scholarly journals Microgravity Alters the Physiological Characteristics of Escherichia coli O157:H7 ATCC 35150, ATCC 43889, and ATCC 43895 under Different Nutrient Conditions

2014 ◽  
Vol 80 (7) ◽  
pp. 2270-2278 ◽  
Author(s):  
H. W. Kim ◽  
A. Matin ◽  
M. S. Rhee
Keyword(s):  
Escherichia Coli ◽  
Optical Density ◽  
Minimal Medium ◽  
Cultured Cells ◽  
Physiological Characteristics ◽  
Nutrient Metabolism ◽  
Content Type ◽  
E Coli ◽  
Food Borne ◽  
Space Conditions

ABSTRACTThe aim of this study is to provide understanding of microgravity effects on important food-borne bacteria,Escherichia coliO157:H7 ATCC 35150, ATCC 43889, and ATCC 43895, cultured in nutrient-rich or minimal medium. Physiological characteristics, such as growth (measured by optical density and plating), cell morphology, and pH, were monitored under low-shear modeled microgravity (LSMMG; space conditions) and normal gravity (NG; Earth conditions). In nutrient-rich medium, all strains except ATCC 35150 showed significantly higher optical density after 6 h of culture under LSMMG conditions than under NG conditions (P< 0.05). LSMMG-cultured cells were approximately 1.8 times larger than NG-cultured cells at 24 h; therefore, it was assumed that the increase in optical density was due to the size of individual cells rather than an increase in the cell population. The higher pH of the NG cultures relative to that of the LSMMG cultures suggests that nitrogen metabolism was slower in the latter. After 24 h of culturing in minimal media, LSMMG-cultured cells had an optical density 1.3 times higher than that of NG-cultured cells; thus, the higher optical density in the LSMMG cultures may be due to an increase in both cell size and number. Since bacteria actively grew under LSMMG conditions in minimal medium despite the lower pH, it is of some concern that LSMMG-culturedE. coliO157:H7 may be able to adapt well to acidic environments. These changes may be caused by changes in nutrient metabolism under LSMMG conditions, although this needs to be demonstrated in future studies.

scholarly journals Genomic Diversity and Virulence Profiles of Historical Escherichia coli O157 Strains Isolated from Clinical and Environmental Sources

2014 ◽  
Vol 81 (2) ◽  
pp. 569-577 ◽  
Author(s):  
Lydia V. Rump ◽  
Narjol Gonzalez-Escalona ◽  
Wenting Ju ◽  
Fei Wang ◽  
Guojie Cao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
The United States ◽  
Genomic Diversity ◽  
Severe Illness ◽  
Pathogenic Potential ◽  
Content Type ◽  
E Coli ◽  
Virulence Markers ◽  
Virulence Potential ◽  
Food Borne

ABSTRACTEscherichia coliO157:H7 is, to date, the majorE. coliserotype causing food-borne human disease worldwide. Strains of O157 with other H antigens also have been recovered. We analyzed a collection of historic O157 strains (n= 400) isolated in the late 1980s to early 1990s in the United States. Strains were predominantly serotype O157:H7 (55%), and various O157:non-H7 (41%) serotypes were not previously reported regarding their pathogenic potential. Although lacking Shiga toxin (stx) andeaegenes, serotypes O157:H1, O157:H2, O157:H11, O157:H42, and O157:H43 carried several virulence factors (iha,terD, andhlyA) also found in virulent serotypeE. coliO157:H7. Pulsed-field gel electrophoresis (PFGE) showed the O157 serogroup was diverse, with strains with the same H type clustering together closely. Among non-H7 isolates, serotype O157:H43 was highly prevalent (65%) and carried important enterohemorrhagicE. coli(EHEC) virulence markers (iha,terD,hlyA, andespP). Isolates from two particular H types, H2 and H11, among the most commonly found non-O157 EHEC serotypes (O26:H11, O111:H11, O103:H2/H11, and O45:H2), unexpectedly clustered more closely with O157:H7 than other H types and carried several virulence genes. This suggests an early divergence of the O157 serogroup to clades with different pathogenic potentials. The appearance of important EHEC virulence markers in closely related H types suggests their virulence potential and suggests further monitoring of those serotypes not implicated in severe illness thus far.

scholarly journals Detection and Identification of Salmonella enterica, Escherichia coli, and Shigella spp. via PCR-Electrospray Ionization Mass Spectrometry: Isolate Testing and Analysis of Food Samples

2012 ◽  
Vol 78 (23) ◽  
pp. 8403-8411 ◽  
Author(s):  
Sarah E. Pierce ◽  
Rebecca L. Bell ◽  
Rosalee S. Hellberg ◽  
Chorng-Ming Cheng ◽  
Kai-Shun Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Electrospray Ionization ◽  
Salmonella Enterica ◽  
Food Samples ◽  
Reference Database ◽  
Ionization Mass ◽  
Content Type ◽  
E Coli ◽  
Food Borne ◽  
Biosensor System

ABSTRACTAn assay to identify the common food-borne pathogensSalmonella,Escherichia coli,Shigella, andListeria monocytogeneswas developed in collaboration with Ibis Biosciences (a division of Abbott Molecular) for the Plex-ID biosensor system, a platform that uses electrospray ionization mass spectroscopy (ESI-MS) to detect the base composition of short PCR amplicons. The new food-borne pathogen (FBP) plate has been experimentally designed using four gene segments for a total of eight amplicon targets. Initial work built a DNA base count database that contains more than 140Salmonella enterica, 139E. coli, 11Shigella, and 36Listeriapatterns and 18 otherEnterobacteriaceaeorganisms. This assay was tested to determine the scope of the assay's ability to detect and differentiate the enteric pathogens and to improve the reference database associated with the assay. More than 800 bacterial isolates ofS. enterica,E. coli, andShigellaspecies were analyzed. Overall, 100% ofS. enterica, 99% ofE. coli, and 73% ofShigellaspp. were detected using this assay. The assay was also able to identify 30% of theS. entericaserovars to the serovar level. To further characterize the assay, spiked food matrices and food samples collected during regulatory field work were also studied. While analysis of preenrichment media was inconsistent, identification ofS. entericafrom selective enrichment media resulted in serovar-level identifications for 8 of 10 regulatory samples. The results of this study suggest that this high-throughput method may be useful in clinical and regulatory laboratories testing for these pathogens.

scholarly journals Identification and Characterization of Spontaneous Deletions within the Sp11-Sp12 Prophage Region of Escherichia coli O157:H7 Sakai

2013 ◽  
Vol 79 (6) ◽  
pp. 1934-1941 ◽  
Author(s):  
Chun Chen ◽  
Carrie R. Lewis ◽  
Kakolie Goswami ◽  
Elisabeth L. Roberts ◽  
Chitrita DebRoy ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Genomic Region ◽  
Escherichia Coli O157 ◽  
Content Type ◽  
E Coli ◽  
Food Borne ◽  
Genes Encoding ◽  
Identification And Characterization

ABSTRACTProphages make up 12% of the enterohemorrhagicEscherichia coligenome and play prominent roles in the evolution and virulence of this food-borne pathogen. Acquisition and loss of and rearrangements within prophage regions are the primary causes of differences in pulsed-field gel electrophoresis (PFGE) patterns among strains ofE. coliO157:H7. Sp11 and Sp12 are two tandemly integrated and putatively defective prophages carried byE. coliO157:H7 strain Sakai. In this study, we identified 3 classes of deletions that occur within the Sp11-Sp12 region, at a frequency of ca. 7.74 × 10−4. One deletion resulted in a precise excision of Sp11, and the other two spanned the junction of Sp11 and Sp12. All deletions resulted in shifts in the XbaI fragment pattern observed by PFGE. We sequenced the inducible prophage pool of Sakai but did not identify any mature phage particles corresponding to either Sp11 or Sp12. Deletions containingpchBandpsrC, which are Sp11-carried genes encoding proteins known or suspected to regulate type III secretion, did not affect the secretion levels of the EspA or EspB effector. Alignment of the Sp11-Sp12 DNA sequence with its corresponding regions in otherE. coliO157:H7 and O55:H7 strains suggested that homologous recombination rather than integrase-mediated excision is the mechanism behind these deletions. Therefore, this study provides a mechanism behind the previously observed genetic instability of this genomic region ofE. coliO157:H7.

scholarly journals The Gene tia, Harbored by the Subtilase-Encoding Pathogenicity Island, Is Involved in the Ability of Locus of Enterocyte Effacement-Negative Shiga Toxin-Producing Escherichia coli Strains To Invade Monolayers of Epithelial Cells

2017 ◽  
Vol 85 (12) ◽  
Author(s):  
Roslen Bondì ◽  
Paola Chiani ◽  
Valeria Michelacci ◽  
Fabio Minelli ◽  
Alfredo Caprioli ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Shiga Toxin ◽  
Cultured Cells ◽  
Pathogenicity Island ◽  
Content Type ◽  
Cell Monolayers ◽  
E Coli ◽  
Enterocyte Effacement ◽  
K 12

ABSTRACT Locus of enterocyte effacement (LEE)-negative Shiga toxin (Stx)-producing Escherichia coli (STEC) strains are human pathogens that lack the LEE locus, a pathogenicity island (PAI) involved in the intimate adhesion of LEE-positive strains to the host gut epithelium. The mechanism used by LEE-negative STEC strains to colonize the host intestinal mucosa is still not clear. The cell invasion determinant tia, previously described in enterotoxigenic E. coli strains, has been identified in LEE-negative STEC strains that possess the subtilase-encoding pathogenicity island (SE-PAI). We evaluated the role of the gene tia, present in these LEE-negative STEC strains, in the invasion of monolayers of cultured cells. We observed that these strains were able to invade Caco-2 and HEp-2 cell monolayers and compared their invasion ability with that of a mutant strain in which the gene tia had been inactivated. Mutation of the gene tia resulted in a strong reduction of the invasive phenotype, and complementation of the tia mutation with a functional copy of the gene restored the invasion activity. Moreover, we show that the gene tia is overexpressed in bacteria actively invading cell monolayers, demonstrating that tia is involved in the ability to invade cultured monolayers of epithelial cells shown by SE-PAI-positive E. coli, including STEC, strains. However, the expression of the tia gene in the E. coli K-12 strain JM109 was not sufficient, in its own right, to confer to this strain the ability to invade cell monolayers, suggesting that at least another factor must be involved in the invasion ability displayed by the SE-PAI-positive strains.

scholarly journals An Escherichia coli O157-Specific Engineered Pyocin Prevents and Ameliorates Infection by E. coli O157:H7 in an Animal Model of Diarrheal Disease

2011 ◽  
Vol 55 (12) ◽  
pp. 5469-5474 ◽  
Author(s):  
Jennifer M. Ritchie ◽  
Jennifer L. Greenwich ◽  
Brigid M. Davis ◽  
Roderick T. Bronson ◽  
Dana Gebhart ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Diarrheal Disease ◽  
Intestinal Inflammation ◽  
Rabbit Model ◽  
Prophylactic Regimen ◽  
Content Type ◽  
Fecal Shedding ◽  
E Coli ◽  
Food Borne ◽  
Enteric Infections

ABSTRACTAvR2-V10.3 is an engineered R-type pyocin that specifically killsEscherichia coliO157, an enteric pathogen that is a major cause of food-borne diarrheal disease. New therapeutics to counteractE. coliO157 are needed, as currently available antibiotics can exacerbate the consequences of infection. We show here that orogastric administration of AvR2-V10.3 can prevent or ameliorateE. coliO157:H7-induced diarrhea and intestinal inflammation in an infant rabbit model of infection when the compound is administered either in a postexposure prophylactic regimen or after the onset of symptoms. Notably, administration of AvR2-V10.3 also reduces bacterial carriage and fecal shedding of this pathogen. Our findings support the further development of pathogen-specific R-type pyocins as a way to treat enteric infections.

scholarly journals Diversity of Shiga Toxin-Producing Escherichia coli (STEC) O26:H11 Strains Examined viastxSubtypes and Insertion Sites of Stx and EspK Bacteriophages

2015 ◽  
Vol 81 (11) ◽  
pp. 3712-3721 ◽  
Author(s):  
Ludivine Bonanno ◽  
Estelle Loukiadis ◽  
Patricia Mariani-Kurkdjian ◽  
Eric Oswald ◽  
Lucille Garnier ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Sequence Type ◽  
Phylogenetic Groups ◽  
Content Type ◽  
Shiga Toxins ◽  
E Coli ◽  
Food Borne ◽  
Insertion Sites ◽  
Human Infections

ABSTRACTShiga toxin-producingEscherichia coli(STEC) is a food-borne pathogen that may be responsible for severe human infections. Only a limited number of serotypes, including O26:H11, are involved in the majority of serious cases and outbreaks. The main virulence factors, Shiga toxins (Stx), are encoded by bacteriophages. Seventy-four STEC O26:H11 strains of various origins (including human, dairy, and cattle) were characterized for theirstxsubtypes and Stx phage chromosomal insertion sites. The majority of food and cattle strains possessed thestx1asubtype, while human strains carried mainlystx1aorstx2a. ThewrbAandyehVgenes were the main Stx phage insertion sites in STEC O26:H11, followed distantly byyecEandsbcB. Interestingly, the occurrence of Stx phages inserted in theyecEgene was low in dairy strains. In most of the 29stx-negativeE. coliO26:H11 strains also studied here, these bacterial insertion sites were vacant. Multilocus sequence typing of 20stx-positive orstx-negativeE. coliO26:H11 strains showed that they were distributed into two phylogenetic groups defined by sequence type 21 (ST21) and ST29. Finally, an EspK-carrying phage was found inserted in thessrAgene in the majority of the STEC O26:H11 strains but in only a minority of thestx-negativeE. coliO26:H11 strains. The differences in thestxsubtypes and Stx phage insertion sites observed in STEC O26:H11 according to their origin might reflect that strains circulating in cattle and foods are clonally distinct from those isolated from human patients.

scholarly journals OmpT Outer Membrane Proteases of Enterohemorrhagic and Enteropathogenic Escherichia coli Contribute Differently to the Degradation of Human LL-37

2011 ◽  
Vol 80 (2) ◽  
pp. 483-492 ◽  
Author(s):  
Jenny-Lee Thomassin ◽  
John R. Brannon ◽  
Bernard F. Gibbs ◽  
Samantha Gruenheid ◽  
Hervé Le Moual
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Time Course ◽  
Dependent Manner ◽  
Content Type ◽  
Reading Frame ◽  
E Coli ◽  
Food Borne ◽  
Mutant Strains

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) and enteropathogenicE. coli(EPEC) are food-borne pathogens that cause serious diarrheal diseases. To colonize the human intestine, these pathogens must overcome innate immune defenses such as antimicrobial peptides (AMPs). Bacterial pathogens have evolved various mechanisms to resist killing by AMPs, including proteolytic degradation of AMPs. To examine the ability of the EHEC and EPEC OmpT outer membrane (OM) proteases to degrade α-helical AMPs,ompTdeletion mutants were generated. Determination of MICs of various AMPs revealed that both mutant strains are more susceptible than their wild-type counterparts to α-helical AMPs, although to different extents. Time course assays monitoring the degradation of LL-37 and C18G showed that EHEC cells degraded both AMPs faster than EPEC cells in an OmpT-dependent manner. Mass spectrometry analyses of proteolytic fragments showed that EHEC OmpT cleaves LL-37 at dibasic sites. The superior protection provided by EHEC OmpT compared to EPEC OmpT against α-helical AMPs was due to higher expression of theompTgene and, in turn, higher levels of the OmpT protein in EHEC. Fusion of the EPECompTpromoter to the EHECompTopen reading frame resulted in decreased OmpT expression, indicating that transcriptional regulation ofompTis different in EHEC and EPEC. We hypothesize that the different contributions of EHEC and EPEC OmpT to the degradation and inactivation of LL-37 may be due to their adaptation to their respective niches within the host, the colon and small intestine, respectively, where the environmental cues and abundance of AMPs are different.

scholarly journals Creation of a Cellooligosaccharide-Assimilating Escherichia coli Strain by Displaying Active Beta-Glucosidase on the Cell Surface via a Novel Anchor Protein

2011 ◽  
Vol 77 (17) ◽  
pp. 6265-6270 ◽  
Author(s):  
Tsutomu Tanaka ◽  
Hitomi Kawabata ◽  
Chiaki Ogino ◽  
Akihiko Kondo
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Optical Density ◽  
Coli Strain ◽  
Thermobifida Fusca ◽  
Content Type ◽  
Anchor Protein ◽  
E Coli ◽  
Beta Glucosidase

ABSTRACTWe demonstrated direct assimilation of cellooligosaccharide usingEscherichia colidisplaying beta-glucosidase (BGL). BGL fromThermobifida fuscaYX (Tfu0937) was displayed on theE. colicell surface using a novel anchor protein named Blc. This strain was grown successfully on 0.2% cellobiose, and the optical density at 600 nm (OD600) was 1.05 after 20 h.

scholarly journals ArcA Controls Metabolism, Chemotaxis, and Motility Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli

2015 ◽  
Vol 83 (9) ◽  
pp. 3545-3554 ◽  
Author(s):  
Fengwei Jiang ◽  
Chunxia An ◽  
Yinli Bao ◽  
Xuefeng Zhao ◽  
Robert L. Jernigan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Seq ◽  
Global Regulator ◽  
Content Type ◽  
E Coli ◽  
Citrate Metabolism ◽  
Food Borne ◽  
Pathogenic Escherichia Coli ◽  
And Control ◽  
Potential Food

Avian pathogenicEscherichia coli(APEC) strains cause one of the three most significant infectious diseases in the poultry industry and are also potential food-borne pathogens threating human health. In this study, we showed that ArcA (aerobicrespiratorycontrol), a global regulator important forE. coli's adaptation from anaerobic to aerobic conditions and control of that bacterium's enzymatic defenses against reactive oxygen species (ROS), is involved in the virulence of APEC. Deletion ofarcAsignificantly attenuates the virulence of APEC in the duck model. Transcriptome sequencing (RNA-Seq) analyses comparing the APEC wild type and thearcAmutant indicate that ArcA regulates the expression of 129 genes, including genes involved in citrate transport and metabolism, flagellum synthesis, and chemotaxis. Further investigations revealed thatcitCEFXGcontributed to APEC's microaerobic growth at the lag and log phases when cultured in duck serum and that ArcA played a dual role in the control of citrate metabolism and transportation. In addition, deletion of flagellar genesmotAandmotBand chemotaxis genecheAsignificantly attenuated the virulence of APEC, and ArcA was shown to directly regulate the expression ofmotA,motB, andcheA. The combined results indicate that ArcA controls metabolism, chemotaxis, and motility contributing to the pathogenicity of APEC.

scholarly journals Detection and Prevalence of Verotoxin-Producing Escherichia coli O157 and Non-O157 Serotypes in a Canadian Watershed

2014 ◽  
Vol 80 (7) ◽  
pp. 2166-2175 ◽  
Author(s):  
R. P. Johnson ◽  
B. Holtslander ◽  
A. Mazzocco ◽  
S. Roche ◽  
J. L. Thomas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Surface Water ◽  
Immunomagnetic Separation ◽  
Human Pathogens ◽  
Public Health Perspective ◽  
Low Frequencies ◽  
Content Type ◽  
E Coli ◽  
Food Borne ◽  
Prevalence Estimates

ABSTRACTVerotoxin-producingEscherichia coli(VTEC) strains are the cause of food-borne and waterborne illnesses around the world. Traditionally, surveillance of the human population as well as the environment has focused on the detection ofE. coliO157:H7. Recently, increasing recognition of non-O157 VTEC strains as human pathogens and the German O104:H4 food-borne outbreak have illustrated the importance of considering the broader group of VTEC organisms from a public health perspective. This study presents the results of a comparison of three methods for the detection of VTEC in surface water, highlighting the efficacy of a direct VT immunoblotting method without broth enrichment for detection and isolation of O157 and non-O157 VTEC strains. The direct immunoblot method eliminates the need for an enrichment step or the use of immunomagnetic separation. This method was developed after 4 years of detecting low frequencies (1%) ofE. coliO157:H7 in surface water in a Canadian watershed, situated within one of the FoodNet Canada integrated surveillance sites. By the direct immunoblot method, VTEC prevalence estimates ranged from 11 to 35% for this watershed, andE. coliO157:H7 prevalence increased to 4% (due to improved method sensitivity). This direct testing method provides an efficient means to enhance our understanding of the prevalence and types of VTEC in the environment. This study employed a rapid evidence assessment (REA) approach to frame the watershed findings with watershedE. coliO157:H7 prevalences reported in the literature since 1990 and the knowledge gap with respect to VTEC detection in surface waters.

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