Publications

application of 5'-nuclease pcr for quantitative detection of listeria monocytogenes in pure cultures, water, skim milk, and unpasteurized whole milk.	pcr techniques have significantly improved the detection and identification of bacterial pathogens. countless adaptations and applications have been described, including quantitative pcr and the latest innovation, real-time pcr. in real-time pcr, e.g., the 5'-nuclease chemistry renders the automated and direct detection and quantification of pcr products possible (p. m. holland et al., proc. natl. acad. sci. usa 88:7276-7280, 1991). we present an assay for the quantitative detection of listeria ...	2000	11010869
use of two-dimensional electrophoresis to study differential protein expression in divercin v41-resistant and wild-type strains of listeria monocytogenes.	the use of bacteriocins from food-grade lactic acid bacteria to fight against the food-borne pathogen listeria monocytogenes has been gaining interest. however, the emergence of resistant cells is frequently reported when listeria is exposed to such antibacterials. a two-dimensional electrophoresis study of whole-cell protein expression of listeria monocytogenes variants sensitive or resistant to the action of a bacteriocin produced by carnobacterium divergens v41, divercin v41, is reported in t ...	2000	11010876
cold shock induction of thermal sensitivity in listeria monocytogenes.	cold shock at 0 to 15 degrees c for 1 to 3 h increased the thermal sensitivity of listeria monocytogenes. in a model broth system, thermal death time at 60 degrees c was reduced by up to 45% after l. monocytogenes scott a was cold shocked for 3 h. the duration of the cold shock affected thermal tolerance more than did the magnitude of the temperature downshift. the z values were 8.8 degrees c for controls and 7.7 degrees c for cold-shocked cells. the d values of cold-shocked cells did not return ...	2000	11010880
cold shock and its effect on ribosomes and thermal tolerance in listeria monocytogenes.	differential scanning calorimetry (dsc) and fatty acid analysis were used to determine how cold shocking reduces the thermal stability of listeria monocytogenes. additionally, antibiotics that can elicit production of cold or heat shock proteins were used to determine the effect of translation blockage on ribosome thermal stability. fatty acid profiles showed no significant variations as a result of cold shock, indicating that changes in membrane fatty acids were not responsible for the cold sho ...	2000	11010881
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 contribution of both oxygen and nitrogen intermediates to the intracellular killing mechanisms of c1q-opsonized listeria monocytogenes by the macrophage-like ic-21 cell line.	listeria monocytogenes is a facultative intracellular pathogen which is internalized by host mammalian cells upon binding to their surface. further listerial growth occurs in the cytosol after escape from the phagosomal-endosomal compartment. we have previously reported that c1q is able to potentiate l. monocytogenes phagocytosis upon bacterial opsonization by ingestion through c1q-binding structures. in this report, we analysed the post-phagocytic events upon internalization of c1q-opsonized l. ...	2000	11012757
interactions of high hydrostatic pressure, pressurization temperature and ph on death and injury of pressure-resistant and pressure-sensitive strains of foodborne pathogens.	the objective of this study is to determine the interactions between high hydrostatic pressure, pressurization temperature, time and ph during pressurization on death and injury of pressure-resistant and pressure-sensitive strains of four foodborne pathogens: staphylococcus aureus 485 and 765, listeria ,monocytogenes ca and oh2, escherichia coli o157:h7 933 and 931, salmonella enteritidis fda and salmonella typhimurium e21274. among these strains s. aureus 485, l. monocytogenes ca, e. coli o157: ...	2000	11014520
subchronic silica exposure enhances respiratory defense mechanisms and the pulmonary clearance of listeria monocytogenes in rats.	both listeria monocytogenes infection and silica exposure have been shown to significantly alter immune responses. in this study, we evaluated the effect of preexposure to silica on lung defense mechanisms using a rat pulmonary l. monocytogenes infection model. male sprague-dawley rats were instilled intratracheally with saline (vehicle control) or silica using either an acute treatment regimen (5 mg/kg; 3 days) or a subchronic treatment protocol (80 mg/kg; 35 days). at 3 or 35 days after silica ...	2000	11015141
absence of serotype-specific surface antigen and altered teichoic acid glycosylation among epidemic-associated strains of listeria monocytogenes.	outbreaks of food-borne listeriosis have often involved strains of serotype 4b. examination of multiple isolates from three different outbreaks revealed that ca. 11 to 29% of each epidemic population consisted of strains which were negative with the serotype-specific monoclonal antibody c74.22, lacked galactose from the teichoic acid of the cell wall, and were resistant to the serotype 4b-specific phage 2671.	2000	11015420
interferon gamma signaling alters the function of t helper type 1 cells.	one mechanism regulating the ability of different subsets of t helper (th) cells to respond to cytokines is the differential expression of cytokine receptors. for example, th2 cells express both chains of the interferon gamma receptor (ifn-gammar), whereas th1 cells do not express the second chain of the ifn-gammar (ifn-gammar2) and are therefore unresponsive to ifn-gamma. to determine whether the regulation of ifn-gammar2 expression, and therefore ifn-gamma responsiveness, is important for the ...	2000	11015439
analysis of the role of the listeria monocytogenes f0f1 -atpase operon in the acid tolerance response.	as little is known about the genes involved in the induction of an acid tolerance response in listeria monocytogenes, the role of the f0f1-atpase was analyzed as a consequence of its role in the acid tolerance of a number of other bacteria and its conserved nature. it was found that acid adapted cells treated with n,n'-dicyclohexylcarbodiimide (dccd) exhibited greatly enhanced sensitivity to low ph stress. degenerate primers were designed to amplify and sequence a portion of the atpd gene. subse ...	2000	11016603
new developments in chromogenic and fluorogenic culture media.	this review describes some recent developments in chromogenic and fluorogenic culture media in microbiological diagnostic. the detection of beta-d-glucuronidase (gud) activity for enumeration of escherichia coli is well known. e. coli o157:h7 strains are usually gud-negative and do not ferment sorbitol. these characteristics are used in selective media for these organisms and new chromogenic media are available. some of the new chromogenic media make the salmonella diagnostic easier and faster. ...	2000	11016610
analysis of the role of betl in contributing to the growth and survival of listeria monocytogenes lo28.	survival of the food-borne pathogen listeria monocytogenes in environments of elevated osmolarity and reduced temperature is attributed, at least in part, to the accumulation of the trimethylammonium compound glycine betaine. previously we identified betl, a gene encoding the secondary glycine betaine transporter betl, which we linked to the salt tolerance of listeria. in this report, we demonstrate that betl, preceded by a consensus sigmab-dependent promoter, is regulated by osmotic up-shock, a ...	2000	11016615
foodborne listeriosis.	listeria monocytogenes emerged as an important foodborne pathogen in the latter part of the 20th century. clinical syndromes caused by this microorganism include sepsis in the immunocompromised patient, meningoencephalitis in infants and adults, and febrile gastroenteritis. focal infections at other sites are less frequent. listeria species are commonly found in raw and unprocessed food products. major outbreaks of listeriosis, with high morbidity and mortality, have been caused by a variety of ...	2000	11017828
polymerase chain reaction for the laboratory diagnosis of aseptic meningitis and encephalitis.	a protocol for testing cerebrospinal fluid specimens using a range of pcr assays for the diagnosis of central nervous system infection was developed and used to test prospectively 383 specimens. pcr assays were used for the detection of adenovirus, borrelia burgdorferi, enteroviruses, epstein barr virus, cytomegalovirus, herpes simplex virus, human herpes virus type 6, jc virus, leptospira interrogans, listeria monocytogenes, lymphocytic choriomeningitis virus, measles virus, mumps virus, mycoba ...	2000	11018820
predictions of growth for listeria monocytogenes and salmonella during fluctuating temperature.	we studied the predictive performance of a dynamic modelling approach, combined with predictions from the food micromodel software, applied to the growth of listeria monocytogenes and salmonella in pasteurised milk, chicken liver pâté and minced chicken, under constant as well as fluctuating temperatures. we found that, in general, the accuracy of a prediction under fluctuation temperature was similar to that under constant temperature. generally, there was a good agreement between predictions a ...	2000	11020037
structural model requirements to describe microbial inactivation during a mild heat treatment.	the classical concept of d and z values, established for sterilisation processes, is unable to deal with the typical non-loglinear behaviour of survivor curves occurring during the mild heat treatment of sous vide or cook-chill food products. structural model requirements are formulated, eliminating immediately some candidate model types. promising modelling approaches are thoroughly analysed and, if applicable, adapted to the specific needs: two models developed by casolari (1988), the inactiva ...	2000	11020040
comparison between the growth of yersinia enterocolitica, listeria monocytogenes, escherichia coli o157:h7 and salmonella spp. in ground beef packed by three commercially used packaging techniques.	growth of the pathogens yersinia enterocolitica, listeria monocytogenes, escherichia coli o157:h7 and strains of salmonella were compared in ground beef packed in modified atmospheres of 60% co2/40% n2/0.4% co (high co2/low co mixture), 70% o2/30% co2 (high o2 mixture) and in chub packs (stuffed in plastic casings). the ground beef was inoculated with rifampicin-resistant or nalidixic acid/streptomycin-resistant strains of the pathogens (final concentration 10(2) - 10(3) bacteria/g) and stored a ...	2000	11020041
cloning, sequencing and characterisation of a listeria monocytogenes gene encoding a fibronectin-binding protein.	listeria monocytogenes is a gram-positive, non-sporulating food-borne pathogen of man and animals that is able to invade many eukaryotic cells. l. monocytogenes possesses several proteins that bind fibronectin. in this study, an l. monocytogenes dna library in puc19 was screened with fibronectin and a gene encoding a 24.6-kda fibronectin-binding protein (fbp) was isolated and sequenced. transcripts of the fbp gene were found in wild-type, in deltaprfa, and prfa-s183a strains, despite the presenc ...	2000	11023185
induction of human immunodeficiency virus (hiv)-specific cd8 t-cell responses by listeria monocytogenes and a hyperattenuated listeria strain engineered to express hiv antigens.	induction of cell-mediated immunity may be essential for an effective aids vaccine. listeria monocytogenes is an attractive bacterial vector to elicit t-cell immunity to human immunodeficiency virus (hiv) because it specifically infects monocytes, key antigen-presenting cells, and because natural infection originates at the mucosa. immunization with recombinant l. monocytogenes has been shown to protect mice from lymphocytic choriomeningitis virus, influenza virus, and tumor inoculation. l. mono ...	2000	11024127
neurolisteriosis presenting as recurrent transient ischemic attacks.	an elderly man experienced recurrent transient episodes of right arm weakness and expressive aphasia. he was initially treated with aspirin and then with coumadin. thirteen days after initial presentation, he became febrile and had signs of meningitis. the illness progressed relentlessly to death 9 weeks after admission to the hospital. necropsy showed prominent meningitis with vasculitis extending into the left frontal lobe. polymerase chain reaction identified the organism as listeria monocyto ...	2000	11026451
application of polynomial models to predict growth of mixed cultures of pseudomonas spp. and listeria in meat.	three models for one rapid and one slow growing strain of pseudomonas fragi and one slow growing strain of p. fluorescens were developed in a meat broth; they were designed to take account of variations in growth and to provide a growth response interval. these models, and another for listeria monocytogenes (lm14 model), were used to predict the growth of spoilage pseudomonas spp. and pathogenic listeria in meat products. the pseudomonas and listeria models provided satisfactory predictions conc ...	2000	11028957
maillard reaction causes suppression of virulence gene expression in listeria monocytogenes.	many environmental signals affect the expression of virulence genes of the food borne pathogen listeria monocytogenes. in addition media composition has been shown to suppress levels of haemolytic activity. using a pr(plca)::luxab reporter gene fusion it was observed that the heat processing of media also reduces the level of virulence gene expression in l. monocytogenes without affecting its growth. physicochemical factors that are considered to enhance the maillard reaction were also found to ...	2000	11028958
synergistic inhibition of listeria monocytogenes on cold-smoked rainbow trout by nisin and sodium lactate.	the inhibition of listeria monocytogenes and mesophilic aerobic bacteria in cold-smoked rainbow trout by nisin, sodium lactate or their combination was studied. nisin (4000-6000 iu/ml), sodium lactate (60%) or their combination (1:1) were injected into rainbow trout at an industrial scale before the smoking process, or injected into the finished smoked product. both types of fish samples were smoked, sliced and vacuum-packed according to normal practice in the plant. packages were opened and l. ...	2000	11028960
control of foodborne pathogens during sufu fermentation and aging.	control of the foodborne pathogens escherichia coli o157:h7, salmonella typhimurium, staphylococcus aureus, and listeria monocytogenes during sufu fermentation was evaluated. before fermentation, pathogens were inoculated onto tofu (substrate for sufu) at 5 log cfu/g or 3 log cfu/g, and starter culture (actinomucor elegans) was inoculated at 3 log cfu/g. after 2 days of fermentation at 30 degrees c, the four pathogens reached 7 to 9 log cfu/g, and the mold count reached 6 to 7 log cfu/g. after f ...	2000	11029011
a sheep in wolf's clothing: listeria innocua strains with teichoic acid-associated surface antigens and genes characteristic of listeria monocytogenes serogroup 4.	listeria monocytogenes serotype 4b has been implicated in numerous food-borne epidemics and in a substantial fraction of sporadic listeriosis. a unique lineage of the nonpathogenic species listeria innocua was found to express teichoic acid-associated surface antigens that were otherwise expressed only by l. monocytogenes of serotype 4b and the rare serotypes 4d and 4e. these l. innocua strains were also found to harbor sequences homologous to the gene gtca, which has been shown to be essential ...	2000	11029438
vaccination with heat-killed listeria as adjuvant reverses established allergen-induced airway hyperreactivity and inflammation: role of cd8+ t cells and il-18.	asthma is a respiratory disorder characterized by airway hyperreactivity (ahr) and inflammation and is associated with high serum ige and overproduction of il-4, il-5, and il-13 by allergen-specific th2 cells. our previous studies demonstrated that heat-killed listeria monocytogenes (hkl) as an adjuvant in immunotherapy successfully reversed ongoing ag-specific th2-dominated responses toward th1-dominated responses, but it was unclear if such immune modulation could reverse ongoing, established ...	2000	10605015
identification and characterization of immunoglobulin g in blood as a major inhibitor of diagnostic pcr.	a major inhibitor of diagnostic pcr in human plasma was identified and the mechanism of inhibition was characterized. human blood was divided by centrifugation into buffy coat, plasma, platelets, and erythrocytes. all these blood fractions were found to be highly inhibitory to a standardized pcr mixture containing the thermostable dna polymerase amplitaq gold. pcr inhibitors in human plasma were purified by chromatographic procedures and were characterized by a process of elimination, so that th ...	2000	10618113
listeria monocytogenes acta protein interacts with phosphatidylinositol 4,5-bisphosphate in vitro.	the n-terminal region of the listeria monocytogenes acta protein, in conjunction with host cell factors, is sufficient for actin polymerization at the bacterial surface. previous data suggested that acta could protect barbed ends from capping proteins. we tested this hypothesis by actin polymerization experiments in the presence of the acta n-terminal fragment and capping protein. acta does not protect barbed ends from capping protein. in contrast, this polypeptide prevents pip(2) from inhibitin ...	2000	10618167
molecular grouping of listeria monocytogenes based on the sequence of the inib gene.	the major part of the gene inlb was sequenced in 24 strains of listeria monocytogenes belonging to serovars 1/2a, 1/2b, 1/2c, 3b and 4b. a phylogenetic analysis based on the inlb nucleotide sequences showed that strains of serovars 1/2a and 1/2c were closely related, as well as those of serovars 1/2b and 3b. strains sharing serovar 4b could be divided into two distinct groups. there were differences in amino-acid sequence between all serovars except between serovars 1/2b and 3b. differences in a ...	2000	10628828
comparative in vitro activity of moxifloxacin against gram-positive clinical isolates.	the in vitro activity of moxifloxacin was compared with that of 15 antibacterial agents against 513 gram-positive microorganisms. the mic(90) (mg/l) of moxifloxacin was 0.06 for quinolone-susceptible staphylococcus aureus and staphylococcus epidermidis, 0.12 for streptococcus pyogenes and streptococcus agalactiae; 0.25 for streptococcus pneumoniae, streptococcus mitis, streptococcus bovis, streptococcus anginosus and actinomyces pyogenes; 0.5 for streptococcus sanguis and listeria monocytogenes, ...	2000	10629010
electron paramagnetic resonance studies of the membrane fluidity of the foodborne pathogenic psychrotroph listeria monocytogenes.	listeria monocytogenes is a foodborne psychrotrophic pathogen that grows at refrigeration temperatures. previous studies of fatty acid profiles of wild-type and cold-sensitive, branched-chain fatty acid deficient mutants of l. monocytogenes suggest that the fatty acid 12-methyltetradecanoic (anteiso-c(15:0)) plays a critical role in low-temperature growth of l. monocytogenes, presumably by maintaining membrane fluidity. the fluidity of isolated cytoplasmic membranes of wild-type (slcc53 and 1040 ...	2000	10631292
th1-biased immune responses induced by dna-based immunizations are mediated via action on professional antigen-presenting cells to up-regulate il-12 production.	the efficacy of dna-based immunization in conferring protective immunity against certain microbial pathogens including human immunodeficiency virus type 1 (hiv-1) has been described. the potential advantage of dna-based immunization over the traditional vaccines largely results from its capacity to efficiently induce th1-biased immune responses against an encoded antigen. we describe how th1-biased immune responses are induced by dna-based immunization, using a dna vaccine construct encoding hiv ...	2000	10606974
sequence variations within prfa dna binding sites and effects on listeria monocytogenes virulence gene expression.	reporter gene fusions were used to investigate the contributions of prfa dna binding sites to listeria monocytogenes virulence gene expression. our results suggest that the dna sequence of prfa binding sites determines the levels of expression of certain virulence genes, such as hly and mpl. other virulence genes, such as acta and plcb, may depend upon additional factors for full regulation of gene expression.	2000	10633124
p45, an extracellular 45 kda protein of listeria monocytogenes with similarity to protein p60 and exhibiting peptidoglycan lytic activity.	a monoclonal antibody obtained by immunization of mice with heat-killed cells of listeria monocytogenes serotype 4d showed reactivity towards a protein (p45) from l. monocytogenes with an apparent molecular mass of 45 kda. this protein was detected in the culture supernatant and at the cell surface of l. monocytogenes. proteins cross-reacting with the monoclonal antibody were present in all listeria strains investigated, except l. grayi. the structural gene was cloned in escherichia coli and seq ...	2000	10648100
synergistic effects of nisin and thymol on antimicrobial activities in listeria monocytogenes and bacillus subtilis.	nisin z and thymol were tested, alone and in combination, for antibacterial activity against listeria monocytogenes atcc 7644 and bacillus subtilis atcc 33712. the antibacterial effect of nisin z, produced by lactococcus lactis ke3 isolated from the traditional moroccan fermented milk, was greatly potentiated by sub-inhibitory concentrations of thymol in both bacterial strains. our data showed that the concentration of nisin required for effective control of food-borne pathogenic bacteria could ...	2000	10650225
ph-regulated activation and release of a bacteria-associated phospholipase c during intracellular infection by listeria monocytogenes.	listeria monocytogenes grows in the cytosol of mammalian cells and spreads from cell to cell without exiting the intracellular milieu. during cell-cell spread, bacteria become transiently entrapped in double-membrane vacuoles. escape from these vacuoles is mediated in part by a bacterial phospholipase c (pc-plc), whose activation requires cleavage of an n-terminal peptide. pc-plc activation occurs in the acidified vacuolar environment. in this study, the ph-dependent mechanism of pc-plc activati ...	2000	10652090
generalized transduction of serotype 1/2 and serotype 4b strains of listeria monocytogenes.	this is the first report of generalized transduction in the gram-positive, food-borne pathogen listeria monocytogenes. bacteriophages were isolated from the environment and from lysogens, or were obtained from other laboratories. of the 59 bacteriophages tested, 34 proved to be capable of transduction. we exploited the ability of l. monocytogenes to grow at room temperature and isolated bacteriophages that were incapable of growth at 37 degrees c. transductions at this temperature therefore elim ...	2000	10652092
complete nucleotide sequence, molecular analysis and genome structure of bacteriophage a118 of listeria monocytogenes: implications for phage evolution.	a118 is a temperate phage isolated from listeria monocytogenes. in this study, we report the entire nucleotide sequence and structural analysis of its 40 834 bp dna. electron microscopic and enzymatic analyses revealed that the a118 genome is a linear, circularly permuted, terminally redundant collection of double-stranded dna molecules. no evidence for cohesive ends or for a terminase recognition (pac) site could be obtained, suggesting that a118 viral dna is packaged via a headful mechanism. p ...	2000	10652093
recent advances with recombinant bacterial vaccine vectors.	bacille calmette-guerin (bcg), listeria monocytogenes, salmonellae and shigellae have shown promise as vaccine vectors in experimental animal models. although disappointing results in humans and non-human primates stalled the development of this vaccination strategy, interest in this approach was reinvigorated recently by the development of bacterial dna-vaccine-vectors. the purpose of this review is to highlight the strengths and weaknesses of bacterial vaccine vectors, and to discuss the futur ...	2000	10652479
carbon dioxide and nisin act synergistically on listeria monocytogenes.	this paper examines the synergistic action of carbon dioxide and nisin on listeria monocytogenes scott a wild-type and nisin-resistant (nis(r)) cells grown in broth at 4 degrees c. carbon dioxide extended the lag phase and decreased the specific growth rate of both strains, but to a greater degree in the nis(r) cells. wild-type cells grown in 100% co(2) were two to five times longer than cells grown in air. nisin (2.5 microg/ml) did not decrease the viability of nis(r) cells but for wild-type ce ...	2000	10653749
effect of flagella on initial attachment of listeria monocytogenes to stainless steel.	at 22 degrees c a flagellin mutant of listeria monocytogenes was found to attach to stainless steel at levels 10-fold lower than wild-type cells, even under conditions preventing active motility. at 37 degrees c, when flagella are not produced, attachment of both strains was identical. therefore, flagella per se facilitate the early stage of attachment.	2000	10653766
reconstitution of listeria motility: implications for the mechanism of force transduction.	listeria monocytogenes and some other infectious bacteria polymerize their host cell's actin into tails that propel the bacteria through the cytoplasm. here we show that reconstitution of this behavior in simpler media resolves two aspects of the mechanism of force transduction. first, since dilute reconstitution media have no cytoskeleton, we consider what keeps the tail from being pushed backward rather than the bacterium being propelled forward. the dependence of the partitioning of motion on ...	2000	10656971
eta-1 (osteopontin): an early component of type-1 (cell-mediated) immunity.	cell-mediated (type-1) immunity is necessary for immune protection against most intracellular pathogens and, when excessive, can mediate organ-specific autoimmune destruction. mice deficient in eta-1 (also called osteopontin) gene expression have severely impaired type-1 immunity to viral infection [herpes simplex virus-type 1 (kos strain)] and bacterial infection (listeria monocytogenes) and do not develop sarcoid-type granulomas. interleukin-12 (il-12) and interferon-gamma production is dimini ...	2000	10657301
human toll-like receptor 2 mediates monocyte activation by listeria monocytogenes, but not by group b streptococci or lipopolysaccharide.	human toll like receptor (tlr) 2 has been implicated as a signaling receptor for lps from gram-negative bacteria and cell wall components from gram-positive organisms. in this study, we investigated whether tlr2 can signal cell activation by the heat-killed group b streptococci type iii (gbs) and listeria monocytogenes (hklm). hklm, but not gbs, showed a time- and dose-dependent activation of chinese hamster ovary cells transfected with human tlr2, as measured by translocation of nf-kappab and i ...	2000	10657659
expression and use of the green fluorescent protein as a reporter system in legionella pneumophila.	the gene encoding the green fluorescent protein (gfp) was used as a reporter gene in legionella pneumophila. to analyze gfp expression in legionella, transcriptional fusions of gfp with the legionella-specific mip (macrophage infectivity potentiator) promoter (p(mip)) and the sod (superoxide dismutase) promoter (p(sod)) derived from listeria monocytogenes were constructed. following transformation into the virulent l. pneumophila strain jr 32, strong gfp-mediated fluorescence was detected with b ...	2000	10660067
pathogen-specific loss of host resistance in mice lacking the ifn-gamma-inducible gene igtp.	interferon-gamma (ifn-gamma) is critical for defense against pathogens, but the molecules that mediate its antimicrobial responses are largely unknown. igtp is the prototype for a family of ifn-gamma-regulated genes that encode 48-kda gtp-binding proteins that localize to the endoplasmic reticulum. we have generated igtp-deficient mice and found that, despite normal immune cell development and normal clearance of listeria monocytogenes and cytomegalovirus infections, the mice displayed a profoun ...	2000	10639151
mutants of listeria monocytogenes defective in in vitro invasion and cell-to-cell spreading still invade and proliferate in hepatocytes of neutropenic mice.	listeria monocytogenes mutants defective in the acta gene, the plcb gene, and the inla and inlb genes were less virulent when injected intravenously into balb/c mice. the growth of these strains as well as of the virulent wild-type strains was increased by treating mice with a neutrophil-specific depleting monoclonal antibody, rb6-8c5. histologic examination of the livers of the treated animals showed intrahepatocytic proliferation of the listeriae in all cases. our data show that more than one ...	2000	10639462
role of listeriolysin o in cell-to-cell spread of listeria monocytogenes.	listeria monocytogenes is a facultative intracellular bacterial pathogen that escapes from a host vacuolar compartment and grows rapidly in the cytosol. listeriolysin o (llo) is a secreted pore-forming protein essential for the escape of l. monocytogenes from the vacuole formed upon initial internalization. however, its role in intracellular growth and cell-to-cell spread events has not been testable by a genetic approach. in this study, purified six-his-tagged llo (hisllo) was noncovalently cou ...	2000	10639481
determination of natural resistance of mice fed dietary lipids to experimental infection induced by listeria monocytogenes.	current understanding based on the effect of dietary lipid manipulation upon immune system function indicates that fatty acids are involved in the modulation of the immune response through different and complex pathways. reduction of several immune parameters by fatty acid action may be applied in the treatment of diseases characterised by an overactivation of the immune system. as a consequence, a reduction of host resistance against infectious agents has been reported in animals fed dietary li ...	2000	10640607
bactericidal activity of isothiocyanate against pathogens on fresh produce.	the bactericidal activity of allyl and methyl isothiocyanate (aitc and mitc) was tested with a rifampicin-resistant strain of salmonella montevideo and streptomycin-resistant strains of escherichia coil o157:h7 and listeria monocytogenes scott a. iceberg lettuce inoculated with high (10(7) to 10(8) cfu/g) and low (10(3) to 10(4) cfu/g) concentrations of bacterial pathogens was treated with aitc and mitc in sealed containers at 4 degrees c for 4 days. aitc showed stronger bactericidal activity th ...	2000	10643765
survival of listeria monocytogenes scott a on vacuum-packaged raw beef treated with polylactic acid, lactic acid, and nisin.	low-molecular-weight polylactic acid (lmw-pla) and lactic acid (la) were used to inhibit growth of listeria monocytogenes scott a on vacuum-packaged beef. nisin was also used simultaneously as an additional hurdle to the growth of this pathogen. inoculated beef cubes were immersed in a solution of 2% lmw-pla, 2% la, 400 iu/ml of nisin, or combinations of each acid and nisin for 5 min and drip-dried for 15 min. the cubes were then vacuum-packaged and stored at 4 degrees c for up to 42 days. surfa ...	2000	10643784
rapid neutrophil response controls fast-replicating intracellular bacteria but not slow-replicating mycobacterium tuberculosis.	being one of the first cells to invade the site of infection, neutrophils play an important role in the control of various bacterial and viral infections. in the present work, the contribution of neutrophils to the control of infection with different intracellular bacteria was investigated. mice were treated with the neutrophil-depleting monoclonal antibody rb6-8c5, and the time course of infection in treated and untreated mice was compared by using intracellular bacterial species and strains va ...	2000	10669354
recombinant human interleukin-11 has anti-inflammatory actions yet does not exacerbate systemic listeria infection.	to determine whether recombinant human (rh) interleukin (il)-11 disrupts the clearance of microbial pathogens, mice were challenged with listeria monocytogenes after receiving high-dose rhil-11, anti-tumor necrosis factor (tnf) monoclonal antibody (mab), anti-il-11 mab, or saline control. the ld50 was not affected by rhil-11 but was 10-fold lower in the anti-tnf mab group (p<.001). plasma il-6, il-1beta, and tnf-alpha levels were not different between rhil-11-treated animals and the control grou ...	2000	10669370
transient expression of bacterial gene fragments in eukaryotic cells: implications for cd8(+) t cell epitope analysis.	cd8(+) t cells are potent effectors of acquired immunity against some viruses and intracellular bacterial pathogens. antigens recognized by cd8(+) t cells are small, 8-9 amino acid peptides derived from proteins produced by the pathogen. these peptides are presented by mhc class i molecules on the surface of the infected cell. when characterizing the cd8(+) t cell response to a bacterial or viral pathogen, it is often necessary to express an antigenic protein in a eukaryotic host cell that is ca ...	2000	10669778
disease patterns in field and bank vole populations during a cyclic decline in central finland.	declining field vole (microtus agrestis) and bank vole (clethrionomys glareolus) populations were sampled (117 field voles and 34 bank voles) in south-central finland during the winter of 1988-89. the last surviving field voles were caught in april and bank voles in february. a subsample (16) of the april field voles were taken live to the laboratory for immunosuppression. the histopathology of the main internal organs and the presence of aerobic bacteria and certain parasites were studied. in t ...	2000	10670697
seven die in french listeria outbreak.		2000	10698871
bacterial pore-forming hemolysins and their use in the cytosolic delivery of macromolecules.	advances in our understanding of fundamental cell biological processes have facilitated an expansion of therapeutic approaches to altering cellular physiology and phenotype. as many of these methods involve macromolecular agents that act on targets within the nucleus or cytoplasm, achieving their full potential ultimately requires the efficient delivery of these agents across the cell membrane barrier into the cytosol. various strategies have been employed to enhance cytosolic delivery. these in ...	2000	10699316
advantage of gene gun-mediated over intramuscular inoculation of plasmid dna vaccine in reproducible induction of specific immune responses.	utilizing a plasmid dna encoding a single cytotoxic t lymphocyte (ctl) epitope and that encoding ovalbumin (ova), we compared the reproducibility in the induction of immune responses by gene gun and intramuscular immunization. as compared to intramuscular inoculation, gene gun dna immunization appeared to bring about highly reproducible and reliable results in the induction of specific ctl and ifn-gamma production to the ctl epitope and production of anti-ova igg. the results obtained by intramu ...	2000	10699319
evaluation of mini-vidas rapid test for detection of listeria monocytogenes from production lines of fresh to cold-smoked fish.	this study was conducted to evaluate the efficacy of the mini-vidas listeria monocytogenes (lmo) system (biomérieux vitek, inc., missouri, usa) for detection of l. monocytogenes in environmental and fish samples from three portuguese cold-smoking plants and from their fresh fish suppliers. mini-vidas-lmo is a fully automated system that uses fluorescent elfa (enzyme linked fluorescent assay) technology for detection of listeria monocytogenes antigens in food. it can be a rapid screening method a ...	2000	10699670
cloning, sequencing, and transcriptional analysis of the dnak heat shock operon of listeria monocytogenes.	the complete dnak operon of listeria monocytogenes was isolated by chromosome walking using the previously cloned dnak gene as a probe. molecular analysis of the locus identified 6 genes in the order hrca, grpe, dnak, dnaj, orf35, and orf29. primer extension analysis revealed 3 transcription start sites-s1, s2, and s3-upstream of the hrca, grpe, and dnaj, respectively. the transcription from s1 was heat inducible. analysis of the sequences revealed the consensus promoter sequences of gram-positi ...	2000	10701836
[changes in the virulence factor expression level in listeria monocytogenes under various environmental conditions].	effects of chelators chelex-100 and activated charcoal on the production of proteins responsible for virulence of listeria monocytogenes, facultative intracellular parasite were studied. bivalent cation chelator chelex-100 stimulates the production of only thiol-dependent hemolysin listeriolysin o. the presence of activated charcoal, a nonspecific chelator, in culture medium stimulated the expression of listeriolysin o and other main virulence factors by increasing the level of their transcripti ...	2000	10702985
[listeriosis: an old or a current health problem?].		2000	10703069
erratum: volume 45, number 1, january 2000	the legend to the issue's cover figure was incorrectly printed. it should have read: cover micrograph: actin-comet tails induced by the bacterial pathogen listeria monocytogenes. vero cells were infected by listeria monoctyogenes. after fixation, cells were labeled with fitc-phalloidin (green) and anti-listeria antibodies (red). photo courtesy of inigo lasa and pascale cossart.	2000	10706779
genes for the synthesis of the osmoprotectant glycine betaine from choline in the moderately halophilic bacterium halomonas elongata dsm 3043, usa.	the genes involved in the oxidative pathway of choline to glycine betaine in the moderate halophile halomonas elongata dsm 3043 were isolated by functional complementation of an escherichia coli strain defective in glycine betaine synthesis. the cloned region was able to mediate the oxidation of choline to glycine betaine in e. coli, but not the transport of choline, indicating that the gene(s) involved in choline transport are not clustered with the glycine betaine synthesis genes. nucleotide s ...	2000	10708384
human toll-like receptors 2 and 4 are targets for deactivation of mononuclear phagocytes by interleukin-4.		2000	10709778
does administration of infliximab increase susceptibility to listeriosis?		2000	10710107
infections and intoxications associated with animal feed and forage which may present a hazard to human health.	animal feed or forage may be the source of a limited number of infections for farm animals that could lead to human illness. likely organisms include salmonella enterica, toxoplasma gondii, trichinella spiralis and possibly the agent of bovine spongiform encephalopathy. the risk to human health from other infectious agents which may contaminate either feed or forage appear to be either negligible, e.g. bacillus anthracis and mycobacterium bovis, or non-existent, e.g. clostridium botulinum toxin ...	2000	10712800
single-strand conformation polymorphisms in the hly gene and polymerase chain reaction analysis of a repeat region in the iap gene to identify and type listeria monocytogenes.	two novel methods that allow the powerful identification of listeria monocytogenes by polymerase chain reaction (pcr) and simultaneous differentiation by special electrophoresis formats are described. the first method involves a pcr-driven single-strand conformation polymorphism (sscp-pcr) assay using a portion of the noncoding region of the hlv gene. the assay was evaluated with 120 genetically distinct l. monocytogenes strains of either foodborne or clinical origin. distribution of listerial s ...	2000	10716561
rapid polymerase chain reaction/dna probe membrane-based assay for the detection of listeria and listeria monocytogenes in food.	we describe the development of polymerase chain reaction (pcr)/dna probe membrane-based colorimetric assays for the detection and identification of listeria and l. monocytogenes. pcr primers designed from the 16s to 23s rrna intergenic spacer region amplified products that were reverse hybridized to membrane-bound oligonucleotide probes specific for listeria and l. monocytogenes with a detection limit of 1 to 10 cfu/25 ml in inoculated raw and pasteurized milk samples. these qualitative assays h ...	2000	10716562
development and evaluation of a 24-hour method for the detection and quantification of listeria monocytogenes in meat products.	a 24-h filter monitor-based test, listeria-select, has been developed to quantify listeria monocytogenes organisms in meat samples with a sensitivity of < or = 1.0 cfu/g. the technique comprises a filter monitor-based system and a colony lift immunoassay to identify and enumerate the target organism. meat homogenates were centrifuged and the eluate was filtered to trap and immobilize the microorganisms on the filter. fraser broth was then added to the filter apparatus to allow the organisms to b ...	2000	10716564
twenty-four-hour direct presumptive enumeration of listeria monocytogenes in food and environmental samples using the iso-grid method with lm-137 agar.	a new culture medium, lm-137 agar, was developed for use with the iso-grid hydrophobic grid membrane filter system for direct presumptive enumeration of listeria monocytogenes in 24 h. the method was validated against three-replicate, three-dilution most probable number procedures based on enrichment methods specified by the u.s. department of agriculture, the association of official analytical chemists international and the u.s. food and drug administration. the study encompassed meats, dairy p ...	2000	10716565
macrophage class a scavenger receptor-mediated phagocytosis of escherichia coli: role of cell heterogeneity, microbial strain, and culture conditions in vitro.	macrophage class a scavenger receptors (sr-ai and sr-aii) contribute to host defense by binding polyanionic ligands such as lipopolysaccharide and lipoteichoic acid. sr-a knockout (sr-a(-/-)) mice are more susceptible to endotoxic shock and listeria monocytogenes infection in vivo, possibly due to decreased clearance of lipopolysaccharide and microorganisms, respectively. we have used flow cytometry to analyze the role of sr-a and other scavenger-like receptors in phagocytosis of bacteria in vit ...	2000	10722588
purified lipopolysaccharide from francisella tularensis live vaccine strain (lvs) induces protective immunity against lvs infection that requires b cells and gamma interferon.	previous results have demonstrated that nonspecific protective immunity against lethal francisella tularensis live vaccine strain (lvs) or listeria monocytogenes infection can be stimulated either by sublethal infection with bacteria or by treatment with bacterial dna given 3 days before lethal challenge. here we characterize the ability of purified lipopolysaccharide (lps) from f. tularensis lvs to stimulate similar early protective immunity. treatment of mice with surprisingly small amounts of ...	2000	10722593
cd8(+) t-cell priming against a nonsecreted listeria monocytogenes antigen is independent of the antimicrobial activities of gamma interferon.	sublethal infection of mice with recombinant listeria monocytogenes expressing a model epitope in either secreted or nonsecreted form results in similar cd8(+) t-cell priming. since nonsecreted bacterial proteins have no obvious access to the endogenous major histocompatibility complex (mhc) class i presentation pathway, presentation of these antigens requires destruction of the bacterium to reveal the nonsecreted molecules to an exogenous mhc class i presentation pathway. gamma interferon (ifn- ...	2000	10722620
bacterial meningitis.	with nearly 8,000 cases in the united states per year, and 2,000 deaths annually, bacterial meningitis continues to be a significant source of morbidity and mortality. the principal pathogens are neisseria meningitidis, streptococcus pneumoniae, group b streptococci, and hemophilus influenzae. in immunocompromised patients, listeria monocytogenes is also an important pathogen. rapid identification and evaluation of the patient with bacterial meningitis and prompt initiation of antibiotics are th ...	2000	10725671
novel bacterial systems for the delivery of recombinant protein or dna.	on the basis of attenuated intracellular bacteria, we have developed two delivery systems for either heterologous proteins or dna vaccine vectors. the first system utilizes attenuated strains of gram-negative bacteria which are engineered to secrete heterologous antigens via the alpha-hemolysin secretion system of escherichia coli. the second system is based on attenuated suicide strains of listeria monocytogenes, which are used for the direct delivery of eukaryotic antigen expression vectors in ...	2000	10727885
oral delivery of dna vaccines using attenuated salmonella typhimurium as carrier.	the efficacious delivery of eukaryotic expression plasmids to inductive cells of the immune system constitutes a key prerequisite for the generation of effective dna vaccines. here, we have explored the use of bacteria as vehicles to orally deliver expression plasmids. attenuated salmonella typhimurium aroa harbouring eukaryotic expression plasmids that encoded virulence factors of listeria monocytogenes were administered orally to balb/c mice. strong cytotoxic and helper t cell responses as wel ...	2000	10727890
osmoprotectants and cryoprotectants for listeria monocytogenes.	listeria monocytogenes is a foodborne pathogen that can grow in high osmotic strength environments and at refrigeration temperatures. glycine betaine, proline betaine, acetylcarnitine, carnitine, gamma-butyrobetaine and 3-dimethylsulphoniopropionate all acted as osmoprotectants, as evidenced by an increase in growth rate of l. monocytogenes 10403s and scott a when provided with these compounds, while being stressed in defined medium containing 0.7 m nacl. these same compounds exhibited cryoprote ...	2000	10728555
ribotype analysis of strain distribution in listeria monocytogenes.	changes in the temporal and spatial patterns of strain distribution for the foodborne pathogen listeria monocytogenes were studied by ribotyping using the qualicon riboprinter system. ribotype patterns were obtained by using the restriction enzymes ecori and pvuii for 72 isolates of l. monocytogenes recovered from smoked salmon samples over a period of 3 years. each pattern was classified both by comparison to a pattern library and by comparison among the 72 isolate patterns. eleven ecori-based ...	2000	10678421
incidence and characterization of listeria monocytogenes from domestic and imported foods in korea.	a total of 1,537 domestic and imported food products were examined for the incidence of listeria monocytogenes between 1993 and 1997 in korea. l. monocytogenes was detected using the u.s. department of agriculture isolation method. isolated l. monocytogenes was confirmed by polymerase chain reaction with hly1 and hly2 primers designed from the listeriolysin o. overall, 122 samples (7.9%) contained l. monocytogenes. the rate of isolation was 4.3% for beef, 19.1% for pork, 30.2% for chicken, 1.2% ...	2000	10678422
listeria monocytogenes as a short-lived delivery system for the induction of type 1 cell-mediated immunity against the p36/lack antigen of leishmania major.	listeria monocytogenes has been used as an experimental live vector for the induction of cd8-mediated immune responses in various viral and tumoral experimental models. susceptibility of balb/c mice to leishmania major infection has been correlated to the preferential development of th2 cd4 t cells through an early production of interleukin 4 (il-4) by a restricted population of cd4 t cells which react to a single parasite antigen, lack (stands for leishmania homologue of receptors for activated ...	2000	10678966
interaction between burkholderia pseudomallei and acanthamoeba species results in coiling phagocytosis, endamebic bacterial survival, and escape.	burkholderia pseudomallei causes melioidosis, a potentially fatal disease whose clinical outcomes include rapid-onset septicemia and relapsing and delayed-onset infections. like other facultative intracellular bacterial pathogens, b. pseudomallei is capable of survival in human phagocytic cells, but unlike mycobacteria, listeria monocytogenes, and salmonella serovar typhimurium, the species has not been reported to survive as an endosymbiont in free-living amebae. we investigated the consequence ...	2000	10678988
novel approaches to monitor bacterial gene expression in infected tissue and host.	elucidating the complex and dynamic host-microbe interactions during infection requires, among other things, detailed knowledge of microbial gene expression in vivo. recently, advances in fluorescence and bioluminescence detection techniques, as well as recombinase-based in vivo expression technology, have rendered monitoring virulence gene expression in vivo a feasible task. these techniques have been adapted by several laboratories to study the spatial and temporal patterns of virulence gene e ...	2000	10679414
bacterial replication in the host cell cytosol.	intracellular bacteria in mammalian host cells can either live in a membrane-bound vacuole modified to support bacterial growth, or escape from the primary phagosome into the host cell cytoplasm. phagosomal escape is best studied in listeria monocytogenes in which a pore-forming cytolysin and two phospholipases are involved in the lysis of the phagosomal membrane. the mechanisms of and requirements for cytoplasmic growth are less clear but there is growing evidence that proficient replication of ...	2000	10679420
ctsr controls class iii heat shock gene expression in the human pathogen listeria monocytogenes.	stress proteins play an important role in virulence, yet little is known about the regulation of stress response in pathogens. in the facultative intracellular pathogen listeria monocytogenes, the clp atpases, including clpc, clpp and clpe, are required for stress survival and intracellular growth. the first gene of the clpc operon of l. monocytogenes encodes a homologue of the bacillus subtilis ctsr repressor of stress response genes. an l. monocytogenes ctsr-deleted mutant displayed enhanced s ...	2000	10692157
growing an actin gel on spherical surfaces.	inspired by the motility of the bacteria listeria monocytogenes, we have experimentally studied the growth of an actin gel around spherical beads grafted with acta, a protein known to be the promoter of bacteria movement. on acta-grafted beads f-actin is formed in a spherical manner, whereas on the bacteria a "comet-like" tail of f-actin is produced. we show experimentally that the stationary thickness of the gel depends on the radius of the beads. moreover, the actin gel is not formed if the ac ...	2000	10692348
rapid determination of listeria monocytogenes by automated enzyme-linked immunoassay and nonradioactive dna probe.	a rapid and reliable analytical method was developed to detect and confirm the presence of listeria monocytogenes in raw and partially processed foods. forty-nine food samples (25 mixed cut vegetable salad, 12 smoked salmon, and 12 sterile smoked salmon) were individually inoculated with high levels [10-100 colony forming units (cfu)/25 g sample] and low levels (1-10 cfu/25 g sample) of l. monocytogenes, and were screened using the vitek immuno diagnostic assay (vidas) listeria monocytogenes (vi ...	2000	10693007
listeria monocytogenes septicemia in a thoroughbred foal.	listeria monocytogenes septicemia was diagnosed in a 6-day-old thoroughbred foal. primary clinical signs included fever, depression, diarrhea, and respiratory distress. hematologic abnormalities included leukopenia, neutropenia, degenerative left shift, and hyperfibrinogenemia. clinical chemistry and blood gas abnormalities included metabolic acidosis, hypoxemia, hypocapnia, hypoglycemia, and hyponatremia. despite aggressive therapeutic intervention and intensive care, the foal died within 12 ho ...	2000	10730952
[listeria monocytogenes endocarditis of a prosthetic valve].		2000	10734764
listeriosis, france.		2000	10734782
influence of catalase and superoxide dismutase on ozone inactivation of listeria monocytogenes.	the effects of ozone at 0.25, 0.40, and 1.00 ppm on listeria monocytogenes were evaluated in distilled water and phosphate-buffered saline. differences in sensitivity to ozone were found to exist among the six strains examined. greater cell death was found following exposure at lower temperatures. early stationary-phase cells were less sensitive to ozone than mid-exponential- and late stationary-phase cells. ozonation at 1.00 ppm of cabbage inoculated with l. monocytogenes effectively inactivate ...	2000	10742219
significance of inoculum size in the lag time of listeria monocytogenes.	the lag time of listeria monocytogenes growing under suboptimal conditions (low nutrient concentrations, ph 6, and 6.5 degrees c) was extended when the inoculum was severely stressed by starvation and the inoculum size was very small. predictive microbiology should deal with bacterial stress and stochastic approaches to improve its value for the agro-food industry.	2000	10742265
outbreak of listeria monocytogenes serovar 4b infection in france.		2000	10743331
local activation of nonspecific defense against a respiratory model infection by application of interferon-gamma: comparison between rat alveolar and interstitial lung macrophages.	pulmonary macrophages play a crucial role in the defense of inhaled pathogens. we characterized functional properties of alveolar (am) and interstitial (im) macrophages from rats. am exhibited a pronounced microbicidal capacity as shown by an elevated production of reactive oxygen intermediates (roi), nitric oxide (no), tumor necrosis factor (tnf)-alpha, and tumor cytotoxicity when compared with im. in contrast, im were superior to am regarding mechanisms mainly involved in the induction and mai ...	2000	10745029
inhibitory combinations of nisin, sodium chloride, and ph on listeria monocytogenes atcc 15313 in broth by an experimental design approach.	the influence of ph (5.0-8.2), nacl concentrations (0-6% w/v), and incubation time (0-24 h) on the inhibitory activity of nisin (0-100 i.u./ml) against listeria monocytogenes (10(3) cfu/ml) was studied using the doehlert experimental design and was confirmed by kinetic experiments. predicted values were in agreement with experimental values. experiments were carried out at 22 degrees c in reconstituted tsb-ye1 broth with or without nacl. nisin had an immediate ph-dependent bactericidal effect, w ...	2000	10746580
identification of new loci involved in adhesion of listeria monocytogenes to eukaryotic cells. european listeria genome consortium.	insertional mutagenesis was performed with tn1545 in the genetic background of an iniab deletion mutant to identify new adhesion determinants in listeria monocytogenes. four insertion mutants defective in adhesion to eukaryotic cells were identified. insertion sites were cloned by inverse-pcr and sequenced. the genetic organization of insertion regions was further analysed by screening and sequencing dna fragments from a hindiii library and by searching databases. three adhesion-defective mutant ...	2000	10746777
gc1q-r/p32, a c1q-binding protein, is a receptor for the inlb invasion protein of listeria monocytogenes.	inlb is a listeria monocytogenes protein that promotes entry of the bacterium into mammalian cells by stimulating tyrosine phosphorylation of the adaptor proteins gab1, cbl and shc, and activation of phosphatidyl- inositol (pi) 3-kinase. using affinity chromatography and enzyme-linked immunosorbent assay, we demonstrate a direct interaction between inlb and the mammalian protein gc1q-r, the receptor of the globular part of the complement component c1q. soluble c1q or anti-gc1q-r antibodies impai ...	2000	10747014
acting like actin. the dynamics of the nematode major sperm protein (msp) cytoskeleton indicate a push-pull mechanism for amoeboid cell motility.		2000	10747081
improvement of the detection of listeria monocytogenes by the application of aloa, a diagnostic, chromogenic isolation medium.	a new selective agar medium, aloa, for the selective and differential isolation of listeria monocytogenes has been evaluated. all stressed cultures of l. monocytogenes serovars tested grew on the medium as bluish colonies surrounded by a distinctive opaque halo and gave a productivity ratio of at least 0.95. non-pathogenic listeria sp. produced bluish colonies without a halo as was also the case for some enterococci and bacilli. special attention must be paid to some bacillus cereus strains and ...	2000	10747223