Seasonal Prevalence of Escherichia coli O157:H7 in Beef Cattle Feces†

2006 ◽  
Vol 69 (12) ◽  
pp. 3018-3020 ◽  
Author(s):  
M. J. ALAM ◽  
L. ZUREK
Keyword(s):  
Escherichia Coli ◽  
Beef Cattle ◽  
Shiga Toxin ◽  
Bacterial Colonization ◽  
Feedlot Cattle ◽  
Escherichia Coli O157 ◽  
Human Pathogen ◽  
E Coli ◽  
Cattle Feces ◽  
Shiga Toxin 2

Cattle are an asymptomatic reservoir of Escherichia coli O157:H7, but the bacterial colonization and shedding patterns are poorly understood. The prevalence and shedding of this human pathogen have been reported to be seasonal with rates typically increasing during warm months. The objectives of this study were (i) to assess the prevalence of E. coli O157:H7 in feces of feedlot cattle in Kansas during summer, fall, and winter months, and (ii) to characterize E. coli O157:H7 by screening for virulence factors. Of 891 fecal samples collected, 82 (9.2%) were positive for E. coli O157:H7. No significant differences in prevalence were detected among summer, fall, and winter months. The highest monthly prevalence (18.1%) was detected in February. All tested isolates were positive for stx2 (Shiga toxin 2) and eaeA (intimin) genes; 14 isolates (12.8%) also carried stx1. Our results indicate the prevalence of E. coli O157:H7 in beef cattle feces is not necessarily season dependent.

Comparing Real-Time and Conventional PCR to Culture-Based Methods for Detecting and Quantifying Escherichia coli O157 in Cattle Feces

2014 ◽  
Vol 77 (2) ◽  
pp. 314-319 ◽  
Author(s):  
M. E. JACOB ◽  
J. BAI ◽  
D. G. RENTER ◽  
A. T. ROGERS ◽  
X. SHI ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Positive Culture ◽  
Feedlot Cattle ◽  
Escherichia Coli O157 ◽  
Conventional Pcr ◽  
Culture Methods ◽  
E Coli ◽  
Cattle Feces ◽  
Culture Negative

Detection of Escherichia coli O157 in cattle feces has traditionally used culture-based methods; PCR-based methods have been suggested as an alternative. We aimed to determine if multiplex real-time (mq) or conventional PCR methods could reliably detect cattle naturally shedding high (≥104 CFU/g of feces) and low (~102 CFU/g of feces) concentrations of E. coli O157. Feces were collected from pens of feedlot cattle and evaluated for E. coli O157 by culture methods. Samples were categorized as (i) high shedders, (ii) immunomagnetic separation (IMS) positive after enrichment, or (iii) culture negative. DNA was extracted pre- and postenrichment from 100 fecal samples from each category (high shedder, IMS positive, culture negative) and subjected to mqPCR and conventional PCR assays based on detecting three genes, rfbE, stx1, and stx2. In feces from cattle determined to be E. coli O157 high shedders by culture, 37% were positive by mqPCR prior to enrichment; 85% of samples were positive after enrichment. In IMS-positive samples, 4% were positive by mqPCR prior to enrichment, while 43% were positive after enrichment. In culture-negative feces, 7% were positive by mqPCR prior to enrichment, and 40% were positive after enrichment. The proportion of high shedder–positive and culture-positive (high shedder and IMS) samples were significantly different from mqPCR-positive samples before and after enrichment (P < 0.01). Similar results were observed for conventional PCR. Our data suggest that mqPCR and conventional PCR are most useful in identifying high shedder animals and may not be an appropriate substitute to culture-based methods for detection of E. coli O157 in cattle feces.

Risk of Escherichia coli O157:H7, Non-O157 Shiga Toxin–Producing Escherichia coli, and Campylobacter spp. in Food Animals and Their Products in Qatar

2015 ◽  
Vol 78 (10) ◽  
pp. 1812-1818 ◽  
Author(s):  
HUSSNI O. MOHAMMED ◽  
KORANA STIPETIC ◽  
AHMED SALEM ◽  
PATRICK McDONOUGH ◽  
YUNG FU CHANG ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Cross Sectional Study ◽  
Campylobacter Coli ◽  
Escherichia Coli O157 ◽  
Cross Sectional ◽  
Fecal Samples ◽  
E Coli ◽  
Cattle Feces ◽  
Campylobacter Spp

Escherichia coli O157:H7, non-O157 E. coli, and Campylobacter spp. are among the top-ranked pathogens that threaten the safety of food supply systems around the world. The associated risks and predisposing factors were investigated in a dynamic animal population using a repeat-cross-sectional study design. Animal and environmental samples were collected from dairy and camel farms, chicken processing plants, and abattoirs and analyzed for the presence of these pathogens using a combination of bacterial enrichment and real-time PCR tests without culture confirmation. Data on putative risk factors were also collected and analyzed. E. coli O157:H7 was detected by PCR at higher levels in sheep and camel feces than in cattle feces (odds ratios [OR], 6.8 and 21.1, respectively). Although the genes indicating E. coli O157:H7 were detected at a relatively higher rate (4.3%) in fecal samples from dairy cattle, they were less common in milk and udder swabs from the same animals (1 and 2%, respectively). Among the food adulterants, E. coli O103 was more common in cattle fecal samples, whereas O26 was more common in sheep feces and O45 in camel feces compared with cattle (OR, 2.6 and 3.1, respectively). The occurrence of E. coli in the targeted populations differed by the type of sample and season of the year. Campylobacter jejuni and Campylobacter coli were more common in sheep and camel feces than in cattle feces. Most of the survey and surveillance of E. coli focused on serogroup O157 as a potential foodborne hazard; however, based on the PCR results, non-O157 Shiga toxin–producing E. coli serotypes appeared to be more common, and efforts should be made to include them in food safety programs.

Validation and Application of a Real-Time PCR Assay Based on the CRISPR Array for Serotype-Specific Detection and Quantification of Enterohemorrhagic Escherichia coli O157:H7 in Cattle Feces†

2018 ◽  
Vol 81 (7) ◽  
pp. 1157-1164 ◽  
Author(s):  
LANCE W. NOLL ◽  
RACHEL CHALL ◽  
PRAGATHI B. SHRIDHAR ◽  
XUMING LIU ◽  
JIANFA BAI ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Shiga Toxin ◽  
Culture Method ◽  
Qpcr Assay ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Cattle Feces ◽  
Crispr Array ◽  
Detection And Quantification

ABSTRACT Several real-time quantitative PCR (qPCR) assays have been developed for detection and quantification of Escherichia coli O157:H7 in complex matrices by targeting genes for serogroup-specific O-antigen (rfbEO157), H7 antigen, and one or more major virulence factors (Shiga toxin and intimin). A major limitation of such assays is that coamplification of H7 and virulence genes in a sample does not signal association of those genes with the O157 serogroup. Clusters of regularly interspaced short palindromic repeats (CRISPR) polymorphisms are highly correlated with certain enterohemorrhagic E. coli (EHEC) serotypes, including O157:H7, and the presence of genes for Shiga toxin (stx1 and stx2) and intimin (eae). Our objectives were to develop and validate a qPCR assay targeting the CRISPR array for the detection and quantification of EHEC O157:H7 in cattle feces and to evaluate the applicability of the assay for detection of and comparison with a four-plex qPCR assay targeting rfbEO157, stx1, stx2, and eae genes and a culture method. Detection limits of the CRISPRO157:H7 qPCR assay for cattle feces spiked with pure cultures were 2.1 × 103 and 2.3 × 100 CFU/g before and after enrichment, respectively. Detection of E. coli O157 in feedlot cattle fecal samples (n = 576) was compared among the CRISPRO157:H7 qPCR assay, culture method, and four-plex qPCR assay. The CRISPRO157:H7 qPCR detected 42.2% of the samples (243 of 576 samples) as positive for E. coli O157:H7, compared with 30.4% (175 samples) by the culture method. Nearly all samples (97.2%; 560 samples) were positive for rfbEO157 by the four-plex PCR, but 21.8% (122 of 560 samples) were negative for the stx and/or eae genes, making it unlikely that EHEC O157:H7 was present in these samples. Cohen's kappa statistic indicated a fair and poor agreement beyond that due to chance between the CRISPR assay and the culture method and four-plex assay, respectively. This novel qPCR assay can detect the EHEC O157:H7 serotype in cattle feces by targeting CRISPR polymorphisms.

scholarly journals Greater Diversity of Shiga Toxin-Encoding Bacteriophage Insertion Sites among Escherichia coli O157:H7 Isolates from Cattle than in Those from Humans

2006 ◽  
Vol 73 (3) ◽  
pp. 671-679 ◽  
Author(s):  
Thomas E. Besser ◽  
Nurmohammad Shaikh ◽  
Nicholas J. Holt ◽  
Phillip I. Tarr ◽  
Michael E. Konkel ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genetic Diversity ◽  
Shiga Toxin ◽  
Insertion Site ◽  
Reservoir Host ◽  
Clinical Isolates ◽  
Escherichia Coli O157 ◽  
Human Pathogen ◽  
E Coli ◽  
Insertion Sites

ABSTRACT Escherichia coli O157:H7, a zoonotic human pathogen for which domestic cattle are a reservoir host, produces a Shiga toxin(s) (Stx) encoded by bacteriophages. Chromosomal insertion sites of these bacteriophages define three principal genotypes (clusters 1 to 3) among clinical isolates of E. coli O157:H7. Stx-encoding bacteriophage insertion site genotypes of 282 clinical and 80 bovine isolates were evaluated. A total of 268 (95.0%) of the clinical isolates, but only 41 (51.3%) of the bovine isolates, belonged to cluster 1, 2, or 3 (P < 0.001). Thirteen additional genotypes were identified in isolates from both cattle and humans (four genotypes), from only cattle (seven genotypes), or from only humans (two genotypes). Two other markers previously associated with isolates from cattle or with clinical isolates showed similar associations with genotype groups within bovine isolates; the tir allele sp-1 and the Q 933W allele were under- and overrepresented, respectively, among cluster 1 to 3 genotypes. Stx-encoding bacteriophage insertion site typing demonstrated that there is broad genetic diversity of E. coli O157:H7 in the bovine reservoir and that numerous genotypes are significantly underrepresented among clinical isolates, consistent with the possibility that there is reduced virulence or transmissibility to humans of some bovine E. coli O157:H7 genotypes.

scholarly journals Escherichia coli O157:H7 Strain Origin, Lineage, and Shiga Toxin 2 Expression Affect Colonization of Cattle

2009 ◽  
Vol 75 (15) ◽  
pp. 5074-5081 ◽  
Author(s):  
Ross M. S. Lowe ◽  
Danica Baines ◽  
L. Brent Selinger ◽  
James E. Thomas ◽  
Tim A. McAllister ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Escherichia Coli O157 ◽  
Human Origin ◽  
E Coli ◽  
Unknown Factor ◽  
Shiga Toxin 2 ◽  
The Impact ◽  
Dose Dependent

ABSTRACT Enterohemorrhagic Escherichia coli O157:H7 has evolved into an important human pathogen with cattle as the main reservoir. The recent discovery of E. coli O157:H7-induced pathologies in challenged cattle has suggested that previously discounted bacterial virulence factors may contribute to the colonization of cattle. The objective of the present study was to examine the impact of lineage type, cytotoxin activity, and cytotoxin expression on the amount of E. coli O157:H7 colonization of cattle tissue and cells in vitro. Using selected bovine- and human-origin strains, we determined that lineage type predicted the amount of E. coli O157:H7 strain colonization: lineage I > intermediate lineages > lineage II. All E. coli O157:H7 strain colonization was dose dependent, with threshold colonization at 103 to 105 CFU and maximum colonization at 107 CFU. We also determined that an as-yet-unknown factor of strain origin was the most dominant predictor of the amount of strain colonization in vitro. The amount of E. coli O157:H7 colonization was also influenced by strain cytotoxin activity and the inclusion of cytotoxins from lineage I or intermediate lineage strains increased colonization of a lineage II strain. There was a higher level of expression of the Shiga toxin 1 gene (stx 1) in human-origin strains than in bovine-origin strains. In addition, lineage I strains expressed higher levels of the Shiga toxin 2 gene (stx 2). The present study supports a role for strain origin, lineage type, cytotoxin activity, and stx 2 expression in modulating the amount of E. coli O157:H7 colonization of cattle.

scholarly journals Transduction of Enteric Escherichia coli Isolates with a Derivative of Shiga Toxin 2-Encoding Bacteriophage φ3538 Isolated from Escherichia coli O157:H7

1999 ◽  
Vol 65 (9) ◽  
pp. 3855-3861 ◽  
Author(s):  
Herbert Schmidt ◽  
Martina Bielaszewska ◽  
Helge Karch
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Laboratory Strain ◽  
Plaque Formation ◽  
Escherichia Coli O157 ◽  
Healthy Individuals ◽  
Wild Type ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Lysogenic Conversion

ABSTRACT We investigated the ability of a detoxified derivative of a Shiga toxin 2 (Stx2)-encoding bacteriophage to infect and lysogenize entericEscherichia coli strains and to develop infectious progeny from such lysogenized strains. The stx2 gene of the patient E. coli O157:H7 isolate 3538/95 was replaced by the chloramphenicol acetyltransferase (cat) gene from plasmid pACYC184. Phage φ3538(Δstx2 ::cat) was isolated after induction of E. coli O157:H7 strain 3538/95 with mitomycin. A variety of strains of enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), Stx-producing E. coli (STEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), andE. coli from the physiological stool microflora were infected with φ3538(Δstx2 ::cat), and plaque formation and lysogenic conversion of wild-type E. coli strains were investigated. With the exception of one EIEC strain, none of the E. coli strains supported the formation of plaques when used as indicators for φ3538(Δstx2 ::cat). However, 2 of 11 EPEC, 11 of 25 STEC, 2 of 7 EAEC, 1 of 3 EIEC, and 1 of 6 E. coli isolates from the stool microflora of healthy individuals integrated the phage in their chromosomes and expressed resistance to chloramphenicol. Following induction with mitomycin, these lysogenic strains released infectious particles of φ3538(Δstx2 ::cat) that formed plaques on a lawn of E. coli laboratory strain C600. The results of our study demonstrate that φ3538(Δstx2 ::cat) was able to infect and lysogenize particular enteric strains of pathogenic and nonpathogenic E. coli and that the lysogens produced infectious phage progeny. Stx-encoding bacteriophages are able to spread stx genes among enteric E. coli strains.

scholarly journals Lineage and Host Source Are Both Correlated with Levels of Shiga Toxin 2 Production by Escherichia coli O157:H7 Strains

2009 ◽  
Vol 76 (2) ◽  
pp. 474-482 ◽  
Author(s):  
Yongxiang Zhang ◽  
Chad Laing ◽  
Zhengzhong Zhang ◽  
Jennyka Hallewell ◽  
Chunping You ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Enzyme Linked Immunosorbent Assay ◽  
Escherichia Coli O157 ◽  
Rt Pcr ◽  
Genetic Lineages ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Flanking Region ◽  
Q Gene

ABSTRACT Escherichia coli O157:H7 strains fall into three major genetic lineages that differ in their distribution among humans and cattle. Several recent studies have reported differences in the expression of virulence factors between E. coli O157:H7 strains from these two host species. In this study, we wished to determine if important virulence-associated “mobile genetic elements” such as Shiga toxin 2 (Stx2)-encoding prophage are lineage restricted or are host source related and acquired independently of the pathogen genotype. DNA sequencing of the stx 2 flanking region from a lineage II (LII) strain, EC970520, revealed that the transcriptional activator gene Q in LI strain EDL933 (upstream of stx 2) is replaced by a pphA (serine/threonine phosphatase) homologue and an altered Q gene in this and all other LII strains tested. In addition, nearly all LI strains carried stx 2, whereas all LII strains carried variant stx 2c and 4 of 14 LI/II strains had copies of both stx 2 and variant stx 2c. Real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) demonstrated that LI and LI/II strains produce significantly more stx 2 mRNA and Stx2 than LII strains. However, among LI strains significantly more Stx2 is also produced by strains from humans than from cattle. Therefore, lineage-associated differences among E. coli O157:H7 strains such as prophage content, toxin type, and toxin expression may contribute to host isolation bias. However, the level of Stx2 production alone may also play an important role in the within-lineage association of E. coli O157:H7 strains with human clinical disease.

Monitoring Escherichia coli O157:H7 in Inoculated and Naturally Colonized Feedlot Cattle and Their Environment

2005 ◽  
Vol 68 (1) ◽  
pp. 26-33 ◽  
Author(s):  
K. STANFORD ◽  
S. J. BACH ◽  
T. H. MARX ◽  
S. JONES ◽  
J. R. HANSEN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Feedlot Cattle ◽  
Mitigation Strategies ◽  
Escherichia Coli O157 ◽  
Feeding Period ◽  
Sample Collection ◽  
E Coli ◽  
Challenge Study ◽  
On Farm ◽  
Feed Samples

On-farm methods of monitoring Escherichia coli O157:H7 were assessed in 30 experimentally inoculated steers housed in four pens over a 12-week period and in 202,878 naturally colonized feedlot cattle housed in 1,160 pens on four commercial Alberta feedlots over a 1-year period. In the challenge study, yearling steers were experimentally inoculated with 1010 CFU of a four-strain mixture of nalidixic acid–resistant E. coli O157:H7. After inoculation, shedding of E. coli O157:H7 was monitored weekly by collecting rectal fecal samples (FEC), oral swabs (ORL), pooled fecal pats (PAT), manila ropes (ROP) orally accessed for 4 h, feed samples, water, and water bowl interface. Collection of FEC from all animals per pen provided superior isolation (P &lt; 0.01) of E. coli O157:H7 compared with other methods, although labor and animal restraint requirements for fecal sample collection were high. When one sample was collected per pen of animals, E. coli O157:H7 was more likely to be detected from the ROP than from the FEC, PAT, or ORL (P &lt; 0.001). In the commercial feedlot study, samples were limited to ROP and PAT, and E. coli O157:H7 was isolated in 18.8% of PAT and 6.8% of ROP samples. However, for animals that had been resident in the feedlot pen for at least 1 month, isolation of E. coli O157:H7 from ROP was not different from that from PAT (P = 0.35). Pens of animals on feed for &lt;30 days were six times more likely to shed E. coli O157:H7 than were animals on feed for &gt;30 days. However, change in diet did not affect shedding of the organism (P &gt; 0.23) provided that animals had acclimated to the feedlot for 1 month or longer. Findings from this study indicate the importance of introduction of mitigation strategies early in the feeding period to reduce transference and the degree to which E. coli O157:H7 is shed into the environment.

scholarly journals Transcriptomic Analysis of Shiga Toxin-Producing Escherichia coli during Initial Contact with Cattle Colonic Explants

2020 ◽  
Vol 8 (11) ◽  
pp. 1662
Author(s):  
Zachary R. Stromberg ◽  
Rick E. Masonbrink ◽  
Melha Mellata
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Bacterial Colonization ◽  
Coli Strain ◽  
Fold Change ◽  
Initial Contact ◽  
Lon Protease ◽  
E Coli ◽  
Log2 Fold Change ◽  
Colonization Factors

Foodborne pathogens are a public health threat globally. Shiga toxin-producing Escherichia coli (STEC), particularly O26, O111, and O157 STEC, are often associated with foodborne illness in humans. To create effective preharvest interventions, it is critical to understand which factors STEC strains use to colonize the gastrointestinal tract of cattle, which serves as the reservoir for these pathogens. Several colonization factors are known, but little is understood about initial STEC colonization factors. Our objective was to identify these factors via contrasting gene expression between nonpathogenic E. coli and STEC. Colonic explants were inoculated with nonpathogenic E. coli strain MG1655 or STEC strains (O26, O111, or O157), bacterial colonization levels were determined, and RNA was isolated and sequenced. STEC strains adhered to colonic explants at numerically but not significantly higher levels compared to MG1655. After incubation with colonic explants, flagellin (fliC) was upregulated (log2 fold-change = 4.0, p < 0.0001) in O157 STEC, and collectively, Lon protease (lon) was upregulated (log2 fold-change = 3.6, p = 0.0009) in STEC strains compared to MG1655. These results demonstrate that H7 flagellum and Lon protease may play roles in early colonization and could be potential targets to reduce colonization in cattle.

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