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

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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Potentially Human-Pathogenic Escherichia coli O26 in Norwegian Sheep Flocks

Applied and Environmental Microbiology ◽

10.1128/aem.00189-11 ◽

2011 ◽

Vol 77 (14) ◽

pp. 4949-4958 ◽

Cited By ~ 21

Author(s):

C. Sekse ◽

M. Sunde ◽

B.-A. Lindstedt ◽

P. Hopp ◽

T. Bruheim ◽

...

Keyword(s):

Escherichia Coli ◽

Variable Number Tandem Repeat ◽

Variable Number ◽

Human Pathogens ◽

Content Type ◽

Representative Sampling ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Close Relationship ◽

Large Survey

ABSTRACTA national survey ofEscherichia coliO26 in Norwegian sheep flocks was conducted, using fecal samples to determine the prevalence. In total, 491 flocks were tested, andE. coliO26 was detected in 17.9% of the flocks. One hundred forty-twoE. coliO26 isolates were examined for flagellar antigens (H typing) and four virulence genes, includingstxandeae, to identify possible Shiga toxin-producingE. coli(STEC) and enteropathogenicE. coli(EPEC). Most isolates (129 out of 142) were identified asE. coliO26:H11. They possessedeaeand may have potential as human pathogens, although only a small fraction were identified as STEC O26:H11, giving a prevalence in sheep flocks of only 0.8%. Correspondingly, the sheep flock prevalence of atypical EPEC (aEPEC) O26:H11 was surprisingly high (15.9%). The genetic relationship between theE. coliO26:H11 isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA), identifying 63 distinct PFGE profiles and 22 MLVA profiles. Although the MLVA protocol was less discriminatory than PFGE and a few cases of disagreement were observed, comparison by partition mapping showed an overall good accordance between the two methods. A close relationship between a few isolates of aEPEC O26:H11 and STEC O26:H11 was identified, but all theE. coliO26:H11 isolates should be considered potentially pathogenic to humans. The present study consisted of a representative sampling of sheep flocks from all parts of Norway. This is the first large survey of sheep flocks focusing onE. coliO26 in general, including results of STEC, aEPEC, and nonpathogenic isolates.

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Genome Sequence of a T4-like Phage, Escherichia Phage vB_EcoM-Sa45lw, Infecting Shiga Toxin-Producing Escherichia coli Strains

Microbiology Resource Announcements ◽

10.1128/mra.00804-19 ◽

2019 ◽

Vol 8 (32) ◽

Author(s):

Yen-Te Liao ◽

Yujie Zhang ◽

Alexandra Salvador ◽

Vivian C. H. Wu

Keyword(s):

Escherichia Coli ◽

Surface Water ◽

Genome Size ◽

Shiga Toxin ◽

Open Reading Frames ◽

Content Type ◽

E Coli ◽

Double Stranded Dna ◽

A Genome ◽

Reading Frames

Escherichia phage vB_EcoM-Sa45lw, a new member of the T4-like phages, was isolated from surface water in a produce-growing area. The phage, containing double-stranded DNA with a genome size of 167,353 bp and 282 predicted open reading frames (ORFs), is able to infect generic Escherichia coli and Shiga toxin-producing E. coli O45 and O157 strains.

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Evaluation of Aerated Steam Treatment of Alfalfa and Mung Bean Seeds To Eliminate High Levels of Escherichia coli O157:H7 and O178:H12, Salmonella enterica, and Listeria monocytogenes

Applied and Environmental Microbiology ◽

10.1128/aem.00443-13 ◽

2013 ◽

Vol 79 (15) ◽

pp. 4613-4619 ◽

Cited By ~ 14

Author(s):

Patrick Studer ◽

Werner E. Heller ◽

Jörg Hummerjohann ◽

David Drissner

Keyword(s):

Escherichia Coli ◽

Listeria Monocytogenes ◽

Salmonella Enterica ◽

Mung Bean ◽

Germination Rate ◽

Steam Treatment ◽

Heat Sensitivity ◽

Human Pathogens ◽

Content Type ◽

E Coli

ABSTRACTSprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated withEscherichia coliO157:H7,Salmonella entericasubsp.entericaserovar Weltevreden, andListeria monocytogenesScott A. In addition, a recently collectedE. coliO178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations ofE. coliO157:H7 andS. entericaon alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies.L. monocytogenesandE. coliO178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).

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Occurrence of Potentially Human-Pathogenic Escherichia coli O103 in Norwegian Sheep

Applied and Environmental Microbiology ◽

10.1128/aem.01825-13 ◽

2013 ◽

Vol 79 (23) ◽

pp. 7502-7509 ◽

Cited By ~ 10

Author(s):

Camilla Sekse ◽

Marianne Sunde ◽

Petter Hopp ◽

Torkjel Bruheim ◽

Kofitsyo Sewornu Cudjoe ◽

...

Keyword(s):

Escherichia Coli ◽

Human Pathogens ◽

Outbreak Strain ◽

Banding Patterns ◽

Sheep Population ◽

Content Type ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Uremic Syndrome ◽

Low Prevalence

ABSTRACTThe investigation of an outbreak of hemorrhagic-uremic syndrome in Norway in 2006 indicated that the outbreak strainEscherichia coliO103:H25 could originate from sheep. A national survey of the Norwegian sheep population was performed, with the aim of identifying and describing a possible reservoir of potentially human-pathogenicE. coliO103, in particular of the H types 2 and 25. The investigation of fecal samples from 585 sheep flocks resulted in 1,222E. coliO103 isolates that were analyzed for the presence ofeaeandstxgenes, while a subset of 369 isolates was further examined for flagellar antigens (H typing),stxsubtypes,bfpA,astA, and molecular typing by pulsed-field gel electrophoresis (PFGE). The total ovineE. coliO103 serogroup was genetically diverse by numbers of H types, virulotypes, and PFGE banding patterns identified, although a tendency of clustering toward serotypes was seen. The flocks positive for potentially human-pathogenicE. coliO103 were geographically widely distributed, and no association could be found with county or geographical region. The survey showed thateae-negative,stx-negativeE. coliO103, probably nonpathogenic to humans, is very common in sheep, with 27.5% of flocks positive. Moreover, the study documented a low prevalence (0.7%) of potentially human-pathogenic Shiga toxin-producingE. coliO103:H2, while STEC O103:H25 was not detected. However, 3.1% and 5.8% of the flocks were positive for enteropathogenicE. coliO103 belonging to H types 2 and 25, respectively. These isolates are of concern as potential human pathogens by themselves but more importantly as possible precursors for human-pathogenic STEC.

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Plant-Pathogenic Oomycetes, Escherichia coli Strains, and Salmonella spp. Frequently Found in Surface Water Used for Irrigation of Fruit and Vegetable Crops in New York State

Applied and Environmental Microbiology ◽

10.1128/aem.01012-14 ◽

2014 ◽

Vol 80 (16) ◽

pp. 4814-4820 ◽

Cited By ~ 24

Author(s):

Lisa A. Jones ◽

Randy W. Worobo ◽

Christine D. Smart

Keyword(s):

Escherichia Coli ◽

Water Quality ◽

New York ◽

Food Safety ◽

Surface Water ◽

New York State ◽

Quality Parameters ◽

Content Type ◽

York State ◽

E Coli

ABSTRACTIn the United States, surface water is commonly used to irrigate a variety of produce crops and can harbor pathogens responsible for food-borne illnesses and plant diseases. Understanding when pathogens infest water sources is valuable information for produce growers to improve the food safety and production of these crops. In this study, prevalence data along with regression tree analyses were used to correlate water quality parameters (pH, temperature, turbidity), irrigation site properties (source, the presence of livestock or fowl nearby), and precipitation data to the presence and concentrations ofEscherichia coli,Salmonellaspp., and hymexazol-insensitive (HIS) oomycetes (PhytophthoraandPythiumspp.) in New York State surface waters. A total of 123 samples from 18 sites across New York State were tested forE. coliandSalmonellaspp., of which 33% and 43% were positive, respectively. Additionally, 210 samples from 38 sites were tested for HIS oomycetes, and 88% were found to be positive, with 10 species ofPhytophthoraand 11 species ofPythiumbeing identified from the samples. Regression analysis found no strong correlations between water quality parameters, site factors, or precipitation to the presence or concentration ofE. coliin irrigation sources. ForSalmonella, precipitation (≤0.64 cm) 3 days before sampling was correlated to both presence and the highest counts. Analyses for oomycetes found creeks to have higher average counts than ponds, and higher turbidity levels were associated with higher oomycete counts. Overall, information gathered from this study can be used to better understand the food safety and plant pathogen risks of using surface water for irrigation.

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

Applied and Environmental Microbiology ◽

10.1128/aem.02616-14 ◽

2014 ◽

Vol 81 (2) ◽

pp. 569-577 ◽

Cited By ~ 8

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.

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Recirculating Immunomagnetic Separation and Optimal Enrichment Conditions for Enhanced Detection and Recovery of Low Levels of Escherichia coli O157:H7 from Fresh Leafy Produce and Surface Water

Journal of Food Protection ◽

10.4315/0362-028x-70.12.2717 ◽

2007 ◽

Vol 70 (12) ◽

pp. 2717-2724 ◽

Cited By ~ 18

Author(s):

SUNEE HIMATHONGKHAM ◽

MARY LEE DODD ◽

JENNY K. YEE ◽

DAVID K. LAU ◽

RAYMOND G. BRYANT ◽

...

Keyword(s):

Escherichia Coli ◽

Surface Water ◽

Real Time ◽

Real Time Pcr ◽

Immunomagnetic Separation ◽

Escherichia Coli O157 ◽

Simple Method ◽

E Coli ◽

Low Levels ◽

Spinach Leaves

The objective of this study was to develop a rapid, simple method for enhanced detection and isolation of low levels of Escherichia coli O157:H7 from leafy produce and surface water using recirculating immunomagnetic separation (RIMS) coupled with real-time PCR and a standard culture method. The optimal enrichment conditions for the method also were determined. Analysis of real-time PCR data (CT values) suggested that incubation of lettuce and spinach leaves rather than rinsates provides better enrichment of E. coli O157:H7. Enrichment of lettuce or spinach leaves at 42°C for 5 h provided better detection than enrichment at 37°C. Extended incubation of surface water for 20 h at 42°C did not improve the detection. The optimized enrichment conditions were also employed with modified Moore swabs, which were used to sample flowing water sites. Positive isolation rates and real-time PCR results indicated an increased recovery of E. coli O157:H7 from all samples following the application of RIMS. Under these conditions, the method provided detection and/or isolation of E. coli O157:H7 at levels as low as 0.07 CFU/g of lettuce, 0.1 CFU/g of spinach, 6 CFU/100 ml of surface water, and 9 CFU per modified Moore swab. During a 6-month field study, modified Moore swabs yielded high isolation rates when deployed in natural watershed sites. The method used in this study was effective for monitoring E. coli O157:H7 in the farm environment, during postharvest processing, and in foodborne outbreak investigations.

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

Applied and Environmental Microbiology ◽

10.1128/aem.02272-12 ◽

2012 ◽

Vol 78 (23) ◽

pp. 8403-8411 ◽

Cited By ~ 20

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.

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

Applied and Environmental Microbiology ◽

10.1128/aem.04037-13 ◽

2014 ◽

Vol 80 (7) ◽

pp. 2270-2278 ◽

Cited By ~ 18

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.

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Isolation and Characterization of Verocytotoxin-Producing Escherichia coli O157 Strains from Dutch Cattle and Sheep

Journal of Clinical Microbiology ◽

10.1128/jcm.36.4.878-882.1998 ◽

1998 ◽

Vol 36 (4) ◽

pp. 878-882 ◽

Cited By ~ 116

Author(s):

A. E. Heuvelink ◽

F. L. A. M. van den Biggelaar ◽

E. de Boer ◽

R. G. Herbes ◽

W. J. G. Melchers ◽

...

Keyword(s):

Escherichia Coli ◽

Immunomagnetic Separation ◽

Human Pathogens ◽

O157 Strain ◽

Adult Cattle ◽

E Coli ◽

Phage Types ◽

Isolation And Characterization ◽

Animal Isolates ◽

Cattle And Sheep

In the periods from July to November 1995 and 1996, fecal samples from Dutch cattle and sheep were collected at the main slaughterhouses of The Netherlands, located at different geographic sites. The samples were examined for the presence of verocytotoxin (VT)-producingEscherichia coli (VTEC) of serogroup O157. E. coli O157 strains could be isolated from 57 (10.6%) of 540 adult cattle, 2 (0.5%) of 397 veal calves, 2 (3.8%) of 52 ewes, and 2 (4.1%) of 49 lambs. Immunomagnetic separation with O157-specific-antibody-coated beads appeared to be significantly more sensitive than conventional plating for detection of the organism in feces. With the exception of two isolates from adult cattle which appeared to be negative for VT genes, all animal isolates were positive for both VT (VT1 and/or VT2) and E. coliattaching-and-effacing gene sequences, and therefore, they were regarded as potential human pathogens. Although genomic typing by pulsed-field gel electrophoresis revealed a wide variety of distinct restriction patterns, comparison of the 63 animal isolates with 33 fecal O157 VTEC strains previously isolated from humans with the diarrhea-associated form of the hemolytic-uremic syndrome by their phage types and VT genotypes showed a marked similarity between animal and human isolates: 30 (90.9%) of the 33 human isolates appeared to be of E. coli O157 strain types also isolated from cattle and sheep. It was concluded that Dutch cattle and sheep are an important reservoir of E. coli O157 strains that are potentially pathogenic for humans.

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