scholarly journals Mechanisms involved in the adaptation of Escherichia coli O157:H7 to the host intestinal microenvironment

2020 ◽  
Vol 134 (24) ◽  
pp. 3283-3301
Author(s):  
Romina J. Fernandez-Brando ◽  
Sean P. McAteer ◽  
Johanna Montañez-Culma ◽  
Yennifer Cortés-Araya ◽  
Jai Tree ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Horizontal Transmission ◽  
Mrna Level ◽  
Host Adaptation ◽  
Enterohemorrhagic Escherichia Coli ◽  
Interspecies Transmission ◽  
Human Populations ◽  
O157 Strain ◽  
New Host ◽  
Protein Levels

Abstract Host adaptation of pathogens may increase intra- and interspecies transmission. We showed previously that the passage of a clinically isolated enterohemorrhagic Escherichia coli (EHEC) O157 strain (125/99) through the gastrointestinal tract of mice increases its pathogenicity in the same host. In this work, we aimed to elucidate the underlying mechanism(s) involved in the patho-adaptation of the stool-recovered (125RR) strain. We assessed the global transcription profile by microarray and found almost 100 differentially expressed genes in 125RR strain compared with 125/99 strain. We detected an overexpression of Type Three Secretion System (TTSS) proteins at the mRNA and protein levels and demonstrated increased adhesion to epithelial cell lines for the 125RR strain. Additional key attributes of the 125RR strain were: increased motility on semisolid agar, which correlated with an increased fliC mRNA level; reduced Stx2 production at the mRNA and protein levels; increased survival at pH 2.5, as determined by acid resistance assays. We tested whether the overexpression of the LEE-encoded regulator (ler) in trans in the 125/99 strain could recreate the increased pathogenicity observed in the 125RR strain. As anticipated ler overexpression led to increased expression of TTSS proteins and bacterial adhesion to epithelial cells in vitro but also increased mortality and intestinal colonization in vivo. We conclude that this host-adaptation process required changes in several mechanisms that improved EHEC O157 fitness in the new host. The research highlights some of the bacterial mechanisms required for horizontal transmission of these zoonotic pathogens between their animal and human populations.

scholarly journals Transcription of the ehx Enterohemolysin Gene Is Positively Regulated by GrlA, a Global Regulator Encoded within the Locus of Enterocyte Effacement in Enterohemorrhagic Escherichia coli

2008 ◽  
Vol 190 (14) ◽  
pp. 4822-4830 ◽  
Author(s):  
Takehito Saitoh ◽  
Sunao Iyoda ◽  
Shouji Yamamoto ◽  
Yan Lu ◽  
Ken Shimuta ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Regulatory System ◽  
Enterohemorrhagic Escherichia Coli ◽  
O157 Strain ◽  
Double Mutant Strain ◽  
Positive Regulators ◽  
Protein Secretion System ◽  
Enterocyte Effacement ◽  
Type 3

ABSTRACT The pathogenicity island termed locus of enterocyte effacement (LEE) encodes a type 3 protein secretion system, whose function is required for full virulence of enterohemorrhagic Escherichia coli (EHEC). GrlR and GrlA are LEE-encoded negative and positive regulators, respectively, for controlling transcription of the ler gene, which encodes a central activator of LEE gene expression. We previously reported that the GrlR-GrlA regulatory system controls not only the LEE genes but also flagellar gene expression in EHEC (S. Iyoda et al., J. Bacteriol. 188:5682-5692, 2006). In order to further explore virulence-related genes under the control of the GrlR-GrlA regulatory system, we characterized a grlR-deleted EHEC O157 strain, which was found to have high and low levels of expression of LEE and flagellar genes, respectively. We report here that the grlR deletion significantly induced enterohemolysin (Ehx) activity of EHEC O157 on plates containing defibrinated sheep erythrocytes. Ehx levels were not induced in the grlR grlA double mutant strain but increased markedly by overexpression of GrlA even in the ler mutant, indicating that GrlA is responsible for this regulation. Ehx of the EHEC O157 Sakai strain is encoded by the ehxCABD genes, which are carried on the large plasmid pO157. The expression of ehxC fused with FLAG tag or a promoterless lacZ gene on pO157 was significantly induced under conditions in which GrlA was overproduced. These results together suggest that GrlA acts as a positive regulator for the ehx transcription in EHEC.

scholarly journals Verotoxin 2 Enhances Adherence of Enterohemorrhagic Escherichia coli O157:H7 to Intestinal Epithelial Cells and Expression of β1-Integrin by IPEC-J2 Cells

2010 ◽  
Vol 76 (13) ◽  
pp. 4461-4468 ◽  
Author(s):  
Bianfang Liu ◽  
Xianhua Yin ◽  
Yanni Feng ◽  
James R. Chambers ◽  
Aiguang Guo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Human Colon ◽  
Enterohemorrhagic Escherichia Coli ◽  
Β1 Integrin ◽  
Intestinal Epithelial ◽  
Wild Type ◽  
O157 Strain ◽  
Human Laryngeal Carcinoma

ABSTRACT Verotoxin (VT) has been implicated in the promotion of adherence to and colonization of intestinal epithelial cells by enterohemorrhagic Escherichia coli (EHEC) O157:H7. The present study investigated the effect of VT2 on the adherence of EHEC O157:H7 strain 86-24 to porcine jejunal (IPEC-J2), human colon (CaCo-2), and human laryngeal carcinoma (HEp-2) cell lines and on the expression in IPEC-J2 cells of synthases for β1-integrin and nucleolin, both of which are implicated in bacterial adherence. The effect on expression of globotriaosylceramide (Gb3) synthase, the receptor for VT, was also examined. Data were obtained by adherence assays and quantitative reverse transcriptase PCR, using EHEC O157 strain 86-24, a vt2 deletion mutant, a vt2 phage-negative strain, and complemented mutants in which the vt2 gene was restored. Compared with the adherence of the parent and complemented mutant strains, the vt2-negative strains adhered significantly less to all three types of cells. Adherence of the wild-type EHEC strain to IPEC-J2 cells was accompanied by increased expression of β1-integrin, nucleolin, and Gb3 synthase. IPEC-J2 cells in association with wild-type EHEC O157:H7 or the complemented mutants expressed higher levels of β1-integrin than did cells in association with the vt2-negative strains or with no bacteria. Expression of nucleolin was decreased by association with the vt2-negative mutant, but complementation failed to restore wild-type expression. The data indicate that VT2 plays a role in the adherence of EHEC O157:H7 to intestinal epithelial cells, possibly by increasing the expression of the host receptor β1-integrin.

scholarly journals Autoinducer 3 and Epinephrine Signaling in the Kinetics of Locus of Enterocyte Effacement Gene Expression in Enterohemorrhagic Escherichia coli

2006 ◽  
Vol 74 (10) ◽  
pp. 5445-5455 ◽  
Author(s):  
Matthew Walters ◽  
Vanessa Sperandio
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Enterohemorrhagic Escherichia Coli ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Protein Levels ◽  
Enterocyte Effacement ◽  
K 12 ◽  
And Function ◽  
Kinetics Of

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for causing outbreaks of bloody diarrhea and hemolytic-uremic syndrome throughout the world. The locus of enterocyte effacement (LEE) consists of five major operons and is required for the formation of attaching and effacing lesions that disrupt intestinal epithelial microvilli. We have previously reported that expression of EHEC LEE genes is regulated by the luxS quorum-sensing system. The luxS gene in EHEC affects the production of autoinducer 3 (AI-3), which activates the LEE. Epinephrine and norepinephrine also activate the LEE in a manner similar to that of AI-3. Previous studies of quorum-sensing regulation of LEE transcription have thus far been restricted to using reporter systems in an E. coli K-12 background. Here, we examined the kinetics of LEE gene transcription, protein expression, and function of the LEE type III secretion apparatus in wild-type (WT) EHEC and an isogenic luxS mutant. The results revealed that the luxS mutant had diminished transcription from the LEE promoters during the mid-exponential growth phase; decreased protein levels of EscJ, Tir, and EspA; and reduced secretion of EspA and EspB. The luxS mutation also caused a delay in the formation of attaching and effacing lesions on cultured epithelial cells compared to the wild type. Epinephrine enhanced LEE expression in both the WT and the luxS mutant, but the WT still exhibited greater LEE activation. The results suggest a possible synergistic relationship between AI-3 and epinephrine. The combined effects of these two signaling molecules may lead to greater LEE expression and a more efficient infection.

scholarly journals Virulence Properties of mcr-1-Positive Escherichia coli Isolated from Retail Poultry Meat

2021 ◽  
Vol 9 (2) ◽  
pp. 308
Author(s):  
Michaela Kubelová ◽  
Ivana Koláčková ◽  
Tereza Gelbíčová ◽  
Martina Florianová ◽  
Alžběta Kalová ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Poultry Meat ◽  
Human Populations ◽  
E Coli ◽  
Antimicrobial Resistance Genes ◽  
Mlst Type ◽  
On Line ◽  
Sequence Types

The great plasticity and diversity of the Escherichia coli genome, together with the ubiquitous occurrence, make E. coli a bacterium of world-wide concern. Of particular interest are pathogenic strains and strains harboring antimicrobial resistance genes. Overlapping virulence-associated traits between avian-source E. coli and human extraintestinal pathogenic E. coli (ExPEC) suggest zoonotic potential and safety threat of poultry food products. We analyzed whole-genome sequencing (WGS) data of 46 mcr-1-positive E. coli strains isolated from retail raw meat purchased in the Czech Republic. The investigated strains were characterized by their phylogroup—B1 (43%), A (30%), D (11%), E (7%), F (4%), B2 (2%), C (2%), MLST type, and serotype. A total of 30 multilocus sequence types (STs), of which ST744 was the most common (11%), were identified, with O8 and O89 as the most prevalent serogroups. Using the VirulenceFinder tool, 3 to 26 virulence genes were detected in the examined strains and a total of 7 (15%) strains met the pathogenic criteria for ExPEC. Four strains were defined as UPEC (9%) and 18 (39%) E. coli strains could be classified as APEC. The WGS methods and available on-line tools for their evaluation enable a comprehensive approach to the diagnosis of virulent properties of E. coli strains and represent a suitable and comfortable platform for their detection. Our results show that poultry meat may serve as an important reservoir of strains carrying both virulence and antibiotic resistance genes for animal and human populations.

scholarly journals Influence of Bacterial Competitors on Salmonella enterica and Enterohemorrhagic Escherichia coli Growth in Microbiological Media and Attachment to Vegetable Seeds

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 285
Author(s):  
Da Liu ◽  
Ronald Walcott ◽  
Kevin Mis Solval ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Salmonella Enterica ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Bacterium ◽  
Enterohemorrhagic Escherichia Coli ◽  
Biocontrol Agents ◽  
Human Pathogens ◽  
Bacterial Strains ◽  
Pathogen Populations

Interests in using biological agents for control of human pathogens on vegetable seeds are rising. This study evaluated whether probiotic bacterium Lactobacillus rhamnosus GG, bacterial strains previously used as biocontrol agents in plant science, as well as a selected plant pathogen could compete with foodborne human pathogens, such as Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC), for growth in microbiological media and attachment to vegetable seeds; and to determine whether the metabolites in cell-free supernatants of competitive bacterial spent cultures could inhibit the growth of the two pathogens. The results suggest that the co-presence of competitive bacteria, especially L. rhamnosus GG, significantly (p < 0.05) inhibited the growth of Salmonella and EHEC. Cell-free supernatants of L. rhamnosus GG cultures significantly reduced the pathogen populations in microbiological media. Although not as effective as L. rhamnosus GG in inhibiting the growth of Salmonella and EHEC, the biocontrol agents were more effective in competing for attachment to vegetable seeds. The study observed the inhibition of human bacterial pathogens by competitive bacteria or their metabolites and the competitive attachment to sprout seeds among all bacteria involved. The results will help strategize interventions to produce vegetable seeds and seed sprouts free of foodborne pathogens.

scholarly journals Quantification of enterohemorrhagic Escherichia coli O157:H7 protein abundance by high-throughput proteome

PLoS ONE ◽  
2018 ◽  
Vol 13 (12) ◽  
pp. e0208520 ◽  
Author(s):  
Wanderson Marques Da Silva ◽  
Jinlong Bei ◽  
Natalia Amigo ◽  
María Pía Valacco ◽  
Ariel Amadio ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Throughput ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Protein Abundance

scholarly journals High Prevalence of Enterohemorrhagic Escherichia coli (EHEC) O157 from Cattle in Selected Regions of Japan

2004 ◽  
Vol 66 (5) ◽  
pp. 585-587 ◽  
Author(s):  
Ayako EZAWA ◽  
Fumie GOCHO ◽  
Koji KAWATA ◽  
Tatsufumi TAKAHASHI ◽  
Naoya KIKUCHI
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
High Prevalence
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