Showing papers on "Shigella dysenteriae published in 2009"

Synthesis, characterization, and immunogenicity in mice of Shigella sonnei O-specific oligosaccharide-core-protein conjugates.

Abstract: Shigellosis, an enteric disease, is on the World Health Organization's priority prevention list. In one study, the Shigella sonnei O-specific polysaccharide (O-SP)-protein conjugate showed 72% protection against disease in Israeli army recruits exposed to high rates (8-14%) of infection. The protection was related to vaccine-induced IgG anti-O-SP levels. Synthetic oligosaccharides of Shigella dysenteriae type 1, bound by their reducing ends to a carrier protein ("sun"-type configuration), induced significantly higher antibody levels than the native O-SP bound to protein by multiple-point attachments ("lattice"-type configuration). Attempts to synthesize the S. sonnei O-SP based oligosaccharides were not successful. Here, we describe the isolation, characterization, and conjugation of low-molecular-mass O-SP-core (O-SPC) fragments. The O-SPC fragments were bound by their reducing ends similar to the preparation of the synthetic S. dysenteriae type 1 conjugates. The O-SPC conjugates used oxime linkages between the terminal Kdo residues at the reducing ends of the S. sonnei saccharides and aminooxy linkers bound to BSA or a recombinant diphtheria toxin. The coupling reaction was carried out at a neutral pH and room temperature. IgG antibody levels induced in young outbred mice by the S. sonnei O-SPC conjugates were significantly higher then those elicited by the O-SP conjugates. Accordingly, we propose to evaluate clinically these conjugates.

Acanthamoeba castellanii an environmental host for Shigella dysenteriae and Shigella sonnei.

Abstract: The interaction between Shigella dysenteriae or Shigella sonnei and Acanthamoeba castellanii was studied by viable counts, gentamicin assay and electron microscopy. The result showed that Shigella dysenteriae or Shigella sonnei grew and survived in the presence of amoebae for more than 3 weeks. Gentamicin assay showed that the Shigella were viable inside the Acanthamoeba castellanii which was confirmed by electron microscopy that showed the Shigella localized in the cytoplasm of the Acanthamoeba castellanii. In conclusion, the relationship between Shigella dysenteriae and Shigella sonnei with Acanthamoeba castellanii is symbiotic, and accordingly free-living amoebae may serve as a transmission reservoir for Shigella in water.

Molecular detection of all 34 distinct O-antigen forms of Shigella.

Abstract: Shigella is the cause of shigellosis or bacillary dysentery, the occurrence of which is estimated to be 165 million cases per year worldwide, resulting in 11 million deaths Rapid and reliable assays for detecting and identifying Shigella in food, environmental and clinical samples are therefore necessary Shigella species are traditionally identified by their O antigens This study developed a DNA microarray targeting O-serotype-specific genes to detect all 34 distinct O-antigen forms of Shigella, including Shigella boydii types 1–18, Shigella dysenteriae types 1–13, Shigella flexneri types 1–5 and 6, and Shigella sonnei A total of 282 strains were used to test the specificity of the microarray, including 186 Shigella and Escherichia coli representative strains, 86 Shigella clinical isolates and ten strains of other bacterial species that are commonly isolated from food or clinical stool specimens The oligonucleotide probes were printed on the microarray in concentrations from 1 to 100 μM, and 10 μM proved to be the optimal probe concentration The detection sensitivity for each serotype was 50 ng genomic DNA or 1 cfu in 25 g milk powder sample following a 6 h enrichment in broth The microarray is specific, sensitive and reproducible, and, to our knowledge, is the first report of a microarray for serotyping all O-antigen forms of Shigella

Bacterial adhesiveness and invasiveness in cell culture monolayer

Abstract: The invasive potential of 45 presumptive enteropathogenic and non-enteropathogenic bacterial strains belonging to the family Enterobacteriaceae have been tested using the Sereny test and HEp-2 cell monolayers examined by a combined light optical method. All the presumptive enteropathogenic strains of Shigella dysenteriae, S. boydii, S. flexneri, S. sonnei and Salmonella typhimurium showed in vitro invasiveness in the HEp-2 cell culture test. Fourteen presumptive non-enteropathogenic strains of Escherichia coli showed no invasiveness in either of the two test systems. Two strains of S. flexneri and all the 6 strains of S. typhimurium gave a negative result in the Sereny test although they were invasive in HEp-2 cell cultures. Otherwise there were correlative results between the cell monolayer test and the Sereny test. In the cell monolayer test the different species of enteropathogenic bacteria showed considerable variation in invasive potential.

The Shigella dysenteriae serotype 1 proteome, profiled in the host intestinal environment, reveals major metabolic modifications and increased expression of invasive proteins.

Abstract: Shigella dysenteriae serotype 1 (SD1) causes the most severe form of epidemic bacillary dysentery. We present the first comprehensive proteome analysis of this pathogen, profiling proteins from bacteria cultured in vitro and bacterial isolates from the large bowel of infected gnotobiotic piglets (in vivo). Overall, 1061 distinct gene products were identified. Differential display analysis revealed that SD1 cells switched to an anaerobic energy metabolism in vivo. High in vivo abundances of amino acid decarboxylases (GadB and AdiA) which enhance pH homeostasis in the cytoplasm and protein disaggregation chaperones (HdeA, HdeB and ClpB) were indicative of a coordinated bacterial survival response to acid stress. Several type III secretion system effectors were increased in abundance in vivo, including OspF, IpaC and IpaD. These proteins are implicated in invasion of colonocytes and subversion of the host immune response in S. flexneri. These observations likely reflect an adaptive response of SD1 to the hostile host environment. Seven proteins, among them the type III secretion system effectors OspC2 and IpaB, were detected as antigens in Western blots using piglet antisera. The outer membrane protein OmpA, the heat shock protein HtpG and OspC2 represent novel SD1 subunit vaccine candidates and drug targets.

Bacterial adhesiveness and invasiveness in cell culture monolayer. 2. In vitro invasiveness of 45 strains belonging to the family Enterobacteriaceae.

Abstract: The invasive potential of 45 presumptive enteropathogenic and non-enteropathogenic bacterial strains belonging to the family Enterobacteriaceae have been tested using the Sereny test and HEp-2 cell monolayers examined by a combined light optical method. All the presumptive enteropathogenic strains of Shigella dysenteriae, S. boydii, S. flexneri, S. sonnei and Salmonella typhimurium showed in vitro invasiveness in the HEp-2 cell culture test. Fourteen presumptive non-enteropathogenic strains of Escherichia coli showed no invasiveness in either of the two test systems. Two strains of S. flexneri and all the 6 strains of S. typhimurium gave a negative result in the Sereny test although they were invasive in HEp-2 cell cultures. Otherwise there were correlative results between the cell monolayer test and the Sereny test. In the cell monolayer test the different species of enteropathogenic bacteria showed considerable variation in invasive potential.

Shiga toxins (Verocytotoxins)

Abstract: Shiga toxins (Stxs) also called Verocytotoxins (Vtxs) and Shiga-like toxins (SLTs), are bacterial toxins produced by some members of the Enterobacteriaceae particulary Shigella dysenteriae and Escherichia coli 0157:H7 as well as Acinetobacter spp (Moraxellaceae), Enterobacter cloacae and Aeromonas hymophilus. The toxin is made of two moieties, the B-moiety that is responsible for its binding to cell surface receptors, and the A-moiety which enters the cytosol and inhibits protein synthesis enzymatically. Their pathological effect in humans is mainly as a result of inhibition of cellular protein synthesis. Shiga toxins are haboured mainly by ruminants, principally cattle as well as sheep, buffaloes, pigs, goats, dogs, cats and pigeons. The two major groups of the toxin, Stx1 and Stx2 are associated with mild or bloody diarrhea to hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) and also, nosocomial infections in humans. Predisposing factors to infection with Shiga toxin producing bacteria includes old age, immunosupression, malnutrition, under developed immunity in neonates, poor hygiene, lack of portable water and excreta contamination of existing traditional water sources. Transmission is through consumption of contaminated food and water, person-to-person and animal contact. High rate of antibiotic resistance amongst Stxs-producing bacteria is causing concern all over the world, therefore improved personal and food hygiene and the provision of portable drinking water appears to be the best preventive measure against the infection.

Antibacterial, antifungal and cytotoxic activities of salviasperanol isolated from Amorphophallus campanulatus

Abstract: Salviasperanol, a diterpenoid isolated from Amorphophallus campanulatus (Roxb.) Bl. (Araceae) was studied for in vitro antibacterial, antifungal, and cytotoxic activities. The disc diffusion technique was used to determine in vitro antibacterial and antifungal activities. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimal inhibitory concentration (MIC) was determined using serial dilution technique to determine antibacterial potency. The MIC values against these bacteria ranged from 8 to 64 μg/mL. The compound showed significant antibacterial activity against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Streptococcus β-haemolyticus) and six Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonus aeruginosa, Salmonella typhi). The compound showed weak antifungal activity against a number of fungi. In the cytotoxicity determination, the LC50 of the compound against brine shrimp ...

A completed structure of the O-polysaccharide from Shigella dysenteriae type 10

Abstract: The structure of the O-specific polysaccharide from Shigella dysenteriae type 10, which has been reported previously in Bioorganic chemistry (1977, vol.3, pp. 1219–1225), is refined: →2)-β-D-Manp-(1→3)-α-D-ManpNAc-(1→3)-β-L-Rhap-(1→4)-α-D-GlcpNAc-(1→.

Method for rapidly detecting shigella dysenteriae

Abstract: The invention belongs to a rapid detection technology of food-borne pathogens, in particular to a loop-mediated isothermal amplification (LAMP) method for detecting shigella dysenteriae DNA. The method comprises the preparation of reagent comprising sample processing reagent, LAMP reactive reagent, a large fragment of Bst DNA polyase, agarose, bromophenol blue loading buffer solution and ethidium bromide solution and the procedures of the detection of amplification products and sediment generation. The method comprises the following steps: firstly, designing a specific primer; secondly, extracting sample DNA; and thirdly, preparing a reaction system. Compared with the currently adopted traditional bacterial culture method, an immunological detection method and other molecular biology methods, the method has the advantages of simple and rapid operation, no special instrument and reagent, sensitivity and specificity and can be applied to the rapid detection of shigella dysenteriae in foods and other samples.

Antibiotic Susceptibility and Plasmid Profiles of Shigella species in Sudan.

Abstract: This study was carried out to determine the antibiotic susceptibility, plasmid profile and conjugative abilities of Shigella species isolated from different towns in Sudan during 2005-2007. Methods: Stool specimens were collected in Carry Blair transport medium from patients presenting with diarrhea from different sites in Sudan between the years 2005-2007. All specimens were inoculated on Mac Conkey’s agar and Xylose Lysine Dioxycholate (XLD) (Mast group Ltd. Merseyside U.K.). Bacteria was isolated and subjected to different antibiotics to detect sensitivity and transference of resistance. Results: One hundred and fourteen Shigella isolates were included in the study. Eighty (70.1%) were Shigella flexeneri representing the dominant isolate, followed by 20 (17.5%) isolates of Shigella dysenteriae , 9 (7.9%) Shigella sonnei and 5 (4.5%) Shigella boydii. Most of the isolates showed resistance to streptomycin (70%), tetracycline (52%) and co-trimoxazole (43%). They were highly sensitive to norfloxacin (97%), nalidixic acid (95%), gentamicin (89%) and chloramphenicol (77%). Multi-drug resistance to two or more antibiotics was apparent in most of the isolates (64, 56.1%). Fifty nine of the resistant Shigella isolates were studied for their ability to transfer resistance to the donor E. coli K12 by conjugation. Of these, six were able to transfer resistance to streptomycin, tetracycline and co-trimoxazole. Extraction of the plasmid DNA from both donors and trans-conjugants showed a single type of plasmid with a molecular weight of 4.6 Kb. Conclusion: The transfer of multi-drug resistant plasmids and the emergence of antibiotic Shigella and other bacterial species should raise the awareness and the seriousness of the uncontrolled (unsupervised) use of antibiotics in the medical practice. Key words : Shigella E. coli, Plasmid, conjugant, resistance transfer.

Diarrhea associated hemolytic uremic syndrome: A 3-year PICU experience from Nepal

Abstract: diffuse, transverse, and longitudinal.1 Nail discolorations are mainly due to direct toxic effects and stimulation of the matrix melanocytes. Transverse melanonychia seems to occur in relation to intermittent courses of chemotherapy.2 This complex pattern of nail changes is accounted by synergy or an additive effect of chemotherapy agents on cellular proliferation of nail compartments.3 The time interval between the start of therapy and the first signs of nail pigmentation may depend on the rate of nail growth; this could explain the later and less frequent appearance of changes in the toenails.4 These nail changes are benign requiring no specific intervention and resolve spontaneously, by moving distally.

The expression of lipopolysaccharide by strains of Shigella dysenteriae, Shigella flexneri and Shigella boydii and their cross-reacting strains of Escherichia coli.

Abstract: Strains of Shigella dysenteriae, Shigella flexneri and Shigella boydii express lipopolysaccharides, that enable the serotyping of strains based on their antigenic structures. Certain strains of S. dysenteriae, S. flexneri and S. boydii are known to share epitopes with strains of Escherichia coli; however, the lipopolysaccharide profiles of the cross-reacting organisms have not been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) lipopolysaccharides profiling. In the present study, type strains of these bacteria were examined using SDS-PAGE/silver staining to compare their respective lipopolysaccharide profiles. Strains of S. dysenteriae, S. boydii and S. flexneri all expressed long-chain lipopolysaccharide, with distinct profile patterns. The majority of strains of Shigella spp., known to cross-react with strains of E. coli, had lipopolysaccharide profiles quite distinct from the respective strain of E. coli. It was concluded that while cross-reacting strains of Shigella spp. and E. coli may express shared lipopolysaccharide epitopes, their lipopolysaccharide structures are not identical.

Use of Eupatorium adenophorum polysaccharide for antibiosis or antivirus

Abstract: The invention relates to the aplication of amigo-smile polyoses used for resisting bacteria or viruses, in particular to the application of the amigo-smile polyoses for preparing a medicament with the effects of resisting the bacteria or the viruses The amigo-smile polyoses of the invention has inhibition effects to a plurality of bacteria or viruses, such as Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus, Escherichia coli, salmonella, Proteus vuigaris, Shigella dysenteriae, Candida albicans or parainfluenza virus, and the like The known method of the prior art can be adopted to prepare the amigo-smile polyoses of the invention into a medicament compound and the medicament compounds of any preparation formulation acceptable on pharmacy, such as granular formulation, oral liquid, capsule, troche, injection, pulvis, and the like

Antimicrobial resistance and plasmid profile analysis of clinically isolated Shigella dysenteriae in Azad Kashmir, Pakistan.

Abstract: The antimicrobial susceptibility patterns for 134 S. dysenteriae isolated from diarrheal patients admitted to hospitals in Azad Kashmir Pakistan were analyzed from 1994 to 1998 to determine their changing trends in response to twenty antibiotics. The isolates showed highest resistance against penicillin followed by carbenicillin, ampicillin, tetracycline, erythromycin, ceftizoxime, kanamycin, co-trimoxazole, piperacillin, amoxicillin, amikacin, streptomycin, nalidixic acid, gentamicin, chloramphenicol, cephalothin and ceftriaxone. All S. dysenteriae isolates were sensitive to cefixime, ciprofloxacin and enoxacin. Multiple drug resistance was observed in this study ranging from three to ten drugs and was resistant to three or more antibiotics at level as high as 300µg/ml. The most common antibiotics resistance pattern was PCaA. The plasmids were observed in 29.9% MDR strains of S. dysenteriae which were found resistant to three or more antibiotics. The number of plasmids varied from one to seven. All the strains contained a heterogeneous population of plasmids ranging between 23.1 kb to <2.0 kb. Based on molecular weight, the pattern of different plasmids was also very diverse. Depending on the number of plasmids, individual strains were grouped into nine different plasmid patterns. The plasmids (23.1 Kb and <23.1 Kb) could only confer ampicillin, chloramphenicol and sulfamethoxazole-trimethoprim resistance to the competent cells of E. coli HB101.

The efficacy and immunogenicity of a live transconjugant hybrid strain of Shigella dysenteriae type 1 in two animal models

Abstract: In our earlier studies, we constructed a hybrid strain of Shigella dysenteriae type 1 by introducing a plasmid vector pPR 1347. After introduction of a lipopolysaccharide (LPS) biosynthesis gene, virulent Shigella dysenteriae type 1 strain became avirulent. In our present study, we have evaluated the immune response and protective efficacy of avirulent live transconjugant Shigella hybrid (LTSH) strain against wild type Shigella dysenteriae type 1, after four doses of oral (rabbit) and intranasal (mouse) immunizations. Serum IgG titers showed exponential increase during immunization and peaking on the 28th day and remained at that level till the 35th day in both the rabbit and the mouse models. When tested, serum IgG titers persisted for 63 days in mice and relatively high for 150 days in case of rabbits. Protection studies showed 100% protection against the challenge with wild type Shigella dysenteriae type 1 strain in rabbits and 80% protection in mice. Our results suggested that the LTSH strain could be a useful vaccine candidate strain in the future.

Preliminary phytochemical screening and in vitro antimicrobial investigation of the stem bark petroleum ether extract of Croton zambesicus Muell Arg.

Abstract: The petroleum ether extract of Croton zambesicus Muell Arg. was subjected to preliminary Phytochemical screening and in vitro antimicrobial tests. The Phytochemical tests were conducted using standard methods of analysis and the extract revealed the presence of cardiac glycosides and steroids. Antimicrobial effects of the plant extract were assayed using the plate-hole agar disc diffusion and nutrient dilution techniques. Test micro-organisms were Shigella dysenteriae, Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Candida albicans , were all clinical isolates. The extract inhibited all the tested organisms at various concentrations except Proteus vulgaris and C. albicans . It showeda minimum inhibitory concentration (MIC) of 25 mg/ml against S. dysenteriae, S. aureus and E. coli while MIC against S. pyogenes and p.aeruginosa were 100 and 50 mg/ml respectively. The minimum bacterial concentration (MBC) was 50 mg/ml against S. dysenteriae, S. aureus and E. coli while MBC against S. pyogenes and P. aeruginosa was 100 mg/ml. Therefore it was concluded that this study laid credibility for the use of the plant against stomach and urinary tract infections whose causative agents are most of the organisms used in this study.

Lactobacilli facilitate maintenance of intestinal membrane integrity during Shigella dysenteriae 1 infection in rats

Abstract: bstract Objective: Lactobacilli are used in various dairy products and fermented foods for their potential health beneficial effects Recently we reported the protective role of Lactobacillus rhamnosus and Lactobacillus acidophilus during Shigella dysenteriae 1 infection Nevertheless, investigations on the membrane-stabilizing effect of L rhamnosus and L acidophilus have not been done Hence, the present study evaluated the effect of L rhamnosus and L acidophilus on the maintenance of intestinal membrane integrity during S dysenteriae 1–induced diarrhea in rats Methods: Rats were divided into eight groups (n 6 in each group) Induced rats received single oral dose of S dysenteriae (12 10 colony-forming units [cfu]/mL) Treated rats received L rhamnosus (1 10cfu/mL) or L acidophilus (1 10cfu/mL) orally for 4 d, alone or in combination, followed by Shigella administration At the end of the experimental period, animals were sacrificed and the assay of membrane-bound adenosine triphosphatases (Na /K -ATPase, Ca -ATPase, and total ATPase), immunoblot analysis of tight junctional proteins (claudin-1 and occludin), and transmission electron microscopic studies were performed Results: Induced rats showed a significant (P 005) reduction in the membrane-bound ATPases and reduced expression of tight junction proteins in the membrane, coupled with their increased expression in the cytosol, indicating membrane damage Transmission electron microscopic studies correlated with biochemical parameters Pretreatment with combination of L rhamnosus and L acidophilus significantly prevented these changes Conclusion: Lactobacillus rhamnosus and L acidophilus synergistically offered better protection to the intestinal membrane when compared with individual treatments with these strains during S dysenteriae 1 infection © 2009 Published by Elsevier Inc