Biomedical subjects

Sylvia Herold

Publications and source records attributed to Sylvia Herold.

4 recordsLinked to original sources

PubMed2005

Global expression of prophage genes in Escherichia coli O157:H7 strain EDL933 in response to norfloxacin.

We investigated the influence of a low concentration of the gyrase inhibitor norfloxacin on the transcriptome of enterohemorrhagic Escherichia coli O157:H7 strain EDL933. For this purpose, we used a commercial DNA microarray containing oligonucleotides specific for E. coli O157:H7 strains EDL933 and RIMD0509952 and E. coli K-12 strain MG1655. Under the conditions applied, 5,963 spots (94% of all spots) could be analyzed. Among these, 118 spots (P < 0.05) indicated transcriptional upregulation and 122 spots (P < 0.05) indicated transcriptional downregulation of the E. coli genes present on the array. Eighty-five upregulated EDL933 genes were phage borne. Fifty-two of them could be ascribed to the Shiga toxin-encoding phages (Stx phages) BP-933W and CP-933V; the other 33 genes belonged to non-Stx prophage elements in the EDL933 genome. Genes present in the BP-933W prophage genome were induced most strongly up to 158-fold in the case of stxA(2) upon induction with norfloxacin. Twenty-two additional upregulated genes appeared to be E. coli O157:H7 strain RIMD0509952-specific phage elements, and the remaining 11 genes were related mainly to recombination and stress functions. Downregulation was indicated predominantly for genes responsible for bacterial primary metabolism, such as energy production, cell division, and amino acid biosynthesis. Interestingly, some genes present in the locus of enterocyte effacement appeared to be downregulated. The results of the study have shown that a low concentration of norfloxacin has profound effects on the transcriptome of E. coli O157:H7.

Anti-Infective Agents↗

PubMed2005

The Shiga toxin 1-converting bacteriophage BP-4795 encodes an NleA-like type III effector protein.

In this study, the complete DNA sequence of Shiga toxin 1-converting bacteriophage BP-4795 was determined. The genome of BP-4795 consists of 85 open reading frames, including two complete IS629 elements and three morons at the end of its late regulatory region. One of these morons encodes a type III effector that is translocated by the locus of enterocyte effacement-encoded type III secretion system into HeLa cells, where it localizes with the Golgi apparatus.

Base Sequence↗

PubMed2005

Genetic analysis of enteropathogenic and enterohemorrhagic Escherichia coli serogroup O103 strains by molecular typing of virulence and housekeeping genes and pulsed-field gel electrophoresis.

We investigated the genetic relationships of 54 Escherichia coli O103 strains from humans, animals, and meat by molecular typing of housekeeping and virulence genes and by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) of seven housekeeping genes revealed seven profiles, I through VII. MLST profiles I plus III cover 45 Shiga toxin-producing E. coli (STEC) O103:H2 strains from Australia, Canada, France, Germany, and Northern Ireland that are characterized by the intimin (eae) epsilon gene and carry enterohemorrhagic E. coli (EHEC) virulence plasmids. MLST profile II groups five human and animal enteropathogenic E. coli (EPEC) O103:H2 strains that were positive for intimin (eae) beta. Although strains belonging to MLST groups II and I plus III are closely related to each other (92.6% identity), major differences were found in the housekeeping icdA gene and in the virulence-associated genes eae and escD. E. coli O103 strains with MLST patterns IV to VII are genetically distant from MLST I, II, and III strains, as are the non-O103 E. coli strains EDL933 (O157), MG1655 (K-12), and CFT073 (O6). Comparison of MLST results with those of PFGE and virulence typing demonstrated that E. coli O103 STEC and EPEC have recently acquired different virulence genes and DNA rearrangements, causing alterations in their PFGE patterns. PFGE typing was very useful for identification of genetically closely related subgroups among MLST I strains, such as Stx2-producing STEC O103 strains from patients with hemolytic uremic syndrome. Analysis of virulence genes contributed to grouping of E. coli O103 strains into EPEC and STEC. Novel virulence markers, such as efa (EHEC factor for adherence), paa (porcine adherence factor), and cif (cell cycle-inhibiting factor), were found widely associated with E. coli O103 EPEC and STEC strains.

Adhesins, Bacterial↗

PubMed2004

Shiga toxin-encoding bacteriophages--genomes in motion.

Shiga toxins (Stx) represent a group of bacterial toxins that are involved in human and animal disease. Stx are mainly produced by Escherichia coli isolated from human and non-human sources, Shigella dysenteriae type 1, and sporadically, by Citrobacter freundii, Enterobacter cloacae and Shigella flexneri. The genes encoding Stx are encoded in the genome of heterogeneous lambdoid prophages (Stx-converting bacteriophages; Stx-phages). They are located in a similar position in the late region of the prophage genome and stx is under control of phage genes. Therefore, induction of Stx-converting prophages triggers increased production of Stx. Following induction, Stx-phages can infect other bacteria in vivo and in vitro. Stx-phages may be considered to represent highly mobile genetic elements that play an important role in the expression of Stx, in horizontal gene transfer, and hence in genome diversification.

Animals↗