scholarly journals A putative microcin amplifies Shiga toxin 2a production ofEscherichia coliO157:H7

2019 ◽  
Author(s):  
Hillary M. Figler ◽  
Lingzi Xiaoli ◽  
Kakolie Banerjee ◽  
Maria Hoffmann ◽  
Kuan Yao ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Treatment Options ◽  
Gene Clusters ◽  
Toxin Production ◽  
Additional Treatment ◽  
Proteinase K ◽  
Gut Microflora ◽  
E Coli

AbstractEscherichia coliO157:H7 is a foodborne pathogen, implicated in various multi-state outbreaks. It encodes Shiga toxin on a prophage, and Shiga toxin production is linked to phage induction. AnE. colistrain, designated 0.1229, was identified that amplified Stx2a production when co-cultured withE. coliO157:H7 strain PA2. Growth of PA2 in 0.1229 cell-free supernatants had a similar effect, even when supernatants were heated to 100°C for 10 min, but not after treatment with Proteinase K. The secreted molecule was shown to use TolC for export and the TonB system for import. The genes sufficient for production of this molecule were localized to a 5.2 kb region of a 12.8 kb plasmid. This region was annotated, identifying hypothetical proteins, a predicted ABC transporter, and a cupin superfamily protein. These genes were identified and shown to be functional in two otherE. colistrains, and bioinformatic analyses identified related gene clusters in similar and distinct bacterial species. These data collectively suggestE. coli0.1229 and otherE. coliproduce a microcin that induces the SOS response in target bacteria. Besides adding to the limited number of microcins known to be produced byE. coli, this study provides an additional mechanism by whichstx2aexpression is increased in response to the gut microflora.ImportanceHow the gut microflora influences the progression of bacterial infections is only beginning to be understood. Antibiotics are counter-indicated forE. coliO157:H7 infections, and therefore treatment options are limited. An increased understanding of how the gut microflora directs O157:H7 virulence gene expression may lead to additional treatment options. This work identifiedE. colithat enhance the production of Shiga toxin by O157:H7, through the secretion of a proposed microcin. This work demonstrates another mechanism by which non-O157E. colistrains may increase Shiga toxin production, and adds to our understanding of microcins, a group of antimicrobials that are less well understood than colicins.

scholarly journals A Putative Microcin Amplifies Shiga Toxin 2a Production of Escherichia coli O157:H7

2019 ◽  
Vol 202 (1) ◽  
Author(s):  
Hillary M. Mosso ◽  
Lingzi Xiaoli ◽  
Kakolie Banerjee ◽  
Maria Hoffmann ◽  
Kuan Yao ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Bacterial Infections ◽  
Treatment Options ◽  
Virulence Gene ◽  
Toxin Production ◽  
Additional Treatment ◽  
Gut Microflora ◽  
Content Type ◽  
Virulence Gene Expression ◽  
E Coli

How the gut microflora influences the progression of bacterial infections is only beginning to be understood. Antibiotics are counterindicated for E. coli O157:H7 infections, limiting treatment options. An increased understanding of how the gut microflora directs O157:H7 virulence gene expression may lead to additional treatment options. This work identified E. coli strains that enhance the production of Shiga toxin by O157:H7 through the secretion of a proposed microcin. Microcins are natural antimicrobial peptides that target specific species, can act as alternatives to antibiotics, and mediate microbial competition. This work demonstrates another mechanism by which non-O157 E. coli strains may increase Shiga toxin production and adds to our understanding of microcins, a group of antimicrobials less well understood than colicins.

scholarly journals Fighting Fire with Fire: Phage Potential for the Treatment of E. coli O157 Infection

Antibiotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 101 ◽  
Author(s):  
Cristina Howard-Varona ◽  
Dean Vik ◽  
Natalie Solonenko ◽  
Yueh-Fen Li ◽  
M. Gazitua ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Bacterial Infections ◽  
Antibacterial Agents ◽  
Prophylactic Treatment ◽  
Phage Therapy ◽  
Toxin Production ◽  
Prophage Induction ◽  
E Coli ◽  
Uremic Syndrome

Hemolytic–uremic syndrome is a life-threating disease most often associated with Shiga toxin-producing microorganisms like Escherichia coli (STEC), including E. coli O157:H7. Shiga toxin is encoded by resident prophages present within this bacterium, and both its production and release depend on the induction of Shiga toxin-encoding prophages. Consequently, treatment of STEC infections tend to be largely supportive rather than antibacterial, in part due to concerns about exacerbating such prophage induction. Here we explore STEC O157:H7 prophage induction in vitro as it pertains to phage therapy—the application of bacteriophages as antibacterial agents to treat bacterial infections—to curtail prophage induction events, while also reducing STEC O157:H7 presence. We observed that cultures treated with strictly lytic phages, despite being lysed, produce substantially fewer Shiga toxin-encoding temperate-phage virions than untreated STEC controls. We therefore suggest that phage therapy could have utility as a prophylactic treatment of individuals suspected of having been recently exposed to STEC, especially if prophage induction and by extension Shiga toxin production is not exacerbated.

scholarly journals Short-Tailed Stx Phages Exploit the Conserved YaeT Protein To Disseminate Shiga Toxin Genes among Enterobacteria

2007 ◽  
Vol 189 (20) ◽  
pp. 7223-7233 ◽  
Author(s):  
Darren L. Smith ◽  
Chloë E. James ◽  
Martin J. Sergeant ◽  
Yan Yaxian ◽  
Jon R. Saunders ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Bacterial Species ◽  
Erwinia Carotovora ◽  
Underlying Mechanism ◽  
Toxin Production ◽  
E Coli ◽  
Phage Adsorption ◽  
Commensal Flora ◽  
Conserved Gene

ABSTRACT Infection of Escherichia coli by Shiga toxin-encoding bacteriophages (Stx phages) was the pivotal event in the evolution of the deadly Shiga toxin-encoding E. coli (STEC), of which serotype O157:H7 is the most notorious. The number of different bacterial species and strains reported to produce Shiga toxin is now more than 500, since the first reported STEC infection outbreak in 1982. Clearly, Stx phages are spreading rapidly, but the underlying mechanism for this dissemination has not been explained. Here we show that an essential and highly conserved gene product, YaeT, which has an essential role in the insertion of proteins in the gram-negative bacterial outer membrane, is the surface molecule recognized by the majority (ca. 70%) of Stx phages via conserved tail spike proteins associated with a short-tailed morphology. The yaeT gene was initially identified through complementation, and its role was confirmed in phage binding assays with and without anti-YaeT antiserum. Heterologous cloning of E. coli yaeT to enable Stx phage adsorption to Erwinia carotovora and the phage adsorption patterns of bacterial species possessing natural yaeT variants further supported this conclusion. The use of an essential and highly conserved protein by the majority of Stx phages is a strategy that has enabled and promoted the rapid spread of shigatoxigenic potential throughout multiple E. coli serogroups and related bacterial species. Infection of commensal bacteria in the mammalian gut has been shown to amplify Shiga toxin production in vivo, and the data from this study provide a platform for the development of a therapeutic strategy to limit this YaeT-mediated infection of the commensal flora.

scholarly journals Replication of plasmids derived from Shiga toxin-converting bacteriophages in starved Escherichia coli

Microbiology ◽  
2011 ◽  
Vol 157 (1) ◽  
pp. 220-233 ◽  
Author(s):  
Bożena Nejman ◽  
Beata Nadratowska-Wesołowska ◽  
Agnieszka Szalewska-Pałasz ◽  
Alicja Węgrzyn ◽  
Grzegorz Węgrzyn
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Transcriptional Activation ◽  
Stringent Response ◽  
Toxin Production ◽  
Replication Initiation ◽  
Host Cells ◽  
Regulation Of Transcription ◽  
E Coli ◽  
Dna Replication Initiation

The pathogenicity of Shiga toxin-producing Escherichia coli (STEC) depends on the expression of stx genes that are located on lambdoid prophages. Effective toxin production occurs only after prophage induction, and one may presume that replication of the phage genome is important for an increase in the dosage of stx genes, positively influencing their expression. We investigated the replication of plasmids derived from Shiga toxin (Stx)-converting bacteriophages in starved E. coli cells, as starvation conditions may be common in the intestine of infected humans. We found that, unlike plasmids derived from bacteriophage λ, the Shiga toxin phage-derived replicons did not replicate in amino acid-starved relA + and relA − cells (showing the stringent and relaxed responses to starvation, respectively). The presence of the stable fraction of the replication initiator O protein was detected in all tested replicons. However, while ppGpp, the stringent response effector, inhibited the activities of the λ P R promoter and its homologues from Shiga toxin-converting bacteriophages, these promoters, except for λ P R, were only weakly stimulated by the DksA protein. We suggest that this less efficient (relative to λ) positive regulation of transcription responsible for transcriptional activation of the origin contributes to the inhibition of DNA replication initiation of Shiga toxin-converting bacteriophages in starved host cells, even in the absence of ppGpp (as in starved relA − hosts). Possible clinical implications of these results are discussed.

scholarly journals A novel antimicrobial peptide significantly enhances acid-induced killing of Shiga toxin-producing Escherichia coli O157 and non-O157 serotypes

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1768-1775 ◽  
Author(s):  
M. Lino ◽  
J. V. Kus ◽  
S. L. Tran ◽  
Z. Naqvi ◽  
B. Binnington ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Antimicrobial Peptide ◽  
Shiga Toxin ◽  
Antimicrobial Agents ◽  
Treatment Options ◽  
Survival Rates ◽  
Acid Stress ◽  
Toxin Production ◽  
Risk Of Progression

Shiga toxin-producing Escherichia coli (STEC) colonizes the human intestine, causing haemorrhagic colitis and haemolytic uraemic syndrome (HUS). Treatment options are limited to intravenous fluids in part because sublethal doses of some antibiotics have been shown to stimulate increased toxin release and enhance the risk of progression to HUS. Preventative antimicrobial agents, especially those that build on the natural antimicrobial action of the host defence, may provide a better option. In order to survive the acid stress of gastric passage, STEC is equipped with numerous acid resistance and DNA repair mechanisms. Inhibition of acid-induced DNA repair may offer a strategy to target survival of ingested STEC. We report here that brief pretreatment with a novel antimicrobial peptide, which was previously shown to inhibit bacterial DNA repair, significantly and profoundly reduces survival of acid-stressed O157 : H7 and non-O157 : H7 STEC seropathotypes that are highly associated with HUS. Reduction in survival rates of STEC range from 3 to 5 log. We also show that peptide/acid treatment results in little or no increase in toxin production, thereby reducing the risk of progression to HUS. This study identifies the peptide wrwycr as a potential new candidate for a preventative antimicrobial for STEC infection.

scholarly journals Evaluating the risk of bacterial infections associated with the most handled Iraqi notes in Kalar

2019 ◽  
Vol 4 (1) ◽  
pp. 26-30 ◽  
Author(s):  
Hassan Mohammad Tawfeeq ◽  
Mohammed Hassan Fatah ◽  
Ahmed Mohammed Tofiq
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Coagulase Negative Staphylococcus ◽  
Fresh Sample ◽  
Mannitol Salt Agar ◽  
E Coli ◽  
Paper Currency ◽  
Currency Note ◽  
And Staphylococcus Aureus

Every day new sources of microbial and especially bacterial infections are reported, which are not taken into account, the fact that these sources have been implicated in the outbreaks of these infections. The goals of the current research focused on the exploration of the scope of microbial pollution of the widely traded paper currency notes of the Iraqi currencies (250, 1000 and 5000 Iraqi Dinars) in Kalar city. 300 banknotes (100 samples for each of the denominations under investigation) in circulation were gathered from different categories of Kalar population and one fresh sample for each of the three currencies (control negative). Each bill was rinsed in 5 ml D.W then cultured on Nutrient agar, Mannitol Salt agar and MacConkey agar, respectively, then incubated at 37 ºC for up to 48 hours. Results revealed the rate of microbial contamination, specifically bacterial ones as 94%, 68%, and 60%, respectively on the denominations of 250, 1000, and 5000 of Iraqi Dinars. In a descending order, and with regard to the prevalence rate, bacterial species contaminated 250, 1000 and 5000 Iraqi denominations respectively were as follows: 55.31%, 32.35% and 36.66% for Bacillus sp.; 14.89%, 38.23% and 20% for coagulase-negative Staphylococcus; 8.51%, 8.82% and 20% for E. coli; 2.12%, 11.76 and 20% for Pseudomonas sp.; 2.12% for each of Klebsiella sp., and Salmonella sp.; 10.63% and 4.25% for Enterobacter sp. and Staphylococcus aureus, respectively, and only on 250 denomination;  2.94% and 5.88% for each of Corynebacterium sp. and Serratia sp. only on 1000 currency note; lastly, 3.33% for Proteus sp. on 5000 IQD only. These outcomes suggest that bacterial contamination of Iraqi Dinars, specifically the 250 denomination is risky and could be regarded as the real source of infectious diseases with the most dangerous pathogenic bacteria.  

scholarly journals Nonpathogenic Escherichia coli Can Contribute to the Production of Shiga Toxin

2003 ◽  
Vol 71 (6) ◽  
pp. 3107-3115 ◽  
Author(s):  
Shantini D. Gamage ◽  
Jane E. Strasser ◽  
Claudia L. Chalk ◽  
Alison A. Weiss
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gastrointestinal Disease ◽  
Intestinal Flora ◽  
Gene Promoter ◽  
Toxin Production ◽  
Lytic Cycle ◽  
Resistant Bacteria ◽  
E Coli ◽  
Shiga Toxin 2

ABSTRACT The food-borne pathogen, Escherichia coli O157:H7, has been associated with gastrointestinal disease and the life-threatening sequela hemolytic uremic syndrome. The genes for the virulence factor, Shiga toxin 2 (Stx2), in E. coli O157:H7 are encoded on a temperate bacteriophage under the regulation of the late gene promoter. Induction of the phage lytic cycle is required for toxin synthesis and release. We investigated the hypothesis that nonpathogenic E. coli could amplify Stx2 production if infected with the toxin-encoding phage. Toxin-encoding phage were incubated with E. coli that were either susceptible or resistant to the phage. The addition of phage to phage-susceptible bacteria resulted in up to 40-fold more toxin than a pure culture of lysogens, whereas the addition of phage to phage-resistant bacteria resulted in significantly reduced levels of toxin. Intestinal E. coli isolates incubated with Shiga toxin-encoding phage produced variable amounts of toxin. Of 37 isolates, 3 produced significantly more toxin than was present in the inoculum, and 1 fecal isolate appeared to inactivate the toxin. Toxin production in the intestine was assessed in a murine model. Fecal toxin recovery was significantly reduced when phage-resistant E. coli was present. These results suggest that the susceptibility of the intestinal flora to the Shiga toxin phage could exert either a protective or an antagonistic influence on the severity of disease by pathogens with phage-encoded Shiga toxin. Toxin production by intestinal flora may represent a novel strategy of pathogenesis.

Prevalence and Characteristics of Shiga Toxin-Producing Escherichia coli in Beef Cattle Slaughtered on Prince Edward Island

2000 ◽  
Vol 63 (11) ◽  
pp. 1583-1586 ◽  
Author(s):  
R. DOUGLAS SCHURMAN ◽  
HARRY HARIHARAN ◽  
SUSAN B HEANEY ◽  
KRIS RAHN
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Prince Edward Island ◽  
Toxin Production ◽  
Positive Sample ◽  
Chain Reaction ◽  
Antimicrobial Drugs ◽  
E Coli ◽  
Human Illness ◽  
Polymerase Chain

Fecal swabs obtained from a random sample of 1,000 beef slaughter steers and heifers from 123 Prince Edward Island (P.E.I.) farms were examined for the presence of Shiga toxin-producing Escherichia coli (STEC) using a Vero cell assay (VCA). Multiple isolates from each positive sample were tested similarly. VCA-positive isolates were confirmed as E. coli biochemically, tested for drug resistance, serotyped, and tested by polymerase chain reaction (PCR). Animals were classified as positive when an isolate was positive on VCA and the presence of the gene responsible for toxin production was confirmed by PCR. The prevalence of STEC in beef slaughter steers and heifers on P.E.I. was 4% (40 of 1,000). The total number of isolates was 43, and these comprised 26 serotypes, including 13 isolates belonging to 6 serotypes known to be associated with human illness. The most frequently isolated STEC serotype was E. coli O157 (5 isolates out of 43). Of the five E. coli O157 isolates, four were E. coli O157:H7, a serious human pathogen. The majority of STEC isolates, including all O157:H7, isolates, were susceptible to 16 commonly used antimicrobial drugs. According to PCR, 65% of the STEC isolates had the gene for Stx1. Four of these isolates, including two O157: H7, had genes for Shiga toxin (Stx)1 and Stx2.

scholarly journals Different Classes of Antibiotics Differentially Influence Shiga Toxin Production

2010 ◽  
Vol 54 (9) ◽  
pp. 3790-3798 ◽  
Author(s):  
Colleen Marie McGannon ◽  
Cynthia Ann Fuller ◽  
Alison Ann Weiss
Keyword(s):  
Shiga Toxin ◽  
Vero Cells ◽  
Toxin Production ◽  
Lytic Cycle ◽  
Temperate Bacteriophage ◽  
E Coli ◽  
Growth Inhibitory ◽  
Target Dna ◽  
Stress Signals ◽  
Very High

ABSTRACTShiga toxin (Stx) inEscherichia coliO157:H7 is encoded as a late gene product by temperate bacteriophage integrated into the chromosome. Phage late genes, includingstx, are silent in the lysogenic state. However, stress signals, including some induced by antibiotics, trigger the phage to enter the lytic cycle, and phage replication and Stx production occur concurrently. In addition to the Stx produced by O157:H7, phage produced by O157:H7 can infect harmless intestinalE. coliand recruit them to produce Shiga toxin. To understand how antibiotics influence Stx production, Stx lysogens were treated with different classes of antibiotics in the presence or absence of phage-sensitiveE. coli, and Stx-mediated inhibition of protein synthesis was monitored using luciferase-expressing Vero cells. Growth-inhibitory levels of antibiotics suppressed Stx production. Subinhibitory levels of antibiotics that target DNA synthesis, including ciprofloxacin (CIP) and trimethoprim-sulfamethoxazole, increased Stx production, while antibiotics that target the cell wall, transcription, or translation did not. More Stx was produced whenE. coliO157:H7 was incubated in the presence of phage-sensitiveE. colithan when grown as a pure culture. Remarkably, very high levels of Stx were detected even when growth of O157:H7 was completely suppressed by CIP. In contrast, azithromycin significantly reduced Stx levels even when O157:H7 viability remained high.

Discovery of Enteric Pathogens in the Alaskan Subsistence Diet

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S129-S129
Author(s):  
Grace Leu-Burke ◽  
Robert Beacham ◽  
Courtney Bennetts
Keyword(s):  
Shiga Toxin ◽  
Toxin Production ◽  
Enteric Pathogen ◽  
Enteric Pathogens ◽  
Transmission Risk ◽  
Health Concern ◽  
E Coli ◽  
Wild Game ◽  
And Migration ◽  
Pathogen Colonization

Abstract Objectives Transmission of enteric pathogens from food ingestion is an ongoing public health concern, with commensal bacteria in ruminant animal species causing human disease. Enteric pathogens Salmonella, Shigella, and Shiga toxin producing Escherichia coli (STEC) have been isolated from domesticated animals. However, the Alaskan subsistence diet relies on wild game, such as reindeer, caribou, and moose for their food supply. Research concerning enteric pathogens in wildlife has not established. Therefore, we conducted a pilot survey on moose and reindeer to determine potential enteric pathogen transfer risk. Methods Between July 2018 and January 2019, we collected 72 fecal samples from reindeer and moose migrating in Fairbanks, Anchorage, and the Matanuska Valley. Samples were cultured for enteric pathogens, including E coli 0157, using standard clinical microbial process. Phenotypic Shiga toxin production was verified by enzyme immunoassay. Results Reindeer were statistically significant for enteric pathogens when compared to moose (P < .05) Eighty percent of the reindeer population were colonized for either Shigella, Yersinia, or Shiga toxin-producing E coli, with 20% positive for multiple pathogens. Non-0157 Shiga toxin production was observed in 30% of reindeer samples, generated by a sorbitol fermenting E coli. In contrast, moose population showed a near absence of enteric pathogens with only 5% positive for Shigella. Salmonella was not identified in either animal. Conclusion Reindeer, moose, and caribou meat are prominent in the Alaskan subsistence diet. Although moose had limited enteric pathogen colonization, reindeer were significant for transmission risk, including non-0157 Shiga toxin producing E coli, which has been linked to hemolytic uremic syndrome. Isolation of a non-0157 STEC in wildlife indicates environmental colonization. Because reindeer and caribou are closely linked in diet and migration, Alaska clinical laboratories should screen for enteric pathogens, including non-0157 Shiga toxins.

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