A Novel
            <i>Shigella dysenteriae</i>
            Serovar Isolated in Canada

Melito, Pasquale L.; Woodward, David L.; Munro, Jamie; Walsh, Julie A.; Foster, R. A.; Tilley, Peter; Paccagnella, Ana; Isaac-Renton, Judith L.; Ismaïl, Johanne; Ng, L.-K.

doi:10.1128/jcm.43.2.740-744.2005

Cited by 19 publications

(17 citation statements)

References 24 publications

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“…Serotyping is not always able to provide a correct species identification, due to cross-reactions or the absence of agglutination. New serotypes are regularly discovered (28,49) and are sometimes found to cross-react with Escherichia coli strains.…”

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confidence: 99%

Selection and Validation of a Multilocus Variable-Number Tandem-Repeat Analysis Panel for Typing Shigella spp

et al. 2008

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The Shigella genus has historically been separated into four species, based on biochemical assays. The classification within each species relies on serotyping. Recently, genome sequencing and DNA assays, in particular the multilocus sequence typing (MLST) approach, greatly improved the current knowledge of the origin and phylogenetic evolution of Shigella spp. The Shigella and Escherichia genera are now considered to belong to a unique genomospecies. Multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) provides valuable polymorphic markers for genotyping and performing phylogenetic analyses of highly homogeneous bacterial pathogens. Here, we assess the capability of MLVA for Shigella typing. Thirty-two potentially polymorphic VNTRs were selected by analyzing in silico five Shigella genomic sequences and subsequently evaluated. Eventually, a panel of 15 VNTRs was selected (i.e., MLVA15 analysis). MLVA15 analysis of 78 strains or genome sequences of Shigella spp. and 11 strains or genome sequences of Escherichia coli distinguished 83 genotypes. Shigella population cluster analysis gave consistent results compared to MLST. MLVA15 analysis showed capabilities for E. coli typing, providing classification among pathogenic and nonpathogenic E. coli strains included in the study. The resulting data can be queried on our genotyping webpage (http://mlva .u-psud.fr). The MLVA15 assay is rapid, highly discriminatory, and reproducible for Shigella and Escherichia strains, suggesting that it could significantly contribute to epidemiological trace-back analysis of Shigella infections and pathogenic Escherichia outbreaks. Typing was performed on strains obtained mostly from collections. Further studies should include strains of much more diverse origins, including all pathogenic E. coli types.

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confidence: 99%

Selection and Validation of a Multilocus Variable-Number Tandem-Repeat Analysis Panel for Typing Shigella spp

et al. 2008

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“…Several studies have been conducted to detect virulence genes in Shigella by mPCR, targeting ipaH , ial , and rfc or stx1 for serotype identification [3,5,7,39]. In 2005, Thong [5] first described a new mPCR system to detect S. flexneri 2a by targeting four virulence genes ( ipaH , ial , set1A and set1B ).…”

Section: Discussionmentioning

confidence: 99%

“…The ipaH , ial , and set1B genes were detected by mPCR with primers designed according to the sequences of these genes in SF301 (Table 1) [3,5,7]. Clinical S. flexneri isolates ( n = 86) were tested using mPCR.…”

Section: Methodsmentioning

confidence: 99%

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Deletion of pic results in decreased virulence for a clinical isolate of Shigella flexneri2a from China

Zhang

Qian

et al. 2013

BMC Microbiol

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BackgroundShigella is a major pathogen responsible for bacillary dysentery, a severe form of shigellosis. Severity of the disease depends on the virulence of the infecting strain. Shigella pathogenicity is a multi-gene phenomenon, involving the participation of genes on an unstable large virulence plasmid and chromosomal pathogenicity islands.ResultsA multiplex PCR (mPCR) assay was developed to detect S. flexneri 2a from rural regions of Zhengding (Hebei Province, China). We isolated and tested 86 strains using our mPCR assay, which targeted the ipaH, ial and set1B genes. A clinical strain of S. flexneri 2a 51 (SF51) containing ipaH and ial, but lacking set1B was found. The virulence of this strain was found to be markedly decreased. Further testing showed that the SF51 strain lacked pic. To investigate the role of pic in S. flexneri 2a infections, a pic knockout mutant (SF301-∆ pic) and two complementation strains, SF301-∆ pic/pPic and SF51/pPic, were created. Differences in virulence for SF51, SF301-∆ pic, SF301-∆ pic/pPic, SF51/pPic and S. flexneri 2a 301 (SF301) were compared. Compared with SF301, both SF51 and SF301-∆ pic exhibited lower levels of Hela cell invasion and resulted in reduced keratoconjunctivitis, with low levels of tissue damage seen in murine eye sections. The virulence of SF301-∆ pic and SF51 was partially recovered in vitro and in vivo through the addition of a complementary pic gene.ConclusionsThe pic gene appears to be involved in an increase in pathogenicity of S. flexneri 2a. This gene assists with bacterial invasion into host cells and alters inflammatory reactions.

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“…Three new Shigella serotypes and an O148 Shiga toxin-producing E. coli strain have been described using the rfb-RFLP test (3)(4)(5)(6). The possibility of searching the database of reference rfb-RFLP patterns using MST might further contribute to the epidemiology of E. coli and Shigella.…”

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confidence: 99%

MST (Molecular Serotyping Tool): a Program for Computer-Assisted Molecular Identification of Escherichia coli and Shigella O Antigens

et al. 2010

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Escherichia coli and Shigella O antigens can be inferred using the rfb-restriction fragment length polymorphism (RFLP) molecular test. We present herein a dynamic programming algorithm-based software to compare the rfb-RFLP patterns of clinical isolates with those in a database containing the 171 previously published patterns corresponding to all known E. coli/Shigella O antigens.Classical Escherichia coli/Shigella O serogrouping is expensive, labor-intensive, and susceptible to errors due to cross-reactivity between adsorbed O-antigen rabbit antisera, as reviewed in reference 2. Furthermore, corrupted expression of genes involved in O-antigen synthesis renders some strains nontypeable ("rough"). Importantly, classical serotyping does not detect new O antigens. These drawbacks are surmounted by the rfb-restriction fragment length polymorphism (RFLP) test (1, 2). Briefly, the rfb locus containing most of the genes involved in O-antigen synthesis is amplified by PCR and digested with MboII, and products are resolved by electrophoresis. A database with 171 rfb-RFLP patterns representing each known Shigella and E. coli O antigen has been published and used to type reference and clinical strains, including an isolate that had become rough in the lab, with 100% specificity and sensitivity (1, 2). We present herein a web-based software program to compare the rfb-RFLP patterns of clinical isolates with those of known E. coli and Shigella O antigens.For the purpose of this work, the concepts of similarity and alignment between two rfb-RFLP patterns were adopted from Needleman and Wunsch's dynamic programming algorithm (7), which detects insertions, deletions, and substitutions as changes in the strings that represent nucleic acid or protein sequences. By analogy, restriction patterns represented by ordered fragment sizes can be aligned and their similarity can be calculated as the sum of penalties for the edit operations that transform one pattern into the other. These edit operations are deletions (missing bands) and transformations (errors on fragment sizing). A scoring function assigns a penalty to each transformation, and a dynamic programming algorithm computes the best editing scores between two patterns, producing an editing matrix. For two patterns, a ϭ a 1 a 2 ⅐ ⅐ ⅐ a m and b ϭ b 1 b 2 ⅐ ⅐ ⅐ b n , where a i is the fragment size at position i of test pattern a and b j is the fragment size at position j of reference pattern b, the editing matrix has (m ϩ 1) ϫ (n ϩ 1) positions, where n is the number of fragments in pattern a and m is the number of fragments in pattern b. The matrix is initialized, filling the first column with each fragment of pattern a and the first row with each fragment of pattern b. The aim is to move across the matrix from the first column and first row to the last column and last row. At each position, it is possible to move only one step either in the diagonal to align two fragments and advance one position in both patterns or in the horizontal (or vertical) to acknowledge a missing fragmen...

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A Novel Shigella dysenteriae Serovar Isolated in Canada

Cited by 19 publications

References 24 publications

Selection and Validation of a Multilocus Variable-Number Tandem-Repeat Analysis Panel for Typing Shigella spp

Selection and Validation of a Multilocus Variable-Number Tandem-Repeat Analysis Panel for Typing Shigella spp

Deletion of pic results in decreased virulence for a clinical isolate of Shigella flexneri2a from China

MST (Molecular Serotyping Tool): a Program for Computer-Assisted Molecular Identification of Escherichia coli and Shigella O Antigens

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