scholarly journals Fitness of Enterohemorrhagic Escherichia coli (EHEC)/Enteroaggregative E. coli O104:H4 in Comparison to That of EHEC O157: Survival Studies in Food andIn Vitro

2016 ◽  
Vol 82 (21) ◽  
pp. 6326-6334 ◽  
Author(s):  
Christina Böhnlein ◽  
Jan Kabisch ◽  
Diana Meske ◽  
Charles M. A. P. Franz ◽  
Rohtraud Pichner
Keyword(s):  
Escherichia Coli ◽  
Meat Product ◽  
Enterohemorrhagic Escherichia Coli ◽  
Content Type ◽  
E Coli ◽  
Adverse Conditions ◽  
Log Reduction ◽  
Fermented Sausages ◽  
Survival Studies

ABSTRACTIn 2011, one of the world's largest outbreaks of hemolytic-uremic syndrome (HUS) occurred, caused by a rareEscherichia coliserotype, O104:H4, that shared the virulence profiles of Shiga toxin-producingE. coli(STEC)/enterohemorrhagicE. coli(EHEC) and enteroaggregativeE. coli(EAEC). The persistence and fitness factors of the highly virulent EHEC/EAEC O104:H4 strain, grown either in food orin vitro, were compared with those ofE. coliO157 outbreak-associated strains. The log reduction rates of the different EHEC strains during the maturation of fermented sausages were not significantly different. Both the O157:NM and O104:H4 serotypes could be shown by qualitative enrichment to be present after 60 days of sausage storage. Moreover, the EHEC/EAEC O104:H4 strain appeared to be more viable thanE. coliO157:H7 under conditions of decreased pH and in the presence of sodium nitrite. Analysis of specific EHEC strains in experiments with an EHEC inoculation cocktail showed a dominance of EHEC/EAEC O104:H4, which could be isolated from fermented sausages for 60 days. Inhibitory activities of EHEC/EAEC O104:H4 toward severalE. colistrains, including serotype O157 strains, could be determined. Our study suggests that EHEC/EAEC O104:H4 is well adapted to the multiple adverse conditions occurring in fermented raw sausages. Therefore, it is strongly recommended that STEC strain cocktails composed of several serotypes, instead ofE. coliO157:H7 alone, be used in food risk assessments. The enhanced persistence of EHEC/EAEC O104:H4 as a result of its robustness, as well as the production of bacteriocins, may account for its extraordinary virulence potential.IMPORTANCEIn 2011, a severe outbreak caused by an EHEC/EAEC serovar O104:H4 strain led to many HUS sequelae. In this study, the persistence of the O104:H4 strain was compared with those of other outbreak-relevant STEC strains under conditions of fermented raw sausage production. Both O157:NM and O104:H4 strains could survive longer during the production of fermented sausages thanE. coliO157:H7 strains.E. coliO104:H4 was also shown to be well adapted to the multiple adverse conditions encountered in fermented sausages, and the secretion of a bacteriocin may explain the competitive advantage of this strain in an EHEC strain cocktail. Consequently, this study strongly suggests that enhanced survival and persistence, and the presumptive production of a bacteriocin, may explain the increased virulence of the O104:H4 outbreak strain. Furthermore, this strain appears to be capable of surviving in a meat product, suggesting that meat should not be excluded as a source of potentialE. coliO104:H4 infection.

scholarly journals The Intimin-Like Protein FdeC Is Regulated by H-NS and Temperature in Enterohemorrhagic Escherichia coli

2014 ◽  
Vol 80 (23) ◽  
pp. 7337-7347 ◽  
Author(s):  
Donna M. Easton ◽  
Luke P. Allsopp ◽  
Minh-Duy Phan ◽  
Danilo Gomes Moriel ◽  
Guan Kai Goh ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Culture Conditions ◽  
Enterohemorrhagic Escherichia Coli ◽  
Infection Model ◽  
Content Type ◽  
E Coli ◽  
Uremic Syndrome ◽  
Animal Hosts ◽  
And Function

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) is a Shiga-toxigenic pathogen capable of inducing severe forms of enteritis (e.g., hemorrhagic colitis) and extraintestinal sequelae (e.g., hemolytic-uremic syndrome). The molecular basis of colonization of human and animal hosts by EHEC is not yet completely understood, and an improved understanding of EHEC mucosal adherence may lead to the development of interventions that could disrupt host colonization. FdeC, also referred to by its IHE3034 locus tag ECOK1_0290, is an intimin-like protein that was recently shown to contribute to kidney colonization in a mouse urinary tract infection model. The expression of FdeC is tightly regulatedin vitro, and FdeC shows promise as a vaccine candidate against extraintestinalE. colistrains. In this study, we characterized the prevalence, regulation, and function offdeCin EHEC. We showed that thefdeCgene is conserved in both O157 and non-O157 EHEC and encodes a protein that is expressed at the cell surface and promotes biofilm formation under continuous-flow conditions in a recombinantE. colistrain background. We also identified culture conditions under which FdeC is expressed and showed that minor alterations of these conditions, such as changes in temperature, can significantly alter the level of FdeC expression. Additionally, we demonstrated that the transcription of thefdeCgene is repressed by the global regulator H-NS. Taken together, our data suggest a role for FdeC in EHEC when it grows at temperatures above 37°C, a condition relevant to its specialized niche at the rectoanal junctions of cattle.

scholarly journals Paenipeptin Analogues Potentiate Clarithromycin and Rifampin against mcr-1-Mediated Polymyxin-Resistant Escherichia coli In Vivo

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Sun Hee Moon ◽  
Yihong Kaufmann ◽  
En Huang
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Outer Membrane ◽  
Infection Model ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Log Reduction

ABSTRACT Polymyxin resistance mediated by the mcr-1 gene threatens the last-resort antibiotics. Linear lipopeptide paenipeptin analogues 1 and 15 disrupted the outer membrane of Gram-negative pathogens and potentiated clarithromycin and rifampin against mcr-1-positive Escherichia coli from the FDA-CDC Antimicrobial Resistance Isolate Bank. In the presence of paenipeptin, clarithromycin and rifampin resulted in over 3-log reduction of E. coli in vitro. Moreover, paenipeptin-antibiotic combinations significantly reduced E. coli in a murine thigh infection model.

scholarly journals A Rhodobacter sphaeroides Protein Mechanistically Similar to Escherichia coli DksA Regulates Photosynthetic Growth

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Christopher W. Lennon ◽  
Kimberly C. Lemmer ◽  
Jessica L. Irons ◽  
Max I. Sellman ◽  
Timothy J. Donohue ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Structure Function ◽  
Rhodobacter Sphaeroides ◽  
Fatty Acid Content ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Globular Domain ◽  
Content Type ◽  
E Coli

ABSTRACTDksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacteriumEscherichia coliand for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly relatedRhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length toE. coliDksA but lacks the Zn finger motif of theE. coliDksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of anE. colistrain lacking thedksAgene and modulates transcriptionin vitrowithE. coliRNA polymerase (RNAP) similarly toE. coliDksA. RSP2654 reduces RNAP-promoter complex stabilityin vitrowith RNAPs fromE. coliorR. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity toE. coliDksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsphas distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp.IMPORTANCEThe role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis inRhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.

scholarly journals Screening of Escherichia coli Species Biodiversity Reveals New Biofilm-Associated Antiadhesion Polysaccharides

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
Olaya Rendueles ◽  
Laetitia Travier ◽  
Patricia Latour-Lambert ◽  
Thierry Fontaine ◽  
Julie Magnus ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Bacterial Adhesion ◽  
Bioactive Molecules ◽  
Bacterial Biofilms ◽  
Gram Positive ◽  
Content Type ◽  
E Coli ◽  
Species Biodiversity

ABSTRACTBacterial biofilms often form multispecies communities in which complex but ill-understood competition and cooperation interactions occur. In light of the profound physiological modifications associated with this lifestyle, we hypothesized that the biofilm environment might represent an untapped source of natural bioactive molecules interfering with bacterial adhesion or biofilm formation. We produced cell-free solutions extracted fromin vitromature biofilms formed by 122 naturalEscherichia coliisolates, and we screened these biofilm extracts for antiadhesion molecules active on a panel of Gram-positive and Gram-negative bacteria. Using this approach, we showed that 20% of the tested biofilm extracts contained molecules that antagonize bacterial growth or adhesion. We characterized a compound, produced by a commensal animalE. colistrain, for which activity is detected only in biofilm extract. Biochemical and genetic analyses showed that this compound corresponds to a new type of released high-molecular-weight polysaccharide whose biofilm-associated production is regulated by the RfaH protein. We demonstrated that the antiadhesion activity of this polysaccharide was restricted to Gram-positive bacteria and that its production reduced susceptibility to invasion and provided rapid exclusion ofStaphylococcus aureusfrom mixedE. coliandS. aureusbiofilms. Our results therefore demonstrate that biofilms contain molecules that contribute to the dynamics of mixed bacterial communities and that are not or only poorly detected in unconcentrated planktonic supernatants. Systematic identification of these compounds could lead to strategies that limit pathogen surface colonization and reduce the burden associated with the development of bacterial biofilms on medical devices.IMPORTANCEWe sought to demonstrate that bacterial biofilms are reservoirs for unknown molecules that antagonize bacterial adhesion. The use of natural strains representative ofEscherichia colispecies biodiversity showed that nonbiocidal antiadhesion polysaccharides are frequently found in mature biofilm extracts (bacterium-free suspensions which contain soluble molecules produced within the biofilm). Release of an antiadhesion polysaccharide confers a competitive advantage upon the producing strain against clinically relevant pathogens such asStaphylococcus aureus. Hence, exploring the biofilm environment provides a better understanding of bacterial interactions within complex communities and could lead to improved control of pathogen colonization.

scholarly journals Antibiotic-Mediated Modulations of Outer Membrane Vesicles in Enterohemorrhagic Escherichia coli O104:H4 and O157:H7

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Andreas Bauwens ◽  
Lisa Kunsmann ◽  
Helge Karch ◽  
Alexander Mellmann ◽  
Martina Bielaszewska
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Shiga Toxin ◽  
Membrane Vesicles ◽  
Polymyxin B ◽  
Outer Membrane Vesicles ◽  
Enterohemorrhagic Escherichia Coli ◽  
Content Type ◽  
E Coli ◽  
Major Virulence Factor

ABSTRACT Ciprofloxacin, meropenem, fosfomycin, and polymyxin B strongly increase production of outer membrane vesicles (OMVs) in Escherichia coli O104:H4 and O157:H7. Ciprofloxacin also upregulates OMV-associated Shiga toxin 2a, the major virulence factor of these pathogens, whereas the other antibiotics increase OMV production without the toxin. These two effects might worsen the clinical outcome of infections caused by Shiga toxin-producing E. coli. Our data support the existing recommendations to avoid antibiotics for treatment of these infections.

scholarly journals In VivoTransmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness

2015 ◽  
Vol 81 (10) ◽  
pp. 3561-3570 ◽  
Author(s):  
Timothy J. Johnson ◽  
Randall S. Singer ◽  
Richard E. Isaacson ◽  
Jessica L. Danzeisen ◽  
Kevin Lang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Dose ◽  
Broad Host Range ◽  
Antibiotic Administration ◽  
Dose Administration ◽  
Content Type ◽  
E Coli ◽  
The Impact ◽  
Selection Of

ABSTRACTIncA/C plasmids are broad-host-range plasmids enabling multidrug resistance that have emerged worldwide among bacterial pathogens of humans and animals. Although antibiotic usage is suspected to be a driving force in the emergence of such strains, few studies have examined the impact of different types of antibiotic administration on the selection of plasmid-containing multidrug resistant isolates. In this study, chlortetracycline treatment at different concentrations in pig feed was examined for its impact on selection and dissemination of an IncA/C plasmid introduced orally via a commensalEscherichia colihost. Continuous low-dose administration of chlortetracycline at 50 g per ton had no observable impact on the proportions of IncA/C plasmid-containingE. colifrom pig feces over the course of 35 days. In contrast, high-dose administration of chlortetracycline at 350 g per ton significantly increased IncA/C plasmid-containingE. coliin pig feces (P< 0.001) and increased movement of the IncA/C plasmid to other indigenousE. colihosts. There was no evidence of conjugal transfer of the IncA/C plasmid to bacterial species other thanE. coli.In vitrocompetition assays demonstrated that bacterial host background substantially impacted the cost of IncA/C plasmid carriage inE. coliandSalmonella.In vitrotransfer and selection experiments demonstrated that tetracycline at 32 μg/ml was necessary to enhance IncA/C plasmid conjugative transfer, while subinhibitory concentrations of tetracyclinein vitrostrongly selected for IncA/C plasmid-containingE. coli. Together, these experiments improve our knowledge on the impact of differing concentrations of tetracycline on the selection of IncA/C-type plasmids.

scholarly journals A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Erin M. Nawrocki ◽  
Hillary M. Mosso ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Microbial Interactions ◽  
Severe Illness ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Lambdoid Prophage

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo. Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.

scholarly journals Comparative Analysis of EspF Variants in Inhibition of Escherichia coli Phagocytosis by Macrophages and Inhibition of E. coli Translocation through Human- and Bovine-Derived M Cells

2011 ◽  
Vol 79 (11) ◽  
pp. 4716-4729 ◽  
Author(s):  
Amin Tahoun ◽  
Gabriella Siszler ◽  
Kevin Spears ◽  
Sean McAteer ◽  
Jai Tree ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Cellular Localization ◽  
M Cells ◽  
Binding Assays ◽  
M Cell ◽  
Content Type ◽  
E Coli ◽  
Coculture System

ABSTRACTThe EspF protein is secreted by the type III secretion system of enteropathogenic and enterohemorrhagicEscherichia coli(EPEC and EHEC, respectively). EspF sequences differ between EHEC O157:H7, EHEC O26:H11, and EPEC O127:H6 in terms of the number of SH3-binding polyproline-rich repeats and specific residues in these regions, as well as residues in the amino domain involved in cellular localization. EspFO127is important for the inhibition of phagocytosis by EPEC and also limits EPEC translocation through antigen-sampling cells (M cells). EspFO127has been shown to have effects on cellular organelle function and interacts with several host proteins, including N-WASP and sorting nexin 9 (SNX9). In this study, we compared the capacities of differentespFalleles to inhibit (i) bacterial phagocytosis by macrophages, (ii) translocation through an M-cell coculture system, and (iii) uptake by and translocation through cultured bovine epithelial cells. TheespFgene fromE. coliserotype O157 (espFO157) allele was significantly less effective at inhibiting phagocytosis and also had reduced capacity to inhibitE. colitranslocation through a human-derivedin vitroM-cell coculture system in comparison toespFO127andespFO26. In contrast,espFO157was the most effective allele at restricting bacterial uptake into and translocation through primary epithelial cells cultured from the bovine terminal rectum, the predominant colonization site of EHEC O157 in cattle and a site containing M-like cells. Although LUMIER binding assays demonstrated differences in the interactions of the EspF variants with SNX9 and N-WASP, we propose that other, as-yet-uncharacterized interactions contribute to the host-based variation in EspF activity demonstrated here.

scholarly journals Advantage of the F2:A1:B- IncF Pandemic Plasmid over IncC Plasmids in In Vitro Acquisition and Evolution of blaCTX-M Gene-Bearing Plasmids in Escherichia coli

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Anne-Claire Mahérault ◽  
Harry Kemble ◽  
Mélanie Magnan ◽  
Benoit Gachet ◽  
David Roche ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Experimental Evolution ◽  
Negative Impact ◽  
Fitness Cost ◽  
M Gene ◽  
Content Type ◽  
E Coli ◽  
Conjugative Plasmids ◽  
K 12

ABSTRACT Despite a fitness cost imposed on bacterial hosts, large conjugative plasmids play a key role in the diffusion of resistance determinants, such as CTX-M extended-spectrum β-lactamases. Among the large conjugative plasmids, IncF plasmids are the most predominant group, and an F2:A1:B- IncF-type plasmid encoding a CTX-M-15 variant was recently described as being strongly associated with the emerging worldwide Escherichia coli sequence type 131 (ST131)-O25b:H4 H30Rx/C2 sublineage. In this context, we investigated the fitness cost of narrow-range F-type plasmids, including the F2:A1:B- IncF-type CTX-M-15 plasmid, and of broad-range C-type plasmids in the K-12-like J53-2 E. coli strain. Although all plasmids imposed a significant fitness cost to the bacterial host immediately after conjugation, we show, using an experimental-evolution approach, that a negative impact on the fitness of the host strain was maintained throughout 1,120 generations with the IncC-IncR plasmid, regardless of the presence or absence of cefotaxime, in contrast to the F2:A1:B- IncF plasmid, whose cost was alleviated. Many chromosomal and plasmid rearrangements were detected after conjugation in transconjugants carrying the IncC plasmids but not in transconjugants carrying the F2:A1:B- IncF plasmid, except for insertion sequence (IS) mobilization from the fliM gene leading to the restoration of motility of the recipient strains. Only a few mutations occurred on the chromosome of each transconjugant throughout the experimental-evolution assay. Our findings indicate that the F2:A1:B- IncF CTX-M-15 plasmid is well adapted to the E. coli strain studied, contrary to the IncC-IncR CTX-M-15 plasmid, and that such plasmid-host adaptation could participate in the evolutionary success of the CTX-M-15-producing pandemic E. coli ST131-O25b:H4 lineage.

scholarly journals Stress-Induced MazF-Mediated Proteins in Escherichia coli

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Akanksha Nigam ◽  
Tamar Ziv ◽  
Adi Oron-Gottesman ◽  
Hanna Engelberg-Kulka
Keyword(s):  
Escherichia Coli ◽  
Proteomic Analysis ◽  
Normal Growth ◽  
Growth Conditions ◽  
Translation Machinery ◽  
Content Type ◽  
E Coli ◽  
Adverse Conditions ◽  
Almost All ◽  
Induced Proteins

ABSTRACT Escherichia coli mazEF is an extensively studied stress-induced toxin-antitoxin (TA) system. The toxin MazF is an endoribonuclease that cleaves RNAs at ACA sites. By that means, under stress, the induced MazF generates a stress-induced translation machinery (STM) composed of MazF-processed mRNAs and selective ribosomes that specifically translate the processed mRNAs. Here, we performed a proteomic analysis of all the E. coli stress-induced proteins that are mediated through the chromosomally borne mazF gene. We show that the mRNAs of almost all of them are characterized by the presence of an ACA site up to 100 nucleotides upstream of the AUG initiator. Therefore, under stressful conditions, induced MazF processes mRNAs that are translated by STM. Furthermore, the presence of the ACA sites far upstream (up to 100 nucleotides) of the AUG initiator may still permit translation by the canonical translation machinery. Thus, such dual-translation mechanisms enable the bacterium under stress also to prepare proteins for immediate functions while coming back to normal growth conditions. IMPORTANCE The stress response, the strategy that bacteria have developed in order to cope up with all kinds of adverse conditions, is so far understood at the level of transcription. Our previous findings of a uniquely modified stress-induced translation machinery (STM) generated in E. coli under stress by the endoribonucleolytic activity of the toxin MazF opens a new chapter in understanding microbial physiology under stress at the translational level. Here, we performed a proteomic analysis of all the E. coli stress-induced proteins that are mediated by chromosomally borne MazF through STM.

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