Publications

microbial co-habitation and lateral gene transfer: what transposases can tell us.	determining the habitat range for various microbes is not a simple, straightforward matter, as habitats interlace, microbes move between habitats, and microbial communities change over time. in this study, we explore an approach using the history of lateral gene transfer recorded in microbial genomes to begin to answer two key questions: where have you been and who have you been with?	2009	19393086
genotoxic activation of the environmental pollutant 3,6-dinitrobenzo[e]pyrene in salmonella typhimurium umu strains expressing human cytochrome p450 and n-acetyltransferase.	3,6-dinitrobenzo[e]pyrene (dnbep) is a potent mutagen identified in surface soil in two metropolitan areas of japan. we investigated whether dnbep can cause genotoxicity through any metabolic activation pathway in bacteria using the parental strain salmonella enterica serovar typhimurium (s. typhimurium) ta1535/psk1002, nitroreductase (nr)-deficient strain nm1000, the o-acetyltransferase (o-at)-deficient strain nm2000, bacterial o-at-overexpressing strain nm2009, and bacterial nr- and o-at-overe ...	2009	19393727
population structure, origins and evolution of major salmonella enterica clones.	the genus salmonella consists of two species s. enterica and s. bongori. s. enterica has a well defined subspecies structure with seven subspecies consistently delineated by sequence variation. frequency of recombination between subspecies and within a subspecies is markedly different. subspecies i undergoes frequent recombination as demonstrated recently, demystifying the long-held belief that salmonella is a highly clonal organism. the majority of disease causing serovars are from subspecies i ...	2009	19393770
salmonella enterica subsp. arizonae bone and joints sepsis. a case report and literature review.	osteoarticular infections caused by salmonella enterica subsp. arizonae are rarely seen in humans but young children and immunocompromised adults are at particular risk of acquiring this bacteria. reptiles and their by-products (e.g. meat preparations or medications) are particularly likely to harbor salmonella. we report on a case of septic arthritis of the hip transmitted by a reptile in a 10-month-old child. we carry out a recall of the complex nomenclature of salmonella, a review of the lite ...	2009	19395336
antimicrobial efficiency of essential oil and freeze-thaw treatments against escherichia coli o157:h7 and salmonella enterica ser. enteritidis in strawberry juice.	this study investigated the antimicrobial efficiency of 3 essential oils (eos), lemongrass, cinnamon leaf, and basil, and freeze-thaw treatment, alone or in combination, against escherichia coli o157:h7 and salmonella enterica ser. enteritidis inoculated in strawberry juice stored at 7 degrees c. eo of lemongrass or cinnamon leaf at 0.1 to 2 microl/ml and freezing at -23 degrees c for 24 or 48 h followed by thawing at 7 degrees c for 4 h all showed significant antimicrobial activities (p < 0.05) ...	2009	19397729
a typhoid fever outbreak in a slum of south dumdum municipality, west bengal, india, 2007: evidence for foodborne and waterborne transmission.	in april 2007, a slum of south dumdum municipality, west bengal reported an increase in fever cases. we investigated to identify the agent, the source and to propose recommendations.	2009	19397806
[molecular subtyping of salmonella enterica serotype enteritidis in a post epidemic period].	in the last two decades, salmonella enterica serotype enteritidis has become one of the main agents causing food borne diseases worldwide. this agent is transmitted mainly by contaminated meat and poultry.	2009	19399324
two site-directed mutations are required for the conversion of a sugar dehydratase into an aminotransferase.	l-colitose and d-perosamine are unusual sugars found in the o-antigens of some gram-negative bacteria such as escherichia coli, vibrio cholerae, and salmonella enterica, among others. the biosynthetic pathways for these two sugars begin with the formation of gdp-mannose from d-mannose 1-phosphate and gtp followed by the subsequent dehydration and oxidation of gdp-mannose to yield gdp-4-keto-6-deoxymannose. following the production of gdp-4-keto-6-deoxymannose, the two pathways diverge. in the ca ...	2009	19402712
an oral recombinant salmonella enterica serovar typhimurium mutant elicits systemic antigen-specific cd8+ t cell cytokine responses in mice.	the induction of antigen-specific cd8+ t cell cytokine responses against an attenuated, oral recombinant salmonella enterica serovar typhimurium vaccine expressing a green fluorescent protein (gfp) model antigen was investigated. a gfp expression plasmid was constructed in which the gfp gene was fused in-frame with the 5' domain of the escherichia coli beta-galactosidase alpha-gene fragment with expression under the lac promoter. groups of mice were orally immunized three times with the bacteria ...	2009	19402893
reduced fluoroquinolone susceptibility in salmonella enterica isolates from travelers, finland.	we tested the fluoroquinolone susceptibility of 499 salmonella enterica isolates collected from travelers returning to finland during 2003-2007. among isolates from travelers to thailand and malaysia, reduced fluoroquinolone susceptibility decreased from 65% to 22% (p = 0.002). all isolates showing nonclassical quinolone resistance were from travelers to these 2 countries.	2009	19402977
characterization of the enzyme aac(3)-id in a clinical isolate of salmonella enterica serovar haifa causing traveler's diarrhea.	the objective of this investigation was to identify the mechanism of decreased susceptibility to gentamicin in a salmonella clinical isolate, leading to the detection of a aminoglycoside acetyltransferase gene found in a class 1 integron.	2009	19403206
rfab, a galactosyltransferase, contributes to the resistance to detergent and the virulence of salmonella enterica serovar enteritidis.	in this study, a deletion mutant of rfab (deltarfab) was observed to be susceptible to sodium dodecyl sulfate and less tolerant to bile salts. in addition, pre-incubation in 10% bile salts increased bacterial tolerance to 30% bile salts. we also showed that the deltarfab mutant invaded hela cells less than the wild type and resulted in a lower ratio of intracellular bacteria. competitive infection of mice showed that the deltarfab mutant was defective in the colonization of host organs and was c ...	2009	19404677
the dna static curvature has a role in the regulation of the omps1 porin gene in salmonella enterica serovar typhi.	the dna static curvature has been described to play a key role as a regulatory element in the transcription process of several bacterial genes. here, the role of dna curvature in the expression of the omps1 porin gene in salmonella enterica serovar typhi is described. the web server mutacurve was used to predict mutations that diminished or restored the extent of dna curvature in the 5' regulatory region of omps1. using these predictions, curvature was diminished by site-directed mutagenesis of ...	2009	19406898
the global consequence of disruption of the acrab-tolc efflux pump in salmonella enterica includes reduced expression of spi-1 and other attributes required to infect the host.	the mechanisms by which rnd pumps contribute to pathogenicity are currently not understood. using the acrab-tolc system as a paradigm multidrug-resistant efflux pump and salmonella enterica serovar typhimurium as a model pathogen, we have demonstrated that acra, acrb, and tolc are each required for efficient adhesion to and invasion of epithelial cells and macrophages by salmonella in vitro. in addition, acrb and tolc are necessary for salmonella to colonize poultry. mutants lacking acra, acrb, ...	2009	19411325
adaptation and cross-adaptation of listeria monocytogenes and salmonella enterica to poultry decontaminants.	information on the potential for acquired reduced susceptibility of bacteria to poultry decontaminants occurring is lacking. minimal inhibitory concentrations (mics) were established for assessing the initial susceptibility and the adaptative and cross-adaptative responses of four bacterial strains (listeria monocytogenes serovar l/2a, l. monocytogenes serovar 4b, salmonella enterica serotype typhimurium, and s. enterica serotype enteritidis) to four poultry decontaminants (trisodium phosphate, ...	2009	19412596
evaluation of iso enrichment real-time pcr methods with internal amplification control for detection of listeria monocytogenes and salmonella enterica in fresh fruit and vegetables.	to provide with a quick method for qualitative detection, in less than three days, of salmonella enterica and listeria monocytogenes in fresh fruit and vegetables.	2009	19413765
a genetic analysis of in vivo selenate reduction by salmonella enterica serovar typhimurium lt2 and escherichia coli k12.	the twin-arginine transport (tat) system is dedicated to the translocation of folded proteins across the bacterial cytoplasmic membrane. proteins are targeted to the tat system by signal peptides containing a twin-arginine motif. in salmonella enterica serovar typhimurium and escherichia coli many tat substrates are known or predicted to bind a molybdenum cofactor in the cytoplasm prior to export. in the case of n- and s-oxide reductases, co-ordination of molybdenum cofactor insertion with prote ...	2009	19415239
a mutant of salmonella enterica serovar typhimurium rna polymerase extracytoplasmic stress response sigma factor sigma(e) with altered promoter specificity.	the alternative sigma factor sigma(e) is critical for envelope stress response and plays a role in pathogenicity of a variety of different bacteria. we previously identified several critical nucleotides in the salmonella enterica serovar typhimurium (s. typhimurium) sigma(e)-dependent rpoep3 promoter that corresponded to the most conserved nucleotides in the sigma(e) consensus sequence of the -10 and -35 promoter elements. in the present study, we exploited a previously established escherichia c ...	2009	19415331
comparison of genetic and physiological properties of salmonella enterica isolates from chickens reveals one major difference between serovar kentucky and other serovars: response to acid.	for unknown reasons, salmonella enterica kentucky has become the serovar most frequently isolated from chickens and chicken carcasses in the united states. in an attempt to identify traits that may underlie this phenomenon, genetic and physiological features of 30 serovar kentucky chicken isolates were compared with those of chicken isolates belonging to a range of other s. enterica serovars. most of the well-known salmonella virulence genes were detected in the serovar kentucky isolates by pcr, ...	2009	19415975
salmonella enterica serovar typhi live vector vaccines finally come of age.	attenuated salmonella typhi vaccine strains hold great promise as live vectors for presentation of foreign antigens from unrelated bacterial, viral and parasitic pathogens to the immune system. although this approach has proved quite successful in experimental animal models for eliciting antigen-specific mucosal, humoral and cellular responses, results have been disappointing for clinical trials carried out thus far. we hypothesize that the paucity of human responses to foreign antigens delivere ...	2009	19417771
the structure of a cytolytic alpha-helical toxin pore reveals its assembly mechanism.	pore-forming toxins (pfts) are a class of potent virulence factors that convert from a soluble form to a membrane-integrated pore. they exhibit their toxic effect either by destruction of the membrane permeability barrier or by delivery of toxic components through the pores. among the group of bacterial pfts are some of the most dangerous toxins, such as diphtheria and anthrax toxin. examples of eukaryotic pfts are perforin and the membrane-attack complex, proteins of the immune system. pfts can ...	2009	19421192
effects of static magnetic field on cell growth, viability, and differential gene expression in salmonella.	in the present study, we investigated the effect of exposure to a static magnetic field (smf) on cell growth, viability, and gene expression of salmonella enterica subsp. enterica serovar hadar. our results indicated that smf exposure (200 mt, 13 hours) failed to alter cellular growth but induced a decrease of colony-forming units (cfu) between 3 and 6 hours followed by an increase from 6 to 9 hours. the analysis of the differential expression of rpoa, dnak, katn, and 16s rrna genes under smf ex ...	2009	19422305
analysis of antimicrobial resistance and plasmid profiles in salmonella serovars associated with tropical seafood of india.	a total of 256 salmonella strains consisting of 29 salmonella serovars isolated from seafood of cochin (india) were analyzed for resistance to antimicrobials commonly used in human and veterinary medicines as therapeutic agents. the 10 most predominant salmonella serovars in seafood were also characterized for presence of plasmids using the alkaline lysis method. antimicrobial susceptibility studies highlighted a comparatively high resistance in salmonella isolates to sulfamethizol and carbenici ...	2009	19422307
serotype distribution and antibiotic resistance of human gastrointestinal isolates of salmonella enterica from crete, greece.		2009	19423479
conjugative transfer of plasmid-located antibiotic resistance genes within the gastrointestinal tract of lesser mealworm larvae, alphitobius diaperinus (coleoptera: tenebrionidae).	the frequency of conjugative transfer of antimicrobial resistance plasmids between bacteria within the gastrointestinal tract of lesser mealworm larvae, a prevalent pest in poultry production facilities, was determined. lesser mealworm larvae were exposed to a negative bacterial control, a donor salmonella enterica serotype newport strain, a recipient escherichia coli, or both donor and recipient to examine horizontal gene transfer of plasmids. horizontal gene transfer was validated post externa ...	2009	19425825
sanitation of faeces from source-separating dry toilets using urea.	to develop a reliable and simple method to produce safe fertilizers from human excreta using urea for sanitation of faeces.	2009	19426280
identifying promoter features of co-regulated genes with similar network motifs.	a large amount of computational and experimental work has been devoted to uncovering network motifs in gene regulatory networks. the leading hypothesis is that evolutionary processes independently selected recurrent architectural relationships among regulators and target genes (motifs) to produce characteristic expression patterns of its members. however, even with the same architecture, the genes may still be differentially expressed. therefore, to define fully the expression of a group of gene ...	2009	19426448
effect of expression level on immune responses to recombinant oral salmonella enterica serovar typhimurium vaccines.	live, attenuated salmonella has been used to express heterologous antigens for development of oral vaccines. often, expression must be regulated because of deleterious effects on the salmonella vector. the effect of varying expression levels on immune response parameters has not been well defined. in this study we introduced mutations in the -10 region of the trc promoter in the expression plasmid to generate series of vaccine strains with different levels of expression of a model antigen, the h ...	2009	19428883
sopb of salmonella enterica serovar typhimurium is a potential dna vaccine candidate in conjugation with live attenuated bacteria.	the immune response against salmonella is multi-faceted involving both the innate and the adaptive immune system. the characterization of specific salmonella antigens inducing immune response could critically contribute to the development of epitope based vaccines for salmonella. we have tried to identify a protective t cell epitope(s) of salmonella, as cell mediated immunity conferred by cd8+ t cells is the most crucial subset conferring protective immunity against salmonella. it being a proven ...	2009	19428891
potential role for the 4,12 antigen in the prevalence of clonal salmonella serovars in poultry.		2009	19429568
isolation of salmonella typhimurium from dead blue and gold macaws (ara ararauna).	two blue and gold macaw (ara ararauna) chicks died of fatal salmonellosis in buenos aires province, argentina. the birds were histopathologically and microbiologically examined. salmonella enterica subspecies enterica serovar typhimurium was isolated from the liver, spleen, heart, lung, kidney, and intestine of both birds. all strains were susceptible to ampicillin, cephalothin, cefotaxime, enrofloxacin, nalidixic acid, gentamicin, streptomycin, chloramphenicol, fosfomycin, tetracycline, nitrofu ...	2009	19432017
salmonella enterica outbreak in a banqueting hall in jerusalem: the unseen hand of the epidemiological triangle?	foodborne salmonella enterica outbreaks constitute both a threat to public health and an economic burden worldwide.	2009	19432037
drug-resistant salmonella typhimurium dt 120: use of pfge and mlva in a putative international outbreak investigation.	isolates of salmonella enterica serovar typhimurium belonging to definitive phage type (dt) 120 (salmonella typhimurium dt 120) from simultaneous outbreaks of infection in the england and denmark have been compared on the basis of antibiogram, pulsed-field gel electrophoresis (pfge), and multiple locus variable number tandem repeat analysis (mlva). isolates from england had the resistance profile (ampicillin, streptomycin, sulfamethoxazole, and tetracycline), mlva profiles 2-4-4-0-2, 2-4-5-0-2, ...	2009	19432517
perturbation of the small intestine microbial ecology by streptomycin alters pathology in a salmonella enterica serovar typhimurium murine model of infection.	the small intestine is an important site of infection for many enteric bacterial pathogens, and murine models, including the streptomycin-treated mouse model of infection, are frequently used to study these infections. the environment of the mouse small intestine and the microbiota with which enteric pathogens are likely to interact, however, have not been well described. therefore, we compared the microbiota and the concentrations of short-chain fatty acids (scfas) present in the ileum and cecu ...	2009	19433544
internalization of salmonella enterica serovar montevideo into greenhouse tomato plants through contaminated irrigation water or seed stock.	tomatoes have been linked to outbreaks of salmonellosis, demonstrating the need to identify sources of contamination. objectives of this study included determining the ability for salmonella enterica serovar montevideo to be internalized into tomatoes from contaminated irrigation water and seed stock, and establishing whether salmonella montevideo can survive in fertilizer solutions. six treatment groups (five plants per group) were irrigated with 350 ml of 7 log cfu/ml of salmonella montevideo ...	2009	19435236
characterization of mgtc, a virulence factor of salmonella enterica serovar typhi.	the mgtc is a virulence factor in salmonella typhimurium that is required for growth at low-mg2+ concentrations and intramacrophage survival. this gene is codified in a conserved region of the salmonella pathogenicity island 3 (spi-3), and is also present in the chromosome of other salmonella serovars. in this study we characterized the mgtc factor in s. typhi, a human specific pathogen, by using mgtc and spi-3 mutant strains. we found that mgtc is the most important factor codified in the spi-3 ...	2009	19436747
scamp3 is a component of the salmonella-induced tubular network and reveals an interaction between bacterial effectors and post-golgi trafficking.	salmonella enterica are facultative intracellular bacterial pathogens that proliferate within host cells in a membrane-bounded compartment, the salmonella-containing vacuole (scv). intracellular replication of salmonella is mediated by bacterial effectors translocated on to the cytoplasmic face of the scv membrane by a type iii secretion system. some of these effectors manipulate the host endocytic pathway, resulting in the formation in epithelial cells of tubules enriched in late endosomal mark ...	2009	19438519
[characterization of attenuated salmonella c500 strain with a delta asd mutant and use as an asd+ balanced-lethal host-vector system].	salmonella enterica serovar choleraesuis strain c500 is a live, attenuated vaccine that has been used in china for over 40 years to prevent piglet paratyphoid. the objective of this study was to evaluate the potential of attenuated salmonella enterica serovar choleraesuis c500 strain with a delta asd mutant as an effective live vaccine vector by the asd+ balanced-lethal host-vector system. here, we compared the characteristics of s. enterica serovar choleraesuis delta asdc500 strain with the par ...	2009	19441223
detection of salmonella enterica serovar typhimurium with puo-stvr2-like virulence-resistance hybrid plasmids in the united kingdom.	the aim of this study was to investigate the presence in the united kingdom (uk) of salmonella enterica serovar typhimurium isolates carrying puo-stvr2-like virulence-resistance hybrid plasmids that originated from pslt. one hundred and fifty ampicillin-resistant isolates of s. typhimurium, collected in different regions of the uk during 2006, were screened for the presence of bla (oxa-1) carried by an inh-like integron (2000 bp/bla (oxa-1)-aada1) characteristic of puo-stvr2. positive isolates w ...	2009	19444492
non-typhoidal salmonella bacteraemia: epidemiology, clinical characteristics and its' association with severe immunosuppression.	non-typhoidal salmonella (nts) is increasingly recognized as an important pathogen associated with bacteraemia especially in immunosuppressed patients. however, there is limited data specifically describing the clinical characteristics and outcome amongst the immunosuppressed patients.	2009	19445730
salmonella typhimurium: insight into the multi-faceted role of the lysr-type transcriptional regulators in salmonella.	the lysr-type transcriptional regulators (lttrs) are widely distributed in various genera of prokaryotes. lttrs are dna binding proteins that can positively or negatively regulate target gene expression and can also repress their own transcription. salmonella enterica comprises a group of gram-negative bacteria capable of causing clinical syndromes that range from self-limiting diarrhoea to severe fibrinopurulent necrotizing enteritis and life threatening systemic disease. the survival and repli ...	2009	19447191
redundant hydrogen peroxide scavengers contribute to salmonella virulence and oxidative stress resistance.	salmonella enterica serovar typhimurium is an intracellular pathogen that can survive and replicate within macrophages. one of the host defense mechanisms that salmonella encounters during infection is the production of reactive oxygen species by the phagocyte nadph oxidase. among them, hydrogen peroxide (h(2)o(2)) can diffuse across bacterial membranes and damage biomolecules. genome analysis allowed us to identify five genes encoding h(2)o(2) degrading enzymes: three catalases (kate, katg, and ...	2009	19447905
rapid detection of salmonella in milk by combined immunomagnetic separation-polymerase chain reaction assay.	during the past few years, milk has presented a risk of salmonella contamination; it has been implicated as the cause in several outbreaks of salmonellosis. because conventional detection methods require 5 to 7 d for completion and involve several subcultivation stages followed by biochemical and serological tests, rapid and sensitive methods have been sought, mainly at the dna level. therefore, a study including milk samples was conducted to evaluate the performance of a combination of 2 techni ...	2009	19447970
effect of analgesics and their derivatives on antibiotic resistance of environmental microbes.	this research is a preliminary study conducted to determine the effects of aspirin (acetyl-salicylic acid) and salicylic acid (analgesics and their derivatives) on the antibiotic resistance of ammonia oxidizing bacterium (aob) (a non-pathogenic environmental microbe) cultured from the texas tech university-water recovery system that treats a space related wastewater for nasa. the effect of salicylic acid was investigated by obtaining the minimal inhibition concentration (mic) of antibiotics (amo ...	2009	19448319
salmonella enterica serovar typhimurium-induced internalization and il-8 expression in hela cells does not have a direct relationship with intracellular ca(2+) levels.	the invasion-associated type iii secretion system (t3ss-1) of s. typhimurium is required to initiate and sustain an acute inflammatory response in the intestine. we investigated the relationship of s. typhimurium t3ss-1-induced il-8 expression and invasion with intracellular ca(2+) mobilization in hela cells. compared to the sipasopabde2 mutant, strains carrying a mutation in sipa, or mutations in sopabde2 induced higher levels of il-8 and greater bacterial internalization despite the fact that ...	2009	19450704
the capsule-encoding viab locus reduces intestinal inflammation by a salmonella pathogenicity island 1-independent mechanism.	salmonella enterica serotype typhimurium elicits acute neutrophil influx in the human intestinal mucosa within 1 or 2 days after infection, resulting in inflammatory diarrhea. in contrast, no overt symptoms are observed within the first 1 or 2 weeks after infection with s. enterica serotype typhi. here we show that introduction of the capsule-encoding viab locus of serotype typhi reduced the ability of serotype typhimurium to elicit acute intestinal inflammation in a streptomycin-pretreated mous ...	2009	19451244
first report of plasmid-mediated quinolone resistance determinant qnrs1 in an escherichia coli strain of animal origin in italy.	a qnrs1-positive strain of escherichia coli was detected among 73 poultry isolates showing ciprofloxacin mics of > or =0.125 microg/ml. the qnrs1 gene was associated with a tn3-like transposon, as previously described to occur in a salmonella enterica serovar infantis strain of animal origin, but the plasmid scaffold carrying this element resembled that of a plasmid previously identified in salmonella enterica serovar dublin. these elements suggest genetic exchanges among salmonella and e. coli ...	2009	19451298
nitric oxide-induced membrane tubulovesicular extensions (cytonemes) of human neutrophils catch and hold salmonella enterica serovar typhimurium at a distance from the cell surface.	nitric oxide (no) plays an important role in host defense against bacterial infections such as salmonellosis. no and 4-bromophenacyl bromide (bpb) induce the formation of long tubulovesicular extensions (tve, cytonemes, membrane tethers) from human neutrophils. these tve serve as cellular sensory and adhesive organelles. in the present study, we demonstrated that in the presence of the no donor, diethylamine nonoate or bpb human neutrophils bound and aggregated salmonella enterica serovar typhim ...	2009	19453754
host-specificity of salmonella enterica serovar gallinarum: insights from comparative genomics.	in this study, we have identified the possible genetic factors responsible for fowl-adaptation of salmonella entericaserovar gallinarum (s. gallinarum). by comparing the genes related to salmonella pathogenicity islands (spi) of s. gallinarum with those of salmonella entericaserovar enteritidis (s. enteritidis) we have identified twenty-four positively selected genes. our results suggest that the genes encoding the structural components of spi-2 encoded type three secretion apparatus (ttss) and ...	2009	19454277
a precious metal heist.	nearly all bacterial pathogens require iron to successfully infect their vertebrate hosts. the host molecule lipocalin-2 exploits this by sequestering bacterial siderophores as a mechanism of protection against infection. raffatellu et al. (2009) show that salmonella enterica serotype typhimurium circumvents this through the production of the modified siderophore salmochelin.	2009	19454345
lipocalin-2 resistance confers an advantage to salmonella enterica serotype typhimurium for growth and survival in the inflamed intestine.	in response to enteric pathogens, the inflamed intestine produces antimicrobial proteins, a process mediated by the cytokines il-17 and il-22. salmonella enterica serotype typhimurium thrives in the inflamed intestinal environment, suggesting that the pathogen is resistant to antimicrobials it encounters in the intestinal lumen. however, the identity of these antimicrobials and corresponding bacterial resistance mechanisms remain unknown. here, we report that enteric infection of rhesus macaques ...	2009	19454351
survival of enteric bacteria and coliphage ms2 in pure human urine.	the survival of escherichia coli, salmonella enterica serovar typhimurium, enterococcus faecalis and coliphage ms2 was studied in stored, fresh and diluted (1 : 1) human urine at 15 and 30 degrees c.	2009	19457041
antimicrobial activity of enterococcus faecium ef 55 against salmonella enteritidis in chicks.	the protective effect of enterococcus faecium ef 55 against salmonella enterica serovar enteritidis phage type 4 (se pt4) was studied in 1-day-old chicks. the ef 55 strain (isolated and characterised by the authors earlier) was applied daily (1.10(9) cfu/0.2 ml pbs) for 7 days. oral inoculation of the se pt4 strain was performed on day 8 in a single dose of 5.10(8) cfu/0.2 ml pbs. the experiment lasted for 21 days. samples were collected on day 1 of the experiment to verify the absence of salmon ...	2009	19457770
a yeast-based genetic screen for identification of pathogenic salmonella proteins.	salmonella uses type iii secretion systems (ttss) to deliver pathogenic proteins into the host cells. these translocated effectors induce bacterial internalization and intracellular proliferation by targeting important cellular processes that are conserved among eukaryotes. here, we assessed the feasibility of performing a genetic screen in yeast to identify novel salmonella effectors, by searching for genes that produce toxicity when expressed in this model system. we identified several known t ...	2009	19459960
molecular typing methodologies for microbial source tracking and epidemiological investigations of gram-negative bacterial foodborne pathogens.	gram-negative bacterial foodborne pathogens are a worldwide cause of morbidity and mortality. the ability to carry out epidemiological investigations to determine the primary sources of bacterial contamination is important to improve public health. multiple methods are available for bacterial source tracking and to determine the distribution of pathogens isolated from sick patients. the molecular based typing methods available fall into three general categories: those based on restriction analys ...	2009	19460308
soxs regulates the expression of the salmonella enterica serovar typhimurium ompw gene.	ompw of salmonella enterica serovar typhimurium has been described as a minor porin involved in osmoregulation, and is also affected by environmental conditions. biochemical and genetic evidence from our laboratory indicates that ompw is involved in efflux of and resistance towards paraquat (pq), and its expression has been shown to be activated in response to oxidative stress. in this study we have explored ompw expression in response to pq. primer extension and transcriptional fusions showed t ...	2009	19460824
structure of o-antigen and functional characterization of o-antigen gene cluster of salmonella enterica o47 containing ribitol phosphate and 2-acetimidoylamino-2,6-dideoxy-l-galactose.	an o-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of salmonella enterica o47 and studied by sugar analysis along with one- and two-dimensional 1h- and 13c-nmr spectroscopy. the following structure of the linear ribitol phosphate-containing repeating unit of the o-polysaccharide was established: -->2)-d-ribitol-5-p-(o-->6)-alpha-d-galp-(1-->3)-alpha-l-fucpnam-(1-->3)-beta-d-glcpnac-(1-->, where fucnam stands for 2-acetimidoylamino-2,6-dideoxy-l-galactose. about 1 ...	2009	19463095
flow cytometric analysis of salmonella enterica serotype typhimurium inactivated with supercritical carbon dioxide.	non-thermal processes for the effective sterilization and inactivation of microorganisms are currently receiving a great deal of attention in food, pharmaceutical and other relevant industries. supercritical carbon dioxide (sc-co(2)) treatment is an alternative method of microbial inactivation that can be safely used in foods and bioactive materials at relatively low temperatures. however, to date, the inactivation of microbial cells by treatment with sc-co(2) has only been evaluated using a con ...	2009	19463861
evaluation of salmonella live vaccines with chromosomal expression cassettes for translocated fusion proteins.	salmonella enterica is a versatile live carrier for the presentation of recombinant vaccine antigens. fusion proteins of a type iii secretion system effector and heterologous vaccine antigens can be translocated by live attenuated salmonella strains and mediate protective immunity against infections. here we investigated the use expression cassettes for translocated fusion protein consisting of effector ssef and antigens of listeria monocytogenes after stable integration into the salmonella chro ...	2009	19464562
the single substitution i259t, conserved in the plasminogen activator pla of pandemic yersinia pestis branches, enhances fibrinolytic activity.	the outer membrane plasminogen activator pla of yersinia pestis is a central virulence factor in plague. the primary structure of the pla beta-barrel is conserved in y. pestis biovars antiqua, medievalis, and orientalis, which are associated with pandemics of plague. the pla molecule of the ancestral y. pestis lineages microtus and angola carries the single amino acid change t259i located in surface loop 5 of the beta-barrel. recombinant y. pestis kim d34 or escherichia coli xl1 expressing pla t ...	2009	19465664
relationships between multidrug-resistant salmonella enterica serovar schwarzengrund and both broiler chickens and retail chicken meats in japan.	we examined 29 isolates of salmonella enterica subspecies enterica serovar schwarzengrund from broiler chickens (n=19) and retail chicken meats (n=10) in japan for antimicrobial susceptibility and pulsed-field gel electrophoresis (pfge) profiling. all isolates exhibited resistance to both bicozamycin and sulfadimethoxine (minimum inhibitory concentration of both antimicrobial agents: >512 microg/ml). nalidixic acid resistance was found in only one broiler chicken isolate. pfge analysis showed th ...	2009	19468180
insights into the evolution of sialic acid catabolism among bacteria.	sialic acids comprise a family of nine-carbon amino sugars that are prevalent in mucus rich environments. sialic acids from the human host are used by a number of pathogens as an energy source. here we explore the evolution of the genes involved in the catabolism of sialic acid.	2009	19470179
outer membrane protein stm3031 (ail/ompx-like protein) plays a key role in the ceftriaxone resistance of salmonella enterica serovar typhimurium.	previously, the putative outer membrane protein stm3031 has been correlated with ceftriaxone resistance in salmonella enterica serovar typhimurium. in this study, this protein was almost undetectable in the ceftriaxone-susceptible strain 01-4, but its levels were increased in 01-4 isogenic strains for which mics were higher. the stm3031 gene deletion mutant, r200(deltastm3031), was generated and showed >64-fold lower ceftriaxone resistance than r200, supporting a key role for stm3031 in ceftriax ...	2009	19470505
extended-spectrum {beta}-lactamases and ampc {beta}-lactamases in ceftiofur-resistant salmonella enterica isolates from food and livestock obtained in germany during 2003-07.	detection and characterization of extended-spectrum beta-lactamases (esbls) and ampc-encoding genes was conducted in german salmonella isolated from different sources from 2003 to 2007.	2009	19474065
the effect of methylation on some biological parameters in salmonella enterica serovar typhimurium.	cell growth is tightly coupled to dna replication and its methylation [proc natl acad sci u s a 93 (1996) 12206-12211]. in a culture medium, growing of salmonella typhimurium (s. typhimurium) mutant cells (dam(-)) decreased (2.5 fold) relative to the wild type strain (dam(+)). in this study, we show that the reason for this growth deficiency is due to the dna methylation. the absence of a dam methyltransferase protein results in poor growth efficiency and disturbs the synchrony of replication in ...	2009	19477083
the base excision repair system of salmonella enterica serovar typhimurium counteracts dna damage by host nitric oxide.	intracellular pathogens must withstand nitric oxide (no.) generated by host phagocytes. salmonella enterica serovar typhimurium interferes with intracellular trafficking of inducible nitric oxide synthase (inos) and possesses multiple systems to detoxify no.. consequently, the level of no. stress encountered by s. typhimurium during infection in vivo has been unknown. the base excision repair (ber) system recognizes and repairs damaged dna bases including cytosine and guanine residues modified b ...	2009	19478870
gold screen-printed-based impedimetric immunobiosensors for direct and sensitive escherichia coli quantisation.	label-free electrochemical impedance immunosensors for the detection and quantification of escherichia coli (e. coli) using self-assembled monolayers (sams)-modified gold screen-printed electrodes (auspes) were developed. two different immunosensor configurations were tested and compared. in the first one, the immunosensing design was based on the covalent immobilization of anti-e. coli at auspes using the homobifunctional cross-linker 3,3'-dithiobis[sulfosuccinimidylpropionate] (dtssp). the oth ...	2009	19481924
[detection of bla ctx-m-14 and aac(3)-ii genes in salmonella enterica serotype kedougou in algeria].		2009	19482452
genome expression analyses revealing the modulation of the salmonella rcs regulon by the attenuator igaa.	intracellular growth attenuator a (igaa) was identified as a salmonella enterica regulator limiting bacterial growth inside fibroblasts. genetic evidence further linked igaa to repression of the rcscdb regulatory system, which responds to envelope stress. how igaa attenuates this system is unknown. here, we present genome expression profiling data of s. enterica serovar typhimurium igaa mutants grown at high osmolarity and displaying exacerbated rcs responses. transcriptome data revealed that ig ...	2009	19124574
characterization of a monoclonal antibody directed against salmonella enterica serovar typhimurium and serovar [4,5,12:i:-].	flagellar extracts of salmonella enterica serovars expressing phase 2 h1 antigenic complex (h:1,2, h:1,5, h:1,6, and h:1,7) and a mutant flagellin obtained by site-directed mutagenesis of the fljb gene from serovar typhimurium at codon 218, transforming threonine to alanine, expressed in escherichia coli (fljb218(a)) were used to analyze the h1 antigenic complex. cross-reactions were detected by western blotting and dot blotting using commercial polyclonal antibodies against the different wild-t ...	2009	19124586
distribution, diversity, and seasonality of waterborne salmonellae in a rural watershed.	salmonella outbreaks from contaminated water and nonanimal foods (e.g., produce) are increasingly reported. to address the environment as a potential source of pathogenic salmonella, we investigated levels of salmonellae and the geographic and temporal variation of salmonella serotypes from surface waters in a region of georgia (united states) with a history of high salmonellosis case rates. monthly water samples were collected from six stations in the little river (upper suwannee basin) for 12 ...	2009	19124594
interleukin-17 in host defence against bacterial, mycobacterial and fungal pathogens.	the mammalian immune system is intricately regulated, allowing for potent pathogen-specific immunity to be rapidly activated in response to infection with a broad and diverse array of potential pathogens. as a result of their ability to differentiate into distinct effector lineages, cd4 t cells significantly contribute to pathogen-specific adaptive immune responses. through the production of effector cytokines, cd4 t helper (th) cells orchestrate the precise mobilization of specific immune cells ...	2009	19125888
the salmonella pathogenicity island (spi) 1 contributes more than spi2 to the colonization of the chicken by salmonella enterica serovar typhimurium.	salmonella enterica serovar typhimurium (typhimurium) is an important pathogen that infects a broad range of hosts. in humans, typhimurium causes a gastroenteritis characterized by vomiting, diarrhea, and abdominal pains. typhimurium infection occurs mainly through the ingestion of contaminated food including poultry, pork, eggs, and milk. chickens that are asymptomatic carriers of typhimurium constitute a potential reservoir for infection. the type three secretion systems encoded by salmonella ...	2009	19126220
structural and functional analysis of the c-terminal dna binding domain of the salmonella typhimurium spi-2 response regulator ssrb.	in bacterial pathogenesis, virulence gene regulation is controlled by two-component regulatory systems. in escherichia coli, the envz/ompr two-component system is best understood as regulating expression of outer membrane proteins, but in salmonella enterica, ompr activates transcription of the ssra/b two-component system located on salmonella pathogenicity island 2 (spi-2). the response regulator ssrb controls expression of a type iii secretory system in which effectors modify the vacuolar memb ...	2009	19126546
distribution of antibody titer against salmonella enterica among healthy individuals in nepal.	enteric fever is an endemic problem in nepal and widal agglutination test is widely used for its diagnosis but a normal baseline titer in healthy population and cutoff values have not been established.	2009	19128506
changes in antimicrobial resistance among salmonella enterica subspecies enterica serovar pullorum isolates in china from 1962 to 2007.	there are few data available for the trends of antimicrobial resistance of salmonella enterica subspecies enterica serovar pullorum (s. pullorum) in china and other parts of the world. thus, the objective of this study was to evaluate the changes in antimicrobial resistance of s. pullorum isolated from diseased chickens in china from 1962 to 2007. a total of 450 s. pullorum isolates were tested for their susceptibility to 17 antimicrobials in a disk diffusion method. 39-95% of the isolates displ ...	2009	19128897
bacterial particle endocytosis by epithelial cells is selective and enhanced by tumor necrosis factor receptor ligands.	bacterial pathogens use virulence strategies to invade epithelial barriers, but active processes of epithelial cells may also contribute to the endocytosis of microbial particles. to focus on the latter, we studied the uptake of fixed and fluorescently labeled bacterial particles in intestinal and bronchoepithelial cell cultures and found it to be enhanced in caco-2bbe and nci-h292 cells after treatment with tumor necrosis factor alpha and an agonist antibody against the lymphotoxin beta recepto ...	2009	19129472
discovery of novel 2',3',4'-trihydroxy-2-phenylacetophenone derivatives as anti-gram-positive antibacterial agents.	a number of 2',3',4'-trihydroxy-2-phenylacetophenone derivatives were synthesized and examined for growth inhibition of several kinds of bacteria. 2',3',4'-trihydroxy-2-phenylacetophenone itself exhibited no antibacterial activity, but some of its derivatives showed various antibacterial activities depending on functional groups introduced on the 2-phenyl ring. eighteen out of 24 compounds synthesized in this study appeared to possess antibacterial activities against at least two gram-positive s ...	2009	19129641
a sensitive liquid chromatography/mass spectrometry-based assay for quantitation of amino-containing moieties in lipid a.	a novel sensitive liquid chromatography/mass spectrometry-based assay was developed for the quantitation of aminosugars, including 2-amino-2-deoxyglucose (glucosamine, glcn), 2-amino-2-deoxygalactose (galactosamine, galn), and 4-amino-4-deoxyarabinose (aminoarabinose, aran), and for ethanolamine (etn), present in lipid a. this assay enables the identification and quantitation of all amino-containing moieties present in lipopolysaccharide or lipid a from a single sample. the method was applied to ...	2009	19130491
tlr2 and tlr4 signaling shapes specific antibody responses to salmonella typhi antigens.	tlr directly induce innate immune responses by sensing a variety of microbial components and are critical for the fine-tuning of subsequent adaptive immune responses. however, their impact and mechanism of action on antibody responses against bacterial antigens are not yet fully understood. salmonella enterica serovar typhi (s. typhi) porins have been characterized as inducers of long-lasting specific antibody responses in mice. in this report, we show that immunization of tlr4-deficient (tlr4(- ...	2009	19130558
is rotavirus contributing to an increase of diarrhoea in a region of spain?	diarrhoeal illnesses are the most frequent of notifiable diseases in aragon. physicians notify diarrhoea cases with presumed infectious origin on a weekly basis. following an increase in 2005-2006, we aimed to identify the responsible organism(s) in order to inform control measures. we described seasonality of diarrhoea notifications for 1998-2004 and 2005-2006. we calculated correlations between diarrhoea notifications and enteric pathogens diagnosed in two aragonese laboratories, and applied l ...	2009	19134236
involvement of the cra global regulatory protein in the expression of the iscrsua operon, revealed during studies of tricarballylate catabolism in salmonella enterica.	in salmonella enterica, tricarballylate (tcb) catabolism requires function of tcub, a membrane-bound protein that contains [4fe-4s] clusters and heme. tcub transfers electrons from reduced flavin adenine dinucleotide in the tcb dehydrogenase (tcua) to electron acceptors in the membrane. we recently showed that functions needed to assemble [fe-s] clusters (i.e., the iscrsua-hscba-fdx operon) compensate for the lack of apbc during growth of an apbc strain on tcb. apbc had been linked to [fe-s] clu ...	2009	19136587
the proteome of salmonella typhimurium grown under in vivo-mimicking conditions.	to successfully infect a host, it is a prerequisite for enteric pathogens such as salmonella enterica serovar typhimurium to adapt to their environment, in casu the gastrointestinal tract. the adoption of an appropriate lifestyle is triggered by environmental signals such as the low oxygen availability and high osmolarity prevalent in the gut. in order to gain more insight in the changes that are induced when s. typhimurium is adapting to these particular conditions, we used 2-d dige technology ...	2009	19137547
campylobacter jejuni drives myd88-independent interleukin-6 secretion via toll-like receptor 2.	gastrointestinal disease caused by campylobacter jejuni is characterized by localized inflammation and the destruction of the epithelial cell barrier that forms host innate protection against pathogens. this can lead to an imbalance in fluid transport across the gastrointestinal tract, resulting in severe diarrhea. the mechanisms of host cell receptor recognition of c. jejuni and downstream immune signaling pathways leading to this inflammatory disease, however, remain unclear. the aim of this s ...	2009	19139198
recovery of salmonella from bermudagrass exposed to simulated wastewater.	most confined swine (sus scrofa) feeding operations in the southeastern united states hold manure in lagoons and apply effluent on bermudagrass [cynodon dactylon (l.) pers.] as fertilizer. salmonella enterica subsp. enterica (ex kauffman and edwards) le minor and popoff, has been reported in mississippi lagoons, but levels and potential for contamination of bermudagrass were unknown. a laboratory method was developed to examine salmonella contamination of bermudagrass and levels of salmonella we ...	2009	19141824
salmonella-containing vacuoles display centrifugal movement associated with cell-to-cell transfer in epithelial cells.	intracellular salmonella enterica serovar typhimurium (serovar typhimurium) occupies a salmonella-containing vacuole (scv) where bacterial effector proteins are secreted into the host cell using type iii secretion systems (t3ss). cytoskeletal motor proteins and t3ss-delivered effector proteins facilitate scv positioning to juxtanuclear positions where bacterial replication occurs. here, we show that this characteristic scv positioning is not maintained by all scvs during infection of hela cells. ...	2009	19103768
salmonella enterica serovar typhimurium strains with regulated delayed attenuation in vivo.	recombinant bacterial vaccines must be fully attenuated for animal or human hosts to avoid inducing disease symptoms while exhibiting a high degree of immunogenicity. unfortunately, many well-studied means for attenuating salmonella render strains more susceptible to host defense stresses encountered following oral vaccination than wild-type virulent strains and/or impair their ability to effectively colonize the gut-associated and internal lymphoid tissues. this thus impairs the ability of reco ...	2009	19103774
multiple regulatory pathways associated with high-level ciprofloxacin and multidrug resistance in salmonella enterica serovar enteritidis: involvement of rama and other global regulators.	mechanisms of antibiotic resistance were examined in nalidixic acid-resistant salmonella enterica serovar enteritidis field isolates displaying decreased susceptibility to ciprofloxacin and in in vitro-derived ciprofloxacin-resistant mutants (104-cip and 5408-cip). all field isolates harbored a single gyra mutation (d87y). deletion of acrb and complementation with wild-type gyra increased quinolone susceptibility. selection for ciprofloxacin resistance was associated with the development of an a ...	2009	19104017
cmy-31 and cmy-36 cephalosporinases encoded by cole1-like plasmids.	two cmy-2 derivatives, cmy-31 (gln(215)-->arg) from salmonella enterica serotype newport and cmy-36 (ala(77)-->cys and gln(193)-->glu) from klebsiella pneumoniae, were characterized. both cephalosporinases functionally resembled cmy-2. bla(cmy) alleles occurred as parts of a putative transposon comprising isecp1b and a citrobacter freundii-derived sequence carried by cole1-like plasmids similar to cmy-5-encoding ptkh11 from klebsiella oxytoca.	2009	19104021
reaction of adomet with thic generates a backbone free radical.	thic is an [4fe-4s] cluster protein that catalyzes the formation of 4-amino-5-hydroxymethyl-2-methylpyrimidine. epr spectroscopic studies demonstrate that, upon interaction with adomet, active thic from salmonella enterica generates a persistent free radical on the alpha-carbon of an amino acid residue. the epr properties of the radical are consistent with any residue other than a gly or ala. exposure to oxygen was accompanied by a fission of the radical-carrying polypeptide chain between the gl ...	2009	19113839
salmonella enterica typhimurium sipa induces cxc-chemokine expression through p38mapk and jun pathways.	the role of salmonella typhimurium type iii secretion system (t3ss-1)-translocated proteins in chemokines' expression and protein phosphorylation was investigated in hela cells. infection of hela cells with s. typhimurium activated il-8 and gro-alpha expression at higher levels than infection with a s. typhimurium sipasopabde2 mutant, confirming that t3ss-1-secreted proteins are required to fully induce chemokine expression in hela cells. a s. typhimurium sipasopabde2 mutant complemented with si ...	2009	19114119
archaeal apbc/nbp35 homologs function as iron-sulfur cluster carrier proteins.	iron-sulfur clusters may have been the earliest catalytic cofactors on earth, and most modern organisms use them extensively. although members of the archaea produce numerous iron-sulfur proteins, the major cluster assembly proteins found in the bacteria and eukarya are not universally conserved in archaea. free-living archaea do have homologs of the bacterial apbc and eukaryotic nbp35 genes that encode iron-sulfur cluster carrier proteins. this study exploits the genetic system of salmonella en ...	2009	19114487
role of the hya hydrogenase in recycling of anaerobically produced h2 in salmonella enterica serovar typhimurium.	double and triple uptake-type hydrogenase mutants were used to determine which hydrogenase recycles fermentatively produced hydrogen. the deltahyb deltahya and deltahyd deltahya double mutants evolved h(2) at rates similar to that of the triple mutant strain, so hya alone oxidizes the bulk of h(2) produced during fermentation. when only hya was present, no hydrogen production was observed in nutrient-limited medium. h(2) uptake assays showed that hya can oxidize both exogenously added h(2) and f ...	2009	19114523
poultry-associated salmonella enterica subsp. enterica serovar 4,12:d:- reveals high clonality and a distinct pathogenicity gene repertoire.	a european baseline survey during the years 2005 and 2006 has revealed that the monophasic salmonella enterica subsp. enterica serovar 4,12:d:- was, with a prevalence of 23.6%, the most frequently isolated serovar in german broiler flocks. in denmark and the united kingdom, its serovar prevalences were 15.15% and 2.8%, respectively. although poultry is a major source of human salmonellosis, serovar 4,12:d:- is rarely isolated in humans (approximately 0.09% per year). molecular typing studies usi ...	2009	19114530
evaluation of new generation salmonella enterica serovar typhimurium vaccines with regulated delayed attenuation to induce immune responses against pspa.	increasing the immunogenicity to delivered antigens by recombinant attenuated salmonella vaccines (rasv) has been the subject of intensive study. with this goal in mind, we have designed and constructed a new generation of rasv that exhibit regulated delayed attenuation. these vaccine strains are phenotypically wild type at the time of immunization and become attenuated after colonization of host tissues. the vaccine strains are grown under conditions that allow expression of genes required for ...	2009	19114649
variation in antimicrobial resistance in sporadic and outbreak-related salmonella enterica serovar typhimurium.	the prevalence of different antimicrobial resistance profiles and variants of the salmonella genomic island 1 (sgi1) was reported for salmonella enterica serovar typhimurium dt104 strains isolated from patients in denmark. variation in antimicrobial resistance and corresponding changes of sgi1 were shown among isolates from a foodborne outbreak.	2009	19116064
deletion of tola in salmonella typhimurium generates an attenuated strain with vaccine potential.	the gram-negative tol-pal system of envelope proteins plays a key role in maintaining outer membrane integrity and contributes to the virulence of several pathogens. we have investigated the role of one of these proteins, tola, in the biology of salmonella enterica serovar typhimurium. deletion of tola rendered strain sl1344 more susceptible to killing by bile and human serum. in addition the mutant had impaired membrane integrity and displayed alterations in lps production. the tola mutant was ...	2009	19118362
osmoregulated periplasmic glucans of salmonella enterica serovar typhimurium are required for optimal virulence in mice.	we purified osmoregulated periplasmic glucans (opgs) from salmonella enterica serovar typhimurium and found them to be composed of 100 % glucose with 2-linked glucose as the most abundant residue, with terminal glucose, 2,3-linked and 2,6-linked glucose also present in high quantities. the two structural genes for opg biosynthesis, opgg and opgh, form a bicistronic operon, and insertion of a kanamycin resistance gene cassette into this operon resulted in a strain devoid of opgs. the opggh mutant ...	2009	19118363
oxidative stress and disruption of labile iron generate specific auxotrophic requirements in salmonella enterica.	the response of a cell to integrated stresses was investigated using environmental and/or genetic perturbations that disrupted labile iron homeostasis and increased oxidative stress. the effects of the perturbations were monitored as nutritional requirements, and were traced to specific enzymic targets. a yggx gsha cyay mutant strain required exogenous thiamine and methionine for growth. the thiamine requirement, which had previously been linked to the fe-s cluster proteins thih and thic, was re ...	2009	19118370
citrate-mediated iron uptake in pseudomonas aeruginosa: involvement of the citrate-inducible feca receptor and the feob ferrous iron transporter.	in an attempt to identify components of a ferric citrate uptake system in pseudomonas aeruginosa, a mutant library of a siderophore-deficient strain (ia614) was constructed and screened for defects in citrate-promoted growth in an fe-restricted medium. a mutant disrupted in gene pa3901, encoding a homologue of the outer-membrane ferric citrate receptor, feca, of escherichia coli (feca(e.c.)), was recovered and shown to be deficient in citrate-promoted growth and citrate-mediated fe uptake. a mut ...	2009	19118371