scholarly journals Differential Attachment of Salmonella enterica and Enterohemorrhagic Escherichia coli to Alfalfa, Fenugreek, Lettuce, and Tomato Seeds

2017 ◽  
Vol 83 (7) ◽  
Author(s):  
Yue Cui ◽  
Ronald Walcott ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Bacterial Pathogens ◽  
Surface Characteristics ◽  
Enterohemorrhagic Escherichia Coli ◽  
Unit Weight ◽  
Plate Count ◽  
Fenugreek Seeds ◽  
Content Type ◽  
Fungicide Treatment ◽  
Tomato Seeds

ABSTRACT Vegetable seeds have the potential to disseminate and transmit foodborne bacterial pathogens. This study was undertaken to assess the abilities of selected Salmonella and enterohemorrhagic Escherichia coli (EHEC) strains to attach to fungicide-treated versus untreated, and intact versus mechanically damaged, seeds of alfalfa, fenugreek, lettuce, and tomato. Surface-sanitized seeds (2 g) were exposed to four individual strains of Salmonella or EHEC at 20°C for 5 h. Contaminated seeds were rinsed twice, each with 10 ml of sterilized water, before being soaked overnight in 5 ml of phosphate-buffered saline at 4°C. The seeds were then vortexed vigorously for 1 min, and pathogen populations in seed rinse water and soaking buffer were determined using a standard plate count assay. In general, the Salmonella cells had higher attachment ratios than the EHEC cells. Lettuce seeds by unit weight had the highest numbers of attached Salmonella or EHEC cells, followed by tomato, alfalfa, and fenugreek seeds. In contrast, individual fenugreek seeds had more attached pathogen cells, followed by lettuce, alfalfa, and tomato seeds. Significantly more Salmonella and EHEC cells attached to mechanically damaged seeds than to intact seeds (P < 0.05). Although, on average, significantly more Salmonella and EHEC cells were recovered from untreated than fungicide-treated seeds (P < 0.05), fungicide treatment did not significantly affect the attachment of individual bacterial strains to vegetable seeds (P > 0.05), with a few exceptions. This study fills gaps in the current body of literature and helps explain bacterial interactions with vegetable seeds with differing surface characteristics. IMPORTANCE Vegetable seeds, specifically sprout seeds, have the potential to disseminate and transmit foodborne bacterial pathogens. This study investigated the interaction between two important bacterial pathogens, i.e., Salmonella and EHEC, and vegetable seeds with differing surface characteristics. This research helps understand whether seed surface structure, integrity, and fungicide treatment affect the interaction between bacterial cells and vegetable seeds.

scholarly journals Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli Cells Artificially Internalized into Vegetable Seeds during Germination

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Da Liu ◽  
Yue Cui ◽  
Ronald Walcott ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Bacterial Pathogens ◽  
Bacterial Species ◽  
Enterohemorrhagic Escherichia Coli ◽  
Human Pathogens ◽  
Gastrointestinal Infections ◽  
Tissue Samples ◽  
Content Type ◽  
Vegetable Seed

ABSTRACTVegetable seeds contaminated with bacterial pathogens have been linked to fresh-produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior ofSalmonella entericaand enterohemorrhagicEscherichia coli(EHEC) cells artificially internalized into vegetable seeds during the germination process. Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains ofSalmonellaor EHEC. Contaminated seeds were germinated at 25°C for 9 days, and different sprout/seedling tissues were microbiologically analyzed every other day. The internalization ofSalmonellaand EHEC cells into vegetable seeds was confirmed by the absence of pathogens in seed-rinsing water and the presence of pathogens in seed homogenates after postinternalization seed surface decontamination. Results show that 317 (62%) and 343 (67%) of the 512 collected sprout/seedling tissue samples were positive forSalmonellaand EHEC, respectively. The averageSalmonellapopulations were significantly larger (P< 0.05) than the EHEC populations. Significantly largerSalmonellapopulations were recovered from the cotyledon and seed coat tissues, followed by the root tissues, but the mean EHEC populations from all sampled tissue sections were statistically similar, except in pregerminated seeds. ThreeSalmonellaand two EHEC strains had significantly larger cell populations on sprout/seedling tissues than other strains used in the study.Salmonellaand EHEC populations from fenugreek and alfalfa tissues were significantly larger than those from tomato and lettuce tissues. The study showed the fate of internalized human pathogens on germinating vegetable seeds and sprout/seedling tissues and emphasized the importance of using pathogen-free seeds for sprout production.IMPORTANCEThe internalization of microorganisms into vegetable seeds could occur naturally and represents a possible pathway of vegetable seed contamination by human pathogens. The present study investigated the ability of two important bacterial pathogens,Salmonellaand enterohemorrhagicEscherichia coli(EHEC), when artificially internalized into vegetable seeds, to grow and disseminate along vegetable sprouts/seedlings during germination. The data from the study revealed that the pathogen cells artificially internalized into vegetable seeds caused the contamination of different tissues of sprouts/seedlings and that pathogen growth on germinating seeds is bacterial species and vegetable seed-type dependent. These results further stress the necessity of using pathogen-free vegetable seeds for edible sprout production.

scholarly journals Presence of Enterohemorrhagic Escherichia coli ST678/O104:H4 in France Prior to 2011

2011 ◽  
Vol 77 (24) ◽  
pp. 8784-8786 ◽  
Author(s):  
Stefan Monecke ◽  
Patricia Mariani-Kurkdjian ◽  
Edouard Bingen ◽  
François-Xavier Weill ◽  
Charlotte Balière ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Content Type

ABSTRACTTwo isolates of enterohemorrhagicEscherichia coli(EHEC) O104:H4 were isolated in France in 2004 and 2009. Both were characterized and compared to the strain which caused the German outbreak in 2011 and to other O104:H4 strains. This suggests that different O104:H4 EHEC strains were present several years prior to the 2011 outbreak.

Bioluminescence: A Rapid Indicator of Escherichia Coli O157:H7 in Selected Yogurt and Cheese Varieties

1997 ◽  
Vol 60 (8) ◽  
pp. 891-897 ◽  
Author(s):  
L. M. HUDSON ◽  
J. CHEN ◽  
A. R. HILL ◽  
M. W. GRIFFITHS
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Cottage Cheese ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Potential Hazard ◽  
Growth And Survival ◽  
E Coli ◽  
Standard Plate Count ◽  
Standard Plate

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 have been commonly associated with products derived from ground beef, but recently the organism has been implicated as the causative agent in outbreaks involving yogurt and cheese. This finding has raised concern about the potential for its growth and survival in fermented dairy products. A bioluminescent strain of E. coli O157:H7 was used to determine postprocessing survival in yogurt with live cultures at pH 4.17, 4.39, and 4.47 stored at 4 and 10°C. In addition, survival of E. coli O157:H7 was monitored during the manufacture of Cottage, Colby, Romano, and Feta cheeses. Results indicated survival for 8 and 5 days at 4 and 10°C respectively in yogurt at pH 4.17, 17 and 15 days at 4 and 10°C respectively in yogurt at pH 4.39, and 17days at both 4 and 10°C in yogurt at pH 4.47. E. coli O157:H7 did not survive cooking procedures at 56°C in Cottage cheese. However, the pathogen survived for 27, 30, and 27 days in Colby, Romano, and Feta cheeses respectively. A high correlation of r2 &gt; 0.89 was obtained between counts of bioluminescenct colonies and standard plate count for all yogurt and cheese varieties, indicating that bioluminescence was a sensitive and rapid indicator of cellular viability for E. coli O157:H7. Survival of the pathogen, as indicated by this method, is possible in highly acidic environments even at refrigeration temperatures. This poses a potential hazard should postprocessing contamination occur.

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 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 Global Regulator of Virulence A (GrvA) Coordinates Expression of Discrete Pathogenic Mechanisms in Enterohemorrhagic Escherichia coli through Interactions with GadW-GadE

2015 ◽  
Vol 198 (3) ◽  
pp. 394-409 ◽  
Author(s):  
Jason K. Morgan ◽  
Ronan K. Carroll ◽  
Carly M. Harro ◽  
Khoury W. Vendura ◽  
Lindsey N. Shaw ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acid Resistance ◽  
Enterohemorrhagic Escherichia Coli ◽  
Sequencing Analysis ◽  
Global Regulator ◽  
Altered Expression ◽  
Content Type ◽  
Pathogenic Mechanisms ◽  
Gut Colonization ◽  
Intestinal Pathogens

ABSTRACTGlobal regulator of virulence A (GrvA) is a ToxR-family transcriptional regulator that activates locus of enterocyte effacement (LEE)-dependent adherence in enterohemorrhagicEscherichia coli(EHEC). LEE activation by GrvA requires the Rcs phosphorelay response regulator RcsB and is sensitive to physiologically relevant concentrations of bicarbonate, a known stimulant of virulence systems in intestinal pathogens. This study determines the genomic scale of GrvA-dependent regulation and uncovers details of the molecular mechanism underlying GrvA-dependent regulation of pathogenic mechanisms in EHEC. In agrvA-null background of EHEC strain TW14359, RNA sequencing analysis revealed the altered expression of over 700 genes, including the downregulation of LEE- and non-LEE-encoded effectors and the upregulation of genes for glutamate-dependent acid resistance (GDAR). Upregulation of GDAR genes corresponded with a marked increase in acid resistance. GrvA-dependent regulation of GDAR and the LEE requiredgadE, the central activator of GDAR genes and a direct repressor of the LEE. Control ofgadEby GrvA was further determined to occur through downregulation of thegadEactivator GadW. This interaction of GrvA with GadW-GadE represses the acid resistance phenotype, while it concomitantly activates the LEE-dependent adherence and secretion of immune subversion effectors. The results of this study significantly broaden the scope of GrvA-dependent regulation and its role in EHEC pathogenesis.IMPORTANCEEnterohemorrhagicEscherichia coli(EHEC) is an intestinal human pathogen causing acute hemorrhagic colitis and life-threatening hemolytic-uremic syndrome. For successful transmission and gut colonization, EHEC relies on the glutamate-dependent acid resistance (GDAR) system and a type III secretion apparatus, encoded on the LEE pathogenicity island. This study investigates the mechanism whereby the DNA-binding regulator GrvA coordinates activation of the LEE with repression of GDAR. Investigating how these systems are regulated leads to an understanding of pathogenic behavior and novel strategies aimed at disease prevention and control.

scholarly journals F Plasmids Are the Major Carriers of Antibiotic Resistance Genes in Human-Associated Commensal Escherichia coli

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Craig Stephens ◽  
Tyler Arismendi ◽  
Megan Wright ◽  
Austin Hartman ◽  
Andres Gonzalez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Transposable Elements ◽  
Dna Sequencing ◽  
Resistance Genes ◽  
Bacterial Pathogens ◽  
Acquired Resistance ◽  
Antibiotic Resistance Genes ◽  
Content Type ◽  
E Coli

ABSTRACT The evolution and propagation of antibiotic resistance by bacterial pathogens are significant threats to global public health. Contemporary DNA sequencing tools were applied here to gain insight into carriage of antibiotic resistance genes in Escherichia coli, a ubiquitous commensal bacterium in the gut microbiome in humans and many animals, and a common pathogen. Draft genome sequences generated for a collection of 101 E. coli strains isolated from healthy undergraduate students showed that horizontally acquired antibiotic resistance genes accounted for most resistance phenotypes, the primary exception being resistance to quinolones due to chromosomal mutations. A subset of 29 diverse isolates carrying acquired resistance genes and 21 control isolates lacking such genes were further subjected to long-read DNA sequencing to enable complete or nearly complete genome assembly. Acquired resistance genes primarily resided on F plasmids (101/153 [67%]), with smaller numbers on chromosomes (30/153 [20%]), IncI complex plasmids (15/153 [10%]), and small mobilizable plasmids (5/153 [3%]). Nearly all resistance genes were found in the context of known transposable elements. Very few structurally conserved plasmids with antibiotic resistance genes were identified, with the exception of an ∼90-kb F plasmid in sequence type 1193 (ST1193) isolates that appears to serve as a platform for resistance genes and may have virulence-related functions as well. Carriage of antibiotic resistance genes on transposable elements and mobile plasmids in commensal E. coli renders the resistome highly dynamic. IMPORTANCE Rising antibiotic resistance in human-associated bacterial pathogens is a serious threat to our ability to treat many infectious diseases. It is critical to understand how acquired resistance genes move in and through bacteria associated with humans, particularly for species such as Escherichia coli that are very common in the human gut but can also be dangerous pathogens. This work combined two distinct DNA sequencing approaches to allow us to explore the genomes of E. coli from college students to show that the antibiotic resistance genes these bacteria have acquired are usually carried on a specific type of plasmid that is naturally transferrable to other E. coli, and likely to other related bacteria.

scholarly journals Identification of Antibiotics That Diminish Disease in a Murine Model of Enterohemorrhagic Escherichia coli Infection

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Sabrina Mühlen ◽  
Isabell Ramming ◽  
Marina C. Pils ◽  
Martin Koeppel ◽  
Jana Glaser ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Content Type ◽  
Shiga Toxins ◽  
Escherichia Coli Infection ◽  
Uremic Syndrome ◽  
Severity Of The Disease ◽  
Selection Of ◽  
Mild Diarrhea

ABSTRACT Infections with enterohemorrhagic Escherichia coli (EHEC) cause disease ranging from mild diarrhea to hemolytic-uremic syndrome (HUS) and are the most common cause of renal failure in children in high-income countries. The severity of the disease derives from the release of Shiga toxins (Stx). The use of antibiotics to treat EHEC infections is generally avoided, as it can result in increased stx expression. Here, we systematically tested different classes of antibiotics and found that their influence on stx expression and release varies significantly. We assessed a selection of these antibiotics in vivo using the Citrobacter rodentium ϕstx2dact mouse model and show that stx2d-inducing antibiotics resulted in weight loss and kidney damage despite clearance of the infection. However, several non-Stx-inducing antibiotics cleared bacterial infection without causing Stx-mediated pathology. Our results suggest that these antibiotics might be useful in the treatment of EHEC-infected human patients and decrease the risk of HUS development.

scholarly journals EspZ of Enteropathogenic and Enterohemorrhagic Escherichia coli Regulates Type III Secretion System Protein Translocation

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Cedric N. Berger ◽  
Valerie F. Crepin ◽  
Kobi Baruch ◽  
Aurelie Mousnier ◽  
Ilan Rosenshine ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Protein Translocation ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Enterohemorrhagic Escherichia Coli ◽  
Host Cells ◽  
Dependent Manner ◽  
Content Type ◽  
Type Iii

ABSTRACTTranslocation of effector proteins via a type III secretion system (T3SS) is a widespread infection strategy among Gram-negative bacterial pathogens. Each pathogen translocates a particular set of effectors that subvert cell signaling in a way that suits its particular infection cycle. However, as effector unbalance might lead to cytotoxicity, the pathogens must employ mechanisms that regulate the intracellular effector concentration. We present evidence that the effector EspZ controls T3SS effector translocation from enteropathogenic (EPEC) and enterohemorrhagic (EHEC)Escherichia coli. Consistently, an EPECespZmutant is highly cytotoxic. Following ectopic expression, we found that EspZ inhibited the formation of actin pedestals as it blocked the translocation of Tir, as well as other effectors, including Map and EspF. Moreover, during infection EspZ inhibited effector translocation following superinfection. Importantly, while EspZ of EHEC O157:H7 had a universal “translocation stop” activity, EspZ of EPEC inhibited effector translocation from typical EPEC strains but not from EHEC O157:H7 or its progenitor, atypical EPEC O55:H7. We found that the N and C termini of EspZ, which contains two transmembrane domains, face the cytosolic leaflet of the plasma membrane at the site of bacterial attachment, while the extracellular loop of EspZ is responsible for its strain-specific activity. These results show that EPEC and EHEC acquired a sophisticated mechanism to regulate the effector translocation.IMPORTANCEEnteropathogenicEscherichia coli(EPEC) and enterohemorrhagicE. coli(EHEC) are important diarrheal pathogens responsible for significant morbidity and mortality in developing countries and the developed world, respectively. The virulence strategy of EPEC and EHEC revolves around a conserved type III secretion system (T3SS), which translocates bacterial proteins known as effectors directly into host cells. Previous studies have shown that when cells are infected in two waves with EPEC, the first wave inhibits effector translocation by the second wave in a T3SS-dependent manner, although the factor involved was not known. Importantly, we identified EspZ as the effector responsible for blocking protein translocation following a secondary EPEC infection. Interestingly, we found that while EspZ of EHEC can block protein translocation from both EPEC and EHEC strains, EPEC EspZ cannot block translocation from EHEC. These studies show that EPEC and EHEC employ a novel infection strategy to regulate T3SS translocation.

scholarly journals Involvement of PatE, a Prophage-Encoded AraC-Like Regulator, in the Transcriptional Activation of Acid Resistance Pathways of Enterohemorrhagic Escherichia coli Strain EDL933

2012 ◽  
Vol 78 (15) ◽  
pp. 5083-5092 ◽  
Author(s):  
Jennifer K. Bender ◽  
Judyta Praszkier ◽  
Matthew J. Wakefield ◽  
Kathryn Holt ◽  
Marija Tauschek ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Transcriptional Activation ◽  
Regulatory Protein ◽  
Acid Resistance ◽  
Enterohemorrhagic Escherichia Coli ◽  
Transcriptional Analysis ◽  
Mobility Shift ◽  
Content Type ◽  
Infectious Dose ◽  
Genes Encoding

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) O157:H7 is a lethal human intestinal pathogen that causes hemorrhagic colitis and the hemolytic-uremic syndrome. EHEC is transmitted by the fecal-oral route and has a lower infectious dose than most other enteric bacterial pathogens in that fewer than 100 CFU are able to cause disease. This low infectious dose has been attributed to the ability of EHEC to survive in the acidic environment of the human stomach.In silicoanalysis of the genome of EHEC O157:H7 strain EDL933 revealed a gene,patE, for a putative AraC-like regulatory protein within the prophage island, CP-933H. Transcriptional analysis inE. colishowed that the expression ofpatEis induced during stationary phase. Data from microarray assays demonstrated that PatE activates the transcription of genes encoding proteins of acid resistance pathways. In addition, PatE downregulated the expression of a number of genes encoding heat shock proteins and the type III secretion pathway of EDL933. Transcriptional analysis and electrophoretic mobility shift assays suggested that PatE also activates the transcription of the gene for the acid stress chaperonehdeAby binding to its promoter region. Finally, assays of acid tolerance showed that increasing the expression of PatE in EHEC greatly enhanced the ability of the bacteria to survive in different acidic environments. Together, these findings indicate that EHEC strain EDL933 carries a prophage-encoded regulatory system that contributes to acid resistance.

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