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small gtpases of the ras superfamily regulate intestinal epithelial homeostasis and barrier function via common and unique mechanisms.the intestinal epithelium forms a stable barrier protecting underlying tissues from pathogens in the gut lumen. this is achieved by specialized integral membrane structures such as tight and adherens junctions that connect neighboring cells and provide stabilizing links to the cytoskeleton. junctions are constantly remodeled to respond to extracellular stimuli. assembly and disassembly of junctions is regulated by interplay of actin remodeling, endocytotic recycling of junctional proteins, and v ...201324868497
novel methods for analysing bacterial tracks reveal persistence in rhodobacter sphaeroides.tracking bacteria using video microscopy is a powerful experimental approach to probe their motile behaviour. the trajectories obtained contain much information relating to the complex patterns of bacterial motility. however, methods for the quantitative analysis of such data are limited. most swimming bacteria move in approximately straight lines, interspersed with random reorientation phases. it is therefore necessary to segment observed tracks into swimming and reorientation phases to extract ...201324204227
critical role of a ferritin-like protein in the control of listeria monocytogenes cell envelope structure and stability under β-lactam pressure.the human pathogen listeria monocytogenes is susceptible to the β-lactam antibiotics penicillin g and ampicillin, and these are the drugs of choice for the treatment of listerial infections. however, these antibiotics exert only a bacteriostatic effect on this bacterium and consequently, l. monocytogenes is regarded as β-lactam tolerant. it is widely accepted that the phenomenon of bacterial tolerance to β-lactams is due to the lack of adequate autolysin activity, but the mechanisms of l. monocy ...201324204978
coestimation of recombination, substitution and molecular adaptation rates by approximate bayesian computation.the estimation of parameters in molecular evolution may be biased when some processes are not considered. for example, the estimation of selection at the molecular level using codon-substitution models can have an upward bias when recombination is ignored. here we address the joint estimation of recombination, molecular adaptation and substitution rates from coding sequences using approximate bayesian computation (abc). we describe the implementation of a regression-based strategy for choosing s ...201324149652
coestimation of recombination, substitution and molecular adaptation rates by approximate bayesian computation.the estimation of parameters in molecular evolution may be biased when some processes are not considered. for example, the estimation of selection at the molecular level using codon-substitution models can have an upward bias when recombination is ignored. here we address the joint estimation of recombination, molecular adaptation and substitution rates from coding sequences using approximate bayesian computation (abc). we describe the implementation of a regression-based strategy for choosing s ...201324149652
inference of the properties of the recombination process from whole bacterial genomes.patterns of linkage disequilibrium, homoplasy, and incompatibility are difficult to interpret because they depend on several factors, including the recombination process and the population structure. here we introduce a novel model-based framework to infer recombination properties from such summary statistics in bacterial genomes. the underlying model is sequentially markovian so that data can be simulated very efficiently, and we use approximate bayesian computation techniques to infer paramete ...201324172133
inference of the properties of the recombination process from whole bacterial genomes.patterns of linkage disequilibrium, homoplasy, and incompatibility are difficult to interpret because they depend on several factors, including the recombination process and the population structure. here we introduce a novel model-based framework to infer recombination properties from such summary statistics in bacterial genomes. the underlying model is sequentially markovian so that data can be simulated very efficiently, and we use approximate bayesian computation techniques to infer paramete ...201324172133
enzymatic basis for n-glycan sialylation: structure of rat α2,6-sialyltransferase (st6gal1) reveals conserved and unique features for glycan sialylation.glycan structures on glycoproteins and glycolipids play critical roles in biological recognition, targeting, and modulation of functions in animal systems. many classes of glycan structures are capped with terminal sialic acid residues, which contribute to biological functions by either forming or masking glycan recognition sites on the cell surface or secreted glycoconjugates. sialylated glycans are synthesized in mammals by a single conserved family of sialyltransferases that have diverse link ...201324155237
enteric bacterial invasion of intestinal epithelial cells in vitro is dramatically enhanced using a vertical diffusion chamber model.the interactions of bacterial pathogens with host cells have been investigated extensively using in vitro cell culture methods. however as such cell culture assays are performed under aerobic conditions, these in vitro models may not accurately represent the in vivo environment in which the host-pathogen interactions take place. we have developed an in vitro model of infection that permits the coculture of bacteria and host cells under different medium and gas conditions. the vertical diffusion ...201324192850
the campylobacter jejuni ciad effector protein activates map kinase signaling pathways and is required for the development of disease.enteric pathogens utilize a distinct set of proteins to modulate host cell signaling events that promote host cell invasion, induction of the inflammatory response, and intracellular survival. human infection with campylobacter jejuni, the causative agent of campylobacteriosis, is characterized by diarrhea containing blood and leukocytes. the clinical presentation of acute disease, which is consistent with cellular invasion, requires the delivery of the campylobacter invasion antigens (cia) to t ...201324144181
impact of a single phage and a phage cocktail application in broilers on reduction of campylobacter jejuni and development of resistance.campylobacteriosis is currently the most frequent foodborne zoonosis in many countries. one main source is poultry. the aim of this study was to enhance the knowledge about the potential of bacteriophages in reducing colonization of broilers with campylobacter , as there are only a few in vivo studies published. commercial broilers were inoculated with 10⁴ cfu/bird of a campylobacter jejuni field strain. groups of 88 birds each were subsequently treated with a single phage or a four-phage cockta ...201324205254
recognition of extracellular bacteria by nlrs and its role in the development of adaptive immunity.innate immune recognition of bacteria is the first requirement for mounting an effective immune response able to control infection. over the previous decade, the general paradigm was that extracellular bacteria were only sensed by cell surface-expressed toll-like receptors (tlrs), whereas cytoplasmic sensors, including members of the nod-like receptor (nlr) family, were specific to pathogens capable of breaching the host cell membrane. it has become apparent, however, that intracellular innate i ...201324155747
o-linked protein glycosylation in mycoplasma.although mycoplasmas have a paucity of glycosyltransferases and nucleotidyltransferases recognizable by bioinformatics, these bacteria are known to produce polysaccharides and glycolipids. we show here that mycoplasmas also produce glycoproteins and hence have glycomes more complex than previously realized. proteins from several species of mycoplasma reacted with a glycoprotein stain, and the murine pathogen mycoplasma arthritidis was chosen for further study. the presence of m. arthritidis glyc ...201324118505
a novel type of n-acetylglutamate synthase is involved in the first step of arginine biosynthesis in corynebacterium glutamicum.arginine biosynthesis in corynebacterium glutamicum consists of eight enzymatic steps, starting with acetylation of glutamate, catalysed by n-acetylglutamate synthase (nags). there are different kinds of known nagss, for example, "classical" arga, bifunctional argj, argo, and s-nags. however, since c. glutamicum possesses a monofunctional argj, which catalyses only the fifth step of the arginine biosynthesis pathway, glutamate must be acetylated by an as of yet unknown nags gene.201324138314
guillain-barre syndrome-like illness in association with electrical shock injury.a 19-year-old man presented 4 weeks after an electrical shock injury with gradual onset limb weakness, altered sensation in the peripheries and respiratory difficulty. there was immediate tingling of the fingers following the electrical injury that persisted. he subsequently had transient facial weakness responsive to oral steroids before the development of further limb symptoms. on admission the clinical picture and investigation findings, including neurophysiology, cerebrospinal fluid examinat ...201324136915
alternative roles for crispr/cas systems in bacterial pathogenesis. 201324146613
flow cytometry-based enrichment for cell shape mutants identifies multiple genes that influence helicobacter pylori morphology.the helical cell shape of helicobacter pylori is highly conserved and contributes to its ability to swim through and colonize the viscous gastric mucus layer. a multi-faceted peptidoglycan (pg) modification programme involving four recently characterized peptidases and two accessory proteins is essential for maintaining h. pylori's helicity. to expedite identification of additional shape-determining genes, we employed flow cytometry with fluorescence-activated cell sorting (facs) to enrich a tra ...201324112477
antimicrobial activity of the bioactive components of essential oils from pakistani spices against salmonella and other multi-drug resistant bacteria.the main objective of this study was the phytochemical characterization of four indigenous essential oils obtained from spices and their antibacterial activities against the multidrug resistant clinical and soil isolates prevalent in pakistan, and atcc reference strains.201324119438
assessment of glycan interactions of clinical and avian isolates of campylobacter jejuni.campylobacter jejuni strain 11168 was demonstrated to have a broad specificity for eukaryotic surface glycosylation using glycan array analysis. the initial screen indicated that sialic acid and mannose are important binding partners after environmental stress, while galactose and fucose structures are likely to be involved in persistent infection.201324119179
corbi: a new r package for biological network alignment and querying.in the last decade, plenty of biological networks are built from the large scale experimental data produced by the rapidly developing high-throughput techniques as well as literature and other sources. but the huge amount of network data have not been fully utilized due to the limited biological network analysis tools. as a basic and essential bioinformatics method, biological network alignment and querying have been applied in many fields such as predicting new protein-protein interactions (ppi ...201324565104
crystal structures of an archaeal oligosaccharyltransferase provide insights into the catalytic cycle of n-linked protein glycosylation.oligosaccharyltransferase transfers an oligosaccharide chain to the asparagine residues in proteins. the archaeal and eubacterial oligosaccharyltransferases are single subunit membrane enzymes, referred to as "aglb" (archaeal glycosylation b) and "pglb" (protein glycosylation b), respectively. only one crystal structure of a full-length pglb has been solved. here we report the crystal structures of the full-length aglb from a hyperthermophilic archaeon, archaeoglobus fulgidus. the aglb and pglb ...201324127570
antimicrobial resistance in human and animal pathogens in zambia, democratic republic of congo, mozambique and tanzania: an urgent need of a sustainable surveillance system.a review of the published and unpublished literature on bacterial resistance in human and animals was performed. sixty-eight articles/reports from the democratic republic of congo (drc), mozambique, tanzania and zambia were reviewed. the majority of these articles were from tanzania. there is an increasing trend in the incidence of antibiotic resistance; of major concern is the increase in multidrug- resistant escherichia coli, klebsiella pneumoniae, staphylococcus aureus, vibrio cholera, non-ty ...201324119299
the fibronectin-binding motif within flpa facilitates campylobacter jejuni adherence to host cell and activation of host cell signaling.campylobacter jejuni is a gram-negative, curved and rod-shaped bacterium that causes human gastroenteritis. acute disease is associated with c. jejuni invasion of the intestinal epithelium. epithelial cells infected with c. jejuni strains containing mutations in the flpa and cadf fibronectin (fn)-binding proteins exhibit reduced invasion of host cells and a c. jejuni cadf flpa double mutant is impaired in the activation of epidermal growth factor receptor (egfr) and rho gtpase rac1. although the ...201326038437
formative research on hygiene behaviors and geophagy among infants and young children and implications of exposure to fecal bacteria.we conducted direct observation of 23 caregiver-infant pairs for 130 hours and recorded wash-related behaviors to identify pathways of fecal-oral transmission of bacteria among infants. in addition to testing fingers, food, and drinking water of infants, three infants actively ingested 11.3 ± 9.2 (mean ± sd) handfuls of soil and two ingested chicken feces 2 ± 1.4 times in 6 hours. hand washing with soap was not common and drinking water was contaminated with escherichia coli in half (12 of 22) o ...201324002485
beware of the patient with thymectomy: good's syndrome in a patient presenting with diarrhea.good's syndrome is a rare cause of immunodeficiency in adults associated with thymoma. we describe an 80-year-old female with chronic diarrhea, multiple opportunistic infections, and cytopenias. she underwent a thymectomy 5 years ago for a thymoma. laboratory tests revealed neutropenia, hypogammaglobulinaemia, complete b-cell lymphopenia, and low cd4 t cells with inverted cd4:cd8 ratio, which is consistent with good's syndrome. we recommend checking immunoglobulin levels in all patients with a h ...201326157815
mgla/sspa complex interactions are modulated by inorganic polyphosphate.the transcription factors mgla and sspa of francisella tularensis form a heterodimer complex and interact with the rna polymerase to regulate the expression of the francisella pathogenicity island (fpi) genes. these genes are essential for this pathogen's virulence and survival within host cells. our goal was to determine if an intracellular metabolite modulate these protein/protein interactions. in this study, we identified inorganic polyphosphate (polyp) as a signal molecule that promotes the ...201324116108
milk oligosaccharide sialyl(α2,3)lactose activates intestinal cd11c+ cells through tlr4.breast milk oligosaccharides shape the intestinal environment by affecting mucosal immunity and bacterial colonization. to clarify the role of milk oligosaccharide sialyl(α2,3)lactose (3sl) in intestinal physiology and disease, we investigated colitis development in il10(-/-) mice exposed to normal or 3sl-deficient milk during lactation. onset and progression of intestinal inflammation were delayed in il10(-/-) mice deficient for the α2,3 sialyltransferase 4 (st3gal4) responsible for 3sl biosynt ...201324101501
patent human infections with the whipworm, trichuris trichiura, are not associated with alterations in the faecal microbiota.the soil-transmitted helminth (sth), trichuris trichiura colonises the human large intestine where it may modify inflammatory responses, an effect possibly mediated through alterations in the intestinal microbiota. we hypothesised that patent t. trichiura infections would be associated with altered faecal microbiota and that anthelmintic treatment would induce a microbiota resembling more closely that observed in uninfected individuals.201324124574
interaction of microbes with mucus and mucins: recent developments.due to the recent rapid expansion in our understanding of the composition of the gut microflora and the consequences of altering that composition the question of how bacteria colonise mucus layers and interact with components of mucus, such as mucin, is now receiving widespread attention. using a combination of mucus secreting cells, and a novel mucin microarray platform containing purified native mucins from different sources we recently demonstrated that two gastrointestinal pathogens, helicob ...201324149677
interaction of microbes with mucus and mucins: recent developments.due to the recent rapid expansion in our understanding of the composition of the gut microflora and the consequences of altering that composition the question of how bacteria colonise mucus layers and interact with components of mucus, such as mucin, is now receiving widespread attention. using a combination of mucus secreting cells, and a novel mucin microarray platform containing purified native mucins from different sources we recently demonstrated that two gastrointestinal pathogens, helicob ...201324149677
fucosylated but not sialylated milk oligosaccharides diminish colon motor contractions.human milk oligosaccharides (hmo) are being studied by different groups exploring a broad range of potential beneficial effects to the breastfed infant. many of these effects have been attributed to a growth promotion effect on certain gut organisms such as bifidobacteria. additionally, evidence indicates that hmo are able to directly promote positive changes in gut epithelium and immune responses under certain conditions. this study utilizes a standardized ex vivo murine colon preparation to ex ...201324098451
transcriptional regulation by ferric uptake regulator (fur) in pathogenic bacteria.in the ancient anaerobic environment, ferrous iron (fe(2+)) was one of the first metal cofactors. oxygenation of the ancient world challenged bacteria to acquire the insoluble ferric iron (fe(3+)) and later to defend against reactive oxygen species (ros) generated by the fenton chemistry. to acquire fe(3+), bacteria produce low-molecular weight compounds, known as siderophores, which have extremely high affinity for fe(3+). however, during infection the host restricts iron from pathogens by prod ...201324106689
purification and characterization of bacteriocin produced by lactobacillus brevis un isolated from dhulliachar: a traditional food product of north east india.a bacteriocin producing strain lactobacillus brevis un isolated from dulliachar-a salted pickle and identified by biochemical and molecular methods. l. brevis un was found to produce bacteriocin with broad spectrum activity against spoilage causing/food borne pathogens viz. l. monocytogenes, c. perfringens, s. aureus, l. mesenteroides, l. plantarum and b. cereus. bacteriocin production was optimized through classical one variable at a time method. the isolate showed maximum bacteriocin productio ...201325320420
purification and characterization of bacteriocin produced by lactobacillus brevis un isolated from dhulliachar: a traditional food product of north east india.a bacteriocin producing strain lactobacillus brevis un isolated from dulliachar-a salted pickle and identified by biochemical and molecular methods. l. brevis un was found to produce bacteriocin with broad spectrum activity against spoilage causing/food borne pathogens viz. l. monocytogenes, c. perfringens, s. aureus, l. mesenteroides, l. plantarum and b. cereus. bacteriocin production was optimized through classical one variable at a time method. the isolate showed maximum bacteriocin productio ...201325320420
gut microbiota dysbiosis and bacterial community assembly associated with cholesterol gallstones in large-scale study.elucidating gut microbiota among gallstone patients as well as the complex bacterial colonization of cholesterol gallstones may help in both the prediction and subsequent lowered risk of cholelithiasis. to this end, we studied the composition of bacterial communities of gut, bile, and gallstones from 29 gallstone patients as well as the gut of 38 normal individuals, examining and analyzing some 299, 217 bacterial 16s rrna gene sequences from 120 samples.201324083370
guillain barre syndrome as a manifestation of neurological melioidosis.neurological melioidosis is a very rare and very few cases have been reported from india. presentation is an extremely varied and as this disease is associated with high mortality, high index of suspicion is needed to diagnose and treat. in this context, we report a patient presenting as guillain barre syndrome evaluated as melioidosis.201324339608
the mucin muc2 limits pathogen burdens and epithelial barrier dysfunction during salmonella enterica serovar typhimurium colitis.salmonella enterica serovar typhimurium is a model organism used to explore the virulence strategies underlying salmonella pathogenesis. although intestinal mucus is the first line of defense in the intestine, its role in protection against salmonella is still unclear. the intestinal mucus layer is composed primarily of the muc2 mucin, a heavily o-glycosylated glycoprotein. the core 3-derived o-glycans of muc2 are synthesized by core 3 β1,3-n-acetylglucosaminyltransferase (c3gnt). mice lacking t ...201323876803
survey of culture, goldengate assay, universal biosensor assay, and 16s rrna gene sequencing as alternative methods of bacterial pathogen detection.cultivation-based assays combined with pcr or enzyme-linked immunosorbent assay (elisa)-based methods for finding virulence factors are standard methods for detecting bacterial pathogens in stools; however, with emerging molecular technologies, new methods have become available. the aim of this study was to compare four distinct detection technologies for the identification of pathogens in stools from children under 5 years of age in the gambia, mali, kenya, and bangladesh. the children were ide ...201323884998
increased emergence of fluoroquinolone-resistant campylobacter jejuni in biofilm. 201323896469
unique structural modifications are present in the lipopolysaccharide from colistin-resistant strains of acinetobacter baumannii.acinetobacter baumannii is a nosocomial opportunistic pathogen that can cause severe infections, including hospital-acquired pneumonia, wound infections, and sepsis. multidrug-resistant (mdr) strains are prevalent, further complicating patient treatment. due to the increase in mdr strains, the cationic antimicrobial peptide colistin has been used to treat a. baumannii infections. colistin-resistant strains of a. baumannii with alterations to the lipid a component of lipopolysaccharide (lps) have ...201323877686
clonal distribution and virulence of campylobacter jejuni isolates in blood.campylobacter jejuni bacteria are highly diverse enteropathogens. seventy-three c. jejuni isolates from blood collected in finland were analyzed by multilocus sequence typing and serum resistance. approximately half of the isolates belonged to the otherwise uncommon sequence type 677 clonal complex. isolates of this clonal complex were more resistant than other isolates to human serum.201324047729
helicobacter pylori salvages purines from extracellular host cell dna utilizing the outer membrane-associated nuclease nuct.helicobacter pylori is a bacterial pathogen that establishes life-long infections in humans, and its presence in the gastric epithelium is strongly associated with gastritis, peptic ulcer disease, and gastric cancer. having evolved in this specific gastric niche for hundreds of thousands of years, this microbe has become dependent on its human host. bioinformatic analysis reveals that h. pylori has lost several genes involved in the de novo synthesis of purine nucleotides, and without this pathw ...201323893109
nitrite reductase nirbd is induced and plays an important role during in vitro dormancy of mycobacterium tuberculosis.mycobacterium tuberculosis is one of the strongest reducers of nitrate among all mycobacteria. reduction of nitrate to nitrite, mediated by nitrate reductase (narghji) of m. tuberculosis, is induced during the dormant stage, and the enzyme has a respiratory function in the absence of oxygen. nitrite reductase (nirbd) is also functional during aerobic growth when nitrite is the sole nitrogen source. however, the role of nirbd-mediated nitrite reduction during the dormancy is not yet characterized ...201323935045
species-specificity of equine and porcine lawsonia intracellularis isolates in laboratory animals.lawsonia intracellularis infection causes proliferative enteropathy (pe) in many mammalian species, with porcine and equine proliferative enteropathy (ppe and epe) known worldwide. hamsters are a well-published animal model for ppe infection studies in pigs. there is no laboratory animal model for epe infection studies and it is not known whether there is species-specificity for equine or porcine isolates of l. intracellularis in animal models. the objective of this study was to determine whethe ...201324124268
the human gut and groundwater harbor non-photosynthetic bacteria belonging to a new candidate phylum sibling to cyanobacteria.cyanobacteria were responsible for the oxygenation of the ancient atmosphere; however, the evolution of this phylum is enigmatic, as relatives have not been characterized. here we use whole genome reconstruction of human fecal and subsurface aquifer metagenomic samples to obtain complete genomes for members of a new candidate phylum sibling to cyanobacteria, for which we propose the designation 'melainabacteria'. metabolic analysis suggests that the ancestors to both lineages were non-photosynth ...201324137540
transmigration route of campylobacter jejuni across polarized intestinal epithelial cells: paracellular, transcellular or both?intact intercellular junctions and cellular matrix contacts are crucial structural components for the formation and maintenance of epithelial barrier functions in humans to control the commensal flora and protect against intruding microbes. campylobacter jejuni is one of the most important zoonotic pathogens causing food-borne gastroenteritis and potentially more severe diseases such as reactive arthritis or guillain-barré syndrome. crossing the intestinal epithelial barrier and host cell invasi ...201324079544
changes in the symptom pattern and the densities of large-intestinal endocrine cells following campylobacter infection in irritable bowel syndrome: a case report.irritable bowel syndrome (ibs) is a common chronic functional gastrointestinal disorder. post-infectious ibs (pi-ibs) is a subset of ibs that accounts for a large proportion of ibs patients. the pi-ibs symptoms meet the rome criteria for ibs with diarrhoea (ibs-d) or ibs with mixed bowel habits (ibs-m). a low-grade inflammation has been reported to occur in pi-ibs. abnormalities in intestinal endocrine cells have been reported in both sporadic ibs and pi-ibs.201324073715
expression, crystallization and preliminary x-ray crystallographic analysis of peptide deformylase from campylobacter jejuni.campylobacter jejuni is one of the major foodborne pathogens causing human infection. peptide deformylase, a metallohydrolase, catalyzes the deformylation of n-formylated methionine in newly synthesized polypeptides in prokaryotes and some eukaryotic organelles. the deformylation process is an essential step in protein synthesis and has attracted much attention as a potential target for the development of novel antibacterial agents. here, the cloned codon-optimized def gene from c. jejuni was sy ...201324100562
archaeal signal transduction: impact of protein phosphatase deletions on cell size, motility, and energy metabolism in sulfolobus acidocaldarius.in this study, the in vitro and in vivo functions of the only two identified protein phosphatases, saci-ptp and saci-pp2a, in the crenarchaeal model organism sulfolobus acidocaldarius were investigated. biochemical characterization revealed that saci-ptp is a dual-specific phosphatase (against pser/pthr and ptyr), whereas saci-pp2a exhibited specific pser/pthr activity and inhibition by okadaic acid. deletion of saci_pp2a resulted in pronounced alterations in growth, cell shape and cell size, wh ...201324078887
comparison of rectal swabs and faeces for real-time pcr detection of enteric agents in rwandan children with gastroenteritis.molecular diagnostics have emerged as an efficient and feasible alternative for broad detection of pathogens in faeces. however, collection of stool samples is often impractical in both clinical work and in epidemiology studies. the aim of this study was to investigate the diagnostic performance of rectal swabs as compared with traditional faeces samples for detection of enteric agents by pcr.201324073740
outbreak investigation: salmonella food poisoning.an outbreak of food poisoning was reported from a military establishment on 29 may 2011 when 43 cases of food poisoning reported sick in a span of few hours.201324600149
viable but nonculturable bacteria: food safety and public health perspective.the viable but nonculturable (vbnc) state is a unique survival strategy of many bacteria in the environment in response to adverse environmental conditions. vbnc bacteria cannot be cultured on routine microbiological media, but they remain viable and retain virulence. the vbnc bacteria can be resuscitated when provided with appropriate conditions. a good number of bacteria including many human pathogens have been reported to enter the vbnc state. though there have been disputes on the existence ...201324191231
cj1411c encodes for a cytochrome p450 involved in campylobacter jejuni 81-176 pathogenicity.cytochrome p450s are b-heme-containing enzymes that are able to introduce oxygen atoms into a wide variety of organic substrates. they are extremely widespread in nature having diverse functions at both biochemical and physiological level. the genome of c. jejuni 81-176 encodes a single cytochrome p450 (cj1411c) that has no close homologues. cj1411c is unusual in its genomic location within a cluster involved in the biosynthesis of outer surface structures. here we show that e. coli expressed an ...201324086558
biochemical analysis and structure determination of bacterial acetyltransferases responsible for the biosynthesis of udp-n,n'-diacetylbacillosamine.udp-n,n'-diacetylbacillosamine (udp-dinacbac) is a unique carbohydrate produced by a number of bacterial species and has been implicated in pathogenesis. the terminal step in the formation of this important bacterial sugar is catalyzed by an acetyl-coa (accoa)-dependent acetyltransferase in both n- and o-linked protein glycosylation pathways. this bacterial acetyltransferase is a member of the left-handed β-helix family and forms a homotrimer as the functional unit. whereas previous endeavors ha ...201324064219
from ambivalent to divalent: has the "zinc age" finally arrived? 201324061143
extracellular secretion of protease htra from campylobacter jejuni is highly efficient and independent of its protease activity and flagellum.the serine protease htra of c. jejuni has been identified as a novel secreted virulence factor which opens cell-to-cell junctions by cleaving e-cadherin. efficient c. jejuni transmigration across polarized human epithelial cells requires the intact flagellum and htra; however, the mechanism of htra secretion into the supernatant is unknown. here we show that htra secretion is highly efficient and does not require its proteolytic activity because the protease-inactive s197a mutant is secreted lik ...201324265934
survey of extra-intestinal immune responses in asymptomatic long-term campylobacter jejuni-infected mice.campylobacter jejuni is among the most frequently reported bacterial pathogens causing diarrhea in humans worldwide. we recently reported a murine infection model mimicking key features of human campylobacteriosis. six days following oral c. jejuni infection immediately after weaning, infant mice developed acute enterocolitis resolving within 2 weeks. thereafter, c. jejuni could still be isolated from the intestines of asymptomatic mice at low levels accompanied by distinct immune responses, bot ...201324265935
eukaryotic oligosaccharyltransferase generates free oligosaccharides during n-glycosylation.asparagine (n)-linked glycosylation regulates numerous cellular activities, such as glycoprotein quality control, intracellular trafficking, and cell-cell communications. in eukaryotes, the glycosylation reaction is catalyzed by oligosaccharyltransferase (ost), a multimembrane protein complex that is localized in the endoplasmic reticulum (er). during n-glycosylation in the er, the protein-unbound form of oligosaccharides (free oligosaccharides; foss), which is structurally related to n-glycan, ...201324062310
genetically dictated change in host mucus carbohydrate landscape exerts a diet-dependent effect on the gut microbiota.we investigate how host mucus glycan composition interacts with dietary carbohydrate content to influence the composition and expressed functions of a human gut community. the humanized gnotobiotic mice mimic humans with a nonsecretor phenotype due to knockout of their α1-2 fucosyltransferase (fut2) gene. the fecal microbiota of fut2(-) mice that lack fucosylated host glycans show decreased alpha diversity relative to fut2(+) mice and exhibit significant differences in community composition. a g ...201324062455
the prevalence and polymorphisms of zonula occluden toxin gene in multiple campylobacter concisus strains isolated from saliva of patients with inflammatory bowel disease and controls.campylobacterconcisus is an oral bacterium. a number of studies detected a significantly higher prevalence of c. concisus in the intestinal tract of patients with inflammatory bowel disease (ibd) as compared to controls. the prevalence of zonula occluden toxin (zot) gene, which encodes a toxin known to increase intestinal permeability, in oral c. concisus strains is unknown. increased intestinal permeability is a feature of ibd. a total of 56 oral c. concisus strains isolated from 19 patients wi ...201324086553
degeneration of a crispr/cas system and its regulatory target during the evolution of a pathogen.crispr/cas systems are bacterial rna-guided endonuclease machineries that target foreign nucleic acids. recently, we demonstrated that the cas protein cas9 controls gene expression and virulence in francisella novicida by altering the stability of the mrna for an immunostimulatory bacterial lipoprotein (blp). genomic analyses, however, revealed that francisella species with increased virulence harbor degenerated crispr/cas systems. we hypothesize that crispr/cas degeneration removed a barrier ag ...201324100224
concurrent automated sequencing of the glycan and peptide portions of o-linked glycopeptide anions by ultraviolet photodissociation mass spectrometry.o-glycopeptides are often acidic owing to the frequent occurrence of acidic saccharides in the glycan, rendering traditional proteomic workflows that rely on positive mode tandem mass spectrometry (ms/ms) less effective. in this report, we demonstrate the utility of negative mode ultraviolet photodissociation (uvpd) ms for the characterization of acidic o-linked glycopeptide anions. this method was evaluated for a series of singly and multiply deprotonated glycopeptides from the model glycoprote ...201324006841
population genetics of lactobacillus sakei reveals three lineages with distinct evolutionary histories.lactobacillus sakei plays a major role in meat fermentation and in the preservation of fresh meat. the large diversity of l. sakei strains represents a valuable and exploitable asset in the development of a variety of industrial applications; however, an efficient method to identify and classify these strains has yet to be developed. in this study, we used multilocus sequence typing (mlst) to analyze the polymorphism and allelic distribution of eight loci within an l. sakei population of 232 str ...201324069179
therapeutic targeting of nod1 receptors.the nucleotide-binding oligomerization domain 1 (nod1) protein is an intracellular receptor for breakdown products of peptidoglycan (pgn), an essential bacterial cell wall component. nod1 responds to γ-d-glutamyl-meso-diaminopimelic acid, which is an epitope unique to pgn structures from all gram-negative bacteria and certain gram-positive bacteria. upon ligand recognition, nod1 undergoes conformational changes and self-oligomerization mediated by the nucleotide-binding nacht domains, followed b ...201323848281
strategy for sensitive and specific detection of yersinia pestis in skeletons of the black death pandemic.yersinia pestis has been identified as the causative agent of the black death pandemic in the 14(th) century. however, retrospective diagnostics in human skeletons after more than 600 years are critical. we describe a strategy following a modern diagnostic algorithm and working under strict ancient dna regime for the identification of medieval human plague victims. an initial screening and dna quantification assay detected the y. pestis specific pla gene of the high copy number plasmid ppcp1. re ...201324069445
campylobacter jejuni colonization is associated with a dysbiosis in the cecal microbiota of mice in the absence of prominent inflammation.campylobacter jejuni causes enterocolitis in humans, but does not incite disease in asymptomatic carrier animals. to survive in the intestine, c. jejuni must successfully compete with the microbiota and overcome the host immune defense. campylobacter jejuni colonization success varies considerably amongst individual mice, and we examined the degree to which the intestinal microbiota was affected in mice (i.e. a model carrier animal) colonized by c. jejuni at high relative to low densities.201324066174
de- and repolarization mechanism of flagellar morphogenesis during a bacterial cell cycle.eukaryotic morphogenesis is seeded with the establishment and subsequent amplification of polarity cues at key times during the cell cycle, often using (cyclic) nucleotide signals. we discovered that flagellum de- and repolarization in the model prokaryote caulobacter crescentus is precisely orchestrated through at least three spatiotemporal mechanisms integrated at tipf. we show that tipf is a cell cycle-regulated receptor for the second messenger--bis-(3'-5')-cyclic dimeric guanosine monophosp ...201324065770
the opportunistic pathogen propionibacterium acnes: insights into typing, human disease, clonal diversification and camp factor evolution.we previously described a multilocus sequence typing (mlst) scheme based on eight genes that facilitates population genetic and evolutionary analysis of p. acnes. while mlst is a portable method for unambiguous typing of bacteria, it is expensive and labour intensive. against this background, we now describe a refined version of this scheme based on two housekeeping (aroe; guaa) and two putative virulence (tly; camp2) genes (mlst4) that correctly predicted the phylogroup (ia1, ia2, ib, ic, ii, i ...201324058439
parallel evolution of genome structure and transcriptional landscape in the epsilonproteobacteria.gene reshuffling, point mutations and horizontal gene transfer contribute to bacterial genome variation, but require the genome to rewire its transcriptional circuitry to ensure that inserted, mutated or reshuffled genes are transcribed at appropriate levels. the genomes of epsilonproteobacteria display very low synteny, due to high levels of reshuffling and reorganisation of gene order, but still share a significant number of gene orthologs allowing comparison. here we present the primary trans ...201324028687
phage display-derived binders able to distinguish listeria monocytogenes from other listeria species.the objective of this study was to produce phage display-derived binders with the ability to distinguish listeria monocytogenes from other listeria spp., which may have potential utility to enhance detection of listeria monocytogenes. to obtain binders with the desired binding specificity a series of surface and solution phage-display biopannings were performed. initially, three rounds of surface biopanning against gamma-irradiated l. monocytogenes serovar 4b cells were performed followed by an ...201324040227
deprivation, timing of preschool infections and h. pylori seropositivity at age 49-51 years: the newcastle thousand families birth cohort.helicobacter pylori infection is acquired in early childhood and persists for life (or until eradication treatment is taken). seropositivity of h. pylori at age 49-51 years was assessed in relation to socio-economic deprivation in early life and the timing of other childhood infections common at that time.201324010891
multilocus sequence typing (and phylogenetic analysis) of campylobacter jejuni and campylobacter coli strains isolated from clinical cases in greece.the molecular epidemiology of c. jejuni and c. coli clinical strains isolated from children with gastroenteritis, was investigated using the multilocus sequence typing method (mlst). this analysis establishes for the first time in greece and constitutes an important tool for the epidemiological surveillance and control of campylobacter infection in our country.201324010733
enterohemorrhagic escherichia coli as causes of hemolytic uremic syndrome in the czech republic.enterohemorrhagic escherichia coli (ehec) cause diarrhea-associated hemolytic uremic syndrome (d+ hus) worldwide, but no systematic study of ehec as the causative agents of hus was performed in the czech republic. we analyzed stools of all patients with d+ hus in the czech republic between 1998 and 2012 for evidence of ehec infection. we determined virulence profiles, phenotypes, antimicrobial susceptibilities and phylogeny of the ehec isolates.201324040117
metabolism, physiological role, and clinical implications of sphingolipids in gastrointestinal tract.sphingolipids in digestive system are responsible for numerous important physiological and pathological processes. in the membrane of gut epithelial cells, sphingolipids provide structural integrity, regulate absorption of some nutrients, and act as receptors for many microbial antigens and their toxins. moreover, bioactive sphingolipids such as ceramide or sphingosine-1-phosphate regulate cellular growth, differentiation, and programmed cell death-apoptosis. although it is well established that ...201324083248
sociocultural determinants of anticipated vaccine acceptance for acute watery diarrhea in early childhood in katanga province, democratic republic of congo.rotavirus and oral cholera vaccines have the potential to reduce diarrhea-related child mortality in low-income settings and are recommended by the world health organization. uptake of vaccination depends on community support, and is based on local priorities. this study investigates local perceptions of acute watery diarrhea in childhood and anticipated vaccine acceptance in two sites in the democratic republic of congo. in 2010, 360 randomly selected non-affected adults were interviewed by usi ...201323878187
a structural comparison of lipopolysaccharide biosynthesis loci of legionella pneumophila serogroup 1 strains.the lipopolysaccharide (lps) is the major immuno-dominant antigen of all legionella species including l. pneumophila. its diversity is the basis for the classification of l. pneumophila into serogroups and monoclonal subgroups and is thought to be involved in strain specific virulence. the understanding of the genetic basis of the lps-antigen is incomplete. thus, we analyzed the genetic locus involved in lps-biosynthesis of l. pneumophila serogroup 1 (sg1) strains with the focus on strain specif ...201324069939
diet, microbial virulence, and helicobacter pylori-induced gastric cancer.gastric adenocarcinoma is a leading cause of cancer-related death worldwide, and helicobacter pylori infection is one of the strongest known risk factors for this malignancy. h. pylori strains exhibit a high level of genetic diversity, and the risk of gastric cancer is higher in persons carrying certain strain types (for example, those that contain a cag pathogenicity island or type s1 vaca alleles) than in persons carrying other strain types. additional risk factors for gastric cancer include s ...201323989802
a regulatory checkpoint during flagellar biogenesis in campylobacter jejuni initiates signal transduction to activate transcription of flagellar genes.many polarly flagellated bacteria require similar two-component regulatory systems (tcss) and σ(54) to activate transcription of genes essential for flagellar motility. herein, we discovered that in addition to the flagellar type iii secretion system (t3ss), the campylobacter jejuni flagellar ms ring and rotor are required to activate the flgsr tcs. mutants lacking the flif ms ring and flig c ring rotor proteins were as defective as t3ss mutants in flgsr- and σ(54)-dependent flagellar gene expre ...201324003178
food safety in home kitchens: a synthesis of the literature.although foodborne illness is preventable, more than 56,000 people per year become ill in the u.s., creating high economic costs, loss of productivity and reduced quality of life for many. experts agree that the home is the primary location where foodborne outbreaks occur; however, many consumers do not believe the home to be a risky place. health care professionals need to be aware of consumers' food safety attitudes and behaviors in the home and deliver tailored food safety interventions that ...201324002725
a rare form of guillan barre syndrome: a child diagnosed with anti-gd1a and anti-gd1b positive pharyngeal-cervical-brachial variant.pharyngeal-cervical-brachial (pcb) variant is a rare form of guillan-barre syndrome (gbs). antibodies against other membrane proteins like gm1b and gd1a have been found only in a small number of patients with guillan barre syndrome variant.201325207134
helicobacter hepaticus, a new pathogenic species of the helicobacter genus: similarities and differences with h. pylori.helicobacter hepaticus was discovered in 1992 as a cause of liver cancer in the a/jcr mouse model. in susceptible mice, infection by h. hepaticus causes chronic gastrointestinal inflammation leading to neoplasia. it can also cause morphological changes in breast-glands leading to neoplasm and adenocarcinoma in mouse models. studies performed on humans have revealed that h. hepaticus may also be a human pathogen since infection by h. hepaticus can be associated with cholecystitis, cholelithiasis ...201324475322
bickerstaff brainstem encephalitis in pediatrics - a case report. 201324470835
pathogenesis of human enterovirulent bacteria: lessons from cultured, fully differentiated human colon cancer cell lines.hosts are protected from attack by potentially harmful enteric microorganisms, viruses, and parasites by the polarized fully differentiated epithelial cells that make up the epithelium, providing a physical and functional barrier. enterovirulent bacteria interact with the epithelial polarized cells lining the intestinal barrier, and some invade the cells. a better understanding of the cross talk between enterovirulent bacteria and the polarized intestinal cells has resulted in the identification ...201324006470
the tetr family of regulators.the most common prokaryotic signal transduction mechanisms are the one-component systems in which a single polypeptide contains both a sensory domain and a dna-binding domain. among the >20 classes of one-component systems, the tetr family of regulators (tfrs) are widely associated with antibiotic resistance and the regulation of genes encoding small-molecule exporters. however, tfrs play a much broader role, controlling genes involved in metabolism, antibiotic production, quorum sensing, and ma ...201324006471
cytochrome bd-i in escherichia coli is less sensitive than cytochromes bd-ii or bo'' to inhibition by the carbon monoxide-releasing molecule, corm-3: n-acetylcysteine reduces co-rm uptake and inhibition of respiration.co-releasing molecules (co-rms) are potential therapeutic agents, able to deliver co - a critical gasotransmitter - in biological environments. co-rms are also effective antimicrobial agents; although the mechanisms of action are poorly defined, haem-containing terminal oxidases are primary targets. nevertheless, it is clear from several studies that the effects of co-rms on biological systems are frequently not adequately explained by the release of co: co-rms are generally more potent inhibito ...201323624261
multiplex real-time pcr for detection of campylobacter, salmonella, and shigella.infectious diarrhea can be classified based on its clinical presentation as noninflammatory or inflammatory disease. in developing countries, among inflammatory diarrhea cases, shigella is the most common cause, followed by campylobacter and salmonella. because the time frame in which treatment choices must be made is short and conventional stool cultures lack good sensitivity, there is a need for a rapid, sensitive, and inexpensive detection technique. the purpose of our study was to develop a ...201323761159
synergistic effects of anti-cmea and anti-cmeb peptide nucleic acids on sensitizing campylobacter jejuni to antibiotics.the cmeabc efflux pump in campylobacter jejuni confers resistance to structurally divergent antimicrobials, and inhibition of cmeabc represents a promising strategy to control antibiotic-resistant campylobacter. antisense peptide nucleic acids (pnas) targeting the three components of cmeabc were evaluated for inhibition of cmeabc expression. the result revealed a synergistic effect of the pnas targeting cmea and cmeb on sensitizing c. jejuni to antibiotics. this finding further demonstrates the ...201323817373
mntabc and mnth contribute to systemic staphylococcus aureus infection by competing with calprotectin for nutrient manganese.during infection, vertebrates limit access to manganese and zinc, starving invading pathogens, such as staphylococcus aureus, of these essential metals in a process termed "nutritional immunity." the manganese and zinc binding protein calprotectin is a key component of the nutrient-withholding response, and mice lacking this protein do not sequester manganese from s. aureus liver abscesses. one potential mechanism utilized by s. aureus to minimize host-imposed manganese and zinc starvation is th ...201323817615
characterization of intracellular growth regulator icgr by utilizing transcriptomics to identify mediators of pathogenesis in shigella flexneri.shigella species gram-negative bacteria which cause a diarrheal disease, known as shigellosis, by invading and destroying the colonic mucosa and inducing a robust inflammatory response. with no vaccine available, shigellosis annually kills over 600,000 children in developing countries. this study demonstrates the utility of combining high-throughput bioinformatic methods with in vitro and in vivo assays to provide new insights into pathogenesis. comparisons of in vivo and in vitro gene expressio ...201323753632
serotypes, virulence factors, and antimicrobial susceptibilities of vaginal and fecal isolates of escherichia coli from giant pandas.although escherichia coli typically colonizes the intestinal tract and vagina of giant pandas, it has caused enteric and systemic disease in giant pandas and greatly impacts the health and survival of this endangered species. in order to understand the distribution and characteristics of e. coli from giant pandas, 67 fecal and 30 vaginal e. coli isolates from 21 giant pandas were characterized for o serogroups, phylogenetic groups, antimicrobial susceptibilities, and pulsed-field gel electrophor ...201323793635
measurement of predation and biofilm formation under different ambient oxygen conditions using a simple gasbag-based system.bdellovibrio bacteriovorus and micavibrio aeruginosavorus are gram-negative bacteria characterized by predatory behavior. the aim of this study was to evaluate the ability of the predators to prey in different oxygen environments. when placed on an orbital shaker, a positive association between the rate of aeration and predation was observed. to further examine the effects of elevated ambient oxygen levels on predation, a simple gasbag system was developed. using the system, we were able to cond ...201323811501
multiplex real-time pcr for detecting and typing clostridium botulinum group iii organisms and their mosaic variants.botulism is a neuroparalytic disease that can occur in all warm-blooded animals, birds, and fishes. the disease in animals is mainly caused by toxins produced by clostridium botulinum strains belonging to group iii, although outbreaks due to toxins produced by group i and ii organisms have been recognized. group iii strains are capable of producing botulinum toxins of type c, d, and c/d and d/c mosaic variants. definitive diagnosis of animal botulism is made by combining clinical findings with l ...201323971808
genomic investigation into strain heterogeneity and pathogenic potential of the emerging gastrointestinal pathogen campylobacter ureolyticus.the recent detection and isolation of c. ureolyticus from patients with diarrhoeal illness and inflammatory bowel diseases warrants further investigation into its role as an emerging pathogen of the human gastrointestinal tract. regarding the pathogenic mechanisms employed by this species we provide the first whole genome analysis of two c. ureolyticus isolates including the type strain. comparative analysis, subtractive hybridisation and gene ontology searches against other campylobacter specie ...201324023611
human milk oligosaccharides protect bladder epithelial cells against uropathogenic escherichia coli invasion and cytotoxicity.the invasive pathogen uropathogenic escherichia coli (upec) is the primary cause of urinary tract infections (utis). recurrent infection that can progress to life-threatening renal failure has remained as a serious global health concern in infants. upec adheres to and invades bladder epithelial cells to establish infection. studies have detected the presence of human milk oligosaccharides (hmos) in urine of breast-fed, but not formula-fed, neonates. we investigated the mechanisms hmos deploy to ...201323990566
human milk oligosaccharides protect bladder epithelial cells against uropathogenic escherichia coli invasion and cytotoxicity.the invasive pathogen uropathogenic escherichia coli (upec) is the primary cause of urinary tract infections (utis). recurrent infection that can progress to life-threatening renal failure has remained as a serious global health concern in infants. upec adheres to and invades bladder epithelial cells to establish infection. studies have detected the presence of human milk oligosaccharides (hmos) in urine of breast-fed, but not formula-fed, neonates. we investigated the mechanisms hmos deploy to ...201323990566
glycoconjugates in host-helminth interactions.helminths are multicellular parasitic worms that comprise a major class of human pathogens and cause an immense amount of suffering worldwide. helminths possess an abundance of complex and unique glycoconjugates that interact with both the innate and adaptive arms of immunity in definitive and intermediate hosts. these glycoconjugates represent a major untapped reservoir of immunomodulatory compounds, which have the potential to treat autoimmune and inflammatory disorders, and antigenic glycans, ...201324009607
steroid-responsive polyradiculopathy in association with focal segmental glomerulosclerosis.an 80-year-old woman presented with simultaneous increasing muscle weakness and nephrotic syndrome. a renal biopsy confirmed focal segmental glomerulosclerosis (fsgs). her neurological diagnosis best fitted with a guillain-barre-like syndrome. there have been several cases of fsgs in combination with both conventional and atypical guillain-barre syndrome (gbs). our patient was treated with high-dose steroids and resolution of both nephrotic syndrome and neurological symptoms occurred over 6 mont ...201326069832
population abundance of potentially pathogenic organisms in intestinal microbiome of jungle crow (corvus macrorhynchos) shown with 16s rrna gene-based microbial community analysis.jungle crows (corvus macrorhynchos) prefer human habitats because of their versatility in feeding accompanied with human food consumption. therefore, it is important from a public health viewpoint to characterize their intestinal microbiota. however, no studies have been involved in molecular characterization of the microbiota based on huge and reliable number of data acquisition. in this study, 16s rrna gene-based microbial community analysis coupled with the next-generation dna sequencing tech ...201324058905
complete genome sequence of the arcobacter butzleri cattle isolate 7h1h.arcobacter butzleri strain 7h1h was isolated in the united kingdom from the feces of a clinically healthy dairy cow. the genome of this isolate was sequenced to completion. here, we present the annotation and analysis of the completed 7h1h genome, along with a comparison of this genome to the existing a. butzleri genomes.201323969057
combining quantitative genetic footprinting and trait enrichment analysis to identify fitness determinants of a bacterial pathogen.strains of extraintestinal pathogenic escherichia c oli (expec) exhibit an array of virulence strategies and are a major cause of urinary tract infections, sepsis and meningitis. efforts to understand expec pathogenesis are challenged by the high degree of genetic and phenotypic variation that exists among isolates. determining which virulence traits are widespread and which are strain-specific will greatly benefit the design of more effective therapies. towards this goal, we utilized a quantita ...201323990803
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