Publications

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genetic flux over time in the salmonella lineage.dna sequences that are shared between closely related organisms while being absent from their common ancestor and from sister lineages of that ancestor are likely to have been acquired by horizontal gene transfer. over time, the composition of those sequences tends to become more similar to the compositional signature of their host (amelioration).200717547764
ctx-m extended-spectrum beta-lactamases, washington state. 200717552121
emergence of shiga toxin 1 genes within shigella dysenteriae type 4 isolates from travelers returning from the island of hispañola.shiga toxins are produced by shigella dysenteriae type 1 and certain strains of escherichia coli. three cases of shiga toxin-producing s. dysenteriae type 4 were identified among travelers to the island of hispañola between 2002 and 2005. clinical and public health practitioners should be aware of this newly identified strain.200717556630
clinical trials of shigella vaccines: two steps forward and one step back on a long, hard road.more than 50 years of research has yielded numerous shigella vaccine candidates that have exemplified both the promise of vaccine-induced prevention of shigellosis and the impediments to developing a safe and effective vaccine for widespread use, a goal that has yet to be attained. this review discusses the most advanced strategies for shigella vaccine development, the immune responses that are elicited following disease or vaccination, the factors that have accelerated or impeded shigella vacci ...200717558427
screening methods used to determine the anti-microbial properties of aloe vera inner gel.the emergence of antibiotic resistant bacterial strains is a growing problem and is an important concern for patients, physicians, healthcare managers, and policymakers as it results in poorer health and economic outcomes. this has led to an urgent global call for new antimicrobial drugs, particularly from natural resources. we have been studying the antimicrobial properties of the inner leaf gel component of aloe barbadensis miller and have used a number of different, simple in vitro assays to ...200717560318
the inner gel component of aloe vera suppresses bacterial-induced pro-inflammatory cytokines from human immune cells.the present study was carried out to examine the anti-inflammatory activity of the inner leaf gel component of aloe barbadensis miller. a simple in vitro assay was designed to determine the effect of the inner gel on bacterial-induced pro-inflammatory cytokine production, namely tnf-alpha and il-1 beta, from peripheral blood leukocytes stimulated with shigella flexneri or lps. this report describes the suppression of both cytokines with a freeze-dried inner gel powder and a commercial health dri ...200717560326
novel extended-spectrum beta-lactamase in shigella sonnei. 200717561568
antimicrobial activity of a series of thiosemicarbazones and their zn(ii) and pd(ii) complexes.thirty-four thiosemicarbazones and s-alkyl thiosemicarbazones, and some of their zn(ii) and pd(ii) complexes were obtained and purified to investigate antimicrobial activity. mic values of the compounds were determined by the disc diffusion method against escherichia coli, klebsiella pneumoniae, proteus mirabilis, pseudomonas aeruginosa, salmonella typhi, shigella flexneri, staphylococcus aureus, s. epidermidis, and candida albicans. the thiosemicarbazones show antibacterial and antifungal effec ...200717571790
preparation and characterization of translocator/chaperone complexes and their component proteins from shigella flexneri.shigella flexneri causes a severe form of bacillary dysentery also known as shigellosis. onset of shigellosis requires bacterial invasion of colonic epithelial cells which is initiated by the delivery of translocator and effector proteins to the host cell membrane and cytoplasm, respectively, by the shigella type iii secretion system (ttss). the shigella translocator proteins, ipab and ipac, form a pore complex in the host cell membrane to facilitate effector delivery; however, prior to their se ...200717571858
dna sequencing of a pathogenicity-related plasmid of an avian septicemic escherichia coli strain.a 43-mda conjugative plasmid isolated from an avian septicemic escherichia coli (apec) strain possessing genes related to the adhesion and invasion capacities of in vitro-cultured cells was sequenced. the results demonstrated that the 43-mda plasmid harbors bacterial pathogenicity-related sequences which probably allow the wild-type pathogenic strain to adhere to and invade tissues and to cause septicemia in poultry. the existence of homology sequences to sequences belonging to other human patho ...200717573664
serotyping, pcr, phage-typing and antibiotic sensitivity testing of salmonella serovars isolated from urban drinking water supply systems of nepal.to study the occurrence and diversity of salmonella serovars in urban water supply systems of nepal.200717576218
survival of shigella sonnei on smooth tomato surfaces, in potato salad and in raw ground beef.this study investigated the survival of a five-strain shigella sonnei cocktail on smooth tomato surfaces, in potato salad and in raw ground beef. all inocula were resistant to the antibiotic rifampicin to allow simple detection of the target culture among the indigenous microflora of the food samples. inoculated tomatoes were stored at 13 degrees c/85% relative humidity, the standard holding conditions for mature, green tomatoes. inoculated potato salad and ground beef samples were stored at 2.5 ...200717428565
preliminary foodnet data on the incidence of infection with pathogens transmitted commonly through food--10 states, 2006.foodborne illnesses are a substantial health burden in the united states. the foodborne diseases active surveillance network (foodnet) of cdc's emerging infections program collects data from 10 u.s. states regarding diseases caused by enteric pathogens transmitted commonly through food. foodnet quantifies and monitors the incidence of these infections by conducting active, population-based surveillance for laboratory-confirmed illnesses. this report describes preliminary surveillance data for 20 ...200717431379
plasmid-mediated quinolone resistance determinant qnrs1 found in salmonella enterica strains isolated in the uk.to determine the prevalence of qnr genes in selected salmonella enterica and escherichia coli isolated in the uk.200717434878
ryhb, an iron-responsive small rna molecule, regulates shigella dysenteriae virulence.regulation of bacterial gene expression by small rna (srna) molecules is an increasingly recognized phenomenon but one that is not yet fully understood. we show that the srna ryhb suppresses several virulence-associated phenotypes of shigella dysenteriae, a causative agent of bacillary dysentery in humans. the virulence genes repressed by s. dysenteriae ryhb include those encoding the type iii secretion apparatus, its secreted effectors, and specific chaperones. suppression of shigella virulence ...200717438026
dipstick for rapid diagnosis of shigella flexneri 2a in stool.shigellosis or bacillary dysentery, an acute bloody diarrhoea, is a major public health burden in developing countries. in the absence of prompt and appropriate treatment, the infection is often fatal, particularly in young malnourished children. here, we describe a new diagnostic test for rapid detection, in stool, at the bedside of patients, of shigella flexneri 2a, the most predominant agent of the endemic form of the disease.200717440606
a novel serovar of shigella dysenteriae from patients with diarrhoea in bangladesh.every year, around 3 % of isolates from patients with diarrhoea at dhaka hospital, icddr,b, are identified as shigella-like organisms (slos) based on their activity in biochemical tests. these isolates do not react with any of the current shigella antisera including all existing and provisional serotypes. among these slos, a unique cluster of seven isolates with an identical plasmid profile was found and these isolates were further characterized by phenotypic and genotypic techniques. all were n ...200717446289
effect of intensive handwashing in the prevention of diarrhoeal illness among patients with aids: a randomized controlled study.patients with aids frequently develop diarrhoeal illness. in this randomized, controlled study, 260 patients were screened for those who had not had diarrhoea in the preceding 3 months and who had received a stable highly active antiretroviral therapy regimen for at least 6 weeks prior to the study enrollment. a total of 148 patients met the inclusion criteria and were enrolled: 75 patients were randomly assigned to an intensive handwashing intervention (i.e. handwashing after defecation, after ...200717446290
structural relation of the antigenic polysaccharides of escherichia coli o40, shigella dysenteriae type 9, and e. coli k47.o-polysaccharides were isolated from the lipopolysaccharides of escherichia coli o40 and shigella dysenteriae type 9 and studied by chemical analyses along with (1)h and (13)c nmr spectroscopy. the following new structure of the o-polysaccharide of e. coli o40 was established: -->2)-beta-d-galp-(1-->4)-beta-d-manp-(1-->4)-alpha-d-galp-(1-->3)-beta-d-glcpnac-(1--> theo-polysaccharide structure of s. dysenteriae type 9 established earlier was revised and found to be identical to the reported struc ...200717395169
altered expression of muc2 and muc5ac in response to shigella infection, an in vivo study.infection of mucosal epithelial cells by shigella species leads to an intense and acute inflammatory bowel disease that is characterized by watery diarrhea and purulent discharge. mucin production is a common defense mechanism to protect the underlying mucosa against pathogens. the molecular mechanism(s) underlying mucin induction is unknown in shigellosis. in this study, we have evaluated the relationship between shigella infection, the expression of muc2 and muc5ac and the participation of sig ...200717395379
detection and identification of bacterial enteropathogens by polymerase chain reaction and conventional techniques in childhood acute gastroenteritis in gaza, palestine.acute gastroenteritis and diarrhea are common and costly problems that cause significant morbidity and mortality in children worldwide. in palestine, diarrhea is one of the major causes of outpatient visits and hospitalizations.200717398132
[shigellosis or bacillary dysentery].shigellosis, commonly known as bacillary dysentery, is an enterobacterial disease caused by the shigella genus, which now belongs to the escherichia tribe, because of their genetic and phenotypic similarities. s. sonnei, flexneri, boydii and dysenteriae differ in their epidemiologic and pathogenic characteristics. s. sonnei is predominant in industrialized countries and causes the mildest disease. s. dysentery is especially dangerous because it occurs in outbreaks, sometimes in catastrophic situ ...200717399943
rotavirus disease in young children from hanoi, vietnam.pathogen prevalences and antimicrobial susceptibilities are essential for the rational development of preventive strategies for diarrheal diseases, but little recent information from vietnam is available. we prospectively studied the prevalence of enteric pathogens in children less than 5 years of age with acute diarrhea and in nondiarrhea controls in a city hospital in hanoi, vietnam for 1 year.200717414396
monitoring of pathogenicity of effluents from the uasb based sewage treatment plant.the microbial profile of an upflow anaerobic sludge blanket reactor based sewage treatment plant located at a suburb of delhi, india, and possible risk due to the pathogenicity of the treated wastewater was investigated. frequency of occurrence of salmonella, shigella and vibrio was 100% at all the stages of sewage treatment. however, recovery of vibrio was the highest among all the pathogens. the order of removal of all the pathogens was same at the different stages of the treatment. ratio of c ...200717295111
bile salts stimulate recruitment of ipab to the shigella flexneri surface, where it colocalizes with ipad at the tip of the type iii secretion needle.shigella flexneri uses its type iii secretion apparatus (ttsa) to deliver invasins into human cells. this ttsa possesses an external needle with ipad at its tip. we now show that deoxycholate promotes the stable recruitment of ipab to the needle tip without inducing a rapid burst of type iii secretion. the maintenance of ipab at the needle tip requires a stable association of ipad with the shigella surface. this is the first demonstration of a translocator protein being stably associated with th ...200717296762
tumor-specific colonization, tissue distribution, and gene induction by probiotic escherichia coli nissle 1917 in live mice.systemic administration of microorganisms into tumor-bearing mice revealed preferential accumulation in tumors in comparison to clearance in organs such as spleen and liver. here we compared the efficiency of tumor-specific colonization of pathogenic salmonella typhimurium strains 14028 and sl1344 to the enteroinvasive escherichia coli 4608-58 strain and to the attenuated salmonella flexneri 2a sc602 strain, as well as to the uropathogenic e. coli cft073, the non-pathogenic e. coli top10, and th ...200717448724
dna microarray-based identification of serogroups and virulence gene patterns of escherichia coli isolates associated with porcine postweaning diarrhea and edema disease.escherichia coli strains causing postweaning diarrhea (pwd) and edema disease (ed) in pigs are limited to a number of serogroups, with o8, o45, o138, o139, o141, o147, o149, and o157 being the most commonly reported worldwide. in this study, a dna microarray based on the o-antigen-specific genes of all 8 e. coli serogroups, as well as 11 genes encoding adhesion factors and exotoxins associated with pwd and ed, was developed for the identification of related serogroups and virulence gene patterns ...200717449692
expression level of heterologous tat genes is crucial for in vivo reconstitution of a functional tat translocase in escherichia coli.the tat system has the remarkable capacity of exporting proteins in folded conformation across the cytoplasmic membrane. the functional tat translocase from gram-negative bacteria consists of tata, tatb and tatc proteins. to gain information about the species specificity of the tat translocase, we cloned tat genes from gram-negative pathogens shigella flexneri 2a str. 301, vibrio cholerae el tor n16961, pseudomonas aeruginosa pao1, thermophilic sulfolobus solfataricus p2, thermus thermophilus hb ...200717336443
shigella flexneri inhibits staurosporine-induced apoptosis in epithelial cells.shigella flexneri is a facultative intracellular organism that causes bacillary dysentery. the shigella ipab protein activates caspase 1 in macrophages, which eventually leads to apoptosis. in contrast, epithelial cells infected with shigella undergo a stress response but do not die. therefore, the objective of this study was to determine if shigella has the ability to inhibit apoptosis in epithelial cells. a modified gentamicin protection assay was used to investigate if hela cells infected wit ...200717339354
genetic characterization of the escherichia coli o66 antigen and functional identification of its wzy gene.escherichia coli is a clonal species, and occurs as both commensal and pathogenic strains, which are normally classified on the basis of their o, h, and k antigens. the o-antigen (o-specific polysaccharide), which consists of a series of oligosaccharide (o-unit) repeats, contributes major antigenic variability to the cell surface. the o-antigen gene cluster of e. coli o66 was sequenced in this study. the genes putatively responsible for the biosynthesis of dtdp-6-deoxy-l-talose and gdp-mannose, ...200717342059
rapid identification of escherichia coli safety and laboratory strain lineages based on multiplex-pcr.escherichia coli k-12, b, c and w strains are the most frequently used bacterial safety and laboratory strains. lineage-specific dna fragments were detected by microplate subtractive hybridization and utilized to create a fast differentiation method using a single pcr reaction to differentiate clearly the four lineages and separate them from pathogenic variants. the method has been evaluated on a comprehensive selection of widely used laboratory strains and a variety of pathogenic e. coli repres ...200717343689
[shigella flexneri modulates host cell epigenetic information as a strategy to shape the transcriptional response]. 200717349276
luminex detection of fecal indicators in river samples, marine recreational water, and beach sand.research to understand and remediate coastal pollution is moving toward a multitiered approach in which traditional enumeration of fecal indicators is accompanied by molecular analysis of a variety of targets. technology that rapidly detects multiple microbial contaminants would benefit from such an approach. the luminex 100 system is a suspension array that assays multiple analytes rapidly in a single well of a microtiter plate. the ability of the system to simultaneously detect multiple fecal ...200717350051
characterization of sulphonamide resistance genes and class 1 integron gene cassettes in enterobacteriaceae, central african republic (car).the aim of this study was to characterize genes encoding sulphonamide resistance and gene cassettes associated with class 1 integrons in trimethoprim-sulphamethoxazole resistant enterobacteriaceae recovered from bangui, central african republic (car).200717350987
[risk of hospitalisation due to foodborne bacterial gastroenteritis--secondary publication].in a matched cohort study we estimate the risk of hospitalisation due to gastroenteritis, complications and sequelae after infections with zoonotic salmonella, campylobacter spp., yersinia enterocolitica, e. coli and shigella infections. out of 52,783 patients, 7,524 (14.4%) were hospitalized with gastroenteritis, 647 (1.2%) with complications and 865 (1.7%) with long-term sequelae. in denmark in 2005 there were 6,010 registered episodes of infections with bacteria that are usually foodborne, co ...200717355849
norovirus outbreak in a district general hospital--new strain identified.media reports about norovirus outbreaks, especially in hospitals and nursing homes, have accumulated in the past years. the reasons for this increasing problem are manifold: resistance against common disinfectants, a high level of contagion (a dose of less than 100 particles may be infective); variability of the virus-genome documented by polymerase chain reaction-studies, as well as further factors concerning modern life-style. the following study describes and analyses a norovirus outbreak in ...200717299671
evaluation of an enzyme immunoassay-based stool antigen test to detect campylobacter jejuni and campylobacter coli.an enzyme immunoassay-based antigen test (ridascreen campylobacter; r-biopharm, darmstadt, germany) was evaluated for the detection of campylobacter jejuni and campylobacter coli in 1050 clinical stool samples as compared with culture on selective medium. after routine inoculation for salmonella, shigella, yersinia, aeromonas, plesiomonas, and campylobacter, the same swab specimens were used for the antigen test. the positivity rate for campylobacter was 9.3% in culture, and the antigen test gav ...200717300899
the phosphothreonine lyase activity of a bacterial type iii effector family.pathogenic bacteria use the type iii secretion system to deliver effector proteins into host cells to modulate the host signaling pathways. in this study, the shigella type iii effector ospf was shown to inactivate mitogen-activated protein kinases (mapks) [extracellular signal-regulated kinases 1 and 2 (erk1/2), c-jun n-terminal kinase, and p38]. ospf irreversibly removed phosphate groups from the phosphothreonine but not from the phosphotyrosine residue in the activation loop of mapks. mass sp ...200717303758
yeast functional genomic screens lead to identification of a role for a bacterial effector in innate immunity regulation.numerous bacterial pathogens manipulate host cell processes to promote infection and ultimately cause disease through the action of proteins that they directly inject into host cells. identification of the targets and molecular mechanisms of action used by these bacterial effector proteins is critical to understanding pathogenesis. we have developed a systems biological approach using the yeast saccharomyces cerevisiae that can expedite the identification of cellular processes targeted by bacter ...200717305427
the role of the vacb gene in the pathogenesis of brucella abortus.brucella species are important zoonotic pathogens affecting a wide variety of mammals. therefore, the identification of new brucella virulence factors is of great interest in understanding bacterial pathogenesis and immune evasion. in this study, we have identified brucella abortus vacb gene that presents 2343 nucleotides and 781 amino acids and it shows 39% identity with shigella flexneri vacb gene that encodes an exoribonuclease rnase r involved in bacterial virulence. further, we have inactiv ...200717306588
h-ns antagonism in shigella flexneri by virb, a virulence gene transcription regulator that is closely related to plasmid partition factors.the virb protein of shigella flexneri is a positive regulator of the major virulence operons of this enteroinvasive intracellular pathogen. virb resembles no other transcription factor but is strongly homologous to plasmid partition proteins. we found that the binding of the virb protein to the promoter region of the icsb virulence gene induced hypersensitivity to cleavage by dnase i over a region to which the h-ns repressor protein binds and completely abolished the protection of this sequence ...200717307842
heme inhibits the dna binding properties of the cytoplasmic heme binding protein of shigella dysenteriae (shus).heme uptake and utilization by pathogenic bacteria are critical for virulence and disease, since heme and heme proteins are a major source of iron within the host. although the role of outer membrane heme receptors in this process has been extensively characterized at the genetic and biochemical level, the role of the cytoplasmic heme binding proteins is not yet clear. the shigella dysenteriae cytoplasmic heme binding protein, shus, has previously been shown to promote utilization of heme as an ...200717323920
conformational stability and differential structural analysis of lcrv, pcrv, bipd, and sipd from type iii secretion systems.diverse gram-negative bacteria use type iii secretion systems (t3ss) to translocate effector proteins into the cytoplasm of eukaryotic cells. the type iii secretion apparatus (t3sa) consists of a basal body spanning both bacterial membranes and an external needle. a sensor protein lies at the needle tip to detect environmental signals that trigger type iii secretion. the shigella flexneri t3sa needle tip protein, invasion plasmid antigen d (ipad), possesses two independently folding domains in v ...200717327391
a method for fast and simple detection of major diarrhoeagenic escherichia coli in the routine diagnostic laboratory.a multiplex pcr was developed for the detection of the following genes characteristic of diarrhoeagenic escherichia coli (dec): verocytotoxins 1 (vtx1) and 2 (vtx2), characteristic of verocytotoxin-producing e. coli (vtec); intimin (eae), found in enteropathogenic e. coli (epec), attaching and effacing e. coli and vtec; heat-stable enterotoxin (esta) and heat-labile enterotoxin (elta), characteristic of enterotoxigenic e. coli (etec); and invasive plasmid antigen (ipah), characteristic of entero ...200717331124
campylobacter reactive arthritis: a systematic review.to review the literature on the epidemiology of campylobacter-associated reactive arthritis (rea).200717360026
shigella sonnei bacteremia: two adult cases and review of the literature.shigella sonnei bacteremia in adult patients is rare. we present 2 cases from our center, and 7 others from the literature are reviewed in detail. diabetes mellitus and malignancy are frequent predisposing conditions. despite severe illness at presentation, our patients achieved good outcomes with prompt initiation of antimicrobial therapy.200717366038
the type iii secretion system needle tip complex mediates host cell sensing and translocon insertion.type iii secretion systems (t3sss) are essential virulence determinants of many gram-negative bacterial pathogens. the shigella t3ss consists of a cytoplasmic bulb, a transmembrane region and a hollow 'needle' protruding from the bacterial surface. physical contact with host cells initiates secretion and leads to assembly of a pore, formed by ipab and ipac, in the host cell membrane, through which proteins that facilitate host cell invasion are translocated. as the needle is implicated in host c ...200717367391
elimination by ozone of shigella sonnei in shredded lettuce and water.several outbreaks of shigellosis have been attributed to the consumption of contaminated fresh-cut vegetables. the minimal processing of these products make it difficult to ensure that fresh produce is safe for consumer. chlorine-based agents have been often used to sanitize produce and reduce microbial populations in water applied during processing operations. however, the limited efficacy of chlorine-based agents and the production of chlorinated organic compounds with potential carcinogenic a ...200717367682
low molecular weight proteins of outer membrane of salmonella typhimurium are immunogenic in salmonella induced reactive arthritis revealed by proteomics.in patients with reactive arthritis (rea)/undifferentiated spondyloarthropathy (uspa), synovial fluid mononuclear cells (sfmc) show proliferation to bacterial antigens that trigger rea, i.e. chlamydia, yersinia, campylobactor, shigella and salmonella species. we have shown previously that sfmc proliferate significantly to outer membrane proteins of s typhimurium in salmonella induced rea. in the present study we characterized the immunoreactive fractions of outer membrane protein (omp) of s typh ...200717376200
inactivation of foodborne pathogens using a one atmosphere uniform glow discharge plasma.this study was conducted to determine the efficacy of a one atmosphere uniform glow discharge plasma (oaugdp) for inactivation of foodborne pathogens and to evaluate the influence of growth temperature, ph, and culture age on their inactivation. escherichia coli o157:h7, listeria monocytogenes, staphylococcus aureus, bacillus cereus, salmonella enteritidis, vibrio parahaemolyticus, yersinia enterocolitica, and shigella flexneri were evaluated. three-strain mixtures of each bacterium were inocula ...200717378708
antimicrobial activity of bacillus subtilis and bacillus pumilus during the fermentation of african locust bean (parkia biglobosa) for soumbala production.to examine predominant isolates of bacillus subtilis and b. pumilus isolated from soumbala for their antimicrobial activity against indicator microorganisms as micrococcus luteus, staphyloccocus aureus, bacillus cereus, enterococus facium, listeria monocytogenes, escherichia coli, salmonella typhimurium, shigella dysenteriae, yersinia enterocolitica, aspergillus ochraceus and penicillium roqueforti.200717381739
l-sorbose utilization by virulent escherichia coli and shigella: different metabolic adaptation of pathotypes.the frequency of l-sorbose utilization differs significantly between pathotypes of escherichia coli and shigella from 93% to 0%. among 266 strains tested, this frequency increased in the order shigella, enterotoxigenic e. coli (etec), enteroinvasive e. coli (eiec), shiga toxin-producing e. coli (stec), enteroaggregative e. coli, enteropathogenic e. coli (epec), and neonatal bacterial meningitis (nbm) e. coli. this suggests an association of pathomechanism with the capability to degrade l-sorbose ...200717382590
in vitro activity of garenoxacin tested against a worldwide collection of ciprofloxacin-susceptible and ciprofloxacin-resistant enterobacteriaceae strains (1999-2004).garenoxacin is a novel des-f(6)-quinolone with a chemical structure that lacks the c6 position fluorine and has a unique difluoromethoxy substitution at position c8. this study evaluated the in vitro activity of garenoxacin tested against a large collection of enterobacteriaceae collected worldwide. the bacterial isolates were consecutively collected from more than 70 medical centers from bloodstream, respiratory, urinary tract, and skin and soft tissue infections. the isolates were tested again ...200717383140
small rnas controlling iron metabolism.iron is one of the most important metals in the metabolism of many organisms, including bacteria, in which it serves as a cofactor in multiple enzymatic reactions. most of the earlier research on iron regulation in bacteria has focused on the transcriptional regulator fur and its effect on the many genes involved in iron uptake. more recent work demonstrates the essential role of a small regulatory rna, ryhb, in iron metabolism. ryhb downregulates a large number of transcripts encoding iron-usin ...200717383226
assessment and interpretation of bacterial viability by using the live/dead baclight kit in combination with flow cytometry.the commercially available live/dead baclight kit is enjoying increased popularity among researchers in various fields of microbiology. its use in combination with flow cytometry brought up new questions about how to interpret live/dead staining results. intermediate states, normally difficult to detect with epifluorescence microscopy, are a common phenomenon when the assay is used in flow cytometry and still lack rationale. it is shown here that the application of propidium iodide in combinatio ...200717384309
[molecular characterization of the strain causing a shigellosis outbreak in a madrid school].the aim of this study is to describe a shigella sonnei outbreak in a school.200717386220
characterization of the outer membrane receptor shua from the heme uptake system of shigella dysenteriae. substrate specificity and identification of the heme protein ligands.shigella dysenteriae, like many bacterial pathogens, has evolved outer membrane receptor-mediated pathways for the uptake and utilization of heme as an iron source. as a first step toward understanding the mechanism of heme uptake we have undertaken a site-directed mutagenesis, spectroscopic, and kinetic analysis of the outer membrane receptor shua of s. dysenteriae. purification of the outer membrane receptor gave a single band of molecular mass 73 kda on sds-page. initial spectroscopic analysi ...200717387178
detecting low concentrations of shigella sonnei in environmental water samples by pcr.outbreaks of shigella sonnei associated with contaminated water have been reported and methods for the simultaneous detection of shigellae and enteroinvasive escherichia coli in water samples have been developed with detection limits of 10(1)-10(2) cfu ml(-1) of water. because 10(1)-10(2)shigellae can cause disease, a more sensitive detection method as an addition to the existing methods for detection of shigella sonnei in water samples is reported here. initially, 33 shigella sonnei and 72 non- ...200717391373
vitamin a deficiency in patients with diarrhea and hiv infection in ethiopia.diarrhea, micronutrient deficiencies and hiv/aids are major public health problems in developing countries, especially in sub-saharan africa. this study was aimed to investigate serum levels of vitamin a in diarrheic patients with and without hiv co-infection compared to healthy controls. two hundred eleven diarrheic patients (110 hiv infected), 87 apparently healthy controls and 41 asymptomatic hiv seropositive blood donors who visited the university of gondar hospital, in gondar, ethiopia were ...200717392128
cholesterol is required to trigger caspase-1 activation and macrophage apoptosis after phagosomal escape of shigella.pro-inflammatory macrophage apoptosis is pivotal in the aetiology of bacillary dysentery, an acute inflammatory diarrhoea caused by shigella spp. s. flexneri triggers its uptake by macrophages, escapes the phagosome and kills the host cell by a cytotoxic pathway, which activates and requires caspase-1 [interleukin (il)-1beta-converting enzyme] and releases mature il-1beta. the bacterial type iii-secreted translocator/effector protein ipab triggers cell death and directly binds to caspase-1. here ...200716925787
in vitro efficacy of bioactive extracts of 15 medicinal plants against esbetal-producing multidrug-resistant enteric bacteria.alcoholic crude extracts and some fractions from 15 traditionally used indian medicinal plants were investigated for their ability to inhibit the growth of extended spectrum beta-lactamases (esbetal)-producing multidrug-resistant enteric bacteria. the test bacteria eschrichia coli and shigella were resistant to 16-23 antibiotics with intermediate or resistance to beta-lactams (minimum inhibitory concentration (mic) value range 16-1024 microg/ml). the crude plant extracts demonstrated zone of inh ...200716875811
phylogenetic analysis of enteric species of the family enterobacteriaceae using the oric-locus.phylogenetic analysis of 38 enteric species belonging to the enterobacteraceae family was carried out using the non-coding locus oric, the chromosomal replication origin. the oric loci were amplified with conserved oligonucleotides and the pcr fragments were sequenced directly. the results establish a phylogenetic tree for the classification of different species of the genera escherichia, shigella, salmonella, enterobacter, citrobacter, klebsiella, raoultella, kluyvera, cedecea and buttiauxella. ...200716904857
structural organization of the needle complex of the type iii secretion apparatus of shigella flexneri.the secretion apparatus known as the needle complex (nc) from the bacterium shigella flexneri was studied by single particle electron microscopy. the isolated intact nc appears in projection to be composed of a basal body consisting of seven rings and a protruding needle appendage. a comparison of averaged projections of the intact nc and its fragments revealed the organization of the nc into several major subcomplexes. one of these lacks an inner membrane ring of the basal body but still presen ...200716920362
acanthamoeba: could it be an environmental host of shigella?shigellosis is a serious public health problem in korea, because large outbreaks of shigella sonnei infections were recorded in many parts of the country during the period 1998-2000. however, the epidemiological features of shigellosis are not well known. in this study, we devised conditions suitable for the growth and replication of shigella in an amoebic intracellular environment, and investigate whether medium conditions affect the survival and replication of shigella within acanthamoeba. we ...200716978610
short report: analysis of clonal relationship among shigella sonnei isolates circulating in argentina.thirty-five isolates of shigella sonnei from patients with diarrhoea in three geographic regions of argentina were examined for genetic diversity by pulsed-field gel electrophoresis (pfge) and plasmid profile. pfge of xbai and blni dna digests confirmed the occurrence of outbreaks in two regions caused by two separate predominant clones of s. sonnei. the third region was characterized by three circulating clones, one of which was possibly associated with an outbreak. similar plasmids were found ...200716999876
screening antimicrobial activity of various extracts of artemisia dracunculus l.the antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of artemisia dracunculus l. were studied. these extracts were tested against nine bacteria and four yeasts strains by the disc diffusion method. the results indicated that the methanol extract of a. dracunculus is more effective against tested microorganisms than chloroform or acetone extracts. the chloroform and acetone extracts were inhibitory only towards pseudomonas aeruginosa (atcc 2785 ...200716986171
bacteriocin-like inhibitor substances produced by mexican strains of bacillus thuringiensis.bacteriocins are antimicrobial peptides synthesized and secreted by bacteria and could potentially be used as natural food preservatives. here, we report the production of bacteriocin-like inhibitor substances (bt-blis) by five mexican strains of bacillus thuringiensis. bacillus thuringiensis subsp. morrisoni (lbit 269), b. thuringiensis subsp. kurstaki (lbit 287), b. thuringiensis subsp kenyae (lbit 404), b. thuringiensis subsp. entomocidus (lbit 420) and b. thuringiensis subsp. tolworthi (lbit ...200717031616
detection of genogroup i and ii human picobirnaviruses showing small genomic rna profile causing acute watery diarrhoea among children in kolkata, india.picobirnaviruses (pbvs) with bisegmented small rna genome profile (1.75 and 1.55kbp for segment 1 and 2, respectively) were detected from 1999 to 2003 in faecal specimens of acute watery diarrhoea cases, largely children (n=20) and an adult in kolkata, india. varying degrees of dehydration necessitated their visit to hospital for further treatment and management of acute watery diarrhoea. pbv was associated with rotavirus (n=3) or astrovirus (n=3) and with both in one case. no co-infection with ...200717049316
self-chaperoning of the type iii secretion system needle tip proteins ipad and bipd.bacteria expressing type iii secretion systems (t3ss) have been responsible for the deaths of millions worldwide, acting as key virulence elements in diseases ranging from plague to typhoid fever. the t3ss is composed of a basal body, which traverses both bacterial membranes, and an external needle through which effector proteins are secreted. we report multiple crystal structures of two proteins that sit at the tip of the needle and are essential for virulence: ipad from shigella flexneri and b ...200717077085
octaplex pcr and fluorescence-based capillary electrophoresis for identification of human diarrheagenic escherichia coli and shigella spp.a multiplex pcr assay, amplifying seven specific virulence genes and one internal control gene in a single reaction, was developed to identify the five main pathotypes of diarrheagenic escherichia coli and shigella spp. the virulence genes selected for each category were stx1, stx2, and eaea for enterohemorrhagic e. coli (ehec), eaea for enteropathogenic e. coli (epec), stib and lti for enterotoxigenic e. coli (etec), ipah for enteroinvasive e. coli (eiec) and shigella spp., and aggr for enteroa ...200717079041
o-acetylation in the o-specific polysaccharide isolated from shigella flexneri serotype 2a.shigella flexneri causes diarrheal diseases especially in infants and children in developing countries. modifications of the lipopolysaccharide (lps) molecule, like bacteriophage-mediated glucosylation and acetylation of the o-specific chain (o-sp), are important for the lps antigenicity and consequently for the immunogenicity of the polysaccharide-based vaccines against shigellosis. here, we report the degree of o-acetylation and the localisation of o-acetyl groups and side-chain glucose substi ...200717087926
ipad is localized at the tip of the shigella flexneri type iii secretion apparatus.type iii secretion (t3s) systems are used by numerous gram-negative pathogenic bacteria to inject virulence proteins into animal and plant host cells. the core of the t3s apparatus, known as the needle complex, is composed of a basal body transversing both bacterial membranes and a needle protruding above the bacterial surface. in shigella flexneri, ipad is required to inhibit the activity of the t3s apparatus prior to contact of bacteria with host and has been proposed to assist translocation o ...200717110044
enteropathogenic escherichia coli, shigella flexneri, and listeria monocytogenes recruit a junctional protein, zonula occludens-1, to actin tails and pedestals.enteropathogenic escherichia coli, shigella flexneri, and listeria monocytogenes induce localized actin polymerization at the cytoplasmic face of the plasma membrane or within the host cytoplasm, creating unique actin-rich structures termed pedestals or actin tails. the process is known to be mediated by the actin-related protein 2 and 3 (arp2/3) complex, which in these cases acts downstream of neural wiskott-aldrich syndrome protein (n-wasp) or of a listerial functional homolog of wasp family p ...200717118974
changing epidemiology of shigellosis and emergence of ciprofloxacin-resistant shigellae in india. 200717122011
a microbial diagnostic microarray technique for the sensitive detection and identification of pathogenic bacteria in a background of nonpathogens.a major challenge in microbial diagnostics is the parallel detection and identification of low-bundance pathogens within a complex microbial community. in addition, a high specificity providing robust, reliable identification at least at the species level is required. a microbial diagnostic microarray approach, using single nucleotide extension labeling with gyrb as the marker gene, was developed. we present a novel concept applying competitive oligonucleotide probes to improve the specificity o ...200717123456
occurrence of campylobacter jejuni in shiraz, southwest iran.to investigate the occurrence of campylobacter jejuni among other bacterial agents of acute diarrhea.200717159366
an injected bacterial effector targets chromatin access for transcription factor nf-kappab to alter transcription of host genes involved in immune responses.phosphorylation of histone h3 at ser10 increases chromatin accessibility to transcription factor nf-kappab on a subset of genes involved in immune responses. here we report that a bacterial pathogen abrogated phosphorylation of histone h3 to 'shape' the transcriptional responses of infected host cells. we identify the shigella flexneri protein effector ospf as a dually specific phosphatase that dephosphorylated mitogen-activated protein kinases in the nucleus, thus preventing histone h3 phosphor ...200717159983
revisiting the molecular evolutionary history of shigella spp.the theory that shigella is derived from multiple independent origins of escherichia coli (pupo et al. 2000) has been challenged by recent findings that the virulence plasmids (vps) and the chromosomes share a similar evolutionary history (escobar-paramo et al. 2003), which suggests that an ancestral vp entered an e. coli strain only once, which gave rise to shigella spp. in an attempt to resolve these conflicting theories, we constructed three phylogenetic trees in this study: a robust chromoso ...200717160643
serological cross-reactivity of environmental isolates of enterobacter, escherichia, stenotrophomonas, and aerococcus with shigella spp.-specific antisera.using protocols designed for the isolation of shigella from environmental freshwater samples from different regions of bangladesh, 11 bacterial strains giving rise to shigella-like colonies on selective agar plates and showing serological cross-reaction with shigella-specific antisera were isolated. phylogenetic analyses revealed that three of the isolates were most closely related to escherichia coli, four to enterobacter sp., two to stenotrophomonas, and two isolates belonged to the gram-posit ...200717171463
shigella ipgb1 promotes bacterial entry through the elmo-dock180 machinery.shigella use a special mechanism to invade epithelial cells called 'the trigger mechanism of entry', which allows epithelial cells to trap several bacteria simultaneously. on contact, shigella deliver effectors into epithelial cells through the type iii secretion system. here, we show that one of the effectors, ipgb1, has a pivotal role in producing membrane ruffles by exploiting the rhog-elmo-dock180 pathway to stimulate rac1 activity. using pulldown assays, we identified engulfment and cell mo ...200717173036
vaccine potential for inactivated shigellae.we used human monocyte-derived dendritic cells (dc) and balb/c mice as models to establish the immunogenic and protective potential of formalin-inactivated shigella spp. incubation of dc with inactivated or live bacteria induced dc maturation and cytokine release. mice immunized orally or intranasally with killed s. flexneri, s. sonnei, or s. dysenteriae developed igg and fecal iga titers to the homologous lps. following respiratory challenge with the live homologous organisms, 80-100% survival ...200717178431
shigella rewrites host transcriptional responses. 200717179964
villin severing activity enhances actin-based motility in vivo.villin, an actin-binding protein associated with the actin bundles that support microvilli, bundles, caps, nucleates, and severs actin in a calcium-dependant manner in vitro. we hypothesized that the severing activity of villin is responsible for its reported role in enhancing cell plasticity and motility. to test this hypothesis, we chose a loss of function strategy and introduced mutations in villin based on sequence comparison with capg. by pyrene-actin assays, we demonstrate that this mutant ...200717182858
structural and genetic evidence that the escherichia coli o148 o antigen is the precursor of the shigella dysenteriae type 1 o antigen and identification of a glucosyltransferase gene.shigella dysenteriae type 1 is the most virulent serotype of shigella. enterotoxigenic escherichia coli o148 is pathogenic and can cause diarrhoea. the following structure was established for the tetrasaccharide repeating unit of the e. coli o148 o antigen: -->3)-alpha-l-rhap-(1-->3)-alpha-l-rhap-(1-->2)-alpha-d-glcp-(1-->3)-alpha-d-glcpnac-(1-->. this differs from the structure reported earlier for s. dysenteriae type 1 by having a glucose (glc) residue in place of a galactose (gal) residue. th ...200717185542
gene cluster analysis method identifies horizontally transferred genes with high reliability and indicates that they provide the main mechanism of operon gain in 8 species of gamma-proteobacteria.the formation mechanism of operons remains unresolved: operons may form by rearrangements within a genome or by acquisition of genes from other species, that is, horizontal gene transfer (hgt). one hindrance to its elucidation is the unavailability of a method to accurately identify hgt, although it is generally considered to occur. it is critically important first to select horizontally transferred (ht) genes reliably and then to determine the extent to which hgt is involved in operon formation ...200717185745
use of linear, weibull, and log-logistic functions to model pressure inactivation of seven foodborne pathogens in milk.survival curves of six foodborne pathogens suspended in ultra high-temperature (uht) whole milk and exposed to high hydrostatic pressure at 21.5 degrees c were obtained. vibrio parahaemolyticus was treated at 300 mpa and other pathogens, listeria monocytogenes, escherichia coli o157:h7, salmonella enterica serovar enteritidis, salmonella enterica serovar typhimurium, and staphylococcus aureus were treated at 600 mpa. all the survival curves showed a rapid initial drop in bacterial counts followe ...200717188197
polar positional information in escherichia coli spherical cells.shigella surface protein icsa and its cytoplasmic derivatives are localized to the old pole of rod-shaped cells when expressed in escherichia coli. in spherical mreb cells, icsa is targeted to ectopic sites and close to one extremity of actin-like mamk filament. to gain insight into the properties of the sites containing polar material, we studied the icsa localization in spherical cells. gfp was exported into the periplasm via the tat pathway and used as a periplasmic space marker. gfp displaye ...200717188233
case-control study of shigellosis in san francisco: the role of sexual transmission and hiv infection.shigella species infect approximately 450,000 persons annually in the united states. person-to-person transmission of shigella species, which have a low infectious dose, occurs frequently, particularly in areas with poor sanitation and hygiene. sexual transmission of shigella species among men who have sex with men (msm) has been inferred from outbreaks of shigellosis among that population, and limited studies have suggested the importance of human immunodeficiency virus (hiv) infection as a ris ...200717205436
another perfect storm: shigella, men who have sex with men, and hiv. 200717205437
an h-ns-like stealth protein aids horizontal dna transmission in bacteria.the sfh protein is encoded by self-transmissible plasmids involved in human typhoid and is closely related to the global regulator h-ns. we have found that sfh provides a stealth function that allows the plasmids to be transmitted to new bacterial hosts with minimal effects on their fitness. introducing the plasmid without the sfh gene imposes a mild h-ns(-) phenotype and a severe loss of fitness due to titration of the cellular pool of h-ns by the a+t-rich plasmid. this stealth strategy seems t ...200717218529
erosion of interaction networks in reduced and degraded genomes.unlike eukaryotes, which often recruit duplicated genes into existing protein-protein interaction (ppi) networks, the low levels of gene duplication coupled with the high probability of lateral transfer of novel genes alters the manner in which ppi networks can evolve in bacteria. by inferring the ppis present in the ancestor to contemporary gammaproteobacteria, we were able to trace the changes in gene repertoires, and their consequences on ppi network evolution, in several bacterial lineages t ...200717219366
analysis of strategies to successfully vaccinate infants in developing countries against enterotoxigenic e. coli (etec) disease.enterotoxigenic escherichia coli (etec) is the most common bacterial cause of diarrhoea in the world, annually affecting up to 400,000,000 children under 5 years of age living in developing countries (dcs). although etec possesses numerous antigens, the relatively conserved colonization factor (cf) antigens and the heat labile enterotoxin (lt) have been associated with protection and most vaccine candidates have exploited these antigens. a safe and effective vaccine against etec is a feasible go ...200717224212
antibacterial activity and in vitro anti-tumor activity of the extract of the larvae of the housefly (musca domestica).one of the significant characteristics of traditional chinese medicine is the use of insects, other terrestrial arthropods and their products as drugs. in the present work, the extract of housefly (musca domestica) larvae was studied by an agar well diffusion assay and minimum bactericidal concentration (mbc) determination for detection of antimicrobial activity and by mtt assay method to test its in vitro anti-tumor activity. in our studies, the extract inhibited six tested bacterial pathogens ...200717227700
immunogenicity and characterization of wrsf2g11: a second generation live attenuated shigella flexneri 2a vaccine strain.recent clinical trials involving live attenuated shigella vaccine strains sc602 and wrss1 have revealed that deletion of the virg(icsa) gene dramatically reduces virulence in human volunteers. these strains can be given at low oral doses and induce a strong, and in some cases, protective immune responses. however, residual vaccine associated reactogenicity suggests that further attenuation is required. a recent clinical trial indicated that the set and sen enterotoxin genes contribute to the sym ...200717229494
role of infection in irritable bowel syndrome.infection by pathogenic organisms leads to mucosal damage and disruption of the gut's extensive commensal flora, factors which may lead to prolonged bowel dysfunction. six to 17% of unselected irritable bowel syndrome (ibs) patients believe their symptoms began with an infection, which is supported by prospective studies showing a 4%-31% incidence of postinfectious ibs-(pi) following bacterial gastroenteritis. the wide range of incidence can be accounted for by differences in risk factors, which ...200717238025
using european travellers as an early alert to detect emerging pathogens in countries with limited laboratory resources.the volume, extent and speed of travel have dramatically increased in the past decades, providing the potential for an infectious disease to spread through the transportation network. by collecting information on the suspected place of infection, existing surveillance systems in industrialized countries may provide timely information for areas of the world without adequate surveillance currently in place. we present the results of a case study using reported cases of shigella dysenteriae serotyp ...200717239228
high genetic stability of integrons in clinical isolates of shigella spp. of worldwide origin.over a 12-year period, 68 shigella strains (31 s. sonnei, 30 s. flexneri, 4 s. dysenteriae, and 3 s. boydii strains) were collected in a french university hospital from the stools of patients who generally had a recent history of travel to various parts of the world (91%), particularly africa (67%). these strains were often resistant (streptomycin, spectinomycin, trimethoprim, tetracycline, and sulfonamides, 66 to 84%; ampicillin and chloramphenicol, 34 to 38%; nalidixic acid, 4%) and even multi ...200717242143
the catalase reaction of shigella species and its use in rapid screening for epidemic shigella dysenteriae type 1.as epidemic dysentery caused by shigella dysenteriae type 1 is associated with high mortality, early identification of outbreaks is important. since s. dysenteriae type 1 differs from most of the enterobacteriaceae in that it does not produce catalase, a test for catalase may provide a useful screening method. the ability of a catalase test to provide rapid identification of s. dysenteriae type 1 has now been assessed, using isolates of this pathogen from five continents, shigella of other speci ...200717244412
shigella's ways of manipulating the host intestinal innate and adaptive immune system: a tool box for survival?shigella, a gram-negative invasive enteropathogenic bacterium, causes the rupture, invasion and inflammatory destruction of the human colonic epithelium. this complex and aggressive process accounts for the symptoms of bacillary dysentery. the so-called invasive phenotype of shigella is linked to expression of a type iii secretory system (ttss) injecting effector proteins into the epithelial cell membrane and cytoplasm, thereby inducing local but massive changes in the cell cytoskeleton that lea ...200717213832
shigella chromosomal ipah proteins are secreted via the type iii secretion system and act as effectors.shigella possess 220 kb plasmid, and the major virulence determinants, called effectors, and the type iii secretion system (ttss) are exclusively encoded by the plasmid. the genome sequences of s. flexneri strains indicate that several ipah family genes are located on both the plasmid and the chromosome, but whether their chromosomal ipah cognates can be secreted from shigella remains unknown. here we report that s. flexneri strain, ysh6000 encodes seven ipah cognate genes on the chromosome and ...200717214743
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