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PubMed1992

Evaluation of two colored latex kits, the Wellcolex Colour Salmonella Test and the Wellcolex Colour Shigella Test, for serological grouping of Salmonella and Shigella species.

Two colored latex kits (the Wellcolex Colour Salmonella Test [WCT-Salmonella] and the Wellcolex Colour Shigella Test [WCT-Shigella]; Division Diagnostics, Laboratories Wellcome S.A., Paris, France), which allow identification of the most frequently encountered Salmonella serogroups and Shigella species, respectively, were evaluated. WCT-Salmonella and WCT-Shigella yielded sensitivities of 98.4 and 98%, respectively, and a specificity of 100% when they were tested on pure cultures received at a reference laboratory.

Evaluation Studies as Topic↗

PubMed2006

Complete genome sequence of Shigella flexneri 5b and comparison with Shigella flexneri 2a.

BACKGROUND: Shigella bacteria cause dysentery, which remains a significant threat to public health. Shigella flexneri is the most common species in both developing and developed countries. Five Shigella genomes have been sequenced, revealing dynamic and diverse features. To investigate the intra-species diversity of S. flexneri genomes further, we have sequenced the complete genome of S. flexneri 5b strain 8401 (abbreviated Sf8401) and compared it with S. flexneri 2a (Sf301). RESULTS: The Sf8401 chromosome is 4.5-Mb in size, a little smaller than that of Sf301, mainly because the former lacks the SHI-1 pathogenicity island (PAI). Compared with Sf301, there are 6 inversions and one translocation in Sf8401, which are probably mediated by insertion sequences (IS). There are clear differences in the known PAIs between these two genomes. The bacteriophage SfV segment remaining in SHI-O of Sf8401 is clearly larger than the remnants of bacteriophage SfII in Sf301. SHI-1 is absent from Sf8401 but a specific related protein is found next to the pheV locus. SHI-2 is involved in one intra-replichore inversion near the origin of replication, which may change the expression of iut/iuc genes. Moreover, genes related to the glycine-betaine biosynthesis pathway are present only in Sf8401 among the known Shigella genomes. CONCLUSION: Our data show that the two S. flexneri genomes are very similar, which suggests a high level of structural and functional conservation between the two serotypes. The differences reflect different selection pressures during evolution. The ancestor of S. flexneri probably acquired SHI-1 and SHI-2 before SHI-O was integrated and the serotypes diverged. SHI-1 was subsequently deleted from the S. flexneri 5b genome by recombination, but stabilized in the S. flexneri 2a genome. These events may have contributed to the differences in pathogenicity and epidemicity between the two serotypes of S. flexneri.

Chromosome Aberrations↗

PubMed1987

[Mobilization of phase I plasmid in Shigella sonnei and stability of its inheritance in rough strains of Shigella and Escherichia].

The plasmid pSS120, determining the synthesis of species specific I phase antigen of Shigella sonnei is mobilized for genetic transfer into E. coli K12 recipient cells with the frequency 12-41%. The frequency depends on the type of mobilized plasmid and recipient strain. The I phase antigen is normally expressed in II phase recipient cells and in E. coli cells. During mobilization pSS120 forms cointegrates representing a recombinant of mobilizing and mobilized plasmids DNA. The study of pSS120 inheritance stability has shown the plasmid to be unstable during culturing of bacteria and to be partially lost from the parent Shigella sonnei strains as well as from the "hybrid" transconjugants obtained. The 60 Md plasmid present in the donor strains of Shigella sonnei is prone to structural fragmentation particularly expressed in Shigella sonnei/E. coli hybrids.

DNA Transposable Elements↗

PubMed1985

Addition of three new serotypes of Shigella boydii to the Shigella schema.

No new serotypes have been added to the Shigella schema since 1958, although several provisional serotypes have been described. We conducted biochemical and serological studies on three provisional Shigella boydii serotypes. Four strains of serotype 2710-54 from four widely separated countries, 7 strains of serotype 3615-53 from three different countries, and 31 strains of serotype 1344-78 (E10163) from six different countries were included. Reactions of all three serotypes were consistent with those of S. boydii. On the basis of these results and other published research, we propose that these three provisional serotypes be admitted to the Shigella schema as S. boydii 16, 17, and 18.

Asia↗

PubMed1989

Isoenzyme analysis of typhoid-Shigella and Escherichia-Shigella hybrid vaccines and their parental strains.

Isoenzyme analysis can be used to measure phenotypic changes and to characterize bacterial strains. The use of isoenzyme analysis to characterize bacterial hybrid vaccine strains that were prepared for human vaccination is described in this report. The hybrid vaccine strains were two lots of Salmonella typhi-Shigella sonnei vaccine, two lots of Escherichia coli-Shigella flexneri vaccine, and their parental strains. The two lots of S. typhi-S. sonnei hybrid vaccine had only 5 of 11 reactive isoenzymes in common. The lot of S. typhi-S. sonnei hybrid vaccine that protected human volunteers in a clinical trial also had a greater degree of relatedness to the parental strain, S. typhi Ty21a, than the nonprotective lot. The two lots of E. coli-S. flexneri vaccine were more similar in terms of their isoenzyme profiles. There were colonial isolates from both lots that had identical isoenzyme profiles. The results also indicate a greater degree of homogenicity between Shigella spp. and E. coli than between either of these species and Salmonella spp. The data also show more isoenzyme activity associated with the nonpathogenic bacteria than with pathogenic isolates. Isoenzyme analysis is a rapid and specific assay that can be used to evaluate bacterial vaccine organisms and to establish isoenzyme profiles associated with vaccine immunogenicity and efficacy.

Bacterial Vaccines↗

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↗

PubMed1993

Serum antibody responses against shigella lipopolysaccharides and invasion plasmid-coded antigens in shigella infected Swedish patients.

Serum antibody responses to shigella lipopolysaccharide (LPS) and invasion plasmid-coded antigens (Ipa) were studied in 74 Swedish patients with culture verified bacillary dysentery using class-specific enzyme immunoassay (EIA). Anti-LPS responses were found in 80% and 79% serum samples, respectively, from S. flexneri and S. sonnei infected patients and anti-Ipa responses in 60% and 43%, respectively. The mean anti-Ipa IgG antibody titres in S. flexneri infected patients remained high for 4-6 months after onset while the anti-LPS IgG antibody titres had dropped to normal levels. The specificity of EIA for shigella Ipa was 90% and for S. dysenteriae, S. flexneri and S. sonnei LPSs it varied between 84% and 90%. No close correlations between the anti-LPS and anti-Ipa antibody responses were observed indicating that they may be differently regulated. The dynamics of the serum antibody responses indicates that an anti-LPS response is a good indicator of a recent shigella infection and an anti-Ipa IgG response a good indicator of a previous infection.

Adult↗

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↗

PubMed1997

Construction and characterization of genetically-marked bivalent anti-Shigella dysenteriae 1 and anti-Shigella flexneri Y live vaccine candidates.

Bivalent vaccine candidates were developed against Shigella dysenteriae 1 and Shigella flexneri, which are among the most frequent causative agents of shigellosis in developing countries. The rfp and rfb gene clusters, which code for S. dysenteriae serotype 1 O-antigen biosynthesis, were inserted into an arsenite resistance minitransposon and randomly integrated into the attenuated S. flexneri aroD serotype Y strain SFL124. Nine recombinant clones that efficiently expressed both homologous and heterologous O-antigens were obtained. Southern blot analysis showed that in one clone the S. dysenteriae 1 genes had integrated into the chromosome, whereas in all the others they had integrated into the virulence plasmid. All recombinant clones exhibited normal growth characteristics, were able to invade and survive within eukaryotic cells to the same extent as the parental strain, and expressed efficiently the recombinant lipopolysaccharide within invaded cells. Immunization of mice with two of the recombinant clones resulted in the production of antibodies specific for both homologous and heterologous O-antigens. The recombinant clones constitute promising vaccine candidates which can readily be distinguished from endemic shigellae by their non-antibiotic resistance marker.

Animals↗

PubMed1998

Antimicrobial resistance in Shigella flexneri and Shigella sonnei in Hong Kong, 1986 to 1995.

Three hundred and thirty-three Shigella isolates obtained in 1986 to 1995 were tested for their susceptibilities to 19 antimicrobial agents. Nalidixic acid resistance had emerged in 59.6% of Shigella flexneri isolates during 1994 to 1995, with all tested resistant isolates having the mutation in gyrA encoding the Ser-83 alteration. Multiresistance (resistance to four or more agents) was more common in S. flexneri than in Shigella sonnei.

Anti-Infective Agents↗

PubMed1991

Site-specific recombinase genes in three Shigella subgroups and nucleotide sequences of a pinB gene and an invertible B segment from Shigella boydii.

Inversional switching systems in procaryotes are composed of an invertible DNA segment and a site-specific recombinase gene adjacent to or contained in the segment. Four related but functionally distinct systems have previously been characterized in detail: the Salmonella typhimurium H segment-hin gene (H-hin), phage Mu G-gin, phage P1 C-cin, and Escherichia coli e14 P-pin. In this article we report the isolation and characterization of three new recombinase genes: pinB, pinD, and defective pinF from Shigella boydii, Shigella dysenteriae, and Shigella flexneri, respectively. The genes pinB and pinD were detected by the complementation of a hin mutation of Salmonella and were able to mediate inversion of the H, P, and C segments. pinB mediated H inversion as efficiently as the hin gene did and mediated C inversion with a frequency three orders of magnitude lower than that of the cin gene. pinD mediated inversion of H and P segments with frequencies ten times as high as those for the genes intrinsic to each segment and mediated C inversion with a frequency ten times lower than that for cin. Therefore, the pinB and pinD genes were inferred to be different from each other. The invertible B segment-pinB gene cloned from S. boydii is highly homologous to the G-gin in size, organization, and nucleotide sequence of open reading frames, but the 5' constant region outside the segment is quite different in size and predicted amino acid sequence. The B segment underwent inversion in the presence of hin, pin, or cin. The defective pinF gene is suggested to hae the same origin as P-pin on e14 by the restriction map of the fragment cloned from a Pin+ transductant that was obtained in transduction from S. flexneri to E. coli delta pin.

Amino Acid Sequence↗

PubMed1962

Studies on the metabolism of Shigella. IV. Nutritional requirements of Shigella flexneri serotype 3.

Pan, Sylvia F. (University of Pittsburgh, Pittsburgh, Pa.), Robert B. Yee, and Horace M. Gezon. Studies on the metabolism of Shigella. IV. Nutritional requirements of Shigella flexneri serotype 3. J. Bacteriol. 83:61-65. 1962.-A study of the nutritional requirements of five strains of Shigella flexneri serotype 3 was carried out. Four of the strains could be cultured in a synthetic medium composed of a mineral salts glucose base, NH(4)H(2)PO(4) or an amino acid as the nitrogen source, and nicotinamide; the fifth one required the presence of both NH(4)H(2)PO(4) and an amino acid in the medium. Variation among the former strains in their nitrogen and vitamin requirements was observed. The least fastidious one produced maximal growth using the simple ammonium salt as its source of nitrogen and did not require the addition of nicotinamide. Two strains were moderately fastidious, producing better growth within 24 hr in the presence of l-aspartic acid instead of NH(4)H(2)PO(4), and requiring nicotinamide as an accessory growth factor. The fourth strain was extremely fastidious, growing poorly or not at all in the synthetic medium. Incubation of large inocula of the fastidious strain in synthetic medium and over a prolonged period resulted in adaptation of the organism to the medium. Some of the adapted cultures grew readily in the presence of NH(4)H(2)PO(4) and did not require nicotinamide.

Amino Acids↗

PubMed1982

Confirmation of aerogenic strains of Shigella boydii 13 and further study of Shigella serotypes by DNA relatedness.

Shigella boydii 13 strains are separable from other Shigella and Escherichia coli strains on the basis of DNA relatedness. From this observation, it was possible to confirm the existence of aerogenic S. boydii 13 strains. DNA relatedness studies also showed that strains of E. coli and strains representing all other serotypes of Shigella, including provisional strains, belong to the same genetic species.

DNA, Bacterial↗

PubMed1998

Study of the relatedness of isolates of Shigella flexneri and Shigella sonnei obtained in 1986 and 1987 and in 1994 and 1995 from Hong Kong.

We used pulsed-field gel electrophoresis (PFGE) to study the genetic relatedness of 235 isolates of Shigella flexneri and Shigella sonnei collected in Hong Kong (97 isolates from 1986 and 1987 and 138 isolates from 1994 and 1995). Altogether, 13 gels were run with bacteriophage lambda ladder DNA (Pharmacia) as an external reference in every sixth lane, standardized reagents and methods, and isolates randomized for species and years. For quantitative illustration of the relationships within a large body of isolates, computer-generated dendrograms were used to determine the number of isolates in pulsotypes at Dice coefficients of similarity of 75% (PT75) and 50% (PT50). For S. flexneri, there was a significant difference in the distribution of isolates collected during the two periods in both PT75 and PT50, with 68% of isolates collected in 1994 and 1995 sharing a coefficient of similarity of >/=68%. For S. sonnei, a significant difference was observed in PT50 only. We also used Upholt's formula for an approximation of the fraction of nucleotide difference between isolates and Molecular Evolutionary Genetics Analysis to determine relative genetic distances. For both species, the relative genetic distances between isolates of the earlier collection period were significantly greater (P < 0.0001), i. e., they were further apart and therefore more diverse than those of the later period. We conclude that it is possible for a typical clinical laboratory to analyze a large amount of PFGE information on Shigella isolates obtained under controlled conditions. Such data analysis should enhance surveillance capabilities and give indications of further work to be done on various aspects of bacterial pathogenicity of the species.

Bacteriophage lambda↗

PubMed1991

A case of shigellosis caused by Shigella dysenteriae type 1 and Shigella flexneri type 5B.

Shigella dysenteriae type 1 and Shigella flexneri type 5b strains were isolated as causative agents of bacterial dysentery in a patient having visited South-East Asia. Both strains are a rare finding for Bulgaria. S. dysenteriae 1 strains have not been isolated since 1962, and there were only single isolates of S. flexneri 5b. The strains were of the same antibiotic resistance patterns. Conjugation experiments showed that resistance is determined by transferrable R-plasmids having identical characteristics. It is assumed that in the patient's gut transfer of an R-plasmid occurs from E. coli of the normal flora to the pathogenic shigellae.

Bulgaria↗

PubMed1985

'O'-antigens are essential virulence factors of Shigella sonnei and Shigella dysenteriae 1.

A novel transposon mutagenesis system has been developed for Shigella. We have used it to isolate specific mutants of Shigella sonnei and Shigella dysenteriae 1 that fail to produce lipopolysaccharide 'O' side chains. The virulence of the mutants was evaluated in the Sereny test and in a HeLa cell invasion assay. All HO'-minus mutants failed to provoke a positive Sereny reaction but retained the ability to invade HeLa cells. This demonstrates that 'O' side chains are virulence factors of S. sonnei and S. dysenteriae 1. 'O'-minus mutants of S. sonnei which still contained the Form I plasmid were capable of invading HeLa cells whilst plasmid-minus mutants were not, demonstrating that this plasmid encodes properties other than 'O'-antigen production that are involved in virulence.

Antigens, Bacterial↗

PubMed2002

Prevalence of the genes for shigella enterotoxins 1 and 2 among clinical isolates of shigella in Israel.

Two enterotoxins, shigella enterotoxin 1 (SHET1) and shigella enterotoxin 2 (SHET2) have been recently characterized and are believed to play a role in the clinical manifestation of shigellosis. One hundred and twenty-one isolates of Shigella spp. of 13 different serotypes and variants and 10 isolates of enteroinvasive Escherichia coli (EIEC) isolated in Israel, were examined by polymerase chain reaction for the presence of SHET1 and SHET2 genes. SHET1 was only prevalent among isolates of S. flexneri 2a while SHET2 was found in all the serotypes that were tested except for several isolates of S. flexneri 1b that lost their virulence plasmid during storage. In addition, we found that the S. flexneri 2a vaccine strain T-32 Istrati contains the gene encoding for SHET1 but not that encoding for SHET2, suggesting that the latter is located within a large deletion occurring in the 140 Mda plasmid of this S. flexneri 2a non-invasive vaccine strain.

Base Sequence↗

PubMed1999

Killed oral Shigella vaccine made from Shigella flexneri 2a protects against challenge in the rabbit model of shigellosis.

The protective efficacy of an orally administered heat-killed virulent strain of Shigella flexneri 2a (5 weekly oral doses) was evaluated in 25 rabbits (14 immunized and 11 non-immunized controls) against challenge with the same strain of Shigella using the rabbit model of shigellosis. All 11 non-immunized rabbits developed bloody diarrhoea following challenge and 6 (54%) died. None of the 14 immunized rabbits developed diarrhoea (all had pellet stools) but 3 (21%) died from causes not associated with diarrhoea. Protection from diarrhoea and dysentery following oral immunization with a killed Shigella species was 100% and highly significant. Death following challenge was 2.5-fold higher in the non-immunized group (p = 0.115) but was not significant. These promising results suggest that further studies should be undertaken to develop a killed oral vaccine against shigellosis.

Administration, Oral↗