scholarly journals The hokW-sokW Locus Encodes a Type I Toxin–Antitoxin System That Facilitates the Release of Lysogenic Sp5 Phage in Enterohemorrhagic Escherichia coli O157

Toxins ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 796
Author(s):  
Kosuke Takada ◽  
Kotone Hama ◽  
Takaomi Sasaki ◽  
Yuichi Otsuka
Keyword(s):  
Escherichia Coli ◽  
Cell Formation ◽  
Enterohemorrhagic Escherichia Coli ◽  
Type I ◽  
Escherichia Coli O157 ◽  
Dependent Manner ◽  
Rnase Iii ◽  
Prophage Induction ◽  
E Coli ◽  
Persister Cell

The toxin-antitoxin (TA) genetic modules control various bacterial events, such as plasmid maintenance, persister cell formation, and phage defense. They also exist in mobile genetic elements, including prophages; however, their physiological roles remain poorly understood. Here, we demonstrate that hokW-sokW, a putative TA locus encoded in Sakai prophage 5 (Sp5) in enterohemorrhagic Escherichia coli O157: H7 Sakai strain, functions as a type I TA system. Bacterial growth assays showed that the antitoxic activity of sokW RNA against HokW toxin partially requires an endoribonuclease, RNase III, and an RNA chaperone, Hfq. We also demonstrated that hokW-sokW assists Sp5-mediated lysis of E. coli cells when prophage induction is promoted by the DNA-damaging agent mitomycin C (MMC). We found that MMC treatment diminished sokW RNA and increased both the expression level and inner membrane localization of HokW in a RecA-dependent manner. Remarkably, the number of released Sp5 phages decreased by half in the absence of hokW-sokW. These results suggest that hokW-sokW plays a novel role as a TA system that facilitates the release of Sp5 phage progeny through E. coli lysis.

scholarly journals Characterization of a Novel Microcin That Kills Enterohemorrhagic Escherichia coli O157:H7 and O26

2012 ◽  
Vol 78 (18) ◽  
pp. 6592-6599 ◽  
Author(s):  
Lauren J. Eberhart ◽  
James R. Deringer ◽  
Kelly A. Brayton ◽  
Ashish A. Sawant ◽  
Thomas E. Besser ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Logarithmic Phase ◽  
Type I ◽  
Escherichia Coli O157 ◽  
Content Type ◽  
E Coli ◽  
Secretion Pathway ◽  
Dependent Inhibition

ABSTRACTA novel phenotype was recently identified in which specific strains ofEscherichia coliinhibit competingE. colistrains via a mechanism that was designated “proximity-dependent inhibition” (PDI). PDI-expressing (PDI+)E. coliis known to inhibit susceptible (PDI−)E. colistrains, including several enterohemorrhagic (EHEC) and enterotoxigenic (ETEC)E. colistrains. In this study, every strain from a genetically diverse panel ofE. coliO157:H7 (n= 25) and additional strains ofE. coliserovar O26 were susceptible to the PDI phenotype. LIVE/DEAD staining was consistent with inhibition by killing of susceptible cells. Comparative genome analysis identified the genetic component of PDI, which is composed of a plasmid-borne (Incl1) operon encoding a putative microcin and associated genes for transport, immunity, and microcin activation. Transfer of the plasmid to a PDI−strain resulted in transfer of the phenotype, and deletion of the genes within the operon resulted in loss of the inhibition phenotype. Deletion of chromosomally encodedtolCalso resulted in loss of the inhibitory phenotype, and this confirmed that the putative microcin is most likely secreted via a type I secretion pathway. Deletion of an unrelated plasmid gene did not affect the PDI phenotype. Quantitative reverse transcription (RT)-PCR demonstrated that microcin expression is correlated with logarithmic-phase growth. The ability to inhibit a diversity ofE. colistrains indicates that this microcin may influence gut community composition and could be useful for control of important enteric pathogens.

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 > 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.

Survival of Enterohemorrhagic Escherichia coli O157:H7 in Retail Mustard

2001 ◽  
Vol 64 (6) ◽  
pp. 783-787 ◽  
Author(s):  
CAROLYN M. MAYERHAUSER
Keyword(s):  
Escherichia Coli ◽  
Foodborne Illness ◽  
Enterohemorrhagic Escherichia Coli ◽  
Test Strain ◽  
Escherichia Coli O157 ◽  
Time Intervals ◽  
Fermented Sausage ◽  
Apple Cider ◽  
E Coli ◽  
Predetermined Time

Escherichia coli O157:H7 survival in acid foods such as unpasteurized apple cider and fermented sausage is well documented. Researchers have determined that E. coli O157:H7 can survive in refrigerated acid foods for weeks. The potential of acid foods to serve as a vector of E. coli O157:H7 foodborne illness prompted this study to determine the fate of this organism in retail mustard containing acetic acid when stored at room and refrigerated temperatures. Various retail brands of dijon, yellow, and deli style mustard, pH ranging from 3.17 to 3.63, were inoculated individually with three test strains of E. coli O157:H7. Samples were inoculated with approximately 1.0 × 106 CFU/g, incubated at room (25 ± 2.5°C) and refrigerated (5 ± 3°C) temperatures, and assayed for surviving test strains at predetermined time intervals. An aliquot was appropriately diluted and plated using sorbitol MacConkey agar (SMAC). When the test strain was not recoverable by direct plating, the sample was assayed by enrichment in modified tryptic soy broth and recovered using SMAC. Growth of E. coli O157:H7 test strains was inhibited in all retail mustard styles. E. coli O157:H7 was not detected in dijon style mustard beyond 3 h at room and 2 days at refrigerated temperatures. Survival in yellow and deli style mustard was not detected beyond 1 h. Overall, test strain survival was greater at refrigerated than room temperature. Retail mustard demonstrated the ability to eliminate effectively any chance contamination by this organism within hours to days, suggesting that these products are not a likely factor in E. coli O157:H7 foodborne illness.

scholarly journals Lymphoid Follicle-Dense Mucosa at the Terminal Rectum Is the Principal Site of Colonization of Enterohemorrhagic Escherichia coli O157:H7 in the Bovine Host

2003 ◽  
Vol 71 (3) ◽  
pp. 1505-1512 ◽  
Author(s):  
Stuart W. Naylor ◽  
J. Christopher Low ◽  
Thomas E. Besser ◽  
Arvind Mahajan ◽  
George J. Gunn ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Primary Source ◽  
Detailed Examination ◽  
Lymphoid Follicle ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Associated Bacteria ◽  
E Coli ◽  
Source Of Infection ◽  
Specific Distribution

ABSTRACT Escherichia coli O157:H7 causes bloody diarrhea and potentially fatal systemic sequelae in humans. Cattle are most frequently identified as the primary source of infection, and E. coli O157:H7 generally colonizes the gastrointestinal tracts of cattle without causing disease. In this study, persistence and tropism were assessed for four different E. coli O157:H7 strains. Experimentally infected calves shed the organism for at least 14 days prior to necropsy. For the majority of these animals, as well as for a naturally colonized animal obtained from a commercial beef farm, the highest numbers of E. coli O157:H7 were found in the feces, with negative or significantly lower levels detected in lumen contents taken from the gastrointestinal tract. Detailed examination demonstrated that in these individuals the majority of tissue-associated bacteria were adherent to mucosal epithelium within a defined region extending up to 5 cm proximally from the recto-anal junction. The tissue targeted by E. coli O157:H7 was characterized by a high density of lymphoid follicles. Microcolonies of the bacterium were readily detected on the epithelium of this region by immunofluorescence microscopy. As a consequence of this specific distribution, E. coli O157:H7 was present predominately on the surface of the fecal stool. In contrast, other E. coli serotypes were present at consistent levels throughout the large intestine and were equally distributed in the stool. This is a novel tropism that may enhance dissemination both between animals and from animals to humans. The accessibility of this site may facilitate simple intervention strategies.

Survival of Enterohemorrhagic Escherichia coli O157:H7 in Water

1998 ◽  
Vol 61 (6) ◽  
pp. 662-667 ◽  
Author(s):  
GUODONG WANG ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Protein Composition ◽  
Water Source ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Reservoir Water ◽  
Cold Temperatures ◽  
Acridine Orange Staining ◽  
E Coli ◽  
Municipal Water

Several recent Escherichia coli O157:H7 outbreaks associated with both drinking and recreational water raise concerns about waterborne illness caused by this pathogen. The survival characteristics of a mixture of five nalidixic acid-resistant E. coli O157:H7 strains (103 CFU/ml) in filtered and autoclaved municipal water, in reservoir water, and in water from two recreational lakes were determined for a period of 91 days at 8, 15, or 25°C. Greatest survival was in filtered autoclaved municipal water and least in lake water. Regardless of the water source, survival was greatest at 8°C and least at 25°C. E. coli O157:H7 populations decreased by 1 to 2 log10 by 91 days at 8°C, whereas the pathogen was not detectable (≥3 log10 decrease) within 49 to 84 days at 25°C in three of the four water sources. SDS-PAGE of surface antigens of surviving cells revealed that there was no major alteration in lipopolysaccharide pattern, but outer membrane protein composition did change. These studies indicate that E. coli O157:H7 is a hardy pathogen that can survive for long periods of time in water, especially at cold temperatures. However, direct viable counts of E. coli O157:H7 determined by acridine orange staining remained essentially the same for 12 weeks at 25°C, whereas viable counts on tryptic soy agar plates decreased to undetectable levels within 12 weeks. Results suggest that E. coli O157:H7 can enter a viable but nonculturable (VBNC) state in water.

Persistence of Enterohemorrhagic Escherichia coli O157:H7 in Soil and on Leaf Lettuce and Parsley Grown in Fields Treated with Contaminated Manure Composts or Irrigation Water

2004 ◽  
Vol 67 (7) ◽  
pp. 1365-1370 ◽  
Author(s):  
MAHBUB ISLAM ◽  
MICHAEL P. DOYLE ◽  
SHARAD C. PHATAK ◽  
PATRICIA MILLNER ◽  
XIUPING JIANG
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Poultry Manure ◽  
Dairy Manure ◽  
Enterohemorrhagic Escherichia Coli ◽  
Avirulent Strain ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Manure Compost ◽  
Contaminated Irrigation Water

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 infections associated with lettuce and other leaf crops have occurred with increasing frequency in recent years. Contaminated manure and polluted irrigation water are probable vehicles for the pathogen in many outbreaks. In this study, the occurrence and persistence of E. coli O157:H7 in soil fertilized with contaminated poultry or bovine manure composts or treated with contaminated irrigation water and on lettuce and parsley grown on these soils under natural environmental conditions was determined. Twenty-five plots, each 1.8 by 4.6 m, were used for each crop, with five treatments (one without compost, three with each of the three composts, and one without compost but treated with contaminated water) and five replication plots for each treatment. Three different types of compost, PM-5 (poultry manure compost), 338 (dairy manure compost), and NVIRO-4 (alkaline-stabilized dairy manure compost), and irrigation water were inoculated with an avirulent strain of E. coli O157:H7. Pathogen concentrations were 107 CFU/g of compost and 105 CFU/ml of water. Contaminated compost was applied to soil in the field as a strip at 4.5 metric tons per hectare on the day before lettuce and parsley seedlings were transplanted in late October 2002. Contaminated irrigation water was applied only once on the plants as a treatment in five plots for each crop at the rate of 2 liters per plot 3 weeks after the seedlings were transplanted. E. coli O157:H7 persisted for 154 to 217 days in soils amended with contaminated composts and was detected on lettuce and parsley for up to 77 and 177 days, respectively, after seedlings were planted. Very little difference was observed in E. coli O157:H7 persistence based on compost type alone. E. coli O157:H7 persisted longer (by >60 days) in soil covered with parsley plants than in soil from lettuce plots, which were bare after lettuce was harvested. In all cases, E. coli O157:H7 in soil, regardless of source or crop type, persisted for >5 months after application of contaminated compost or irrigation water.

Comparative Evaluation of a Phage Protein Ligand Assay with Real-Time PCR and a Reference Method for the Detection of Escherichia coli O157:H7 in Raw Ground Beef and Trimmings

2011 ◽  
Vol 74 (1) ◽  
pp. 6-12 ◽  
Author(s):  
F. SAVOYE ◽  
P. FENG ◽  
C. ROZAND ◽  
M. BOUVIER ◽  
A. GLEIZAL ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Ground Beef ◽  
Reference Method ◽  
Enterohemorrhagic Escherichia Coli ◽  
Detection Methods ◽  
Escherichia Coli O157 ◽  
Rt Pcr ◽  
Raw Meat ◽  
E Coli

Enterohemorrhagic Escherichia coli O157:H7 is an important pathogen associated with infections caused by consumption of undercooked raw meat. Sensitive and rapid detection methods for E. coli O157:H7 are essential for the meat industry to ensure a safe meat supply. This study was conducted to compare the sensitivity of the VIDAS ultraperformance E. coli test (ECPT UP) with a noncommercial real-time (RT) PCR method and the U.S. Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS) reference method for detecting E. coli O157:H7 in raw ground beef. Optimal enrichment times and the efficacy of testing different types of raw meat, either as individual samples (25 g) or as composites (375 g), were examined. For 25-g samples of each type of raw ground beef tested, 6 h of enrichment was sufficient for both the VIDAS ECPT UP and RT-PCR methods, but for 375-g samples, 24 h of enrichment was required. Both the VIDAS ECPT UP and RT-PCR methods produced results similar to those obtained with the USDA-FSIS reference method after 18 to 24 h of enrichment. The primer specificity of the RT-PCR assay and the highly specific phage ligand used in the VIDAS ECPT UP for target recognition enabled the detection of low levels of E. coli O157:H7 in 25 g of various types of raw ground beef. The tests also allowed the detection of E. coli O157:H7 in composite raw ground beef and trimmings in samples of up to 375 g.

Evaluating Escherichia coli O157 Control in Finnish Primary Production

2014 ◽  
Vol 77 (3) ◽  
pp. 371-379
Author(s):  
ANNA LEIMI ◽  
ANTTI MIKKELÄ ◽  
PIRKKO TUOMINEN
Keyword(s):  
Escherichia Coli ◽  
Primary Production ◽  
Control Program ◽  
Credible Interval ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Production Chain ◽  
E Coli ◽  
Zoonotic Infections ◽  
True Prevalence

Enterohemorrhagic Escherichia coli (EHEC) has become a threat in the modern cattle sector because of its adverse impact on human health. Systems have been developed to reduce the risk of EHEC infection associated with the beef production chain. In Finland, the risk management of EHEC is mainly targeted at primary production, which is controlled by a national program. The prevalence of E. coli O157 in slaughter animals and herds appears to have remained relatively low over the years (0.2 to1.2%and 0.3 to 1.5%, respectively). The effectiveness of the Finnish EHEC control program (FECP) was analyzed with a Bayesian statistical model based on the results from 2006 through 2010. According to the model, the estimated true prevalence of EHEC in slaughter animals was at its highest in 2007 (95%credible interval [CI], 0.94 to 1.85%of animals), and the estimated true prevalence in herds was its highest in 2007 (95% CI, 1.28 to 2.55% of herds). However, the estimated probability of the FECP detecting an EHEC-positive slaughter animal or herd was 0.52 to 0.58%and 4.74 to 6.49%, respectively. The inability to detect EHEC-positive animals was partly due to animal-based random sampling, which ignores herd-level testing and therefore emphasizes the testing of slaughter animals from herds that send more animals to slaughter. Some slaughterhouses collected samples incorrectly as a consequence of an incorrectly implemented FECP. Farmers may also have questionable reasons for choosing to send animals to be slaughtered in small abattoirs, in which testing is less likely, to avoid suspicion of EHEC or other zoonotic infections.

Selection of In Vivo Expressed Genes of Escherichia coli O157:H7 Strain EDL933 in Ground Meat under Elevated Temperature Conditions

2012 ◽  
Vol 75 (10) ◽  
pp. 1743-1750 ◽  
Author(s):  
ANDREA KROJ ◽  
HERBERT SCHMIDT
Keyword(s):  
Escherichia Coli ◽  
Elevated Temperatures ◽  
Genomic Library ◽  
Transport Processes ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Ground Meat ◽  
E Coli ◽  
Selection Of

Enterohemorrhagic Escherichia coli O157:H7 strains are important foodborne pathogens that are often transmitted to humans by the ingestion of raw or undercooked meat of bovine origin. To investigate adaptation of this pathogen during persistence and growth in ground meat, we established an in vivo expression technology model to identify genes that are expressed during growth in this food matrix under elevated temperatures (42°C). To improve on the antibiotic-based selection method, we constructed the promoter trap vector pAK-1, containing a promoterless kanamycin resistance gene. A genomic library of E. coli O157:H7 strain EDL933 was constructed in pAK-1 and used for promoter selection in ground meat. The 20 in vivo expressed genes identified were associated with transport processes, metabolism, macromolecule synthesis, and stress response. For most of the identified genes, only hypothetical functions could be assigned. The results of our study provide the first insights into the complex response of E. coli O157:H7 to a ground meat environment under elevated temperatures and establish a suitable vector for promoter studies or selection of in vivo induced promoters in foods such as ground meat.

Survival and Growth of Listeria monocytogenes and Enterohemorrhagic Escherichia coli O157:H7 in Minimally Processed Artichokes

2003 ◽  
Vol 66 (12) ◽  
pp. 2203-2209 ◽  
Author(s):  
SUSANA SANZ ◽  
MERCEDES GIMÉNEZ ◽  
CARMEN OLARTE
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Tap Water ◽  
Storage Period ◽  
Enterohemorrhagic Escherichia Coli ◽  
Fecal Coliforms ◽  
Escherichia Coli O157 ◽  
Natural Background ◽  
Minimally Processed ◽  
E Coli

The ability of Listeria monocytogenes and Escherichia coli O157:H7 inoculated by immersion (at 4.6 and 5.5 log CFU/g, respectively) to survive on artichokes during various stages of preparation was determined. Peeling, cutting, and disinfecting operations (immersion in 50 ppm of a free chlorine solution at 4°C for 5 min) reduced populations of L. monocytogenes and E. coli O157:H7 by only 1.6 and 0.8 log units, respectively. An organic acid rinse (0.02% citric acid and 0.2% ascorbic acid) was more effective than a tap water rinse in removing these pathogens. Given the possibility of both pathogens being present on artichokes at the packaging stage, their behavior during the storage of minimally processed artichokes was investigated. For this purpose, batches of artichokes inoculated with L. monocytogenes or E. coli O157:H7 (at 5.5 and 5.2 log CFU/g, respectively) were packaged in P-Plus film bags and stored at 4°C for 16 days. During this period, the equilibrium atmosphere composition and natural background microflora (mesophiles, psychrotrophs, anaerobes, and fecal coliforms) were also analyzed. For the two studied pathogens, the inoculum did not have any effect on the final atmospheric composition (10% O2, 13% CO2) or on the survival of the natural background microflora of the artichokes. L. monocytogenes was able to survive during the entire storage period in the inoculated batches, while the E. coli O157:H7 level increased by 1.5 log units in the inoculated batch during the storage period. The modified atmosphere was unable to control the behavior of either pathogen.

Sign in / Sign up

Export Citation Format

Share Document