<i>Escherichia coli</i>
            O157:H7 Strains That Persist in Feedlot Cattle Are Genetically Related and Demonstrate an Enhanced Ability To Adhere to Intestinal Epithelial Cells

Carlson, Brandon A.; Nightingale, Kendra K.; Mason, Gary L.; Ruby, John R.; Choat, W. T.; Loneragan, Guy H.; Smith, G. C.; Sofos, John N.; Belk, K. E.

doi:10.1128/aem.00972-09

Cited by 69 publications

(51 citation statements)

References 54 publications

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“…Other studies observed intermittent shedding of STEC by adult dairy cows, each animal potentially shedding for several months (63,(99)(100)(101). Similar intermittent shedding patterns have been observed in feedlot cattle (58,102). Individual and herd shedding patterns have been associated with several factors, including diet, herd size, housing type, and age of the animal (3).…”

Section: Discussionmentioning

confidence: 70%

Dynamics of Escherichia coli Virulence Factors in Dairy Herds and Farm Environments in a Longitudinal Study in the United States

Lambertini

Karns

Kessel

et al. 2015

Appl Environ Microbiol

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g Pathogenic Escherichia coli or its associated virulence factors have been frequently detected in dairy cow manure, milk, and dairy farm environments. However, it is unclear what the long-term dynamics of E. coli virulence factors are and which farm compartments act as reservoirs. This study assessed the occurrence and dynamics of four E. coli virulence factors (eae, stx 1 , stx 2 , and the gamma allele of the tir gene [␥-tir]) on three U.S. dairy farms. Fecal, manure, water, feed, milk, and milk filter samples were collected from 2004 to 2012. Virulence factors were measured by postenrichment quantitative PCR (qPCR). All factors were detected in most compartments on all farms. Fecal and manure samples showed the highest prevalence, up to 53% for stx and 21% for ␥-tir in fecal samples and up to 84% for stx and 44% for ␥-tir in manure. Prevalence was low in milk (up to 1.9% for stx and 0.7% for ␥-tir). However, 35% of milk filters were positive for stx and 20% were positive for ␥-tir. All factors were detected in feed and water. Factor prevalence and levels, expressed as qPCR cycle threshold categories, fluctuated significantly over time, with no clear seasonal signal independent from year-to-year variability. Levels were correlated between fecal and manure samples, and in some cases autocorrelated, but not between manure and milk filters. Shiga toxins were nearly ubiquitous, and 10 to 18% of the lactating cows were potential shedders of E. coli O157 at least once during their time in the herds. E. coli virulence factors appear to persist in many areas of the farms and therefore contribute to transmission dynamics. Diarrheagenic Escherichia coli isolates of several pathovars of public health importance, such as enteropathogenic E. coli (EPEC), Shiga-toxigenic E. coli (STEC), and enterohemorrhagic E. coli (EHEC), have been observed in dairy herds (1-3) as well as in milk (4-10) and other dairy products (4-8, 11, 12). Beef cattle are also known to harbor pathogenic E. coli (13-16). Dairy animals also enter the meat production chain, contributing to meatborne infections (17). Infection by these classes of pathogenic E. coli can have serious health impacts in humans (8). The cost of human health losses in the United States due to E. coli O157 alone was estimated to amount to $405 million per year (18). Numerous E. coli outbreaks have been linked to the consumption of milk and dairy products (19)(20)(21)(22) and to direct contact with dairy farm animals and environments (23, 24). Milk contamination is usually due to fecal contamination. Intestinal colonization by STEC serogroups such as E. coli O157 is usually subclinical in cows and calves and therefore is often undetected. STEC and EHEC have almost never been associated with nonenteric infections in cows, such as mastitis, although other classes of pathogenic E. coli have been known to cause mastitis (25).A virulence factor is a phenotypic trait, usually a large molecule or complex, which determines the ability of E. coli and other bacterial pathogens to infect a h...

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Section: Discussionmentioning

confidence: 70%

Dynamics of Escherichia coli Virulence Factors in Dairy Herds and Farm Environments in a Longitudinal Study in the United States

Lambertini

Karns

Kessel

et al. 2015

Appl Environ Microbiol

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“…This characterization was aimed at identifying strain-specific traits that would be necessary for attaining supershedder levels in the lower GI tract of cattle. To address this issue, it was deemed a high priority to collect samples from a diverse group of cattle, as previous studies have reported dominant E. coli O157:H7 genotypes within individual feedlots (29,30). This priority led to the collection of a majority of the samples from cattle at harvest.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Escherichia coli O157:H7 Strains Isolated from Supershedding Cattle

Arthur

Ahmed

Chase-Topping

et al. 2013

Appl Environ Microbiol

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Previous reports have indicated that a small proportion of cattle shedding high levels of Escherichia coli O157:H7 is the main source for transmission of this organism between animals. Cattle achieving a fecal shedding status of 10 4 CFU of E. coli O157: H7/gram or greater are now referred to as supershedders. The aim of this study was to investigate the contribution of E. coli O157:H7 strain type to supershedding and to determine if supershedding was restricted to a specific set of E. coli O157:H7 strains. Fecal swabs (n ‫؍‬ 5,086) were collected from cattle at feedlots or during harvest. Supershedders constituted 2.0% of the bovine population tested. Supershedder isolates were characterized by pulsed-field gel electrophoresis (PFGE), phage typing, lineage-specific polymorphism assay (LSPA), Stx-associated bacteriophage insertion (SBI) site determination, and variant analysis of Shiga toxin, tir, and antiterminator Q genes. Isolates representing 52 unique PFGE patterns, 19 phage types, and 12 SBI clusters were obtained from supershedding cattle, indicating that there is no clustering to E. coli O157:H7 genotypes responsible for supershedding. While being isolated directly from cattle, this strain set tended to have higher frequencies of traits associated with human clinical isolates than previously collected bovine isolates with respect to lineage and tir allele, but not for SBI cluster and Q type. We conclude that no exclusive genotype was identified that was common to all supershedder isolates. E scherichia coli O157:H7 is an important food-borne pathogen that poses a serious public health concern and financial burden. Cattle are the principal animal reservoir of E. coli O157:H7, and while the rumen has been shown to harbor this pathogen on occasion, it is found more frequently in the distal portion of the bovine gastrointestinal (GI) tract, with the rectoanal junction (RAJ) identified as the predominant colonization site (1, 2). Once colonized, an animal can shed various concentrations of E. coli O157:H7 organisms in the feces. Among colonized individuals, a small proportion will excrete E. coli O157:H7 at levels of Ն10 4 CFU/g of feces. These animals have been referred to as supershedders and are reported to be responsible for increased transmission of E. coli O157:H7 within cattle production environments as well as having significant effects on contamination of the cattle hide and carcass (3-6).Matthews et al. (7) presented data suggesting that 20% of the E. coli O157:H7 infections in cattle on Scottish farms were responsible for 80% of the transmission of the organism between animals. Another study showed that 9% of the animals shedding E. coli O157:H7 at harvest produced over 96% of the total E. coli O157:H7 fecal load for the group (6). Conversely, feedlot cattle that did not shed E. coli O157:H7 over the course of study were five times more likely to be housed in a pen that did not contain a supershedder (8). In addition, Arthur et al. (3) have shown that 95% of feedlot pens containing at least one sup...

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“…A 1-year survey of Alberta dairies yielded 65 isolates of EC H7 grouped into 23 PFGE 2-enzyme profiles; 60=65 belonged to three patterns with >90% homology . In a long-term study of EC O157:H7 carriage by feedlot cattle, 132 isolates were divided into 32 PFGE types; one type accounted for 53% of all isolates, and showed high adherence to Caco-2 cells (Carlson et al, 2009). Persistent and dominant strains may be those that can easily colonize cattle and survive in the farm environment; the pen prevalence may be continuous for 5 months, and a given strain may persist on a farm for >2 years (Shere et al, 1998).…”

Section: Ehec In the Farm Environmentmentioning

confidence: 99%

Escherichia coliO157:H7: Animal Reservoir and Sources of Human Infection

Ferens

Hovde

2011

Foodborne Pathogens and Disease

481

327

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This review surveys the literature on carriage and transmission of enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the context of virulence factors and sampling=culture technique. EHEC of the O157:H7 serotype are worldwide zoonotic pathogens responsible for the majority of severe cases of human EHEC disease. EHEC O157:H7 strains are carried primarily by healthy cattle and other ruminants, but most of the bovine strains are not transmitted to people, and do not exhibit virulence factors associated with human disease. Prevalence of EHEC O157:H7 is probably underestimated. Carriage of EHEC O157:H7 by individual animals is typically shortlived, but pen and farm prevalence of specific isolates may extend for months or years and some carriers, designated as supershedders, may harbor high intestinal numbers of the pathogen for extended periods. The prevalence of EHEC O157:H7 in cattle peaks in the summer and is higher in postweaned calves and heifers than in younger and older animals. Virulent strains of EHEC O157:H7 are rarely harbored by pigs or chickens, but are found in turkeys. The bacteria rarely occur in wildlife with the exception of deer and are only sporadically carried by domestic animals and synanthropic rodents and birds. EHEC O157:H7 occur in amphibian, fish, and invertebrate carriers, and can colonize plant surfaces and tissues via attachment mechanisms different from those mediating intestinal attachment. Strains of EHEC O157:H7 exhibit high genetic variability but typically a small number of genetic types predominate in groups of cattle and a farm environment. Transmission to people occurs primarily via ingestion of inadequately processed contaminated food or water and less frequently through contact with manure, animals, or infected people.

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Escherichia coli O157:H7 Strains That Persist in Feedlot Cattle Are Genetically Related and Demonstrate an Enhanced Ability To Adhere to Intestinal Epithelial Cells

Cited by 69 publications

References 54 publications

Dynamics of Escherichia coli Virulence Factors in Dairy Herds and Farm Environments in a Longitudinal Study in the United States

Dynamics of Escherichia coli Virulence Factors in Dairy Herds and Farm Environments in a Longitudinal Study in the United States

Characterization of Escherichia coli O157:H7 Strains Isolated from Supershedding Cattle

Escherichia coliO157:H7: Animal Reservoir and Sources of Human Infection

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