria monocytogenes on plastic kitchen cutting boards by electrolyzed oxidizing water.one milliliter of culture containing a five-strain mixture of escherichia coli o157:h7 (approximately 10(10) cfu) was inoculated on a 100-cm2 area marked on unscarred cutting boards. following inoculation, the boards were air-dried under a laminar flow hood for 1 h, immersed in 2 liters of electrolyzed oxidizing water or sterile deionized water at 23 degrees c or 35 degrees c for 10 or 20 min; 45 degrees c for 5 or 10 min; or 55 degrees c for 5 min. after each temperature-time combination, the s ...199910456736
influence of guar gum on the thermal stability of listeria innocua, listeria monocytogenes, and gamma-glutamyl transpeptidase during high-temperature short-time pasteurization of bovine milk.mathematical models describing the thermal inactivation of gamma-glutamyl transpeptidase (tp) and listeria innocua in milk during high-temperature short-time (htst) pasteurization were validated with data from tp, l. innocua, and l. monocytogenes trials in guar gum-milk. holding tube times were determined for turbulent flow using water, and for laminar flow using a guar gum (0.27% wt/wt)-sucrose (5.3% wt/wt)-water mixture. inactivation of tp and l. innocua was lower in a solution of guar gum (0. ...199910456737
inhibition of food-related pathogenic bacteria by god-transformed penicillium nalgiovense strains.two strains of penicillium nalgiovense, which carried the god gene of aspergillus niger and had increased glucose oxidase (god) activity compared with the wild-type strain, were tested for their ability to suppress the growth of certain food-related pathogenic bacteria. in contrast to the wild type, which showed no antibacterial effect when grown in mixed culture with different bacteria, the two transformed strains were highly antagonistic. the strain that expressed higher amounts of god in gene ...199910456750
disinfection of mung bean seed with gaseous acetic acid.mung bean seed inoculated with salmonella typhimurium, escherichia coli o157:h7, and listeria monocytogenes (3 to 5 log cfu/g) was exposed to gaseous acetic acid in an aluminum fumigation chamber. salmonella typhimurium and e. coli o157:h7 were not detected by enrichment of seeds treated with 242 microl of acetic acid per liter of air for 12 h at 45 degrees c. l. monocytogenes was recovered by enrichment from two of 10 25-g seed samples treated in this manner. fumigation with gaseous acetic acid ...199910456753
use of recombinant viruses to deliver cytokines influencing the course of experimental bacterial infection.the feasibility of using viral constructs expressing cytokine genes to influence the course of bacterial infection was tested in mice. the mice were first infected with vaccinia or fowlpox viruses expressing the cytokine of interest, then challenged with the facultative intracellular bacterial pathogen listeria monocytogenes. the course of infection was assessed by subsequent bacterial counts. expression of ifn-gamma or tnf was protective. vaccinia virus was more efficient at delivering ifn-gamm ...199910457199
typing listeria monocytogenes by random amplified polymorphic dna (rapd) fingerprinting.twenty epidemiologically unrelated listeria monocytogenes strains isolated from different animals, locations and on different dates in japan were classified into 18 types by the random amplified polymorphic dna (rapd) fingerprinting technique with four primers. further, seven epidemiologically related l. monocytogenes strains isolated from raw milk and a bulk tank on a dairy farm represented the same rapd type suggesting that they were all of the same origin. therefore, rapd-polymerase chain rea ...199910458115
beta-estradiol-induced decrease in il-12 and tnf-alpha expression suppresses macrophage functions in the course of listeria monocytogenes infection in mice.mice treated with a contraceptive dose of beta-estradiol (e2) demonstrated changes in their macrophage (mphi) number and functions. while e2 increased and decreased the mphi number in pbmc and pec respectively, it enhanced the in vitro phagocytosis of fitc-labeled beads by both cells. e2 treatment also enhanced the phagocytic function of mphi as assessed by the in vivo carbon clearance assay. in contrast, the in vitro intracellular killing function of adherent cells in peritoneal exudate cells ( ...199910458538
effects of chlorella vulgaris on bone marrow progenitor cells of mice infected with listeria monocytogenes.in this study we investigated the effects of the treatment with chlorella vulgaris extract (cve) on the hematopoietic response of granulocyte-macrophage colony-forming unit (cfu-gm) of mice infected with a sublethal dose of listeria monocytogenes (1 x 10(4) organisms/animal). cve was given orally as 50 mg/kg/day for 5 days. in the cve treated/infected groups l. monocytogenes was administered at the end of cve treatment. the colony stimulating activity of the serum (csa) was also studied in all g ...199910458539
health risks associated with unpasteurized goats' and ewes' milk on retail sale in england and wales. a phls dairy products working group study.a pilot study to determine the microbiological quality of unpasteurized milk from goats and ewes sampled from farm shops, health food shops, and other retail premises found that 47%, (47/100) of goats' and 50% (13/26) of ewes' milk samples failed the standards prescribed by the dairy products (hygiene) regulations 1995. in addition, staphylococcus aureus, haemolytic streptococci or enterococci, were present in excess of 10(2) c.f.u./ml in 9 (7 %) 2 (2 %) and 19 (15%) samples, respectively. salmo ...199910459642
leishmania species: models of intracellular parasitism.leishmania species are obligate intracellular parasites of cells of the macrophage-dendritic cell lineage. indeed, the ability to survive and multiply within macrophages is a feature of a surprising number of infectious agents of major importance to public health, including mycobacterium tuberculosis, mycobacterium leprae, listeria monocytogenes, salmonella typhimurium, toxoplasma gondii and trypanosoma cruzi. the relationship between such organisms and their host cells is particularly intriguin ...199910462516
the effects of chlorella vulgaris in the protection of mice infected with listeria monocytogenes. role of natural killer cells.in this work we have demonstrated the effects of oral administration of chlorella vulgaris (cv) on natural killer cells (nk) activity of mice infected with a sublethal dose of viable listeria monocytogenes. the treatment with c. vulgaris produced a significant increase on nk cells activity in normal (non-infected) animals compared to the animals that received only vehicle (water) (p < 0.0001). similarly, the infection alone produced a significant increase on nk cells activity, which was observed ...199910466083
sulfasalazine prevents t-helper 1 immune response by suppressing interleukin-12 production in macrophages.interleukin-12 (il-12) plays a pivotal role in the development of t-helper 1 (th1) immune response, which may be involved in the pathogenesis of chronic inflammatory autoimmune disorders. in this study we investigated the effects of sulfasalazine, a drug for treating inflammatory bowel disease and rheumatoid arthritis, on the production of il-12 from mouse macrophages stimulated with lipopolysaccharide (lps). sulfasalazine potently inhibited the production of il-12 in a dose-dependent manner, in ...199910469239
the role of kupffer cells and regulation of neutrophil migration into the liver by macrophage inflammatory protein-2 in primary listeriosis in mice.depletion of mouse kupffer cells and splenic macrophages following intravenous administration of liposome-entrapped clodronate severely reduced host resistance to primary infection with listeria monocytogenes. infection of clodronate-treated mice with a sublethal dose of l. monocytogenes resulted in death of the mice within 3 days. the macrophage depletion resulted in marked increases in bacterial growth in the liver and spleen, but not in other tissues. the proliferation of l. monocytogenes was ...199910469395
bacterial meningitis and the newborn infant.bacterial meningitis in the neonate differs from meningitis in the older infant and child in a number of ways. bacterial pathogens primarily are associated with the maternal genitourinary tract. symptoms and physical findings may be nonspecific, and a high index of suspicion is needed. management may vary depending on the maturity of the infant and the bacterial pathogen that is isolated.199910470563
the antibacterial efficacy of trovafloxacin against an experimental infection with listeria monocytogenes in hydrocortisone-treated mice.the efficacy of trovafloxacin in treating listeria monocytogenes infections in glucocorticosteroid-treated mice was compared with the efficacy of amoxycillin. swiss mice were treated with daily injections of 2.5 mg hydrocortisone s.c. and then infected i.v. with 1 x 10(7) cfu of l. monocytogenes. untreated, this level of infection resulted in 100% mortality between day 3 and day 5 after infection. both s.c. trovafloxacin and amoxycillin were effective in reducing the number of viable l. monocyto ...199910473230
identification of an atp-driven, osmoregulated glycine betaine transport system in listeria monocytogenes.the ability of the gram-positive, food-borne pathogen listeria monocytogenes to tolerate environments of elevated osmolarity and reduced temperature is due in part to the transport and accumulation of the osmolyte glycine betaine. previously we showed that glycine betaine transport was the result of na(+)-glycine betaine symport. in this report, we identify a second glycine betaine transporter from l. monocytogenes which is osmotically activated but does not require a high concentration of na(+) ...199910473414
variation in resistance to hydrostatic pressure among strains of food-borne pathogens.among food-borne pathogens, some strains could be resistant to hydrostatic pressure treatment. this information is necessary to establish processing parameters to ensure safety of pressure-pasteurized foods (n. kalchayanand, a. sikes, c. p. dunne, and b. ray, j. food prot. 61:425-431, 1998). we studied variation in pressure resistance among strains of listeria monocytogenes, staphylococcus aureus, escherichia coli o157:h7, and salmonella species at two temperatures of pressurization. early-stati ...199910473446
efficacy of electrolyzed oxidizing water for inactivating escherichia coli o157:h7, salmonella enteritidis, and listeria monocytogenes.the efficacy of electrolyzed oxidizing water for inactivating escherichia coli o157:h7, salmonella enteritidis, and listeria monocytogenes was evaluated. a five-strain mixture of e. coli o157:h7, s. enteritidis, or l. monocytogenes of approximately 10(8) cfu/ml was inoculated in 9 ml of electrolyzed oxidizing water (treatment) or 9 ml of sterile, deionized water (control) and incubated at 4 or 23 degrees c for 0, 5, 10, and 15 min; at 35 degrees c for 0, 2, 4, and 6 min; or at 45 degrees c for 0 ...199910473453
bacterial populations associated with a sorghum-based fermented weaning cereal.microbiological surveys, to determine the quality and safety, were conducted on 45 sorghum samples comprising dry powders (n = 15) and corresponding fermented (n = 15) and cooked fermented porridge (n = 15) samples collected from households in an informal settlement of the gauteng province of south africa. mean aerobic plate counts, gram-negative counts and bacterial spore counts of sorghum powder samples decreased in fermented and cooked fermented porridge samples. however, mean lactic acid bac ...199910477073
genomic typing of listeria monocytogenes strains by automated laser fluorescence analysis of amplified fragment length polymorphism fingerprint patterns.the genetic relationship between isolates of listeria monocytogenes belonging to different serotypes was determined and the suitability of automated laser fluorescent analysis (alfa) of amplified fragment length polymorphism (aflp) fingerprints was assessed by genomic typing of 106 l. monocytogenes isolates belonging to serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4ab, 4b, 4c, 4d, 4e, 1, and 7. digitised aflp fingerprints were obtained that showed approximately 50 clearly distinguishable selectiv ...199910477075
a monoclonal antibody directed against the murine macrophage surface molecule f4/80 modulates natural immune response to listeria monocytogenes.whole spleen cell cultures from scid mice release high levels of ifn-gamma when exposed to heat-killed listeria monocytogenes (hkl). this microbe-induced and t cell-independent response depends on both macrophages (mphi) and nk cells: hkl-stimulated mphi release tnf-alpha and il-12, which together activate nk cells for ifn-gamma release. we show here that this cytokine-mediated activation cascade can be modulated by a mab against the mphi surface glycoprotein f4/80. hkl-induced il-12, tnf-alpha, ...199910477612
suppression of acquired immunity against listeria monocytogenes by amphotericin b-mediated inhibition of cd8 t cell function.amphotericin b is frequently used for the treatment of fungal infections of immunocompromised individuals. whereas immunomodulatory side effects of this agent are known, the influence of amphotericin b was studied in the model of murine listeria monocytogenes infection. treatment of l. monocytogenes-immune mice with a nontoxic dose of amphotericin b (0.75 mg/kg) reduced antilisterial protection by 4-5 orders of magnitude, while it had no significant effect on natural immunity against l. monocyto ...199910479147
modulation of intracellular growth of listeria monocytogenes in human enterocyte caco-2 cells by interferon-gamma and interleukin-6: role of nitric oxide and cooperation with antibiotics.the influence of interferon (ifn)-gamma and interleukin (il)-6 on the intracellular growth of listeria monocytogenes phagocytosed from the apical pole was examined in polarized caco-2 cells. ifn-gamma (from the apical pole) and il-6 (from the basolateral pole) considerably reduced the bacterial intracellular growth, an effect largely abolished by l-monomethyl arginine. both cytokines caused overexpression of inducible nitric oxide synthase. il-6, but not ifn-gamma, caused a partial restriction o ...199910479148
listeria monocytogenes and recurrent mycobacterial infections in a child with complete interferon-gamma-receptor (ifngammar1) deficiency: mutational analysis and evaluation of therapeutic options.we describe the history of a girl with interferon-gamma-receptor (ifngammar1) deficiency and studies performed to identify the molecular and clinical characteristics of this recently discovered disorder. this is the first report of a child from northern europe with ifngammar1 deficiency. the patient, now 7 years old, first presented with swelling and reddening at the bacille calmette-guerin (bcg) vaccination site, swelling of lymph nodes, hepatomegaly, and an unusually severe varicella rash at t ...199910480427
[bacteria killing by macrophages via nf-il6 gene dependent mechanism: the susceptibility to mycobacterium leprae in nf-il6 knockout mice].transcription factor, nf-il6 recognizes the same nucleotide sequences as c/ebp, and it is predominantly expressed in macrophages. tanaka et al. reported that nf-il6 knockout mice are highly susceptible to listeria monocytogenes and salmonella typhimurium due to impairment of bacteria killing by activated macrophages. we have tried to see the susceptibility for mycobacterium leprae infection with intraperitoneal(i.p.) or both hind foot pad (bhf) in the nf-il6 knockout mice with wild control mice. ...199910481452
listeria monocytogenes infection of caco-2 human epithelial cells induces activation of transcription factor nf-kappa b/rel-like dna binding activities.the effect of listeria monocytogenes infection on the cellular level of transcription factor nf-kappa b in the human epithelia-like cell line caco-2 was investigated. infection with l. monocytogenes or treatment with lipoteichoic acid induced the formation of three nf-kappa b-like dna-protein complexes c1, c2, and c3, which were identified as containing either, rela and p50, relb and p50, or p50, respectively. nf-kappa b activation in l. monocytogenes-infected caco-2 cells was distinct from nf-k ...199910483730
the relationship between acid stress responses and virulence in salmonella typhimurium and listeria monocytogenes.all pathogenic bacteria possess the ability to evade or surmount body defenses (stresses, as experienced by the bacterium) long enough to cause a sufficient reaction, which is then manifested as a disease or illness. while opportunistic pathogens will only cause illness in the event of a predisposing weakness in these defenses, many pathogens must take on and overcome intact defenses. this is particularly true of gastrointestinal pathogens such as listeria monocytogenes and salmonella spp., whic ...199910488846
the development of a combined surface adhesion and polymerase chain reaction technique in the rapid detection of listeria monocytogenes in meat and poultry.a procedure combining enrichment surface adhesion and polymerase chain detection (sa-pcr) was developed and applied in the detection of listeria monocytogenes in meat products. minced beef samples were inoculated with l. monocytogenes (log(10)3 cfu g(-1)) and incubated for 10 h at 30 degrees c in buffered peptone water. l. monocytogenes was recovered from the culture by attachment to a polycarbonate membrane immersed for 15 min in the enriched meat culture. the membrane and attached bacteria wer ...199910490225
activation of the cdc42 effector n-wasp by the shigella flexneri icsa protein promotes actin nucleation by arp2/3 complex and bacterial actin-based motility.to propel itself in infected cells, the pathogen shigella flexneri subverts the cdc42-controlled machinery responsible for actin assembly during filopodia formation. using a combination of bacterial motility assays in platelet extracts with escherichia coli expressing the shigella icsa protein and in vitro analysis of reconstituted systems from purified proteins, we show here that the bacterial protein icsa binds n-wasp and activates it in a cdc42-like fashion. dramatic stimulation of actin asse ...199910491394
listeria monocytogenes exploits normal host cell processes to spread from cell to cell.the bacterial pathogen, listeria monocytogenes, grows in the cytoplasm of host cells and spreads intercellularly using a form of actin-based motility mediated by the bacterial protein acta. tightly adherent monolayers of mdck cells that constitutively express gfp-actin were infected with l. monocytogenes, and intercellular spread of bacteria was observed by video microscopy. the probability of formation of membrane-bound protrusions containing bacteria decreased with host cell monolayer age and ...199910491395
predictive thermal inactivation model for listeria monocytogenes with temperature, ph, nacl, and sodium pyrophosphate as controlling factors.the effects and interactions of heating temperature (55 to 65 degrees c), ph (4 to 8), salt (nacl; 0 to 6%, wt/vol), and sodium pyrophosphate (spp; 0 to 0.3%, wt/vol) on the heat inactivation of a four-strain mixture of listeria monocytogenes in beef gravy were examined. a factorial experimental design comparing 48 combinations of heating temperature, salt concentration, ph value, and spp content was used. heating was carried out using a submerged-coil heating apparatus. the recovery medium was ...199910492471
effects of the growth procedure on the surface hydrophobicity of listeria monocytogenes cells and their adhesion to stainless steel.the aim of this study was to examine the physicochemical surface properties and the ability to adhere to stainless steel of three strains of listeria monocytogenes after different cultivation procedures. to this end, bacteria were cultivated at 37 degrees c after storage at two frequently used temperatures (4 degrees c or -80 degrees c) and were then transferred into the liquid medium (trypticase soy broth supplemented with 6 g liter(-1) of yeast extract, ph 7.3) between one and four times. in a ...199910492472
nisin reduces the thermal resistance of listeria monocytogenes scott a in liquid whole egg.d-values (decimal reduction times) and z-values (increase in temperature required for a 1-log change in d-value) for listeria monocytogenes scott a were determined in liquid whole egg with nisin (0 or 10 microg ml(-1)) and nacl (0 or 10%) by a submerged glass ampoule procedure. samples were plated onto nonselective agar at appropriate intervals, and d-values were determined using a modified biphasic logistic equation. addition of nacl increased d-values at all temperatures tested. the addition o ...199910492473
development of a lacticin 3147-enriched whey powder with inhibitory activity against foodborne pathogens.the broad-spectrum bacteriocin lacticin 3147, produced by lactococcus lactis dpc3147, is inhibitory to a wide range of gram-positive food spoilage and pathogenic organisms. a 10% solution of demineralized whey powder was fermented with dpc3147 at a constant ph of 6.5. the fermentate was spray dried, and the resulting powder exhibited inhibitory activity. the ability of the lacticin 3147-enriched powder to inhibit listeria monocytogenes scott a and staphylococcus aureus 10 was assessed in buffer ...199910492475
a proteomic approach to study the acid response in listeria monocytogenes.the responses of listeria monocytogenes to acidic conditions were studied at the level of protein synthesis at a lethal acidic ph (acid stress) and an intermediary nonlethal acidic ph (acid adaptation). the radiolabeled acid-induced proteins were separated by two-dimensional (2-d) electrophoresis and analyzed by a computer-aided 2-d gel analysis system. the two acidic conditions upgraded a number of constitutive proteins and induced synthesis of a number of novel proteins. the majority of these ...199910493126
phenotypic modulation by intracellular bacterial pathogens.microorganisms have the capacity to sense their environment and to respond to it by alteration in gene expression and protein synthesis. two-dimensional electrophoresis (2-de) provides a powerful tool to examine the global response in bacterial protein synthesis upon exposure to different environmental signals. one of the most complex environments encountered by facultative intracellular pathogenic bacteria is the intracellular environment of the host cell. numerous studies have documented that ...199910493129
mhc class i restricted t cell responses to listeria monocytogenes, an intracellular bacterial pathogen.studies of the murine immune response to infection with the intracellular bacterial pathogen listeria monocytogenes have provided a wealth of information about innate and acquired immune defenses in the setting of an infectious disease. our studies have focused on the mhc class i restricted, cd8+ t cell responses of balb/c mice to l. monocytogenes infection. four peptides that derive from proteins that l. monocytogenes secretes into the cytosol of infected cells are presented to cytotoxic t lymp ...199910493175
antibiotics in neonatal infections: a review.the bacteria most commonly responsible for early-onset (materno-fetal) infections in neonates are group b streptococci, enterococci, enterobacteriaceae and listeria monocytogenes. coagulase-negative staphylococci, particularly staphylococcus epidermidis, are the main pathogens in late-onset (nosocomial) infections, especially in high-risk patients such as those with very low birthweight, umbilical or central venous catheters or undergoing prolonged ventilation. the primary objective of the paedi ...199910493270
fifteen years of experience with bacterial meningitis.introduction of haemophilus influenzae type b (hib) vaccines has dramatically altered the epidemiology of bacterial meningitis in children. the goal of this study was to describe these changes in a pediatric teaching hospital.199910493344
ubiquicidin, a novel murine microbicidal protein present in the cytosolic fraction of macrophages.previously we have identified and characterized three murine microbicidal proteins purified from the granule fraction of cells from the murine macrophage cell line raw264.7. during these studies evidence was obtained for the presence of an additional antimicrobial protein in the cytosolic fraction of raw264.7 cells that had been activated with interferon-gamma (ifn-gamma). in this study we have purified this protein, designated ubiquicidin, to apparent homogeneity and demonstrated that it is a c ...199910496312
aromatic and basic residues within the evh1 domain of vasp specify its interaction with proline-rich ligands.short contiguous peptides harboring proline-rich motifs are frequently involved in protein-protein interactions, such as associations with src homology 3 (sh3) and ww domains. although patches of aromatic residues present in either domain interact with polyprolines, their overall structures are distinct, suggesting that additional protein families exist that use stacked aromatic amino acids (aa domains) to bind polyproline motifs [1] [2] [3]. a polyproline motif (e/dfpppptd/e in the single-lette ...199910498433
the isolation of certain pathogen microorganisms from raw milk.in this research, a total of 211 raw milk samples in different areas of ankara were collected from various dairy plants. each of these samples was tested for the presence of yersinia enterocolitica, listeria monocytogenes and campylobacter spp. from a total of 14 (6.63%) y. enterocolitica and y. enterocolitica-like organisms were isolated. 8 (3.79%) of the total isolation were identified as y. enterocolitica whereas 6 (2.84%) of these were found to be y. enterocolitica-like organisms. in additio ...199910499148
[listeria monocytogenes pneumonia: a severe complication in a patient with neoplasia].listeriosis is a infectious disease which can affect to immunosuppressed patients. we report a case of pneumonia by listeria monocytogenes as unusual presentation, because the central nervous system infections are the most common clinical entities. many cases reported had a underlying disease, most commonly hodgkin's disease, and had received immunosuppressive therapy. in our case the patient was considered to be immunosuppressed by had received corticosteroids and had been diagnosed of stage ii ...199910507170
effect of milk proteins on adhesion of bacteria to stainless steel surfaces.stainless steel coupons were treated with skim milk and subsequently challenged with individual bacterial suspensions of staphylococcus aureus, pseudomonas fragi, escherichia coli, listeria monocytogenes, and serratia marcescens. the numbers of attached bacteria were determined by direct epifluorescence microscopy and compared with the attachment levels on clean stainless steel with two different surface finishes. skim milk was found to reduce adhesion of s. aureus, l. monocytogenes, and s. marc ...199910508087
detection and differentiation of listeria spp. by a single reaction based on multiplex pcr.the iap gene encodes the protein p60, which is common to all listeria species. a previous comparison of the dna sequences indicated conserved and species-specific gene portions. based on these comparisons, a combination consisting of only five different primers that allows the specific detection and differentiation of listeria species with a single multiplex pcr and subsequent gel analysis was selected. one primer was derived from the conserved 3' end and is specific for all listeria species; th ...199910508109
survival of listeria monocytogenes in commercial cheese brines.the survival of listeria monocytogenes was determined in commercial cheese brines collected from cheese factories in wisconsin and northern illinois. survival of l. monocytogenes inoculated into commercial cheese brines ranged from < 7 d to over 259 d. survival did not correlate with ph, salt content, nitrogen content, mineral content, or inherent microbial populations but was negatively associated with addition of sodium hypochlorite at the dairy plant. the l. monocytogenes generally survived l ...199910509244
cutting edge: paradigm revisited: antibody provides resistance to listeria infection.listeriolysin o (llo) is a secreted pore-forming toxin of the facultative intracellular bacterium listeria monocytogenes. we assessed the ability of a murine anti-llo mab to affect the course of infection in mice challenged with listeria. this mab was previously shown to be capable of neutralizing llo-mediated pore formation in vitro, and here we show that the passive administration of this ab to mice before infection provides increased resistance. mice treated with the mab were protected from a ...199910510340
effective dna vaccination against listeriosis by prime/boost inoculation with the gene gun.protective immunity against listeria monocytogenes strongly depends on cd8+ t lymphocytes, and both ifn-gamma secretion and target cell killing are considered relevant to protection. we analyzed whether we could induce a protective type 1 immune response by dna vaccination with the gene gun using plasmids encoding for two immunodominant listerial ags, listeriolysin and p60. to induce a th1 response, we 1) coprecipitated a plasmid encoding for gm-csf, 2) employed a prime/boost vaccination schedul ...199910510394
curcumin inhibits th1 cytokine profile in cd4+ t cells by suppressing interleukin-12 production in macrophages.1 interleukin-12 (il-12) plays a central role in the immune system by driving the immune response towards t helper 1 (th1) type responses which are characterized by high ifn-gamma and low il-4 production. in this study we investigated the effects of curcumin, a natural product of plants obtained from curcuma longa (turmeric), on il-12 production by mouse splenic macrophages and the subsequent ability of these cells to regulate cytokine production by cd4+ t cells. 2 pretreatment with curcumin sig ...199910510448
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