scholarly journals Development of MoSe2 Nano-Urchins as a Sensing Platform for a Selective Bio-Capturing of Escherichia. coli Shiga Toxin DNA

Biosensors ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 77 ◽  
Author(s):  
Jagriti Narang ◽  
Annu Mishra ◽  
Roberto Pilloton ◽  
Alekhya VV ◽  
Shikha Wadhwa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Shiga Toxin ◽  
Fourier Transforms ◽  
Glass Electrode ◽  
Oxide Glass ◽  
Current Response ◽  
Detection Range ◽  
Sensing Platform ◽  
Detection Of Biomolecules

The present study was aimed to develop “fluorine doped” tin oxide glass electrode with a MoSe2 nano-urchin based electrochemical biosensor for detection of Escherichia. coli Shiga toxin DNA. The study comprises two conductive electrodes, and the working electrodes were drop deposited using MoSe2 nano-urchin, and DNA sequences specific to Shiga toxin Escherichia. coli. Morphological characterizations were performed using Fourier transforms infrared spectrophotometer; X-ray diffraction technique and scanning electron microscopy. All measurements were done using methylene blue as an electrochemical indicator. The proposed electrochemical geno-sensor showed good linear detection range of 1 fM–100 μM with a low detection limit of 1 fM where the current response increased linearly with Escherichia. coli Shiga toxin dsDNA concentration with R2 = 0.99. Additionally, the real sample was spiked with the dsDNA that shows insignificant interference. The results revealed that the developed sensing platform significantly improved the sensitivity and can provide a promising platform for effective detection of biomolecules using minute samples due to its stability and sensitivity.

scholarly journals Sequence-based typing of genetic targets encoded outside of the O-antigen gene cluster is indicative of Shiga toxin-producing Escherichia coli serogroup lineages

2007 ◽  
Vol 56 (5) ◽  
pp. 620-628 ◽  
Author(s):  
Matthew W. Gilmour ◽  
Adam B. Olson ◽  
Ashleigh K. Andrysiak ◽  
Lai-King Ng ◽  
Linda Chui
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Dna Sequences ◽  
Shiga Toxin ◽  
Clinical Isolates ◽  
Comparative Analyses ◽  
Antigen Gene ◽  
O Antigen ◽  
Additional Support ◽  
H Serotypes

Serogroup classifications based upon the O-somatic antigen of Shiga toxin-producing Escherichia coli (STEC) provide significant epidemiological information on clinical isolates. Each O-antigen determinant is encoded by a unique cluster of genes present between the gnd and galF chromosomal genes. Alternatively, serogroup-specific polymorphisms might be encoded in loci that are encoded outside of the O-antigen gene cluster. Segments of the core bacterial loci mdh, gnd, gcl, ppk, metA, ftsZ, relA and metG for 30 O26 STEC strains have previously been sequenced, and comparative analyses to O157 distinguished these two serogroups. To screen these loci for serogroup-specific traits within a broader range of clinically significant serogroups, DNA sequences were obtained for 19 strains of 10 additional STEC serogroups. Unique alleles were observed at the gnd locus for each examined STEC serogroup, and this correlation persisted when comparative analyses were extended to 144 gnd sequences from 26 O-serogroups (comprising 42 O : H-serotypes). These included O157, O121, O103, O26, O5 : non-motile (NM), O145 : NM, O113 : H21, O111 : NM and O117 : H7 STEC; and furthermore, non-toxin encoding O157, O26, O55, O6 and O117 strains encoded distinct gnd alleles compared to STEC strains of the same serogroup. DNA sequencing of a 643 bp region of gnd was, therefore, sufficient to minimally determine the O-antigen of STEC through molecular means, and the location of gnd next to the O-antigen gene cluster offered additional support for the co-inheritance of these determinants. The gnd DNA sequence-based serogrouping method could improve the typing capabilities for STEC in clinical laboratories, and was used successfully to characterize O121 : H19, O26 : H11 and O177 : NM clinical isolates prior to serological confirmation during outbreak investigations.

scholarly journals Genomic Subtraction To Identify and Characterize Sequences of Shiga Toxin-Producing Escherichia coli O91:H21

2002 ◽  
Vol 68 (5) ◽  
pp. 2316-2325 ◽  
Author(s):  
Nathalie Pradel ◽  
Sabine Leroy-Setrin ◽  
Bernard Joly ◽  
Valérie Livrelli
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Shiga Toxin ◽  
Shigella Flexneri ◽  
Virulence Determinants ◽  
E Coli ◽  
Virulence Plasmids ◽  
Subtraction Procedure ◽  
Uremic Syndrome ◽  
Genomic Subtraction

ABSTRACT To identify Shiga toxin-producing Escherichia coli genes associated with severe human disease, a genomic subtraction technique was used with hemolytic-uremic syndrome-associated O91:H21 strain CH014 and O6:H10 bovine strains. The method was adapted to the Shiga toxin-producing E. coli genome: three rounds of subtraction were used to isolate DNA fragments specific to strain CH014. The fragments were characterized by genetic support analysis, sequencing, and hybridization to the genome of a collection of Shiga toxin-producing E. coli strains. A total of 42 fragments were found, 19 of which correspond to previously identified unique DNA sequences in the enterohemorrhagic E. coli EDL933 reference strain, including 7 fragments corresponding to prophage sequences and others encoding candidate virulence factors, such a SepA homolog protein and a fimbrial usher protein. In addition, the subtraction procedure yielded plasmid-related sequences from Shigella flexneri and enteropathogenic and Shiga toxin-producing E. coli virulence plasmids. We found that lateral gene transfer is extensive in strain CH014, and we discuss the role of genomic mobile elements, especially bacteriophages, in the evolution and possible transfer of virulence determinants.

scholarly journals Evaluation of Major Types of Shiga Toxin 2e-Producing Escherichia coli Bacteria Present in Food, Pigs, and the Environment as Potential Pathogens for Humans

2008 ◽  
Vol 74 (15) ◽  
pp. 4806-4816 ◽  
Author(s):  
Lothar Beutin ◽  
Ulrike Krüger ◽  
Gladys Krause ◽  
Angelika Miko ◽  
Annett Martin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Shiga Toxin ◽  
Diarrheal Disease ◽  
Toxin Production ◽  
Enzyme Linked Immunosorbent Assay ◽  
Nucleotide Sequencing ◽  
Human Pathogens ◽  
Virulence Markers ◽  
Escherichia Coli Bacteria

ABSTRACT Shiga toxin 2e (Stx2e)-producing strains from food (n = 36), slaughtered pigs (n = 25), the environment (n = 21), diseased pigs (n = 19), and humans (n = 9) were investigated for production of Stx2e by enzyme-linked immunosorbent assay, for virulence markers by PCR, and for their serotypes to evaluate their role as potential human pathogens. Stx2e production was low in 64% of all 110 strains. Stx2e production was inducible by mitomycin C but differed considerably between strains. Analysis by nucleotide sequencing and transcription of stx 2e genes in high- and low-Stx2e-producing strains showed that toxin production correlated with transcription rates of stx 2e genes. DNA sequences specific for the int, Q, dam, and S genes of the stx 2e bacteriophage P27 were found in 109 strains, indicating cryptic P27-like prophages, although 102 of these were not complete for all genes tested. Genes encoding intimin (eae), enterohemorrhagic Escherichia coli hemolysin (ehx), or other stx 1 or stx 2 variants were not found, whereas genes for heat-stable enterotoxins STI, STII, or EAST1 were present in 54.5% of the strains. Seven major serotypes that were associated with diseased pigs (O138:H14, O139:H1, and O141:H4) or with slaughter pigs, food, and the environment (O8:H4, O8:H9, O100:H30, and O101:H9) accounted for 60% of all Stx2e strains. The human Stx2e isolates did not belong to these major serotypes of Stx2e strains, and high production of Stx2e in human strains was not related to diarrheal disease. The results from this study and other studies do not point to Stx2e as a pathogenicity factor for diarrhea and hemolytic uremic syndrome in humans.

scholarly journals Bacteriophages of Shiga Toxin-Producing Escherichia coli and Their Contribution to Pathogenicity

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 404
Author(s):  
Lorena Rodríguez-Rubio ◽  
Nadja Haarmann ◽  
Maike Schwidder ◽  
Maite Muniesa ◽  
Herbert Schmidt
Keyword(s):  
Escherichia Coli ◽  
Life Cycle ◽  
Dna Sequences ◽  
Shiga Toxin ◽  
Late Phase ◽  
Temperate Phage ◽  
Shiga Toxins ◽  
Genetic Features ◽  
Physical Stimuli ◽  
Foreign Genes

Shiga toxins (Stx) of Shiga toxin-producing Escherichia coli (STEC) are generally encoded in the genome of lambdoid bacteriophages, which spend the most time of their life cycle integrated as prophages in specific sites of the bacterial chromosome. Upon spontaneous induction or induction by chemical or physical stimuli, the stx genes are co-transcribed together with the late phase genes of the prophages. After being assembled in the cytoplasm, and after host cell lysis, mature bacteriophage particles are released into the environment, together with Stx. As members of the group of lambdoid phages, Stx phages share many genetic features with the archetypical temperate phage Lambda, but are heterogeneous in their DNA sequences due to frequent recombination events. In addition to Stx phages, the genome of pathogenic STEC bacteria may contain numerous prophages, which are either cryptic or functional. These prophages may carry foreign genes, some of them related to virulence, besides those necessary for the phage life cycle. Since the production of one or more Stx is considered the major pathogenicity factor of STEC, we aim to highlight the new insights on the contribution of Stx phages and other STEC phages to pathogenicity.

scholarly journals Genomic Characterization of Two Shiga Toxin–Converting Bacteriophages Induced From Environmental Shiga Toxin–Producing Escherichia coli

2021 ◽  
Vol 12 ◽  
Author(s):  
Yujie Zhang ◽  
Yen-Te Liao ◽  
Alexandra Salvador ◽  
Vivian C. H. Wu
Keyword(s):  
Escherichia Coli ◽  
Phylogenetic Analysis ◽  
Dna Sequences ◽  
Shiga Toxin ◽  
Genomic Diversity ◽  
Whole Genome ◽  
E Coli ◽  
Uremic Syndrome ◽  
Genomic Characterization

Shiga toxin (Stx), encoded by stx genes located in prophage sequences, is the major agent responsible for the pathogenicity of Shiga toxin-producing Escherichia coli (STEC) and is closely associated with the development of hemolytic uremic syndrome (HUS). Although numerous Stx prophage sequences have been reported as part of STEC bacterial genomes, the information about the genomic characterization of Stx-converting bacteriophages induced from STEC strains is relatively scarce. The objectives of this study were to genomically characterize two Stx-converting phages induced from environmental STEC strains and to evaluate their correlations with published Stx-converting phages and STEC strains of different origins. The Stx1-converting phage Lys8385Vzw and the Stx2-converting phage Lys19259Vzw were induced from E. coli O103:H11 (RM8385) and E. coli O157:H7 (RM19259), respectively. Whole-genome sequencing of these phages was conducted on a MiSeq sequencer for genomic characterization. Phylogenetic analysis and comparative genomics were performed to determine the correlations between these two Stx-converting phages, 13 reference Stx-converting phages, and 10 reference STEC genomes carrying closely related Stx prophages. Both Stx-converting phages Lys8385Vzw and Lys19259Vzw had double-stranded DNA, with genome sizes of 50,953 and 61,072 bp, respectively. Approximately 40% of the annotated coding DNA sequences with the predicted functions were likely associated with the fitness for both phages and their bacterial hosts. The whole-genome–based phylogenetic analysis of these two Stx-converting phages and 13 reference Stx-converting phages revealed that the 15 Stx-converting phages were divided into three distinct clusters, and those from E. coli O157:H7, in particular, were distributed in each cluster, demonstrating the high genomic diversity of these Stx-converting phages. The genomes of Stx-converting phage Lys8385Vzw and Lys19259Vzw shared a high-nucleotide similarity with the prophage sequences of the selected STEC isolates from the clinical and environmental origin. The findings demonstrate the genomic diversity of Stx-converting phages induced from different STEC strains and provide valuable insights into the dissemination of stx genes among E. coli population via the lysogenization of Stx-converting phages.

scholarly journals Association of Ct Values from Real-Time PCR with Culture in Microbiological Clearance Samples for Shiga Toxin-Producing Escherichia coli (STEC)

2020 ◽  
Vol 8 (11) ◽  
pp. 1801
Author(s):  
Michael Bording-Jorgensen ◽  
Brendon D. Parsons ◽  
Gillian A.M. Tarr ◽  
Binal Shah-Gandhi ◽  
Colin Lloyd ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Shiga Toxin ◽  
Real Time Pcr ◽  
Gene Detection ◽  
Culture Positivity ◽  
Hands On ◽  
Culture Independent ◽  
Chromogenic Agar ◽  
Stool Samples

Shiga toxin-producing Escherichia coli (STEC) are associated with acute gastroenteritis worldwide, which induces a high economic burden on both healthcare and individuals. Culture-independent diagnostic tests (CIDT) in frontline microbiology laboratories have been implemented in Alberta since 2019. The objectives of this study were to determine the association between gene detection and culture positivity over time using STEC microbiological clearance samples and also to establish the frequency of specimen submission. Both stx genes’ amplification by real-time PCR was performed with DNA extracted from stool samples using the easyMAG system. Stools were inoculated onto chromogenic agar for culture. An association between gene detection and culture positivity was found to be independent of which stx gene was present. CIDT can provide rapid reporting with less hands-on time and technical expertise. However, culture is still important for surveillance and early cluster detection. In addition, stool submissions could be reduced from daily to every 3–5 days until a sample is negative by culture.

scholarly journals Effects of Plant Age and Root Damage on Internalization of Shiga Toxin-Producing Escherichia coli in Leafy Vegetables and Herbs

Horticulturae ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 68
Author(s):  
Yi-Ju Wang ◽  
Amanda J. Deering ◽  
Hye-Ji Kim
Keyword(s):  
Escherichia Coli ◽  
Plant Species ◽  
Shiga Toxin ◽  
Production Systems ◽  
Plant Age ◽  
Leafy Vegetables ◽  
Root Damage ◽  
Hygiene Practices ◽  
Hydroponic Systems ◽  
Stx1 Gene

Our previous study reported that fresh produce grown in aquaponic and hydroponic systems can pose potential food safety hazards due to an accidental introduction of contaminated fish and cross-contamination between the systems. In this study, we examined the effects of plant species and age on the likelihood and level of internalization of Shiga toxin-producing Escherichia coli (STEC) in aquaponic and hydroponic systems. Four plant species, basil (Ocimum basilicum L. cv. Genovese), cilantro (Coriandrum Sativum L.), lettuce (Lactuca sativa cv. Cherokee), and kale (Brassica oleracea var. sabellica), received root damage treatment as seedlings before transplanting or mature plants at three weeks after transplanting by cutting off 1-cm tips of one-third of the roots. Enrichments and selective media were used for the isolation, and presumptive positive colonies were confirmed by PCR for the presence of stx1 gene in plant tissues, recirculating water, and fish feces collected at four weeks after transplanting. In hydroponic systems, STEC was found neither in the solution nor in the roots and leaves of all four plant species, possibly through improved sanitation and hygiene practices. However, consistent with our previous findings, STEC was found in the water, on the plant roots, and in the fish feces in aquaponic systems, even after thorough sanitation prior to the study. Regardless of plant age, STEC was internalized in the roots of all plant species when the roots were damaged, but there was no difference in the degree of internalization with STEC among plant species. STEC was present in the leaves only when seedlings received root damage treatment and were grown to maturity, indicating that root damage allows STEC to internalize in the roots within a week, but a longer period is required for STEC to internalize into the leaves. We concluded that root damage on seedlings can cause the internalization of E. coli O157:H7 in the edible parts of leafy vegetables and herbs in soilless production systems.

Sign in / Sign up

Export Citation Format

Share Document