Showing papers on "Shigella dysenteriae published in 2005"

Genome dynamics and diversity of Shigella species, the etiologic agents of bacillary dysentery

Abstract: The Shigella bacteria cause bacillary dysentery, which remains a significant threat to public health. The genus status and species classification appear no longer valid, as compelling evidence indicates that Shigella, as well as enteroinvasive Escherichia coli, are derived from multiple origins of E.coli and form a single pathovar. Nevertheless, Shigella dysenteriae serotype 1 causes deadly epidemics but Shigella boydii is restricted to the Indian subcontinent, while Shigella flexneri and Shigella sonnei are prevalent in developing and developed countries respectively. To begin to explain these distinctive epidemiological and pathological features at the genome level, we have carried out comparative genomics on four representative strains. Each of the Shigella genomes includes a virulence plasmid that encodes conserved primary virulence determinants. The Shigella chromosomes share most of their genes with that of E.coli K12 strain MG1655, but each has over 200 pseudogenes, 300 approximately 700 copies of insertion sequence (IS) elements, and numerous deletions, insertions, translocations and inversions. There is extensive diversity of putative virulence genes, mostly acquired via bacteriophage-mediated lateral gene transfer. Hence, via convergent evolution involving gain and loss of functions, through bacteriophage-mediated gene acquisition, IS-mediated DNA rearrangements and formation of pseudogenes, the Shigella spp. became highly specific human pathogens with variable epidemiological and pathological features.

Prevalence of Shigella species and their antimicrobial resistance patterns in Eastern Nepal.

Abstract: The study was conducted to determine the prevalence of Shigella species and their antimicrobial resistance patterns in eastern Nepal. Stool samples submitted to the diagnostic laboratory of B.P. Koirala Institute of Health Sciences, Nepal, during August 2000_July 2004, were cultured for Shigella species and were confirmed by biochemical and serological tests. Of 53 Shigella species isolated, Shigella dysenteriae type 1 was the most predominant isolate (73.7%), followed by S. flexneri (23%) and S. boydii (4%). The majority (79%) of Shigella species were isolated from children aged less than five years. An overall high resistance was observed for trimethoprim-sulphamethoxazole, ampicillin, nalidixic acid, mecillinam, and ciprofloxacin. There was a statistically significant (p<0.001) increasing trend in the prevalence of ciprofloxacin resistance in S. dysenteriae type 1. The results suggest reconsideration of the empiric use of these antimicrobial agents for shigellosis. A further study is required to evaluate additional antimicrobial agents. Key words: Shigella ; Dysentery, Bacillary; Drug resistance, Microbial; Drug therapy; Nepal

Use of Ramification Amplification Assay for Detection of Escherichia coli O157:H7 and Other E. coli Shiga Toxin-Producing Strains

Abstract: Escherichia coli O157:H7 and other Shiga toxin-producing E. coli (STEC) strains are important human pathogens that are mainly transmitted through the food chain. These pathogens have a low infectious dose and may cause life-threatening illnesses. However, detection of this microorganism in contaminated food or a patient's stool specimens presents a diagnostic challenge because of the low copy number in the sample. Often, a more sensitive nucleic acid amplification method, such as PCR, is required for rapid detection of this microorganism. Ramification amplification (RAM) is a recently introduced isothermal DNA amplification technique that utilizes a circular probe for target detection and achieves exponential amplification through the mechanism of primer extension, strand displacement, and ramification. In this study, we synthesized a circular probe specific for the Shiga toxin 2 gene (stx2). Our results showed that as few as 10 copies of stx2 could be detected, indicating that the RAM assay was as sensitive as conventional PCR. We further tested 33 isolates of E coli O157:H7, STEC, Shigella dysenteriae, and nonpathogenic E. coli by RAM assay. Results showed that all 27 STEC isolates containing the stx2 gene were identified by RAM assay, while S. dysenteriae and nonpathogenic E. coli isolates were undetected. The RAM results were 100% in concordance with those of PCR. Because of its simplicity and isothermal amplification, the RAM assay could be a useful method for detecting STEC in food and human specimens.

Porin of Shigella dysenteriae enhances Toll-like receptors 2 and 6 of mouse peritoneal B-2 cells and induces the expression of immunoglobulin M, immunoglobulin G2a and immunoglobulin A

Abstract: SummaryPorin of Shigella dysenteriae type 1 increased the mRNA levels for Toll-likereceptors TLR2 and TLR6, by 1 8-fold and twofold, respectively, in perito-neal cavity B-2 cells from C57BL/6 mice, implicating that the co-expressionof TLR2 and TLR6 occurs as a combinatorial repertoire in response toporin. Among the two key TLRs, TLR2 and TLR4, which are primarilyresponsible for recognizing the majority of bacterial products, TLR2 aloneparticipates in porin recognition. TLR2 expression was increased on B-2cells, whereas the expression of TLR4 remained unaffected. Besides TLRs,mRNA for myeloid differentiation factor 88 (MyD88), an effector moleculeassociated with the TLR-mediated response, was enhanced by twofold, sug-gesting its involvement in the activity of porin. The B-2 cells showed a1 8-fold increase in mRNA expression of the signalling molecule, nuclearfactor-kappa B (NF-B), in the presence of porin. Porin treatment of B-2cells selectively up-regulated the expression of the costimulatory molecule,CD86, by 44-fold. Porin induced the cell-surface expression of immuno-globulin (Ig)M, of IgG2a preferentially among the IgG subclasses, and ofIgA, on B-2 cells. The porin-mediated inductions of IgG2a and IgA wereaugmented by interleukin-6 on B-2 cells, by 27- and 1 6-fold, respectively.Keywords: B-2 cell; CD86; IgA; IgG2a; porin; Toll-like receptor

Re-emergence of multi-drug resistant Shigella dysenteriae with added resistance to ciprofloxacin in north India & their plasmid profiles.

Abstract: Background & objectives: Multi drug resistant Shigellae pose a major threat in control of shigellosis with. Shigella dysenteriae being the most prevalent species at our centre before 1994. A gradual decrease in S. dysenteriae occurred over the years with a corresponding increase in S. flexneri which became the predominant serotype. From May to November 2003, an increase in number of patients admitted with clinical diagnosis of dysentery was noted in comparison to previous years, with a corresponding increase in the isolation of multi drug resistant S. dysenteriae. We report here the re-emergence of multi drug resistant S. dysenteriae at our tertiary care centre in north India after a gap of about 10 yr. Plasmid analysis of S. dysenteriae was also performed to study the origin and clonality of the isolates. Methods: Stool samples were collected in Cary-Blair medium and processed by standard methods. Shigellae were confirmed by serotyping. Minimum inhibitory concentration was done by agar dilution method and E-test. Plasmid profiling of 18 isolates (16 S. dysenteriae 1 and 2 S. dysenteriae 2) was performed by modified alkali lysis method. Clinical details of patients were noted. Results: A total of 64 patients with dysentery were admitted during the study period. Patients presented with unusually severe symptoms and six developed complications. Treatment failure with ciprofloxacin occurred in six patients who received cefotaxime and amikacin. There were 38 children below 5 yr of age. S. dysenteriae (18 isolates of S. dysenteriae 1 and 2 isolates of S. dysenteriae 2) were isolated from 20 of the 64 (31.2%) stool samples. S. dysenteriae re-emerged as the commonest isolate after a gap of nearly 10 yr. Fourteen of the 20 S. dysenteriae isolates were multi drug resistant; 12 were resistant to ciprofloxacin with MIC of 8-32 mg/ml. Plasmid profile analysis revealed that 6 of 11 ciprofloxacin resistant S. dysenteriae 1 had similar profiles. Interpretation & conclusion: Emergence of a clone of ciprofloxacin resistant S. dysenteriae 1 in north India is disturbing as treatment options in our geographic area are limited in view of already existing high drug resistance to nalidixic acid, co-trimoxazole and amoxycillin. A close monitoring of shifts in serogroup distribution and antibiotic resistance is required to guide clinicians for treatment of shigellosis.

A Novel Shigella dysenteriae Serovar Isolated in Canada

Abstract: The etiological agent most commonly associated with bacillary dysentery is Shigella. As part of its mandate, the Bacteriology and Enteric Disease Program of Health Canada identifies and serotypes unusual isolates of Shigella received from provincial laboratories of public health. In this report, six unusual isolates from three provinces were analyzed biochemically and serologically using slide and tube agglutinations and molecularly using standard pulsed-filed gel electrophoresis (PFGE), PCR, and PCR-restriction fragment length polymorphism (RFLP) techniques. All six isolates were identical. PFGE analysis grouped these strains; biochemically, they were mannitol negative and consistent with the profile of Shigella. Serologically, these strains produced weak reactions in Shigella dysenteriae serovars 4 and 16 and Escherichia coli O159 and O173 antisera. Molecular serotyping by PCR-RFLP of the rfb gene produced an S. dysenteriae serovar 2/E. coli O112ac pattern. They were positive by PCR for ipaH and ial enteroinvasive genes but negative for all other genes tested. Antiserum was prepared from one of the isolates and tested against Shigella and E. coli reference strains as well as the other isolates. The antiserum reacted with the five remaining isolates and showed cross-reactivity with S. dysenteriae serovars 1, 4, and 16; Shigella flexneri type 3; and E. coli O118, O159, O168, O172, and O173 antigens. Absorbing the sera with E. coli O159 and S. dysenteriae serovar 4 antigen removed all cross-reactions and only slightly reduced the homologous titer. Based on biochemical, molecular, and complete serological analysis, we propose that these six isolates represent a new provisional serovar of S. dysenteriae, type strain BEDP 02-5104.

Shigella dysenteriae type 1-induced diarrhea in rats.

Abstract: With the aim of setting up an animal model of Shigella dysenteriae-induced diarrhea, Wistar rats received per os increasing densities of S. dysenteriae type 1 (Sd1). Inoculum of 12 x 10(8) Sd1 provoked dysenteric diarrhea within 24 h. Feces of healthy rats were molded, brown to black and rough. Rats developing diarrhea presented blood at the anal orifice; stools were soft or liquid containing mucus, or molded, smooth and mucus-coated. At times, stools appeared longer, dark and shiny due to the presence of mucus and blood, or molded, lumpy and brittle. Diarrheal induction was associated with abdominal ailment, progressive increase in stool weight and frequency, and increase in bacterial population. Sixty-seven percent of the total number of deaths had occurred by day 6 after diarrheal induction. These results indicate that Sd1 induced in rats a model of shigellosis which might be helpful for physiopathological and pharmacological studies of this type of infectious diarrhea.

Shiga Toxins: Potent Poisons, Pathogenicity Determinants, and Pharmacological Agents.

Abstract: The Shiga toxins (Stxs), also known as Vero toxins and previously called Shiga-like toxins, are a family of potent protein synthesis inhibitors made by Shigella dysenteriae type 1 and some serogroups of Escherichia coli that cause bloody diarrhea in humans. Stxs act as virulence factors for both S. dysenteriae and E. coli and contribute to the disease process initiated by those organisms both directly and indirectly. A handful of methods exist for toxin purification, and the toxins can now even be purchased commercially. However, the Stxs are now classified as select agents, and specific rules govern the distribution of both the toxin and clones of the toxin. Toxin delivery into the host in S. dysenteriae type 1 is most likely aided by the invasiveness of that organism. Although the Stxs are made and produced by bacteria, they do not appear to act against either their host organism or other bacteria under normal circumstances, most likely because the A subunit is secreted from the cytoplasm as soon as it is synthesized and because the holotoxin cannot enter intact bacterial cells. The effectiveness of antibiotic therapy in patients infected with Stx-producing E. coli (STEC) such as O157:H7 as well as the potential risks of such treatment are areas of controversy. Several studies indicate that the course of the diarrhea stage of the disease is unaltered by antibiotic treatment. Several groups anticipate that a therapy that targets the Stxs is an important component of trying to alleviate disease caused by Stx-producing bacteria.

Haemolytic uraemic syndrome due to ciprofloxacin-resistant Shigella dysenteriae serotype 1.

Abstract: A case of haemolytic uraemic syndrome following dysentery due to ciprofloxacin-resistant Shigella dysenteriae serotype 1 is reported for the first time. The increasing resistance of S. dysenteriae serotype 1 to many commonly available antimicrobial agents has implications for the management of dysentery. The choice of antimicrobial treatment for S. dysenteriae serotype 1 infections should take into account widespread drug resistance and the risk of haemolytic uraemic syndrome.

Isolation and characterization of provisional serovar Shigella boydii E16553 from diarrhoeal patients in Bangladesh.

Abstract: In previous studies with strains of the Shigella dysenteriae provisional serovars E22383 and E23507 from diarrhoeal stools from patients in Bangladesh, two strains of Shigella species were identified as Shigella boydii provisional serovar E16553 by a reference laboratory. Further tests with an antiserum to an international type strain of the provisional serovar E16553 identified an additional 15 isolates. None of the isolates reacted with antisera to the established Shigella serovars or any other provisional serovars reported so far and all showed biochemical reactions typical of S. boydii. All of the isolates harboured the 140 MDa invasion plasmid, had the ipaH gene and produced keratoconjunctivitis in the guinea pig eye. All isolates were susceptible to ampicillin, sulfamethoxazole-trimethoprim, nalidixic acid, ciprofloxacin and mecillinam but eight strains were resistant to tetracycline. A single PFGE type (type A) was shown for all 17 clinical isolates, indicating a common source of origin. The pulsotype of the Bangladeshi isolates was closely related to that of a Japanese strain but was different from that of the type strain. On the basis of these biochemical, serological and virulence markers, and diverse geographical origin, it is recommended that the provisional status of serovar E16553 be changed and that it be included in the international serotyping classification scheme as S. boydii 19.

Live, oral vaccine for protection against shigella dysenteriae serotype 1

Abstract: The invention relates to Salmonella typhi Ty21a comprising core-linked Shigella dysenteriae type 1 O-specific polysaccharide (O-Ps) and DNA encoding O antigen biosynthesis, said DNA selected from the group consisting of: a) the DNA sequence set out in any one of SEQ ID NOs: 1 and 2 and species homologs thereof; b) DNA encoding S. dysenteriae polypeptides encoded by any one of SEQ ID NOs: 1 and 2, and species homologs thereof; and c) DNA encoding a O antigen biosynthesis gene product that hybridizes under moderately stringent conditions to the DNA of (a) or (b); and related sequences, compositions of matter, vaccines, methods of using, and methods of making.

An unusual cluster of dysentery due to Shigella dysenteriae type 4 in Dhaka, Bangladesh.

Abstract: Shigella infections occur in both epidemic and sporadic forms in south Asia, including Bangladesh. The genus Shigella is composed of four species: Shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonnei. In S. dysenteriae, there are 15 recognized serotypes, of which serotype 1 attracts special attention for its epidemic-causing potential, the Shiga toxin it produces and its associationwithmost serious complications (Bennish et al., 1990). Epidemics usually occur in areas with crowding and poor sanitary conditions where transmission from person to person is common, or when food or water is contaminated by the organism (Chiou et al., 2001).

Isolation and Identification of Rabbits Shigella Dysenteriae in a Large Scale Warren

Abstract: A high incidence of a disease and death rate of rabbit warren of Shihezi present in a large scale in the past three years.The clinic symptom is different abscess appeared under the skin with the dopes appeared like cheese,especially often occurred on cervix,back and extremities.At the beginning of the disease body temperature went up but the peptide and spirit were normal.Finally the abscess frazzled and muscle atrophy to die.Shigella dysenteriae was identified finally through bacterial cultivated,morphologic observe,animal and medical sensitivity experiments and identification of trait.It can endure the common antibiotics but was sensitive to erythromycin and part of materia medica.

Sepsis caused by food-borne infection with Escherichia coli.

Abstract: We report a case of sepsis caused by Escherichia coli (E. coli) of serotype O-143. A 78-year-old man developed symptoms of gastroenteritis after ingesting raw meat on noodles. He rapidly developed respiratory failure. Blood culture grew E. coli. The sepsis seemed to have directly spread from a food-borne infection. The development of primary sepsis after ingesting E. coli is very rare. We suspect that bacterial translocation played a major role. Serotype O-143 is recognized in enteroinvasive E. coli (EIEC) as well as in Shigella dysenteriae. The pathogen in the present case is suspected of being EIEC although the isolated E. coli strain was negative for the inv and ipa genes.

Phosphotidylinositol-3 kinase-mediated signals in mice immunized with the 57 kDa major antigenic outer-membrane protein of Shigella dysenteriae type 1.

Abstract: Antigen-specific T-cell signalling via T-cell antigen receptor stimulation was carried out in BALB/c mice immunized with the 57 kDa major antigenic component of Shigella dysenteriae 1 outer-membrane proteins In presence of anti-CD3, the 57 kDa antigen was found to increase the level of IL-2 significantly instead of IL-4 IL-2 production in T cells was consistent with an increase in intracellular free Ca2+ [(Ca2+)i] concentration The antigen-specific modulation was observed during T-cell signalling, with enhanced release of [(Ca2+)i] IL-2-receptor stimulation via IL-2 did not significantly induce the release of IL-2 with consistent intracellular Ca2+ production Furthermore, the protein tyrosine kinase was activated during anti-CD3 stimulation, which up-regulated the phosphatidylinositol kinase of p85-mediated serine kinase protein kinase-C of p70 Phosphoinositide-specific kinases are regulated by the phosphorylation of tyrosine kinase through the activation of the T-cell antigen receptor The above findings indicate that phosphotidylinositol-3 kinase-mediated signals are up-regulated through [(Ca2+)i], which is essential for Th1-type responses

Inhibitory effect of Bacillus coagulans TBC 169 strain on the pathogenic bacteria in intestinal tract

Abstract: Objective To study the inhibitory effect of Bacillus coagulans(BC) TBC 169 strain on E.coli,Shigella dysenteriae,Salmonella typhi,Proteus vulgaris,Pseubomonas aeruginosa and Staphylococcus aureus which belong to pathogenic bacteria of intestinal tract.Methods The pathogenic bacteria were singly cultured first,respectively,and pH levels and viable bacteria amounts were determined at various time.Then BC was mixture cultured with other bacteria,respectiely,and pH levels and viable bacteria amounts were detemined again.The data obtained from the single and mixed culture were compared.Results BC TBC 169 strain had obvious inhibitory effect on the E.coli,Shigella dysenteriae,Salmonella typhi etc,peculiar,on the inhibitor effect of the Salmonella typhi and Pseubomonas aeruginosa was very good.Conclusion BC TBC 169 strain had obvious inhibitory effect on the pathogenic becteriae of intestinal tract.

[Construction and characterization of a live attenuated Shigella flexneri 2a vaccine strain, sf301 Delta virG and dsbA33G].

Abstract: Construction and characterization of a live attenuated Shigella flexneria 2a sf301 vaccine strain to prevent the endemic of shigellosis. Using Chinese majority epidemic Shigella flexneri 2a serotype sf301 as the target, p Delta virG, a deletion derivation of the virG gene in the SacB suicide vector pCVD442 and pDsbA33G, an mutant of a disulfide bond catalyst DsbA, replaced its 33 amiano acid Cystine by Glycerin in pCVD442, were used to generate a attenuated mutant strain sf301: Delta virG: DsbA33 G. Its virulence was evaluated by Sereny test, the invasive ability was detected by HeLa cell invasive assay, immunogenicity was detected by immunized Guinea pigs through inoculated guinea pigs' conjunctive sac. Sereny test was negative and HeLa invasive assay showed sf301: Delta virG: DsbA33 G retained partial invasive ability. In contrast to control group, sf301: Delta virG: DsbA33 G could induced significantly high antibody levels of IgA and IgG against sf301 LPS in animal's mucosal lavage fluids and sera in both primary immunization protocol and boosting protocol. The numbers of ASCs in local draining lymph nodes and spleens were significantly higher than control group. The immune response to sf301: Delta virG: DsbA33 G could provide completely protection from the challenge of wild type sf301. sf301: Delta virG: DsbA33 G is a safe and effective oral candidate vaccine to prevent the infection of Shigella strains.

Analysis on Distribution of shigella Dysenteriae Flora and Drug Resistance in 2003 in Partial Regions of Zhejiang Province

Abstract: Objective This analysis was to help understand the distribution of subtypes of Shigellae and their resistance to drugs so as to improve the pertinence of preventive and cure measures and avoid the abuse of antibiotics. Methods 158 strains of Shigellae was identified and grouped in terms of GB16002-1995 and Kirby-Bauer Methods was used to determine their sensitivities to 14 antibiotics.Results In 158 strains of Shigellae, there were 113 strains of Sh. Flexneri (71 52%), 22 strains of Sh. Boydii (13 92%), 14 strains of Sh. Sonnet (8 86%) and 9 strains of Sh. Dysenteriae (5 70%); 91 strains of shigellae were resistant to Amphicillin with the highest rate up to 95 60% and the next was Streptomycin (72 53%); bacteria were the most sensitive to Ceftazidime with a rate of 95 60%. Conclusion In recent years, there has been a notable change in the distribution of Shigella subtypes and their sensitivities to antibiotics in zhejiang province, and medical departments should strengthen the monitoring on subtypes of Shigellae and their drug resistance.