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At least 19 recordsLinked to original sources
PubMed2001

Gene cloning and characterization of alanine racemases from Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei.

Alanine racemase genes (alr) from Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei were cloned and expressed in Escherichia coli JM109. All genes encoded a polypeptide of 359 amino acids, and showed more than 99% sequence identities with each other. In particular, the S. dysenteriae alr was identical with the S. flexneri alr. Differences in the amino acid sequences between the four Shigella enzymes were only two residues: Gly138 in S. dysenteriae and S. flexneri (Glu138 in the other) and Ile225 in S. sonnei (Thr225 in the other). The S. boydii enzyme was identical with the E. coli K12 alr enzyme. Each Shigella alr enzyme purified to homogeneity has an apparent molecular mass about 43,000 by SDS-gel electrophoresis, and about 46,000 by gel filtration. However, all enzymes showed an apparent molecular mass about 60,000 by gel filtration in the presence of a substrate, 0.1 M l-alanine. These results suggest that the Shigella alr enzymes having an ordinary monomeric structure interact with other monomer in the presence of the substrate. The enzymes were almost identical in the enzymological properties, and showed lower catalytic activities (about 210 units/mg) than those of homodimeric alanine racemases reported.

Alanine Racemase↗
PubMed2004

In vitro adhesion and invasion inhibition of Shigella dysenteriae, Shigella flexneri and Shigella sonnei clinical strains by human milk proteins.

BACKGROUND: Shigella is the etiological agent of shigellosis, a disease responsible for more than 500,000 deaths of children per year, in developing countries. These pathogens colonize the intestinal colon, invade, spreading to the other enterocytes. Breastfeeding plays a very important role in protecting infants from intestinal infections. Amongst milk compounds, glycosylated proteins prevent the adhesion of many enteropathogens in vitro. The aim of this work was to determine the effect of human milk proteins on the colonization potential of Shigella dysenteriae, S. flexneri and S. sonnei. To fulfill this purpose, pooled milk samples from five donors, were fractionated by gel filtration and affinity chromatography. Using tissue culture, the milk fractions obtained were tested in Shigella adhesion and invasion assays. RESULTS: Our revealed showed that both adhesion and invasion of Shigella species were inhibited by low concentration of secretory immunoglobulin A, lactoferrin and free secretory component. This work also showed that, these proteins bind to superficial and whole-cell Shigella proteins. CONCLUSIONS: Our findings suggest that human milk may act inhibiting adhesion and, consequently, invasion of Shigella, thereafter preventing shigellosis in infants.

Antibodies, Bacterial↗
PubMed1993

Rapid detection of Shigella dysenteriae and Shigella flexneri in faeces by an immunomagnetic assay with monoclonal antibodies.

A rapid and sensitive method for the detection of Shigella dysenteriae type 1 and Shigella flexneri serotypes in faeces based on capture of the bacteria with immunomagnetic particles is described. The particles were coated with either of two different monoclonal antibodies specific for the O-antigens of Shigella dysenteriae type 1 and Shigella flexneri serotypes. Captured bacteria were detected by an enzyme immunoassay with O-antigen specific rabbit antiserum. The whole assay required 2 to 3 hours to perform and the sensitivity limit was 10(3) cfu/ml as determined by viable cell counting. One hundred and fifty enterobacteria strains, including 100 Shigella strains from a strain collection, and 302 fresh faecal samples were used for the study. All Shigella dysenteriae type 1 and Shigella flexneri culture-positive faecal samples were positive in the immunomagnetic assay. In addition 18 of 252 culture-negative faecal samples were positive. The immunomagnetic assay was compared with latex agglutination and indirect immunofluorescence using culture as the reference method. The immunomagnetic assay had a sensitivity of 100%, latex agglutination a sensitivity of 72% with 28% false-negative results, and indirect immunofluorescence a sensitivity of 95%. The immunomagnetic assay was superior in sensitivity since it also detected Shigella in faecal samples up to two days after antibiotic therapy had been started, which both latex agglutination and indirect immunofluorescence failed to do. The high sensitivity in detecting live and dead bacteria, and the ease of performance of the immunomagnetic assay render it an attractive method for detection of Shigella.

Animals↗
PubMed1998

Involvement of an efflux system in high-level fluoroquinolone resistance of Shigella dysenteriae.

Shigella dysenteriae represent one of the growing list of antibiotic-resistant bacteria. Quinolones are widely employed to treat shigellosis. However, quinolone resistance has already been reported, necessitating an understanding of the mechanisms of development of resistance. We demonstrate that high-level fluoroquinolone resistance of S. dysenteriae exposed to these antibiotics may occur in the absence of gyrA mutations and involve a proton motive force(pmf)-dependent efflux system.

Anti-Bacterial Agents↗
PubMed2024

An integrated in-silico approach for drug target identification in human pathogen Shigella dysenteriae.

Shigella dysenteriae, is a Gram-negative bacterium that emerged as the second most significant cause of bacillary dysentery. Antibiotic treatment is vital in lowering Shigella infection rates, yet the growing global resistance to broad-spectrum antibiotics poses a significant challenge. The persistent multidrug resistance of S. dysenteriae complicates its management and control. Hence, there is an urgent requirement to discover novel therapeutic targets and potent medications to prevent and treat this disease. Therefore, the integration of bioinformatics methods such as subtractive and comparative analysis provides a pathway to compute the pan-genome of S. dysenteriae. In our study, we analysed a dataset comprising 27 whole genomes. The S. dysenteriae strain SD197 was used as the reference for determining the core genome. Initially, our focus was directed towards the identification of the proteome of the core genome. Moreover, several filters were applied to the core genome, including assessments for non-host homology, protein essentiality, and virulence, in order to prioritize potential drug targets. Among these targets were Integration host factor subunit alpha and Tyrosine recombinase XerC. Furthermore, four drug-like compounds showing potential inhibitory effects against both target proteins were identified. Subsequently, molecular docking analysis was conducted involving these targets and the compounds. This initial study provides the list of novel targets against S. dysenteriae. Conclusively, future in vitro investigations could validate our in-silico findings and uncover potential therapeutic drugs for combating bacillary dysentery infection.

Shigella dysenteriae↗
PubMed1974

Shigella dysenteriae and Shigella boydii in England and Wales during 1972 and 1973.

During 1972 and 1973 the Salmonella and Shigella Reference Laboratory examined 133 strains of Shigella dysenteriae and Shigella boydii isolated from patients in England and Wales. Of those infected 89 had recently travelled abroad and a further seven had been in close contact with travellers recently returned to this country. Though these subgroups were of little numerical significance they are of considerable epidemiological interest. The increase in tourism from the British Isles to North Africa and Asia is likely to lead to an increased incidence of infections due to these organisms, both in travellers infected abroad and in their contacts within the British Isles.

Cross Infection↗
PubMed1981

Protein synthesis in HeLa or Henle 407 cells infected with Shigella dysenteriae 1, Shigella flexneri 2a, or Salmonella typhimurium W118.

The incorporation of [14C]leucine into protein was studied in two mammalian cell lines which had been infected with strains of Shigella dysenteriae 1, Shigella flexneri 2a, or Salmonella typhimurium W118. These cell lines differed in susceptibility to the effects of exogenously applied Shiga cytotoxin. All invasive shigella strains (which synthesize this toxin to a greater or lesser degree) were found to inhibit protein synthesis in both cell lines with equal efficiency. Leucine accumulation continued in these cells, but the labeled amino acid was preferentially incorporated into bacterial protein. S. typhimurium W118, which has not been shown to elaborate a Shiga-like toxin, had little effect on protein synthesis in infected host cells.

Bacterial Proteins↗
PubMed1982

[Use of coagglutination for serotyping Shigella dysenteriae and Shigella boydii].

The coagglutination test was used to identify Shigella boydii and Shigella dysenteriae. A trial was carried out with 13 native rabbit antisera to S. boydii and 10 antisera to S. dysenteriae, as well as with coagglutinating reagents prepared from these antisera. The use of coagglutinating reagents was shown to ensure the complete specificity of the results, to prevent the adsorption of diagnostic antisera and to decrease their consumption 50 times. The importance of the coagglutination test for the identification of shigellae is discussed.

Adsorption↗
PubMed1966

Properties and regulation of the beta-D-galactosidase in Shigella dysenteriae and in Escherichia coli-Shigella dysenteriae hybrids.

Sarkar, S. (Massachusetts Institute of Technology, Cambridge). Properties and regulation of the beta-d-galactosidase in Shigella dysenteriae and in Escherichia coli-Shigella dysenteriae hybrids. J. Bacteriol. 91:1477-1488. 1966.-Shigella dysenteriae strain 60 has a beta-d-galactosidase related to that of Escherichia coli but more heat-sensitive and with a turnover number about 10 times lower. Hybridization by transduction produces strains with enzymes of intermediate properties by recombination within the z gene. Both E. coli and S. dysenteriae have a regulatory i(+) gene. Recombination between i(-) mutants of the two organisms leads to restoration of the i(+) genotype. In S. dysenteriae 60, most of the i(-) mutants are subject to genetic suppression by suppressor mutations at unlinked loci. The effect of these suppressors on the products of the suppressed i(-) genes is discussed.

Centrifugation↗
PubMed1993

Synthesis, characterization, and clinical evaluation of conjugate vaccines composed of the O-specific polysaccharides of Shigella dysenteriae type 1, Shigella flexneri type 2a, and Shigella sonnei (Plesiomonas shigelloides) bound to bacterial toxoids.

The theoretic basis for developing conjugate vaccines, to induce immunoglobulin G (IgG) lipopolysaccharide (LPS) antibodies for the prevention of shigellosis, has been described (J. B. Robbins, C.-Y. Chu, and R. Schneerson, Clin. Infect. Dis. 15:346-361, 1992). The O-specific polysaccharides (O-SPs) of Shigella dysenteriae type 1, S. flexneri type 2a, and S. sonnei were covalently bound to carrier proteins. Alone, the O-SPs were not immunogenic in mice. Conjugates of these O-SPs, injected into young outbred mice subcutaneously as saline solutions containing 2.5 micrograms of saccharide, elicited serum IgG and IgM antibodies with booster responses; adsorption onto alum enhanced their immunogenicity. Injection of 25 micrograms of these conjugates into adult volunteers elicited mild local reactions only. Each conjugate induced a significant rise of the geometric mean serum IgG, IgM, and IgA LPS antibody levels. A second injection 6 weeks later did not elicit booster responses, and adsorption of the conjugates onto alum did not enhance their immunogenicity. Conjugate-induced levels of IgA, but not IgG or IgM, declined to preimmunization levels at day 56. The levels of postimmunization antibodies of the three immunoglobulin classes were similar to or higher than those of recruits in the Israel Defense Force following shigellosis caused by S. flexneri type 2a or S. sonnei. These data provide the basis for evaluating these conjugates to prevent shigellosis.

Adolescent↗
PubMed1998

Shigellosis in children: a clinico-epidemiological comparison between Shigella dysenteriae type I and Shigella flexneri.

We reviewed the clinical and epidemiological features of 390 children under 5 years of age infected with either Shigella dysenteriae type I or Shigella flexneri attending a diarrhoea treatment centre from 1993 to 1995 in Dhaka, Bangladesh. Older age (24 months or more), underweight and wasting but not stunting were the host factors significantly more associated with Shigella dysenteriae type I infection than in Shigella flexneri-infected children. Moreover, use of antibiotics at home, use of water from tubewells or pipe-water for drinking and lack of sanitary facilities for defaecation were the behavioural and environmental factors strongly associated with S. dysenteriae type I infection. Children with diarrhoea due to S. flexneri presented with more watery/liquid stools and had a shorter duration of illness. Duration of diarrhoea for 4 or more days was typical of S. dysenteriae type I infection. Interventions to address malnutrition and to promote environmental hygiene would be predicted to offer greater protection against shigellosis due to S. dysenteriae than S. flexneri.

Bangladesh↗