A longitudinal study of the prevalence and super-shedding of Escherichia coli O157 in dairy heifers

Williams, Katrina; Ward, Michael P.; Dhungyel, Om P.; Hall, Evelyn; Breda, Luciana

doi:10.1016/j.vetmic.2014.07.001

Cited by 19 publications

(16 citation statements)

References 43 publications

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“…Similar examples of clonal turnover within a herd have previously been found using both MLVA and PFGE analysis (Lahti et al ., ; LeJeune et al ., ; Sanderson et al ., ; Williams et al ., ). A US study using MLVA (Williams et al ., ) found three distinct types prevalent among a feedlot. Two of these types were found to be prevalent in the early stages of the study before their prevalence waned and the third type took over in the later stages.…”

Section: Discussionmentioning

confidence: 97%

Population and evolutionary dynamics of Shiga‐toxin producing Escherichia coli O157 in a beef herd: A longitudinal study

Jones

Octavia

Lammers

et al. 2017

Environmental Microbiology

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Shiga toxin producing Escherichia coli O157:H7 (STEC O157) is naturally found in the gastrointestinal tract of cattle and can cause severe disease in humans. There is limited understanding of the population dynamics and microevolution of STEC O157 at herd level. In this study, isolates from a closed beef herd of 23 cows were used to examine the population turnover in the herd. Of the nine STEC O157 clades previously described, clade 7 was found in 162 of the 169 isolates typed. Multiple locus variable number tandem repeat analysis (MLVA) differentiated 169 isolates into 33 unique MLVA types. Five predominant MLVA types were evident with most of the remaining types containing only a single isolate. MLVA data suggest that over time clonal replacement occurred within the herd. Genome sequencing of 18 selected isolates found that the isolates were divided into four lineages, representing four different 'clones' in the herd. Genome data confirmed clonal replacement over time and provided evidence of cross transmission of strains between cows. The findings enhanced our understanding of the population dynamics of STEC O157 in its natural host that will help developing effective control measures to prevent the spread of the pathogen to the human population.

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Section: Discussionmentioning

confidence: 97%

Population and evolutionary dynamics of Shiga‐toxin producing Escherichia coli O157 in a beef herd: A longitudinal study

Jones

Octavia

Lammers

et al. 2017

Environmental Microbiology

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“…Biofilms are not static, and the sloughing off of viable bacteria promotes the colonization of downstream environments (Van Houdt and Michiels, 2005). Recent research by Williams et al (2014) has demonstrated that five heifers with multiple super-shedding events also had high number of samples from which E. coli O157:H7 was not detected. Specifically, three of these heifers showed intermittent and infrequent low levels of shedding with clusters of high level of shedding fitting a pattern of clearance and reinfection, consistent with a biofilm-sloughing phenomenon.…”

Section: Defining a Super-sheddermentioning

confidence: 99%

“…Furthermore, changes in management practices such as increased handling, mixing with cohorts, or a change in diet failed to induce a return of the host to a super-shedding state. Williams et al (2014) reported that heifers that were detected as super-shedding were not identifiable as long-term shedders and suggested that the use of ''super-shedding event'' could be a better descriptor of the phenomenon as opposed to the term ''supershedder'' as a reference to a specific animal. A number of factors other than the intermittent nature of shedding of E. coli O157:H7 by feedlot cattle could contribute to variability of shedding, including the feedlot selected, the sampling season, or even year-to-year differences in pathogen prevalence .…”

Section: Super-shedding Of E Coli O157:h7mentioning

confidence: 99%

Perspectives on Super-Shedding ofEscherichia coliO157:H7 by Cattle

Munns

Selinger

Stanford

et al. 2015

Foodborne Pathogens and Disease

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Escherichia coli O157:H7 is a foodborne pathogen that causes illness in humans worldwide. Cattle are the primary reservoir of this bacterium, with the concentration and frequency of E. coli O157:H7 shedding varying greatly among individuals. The term "super-shedder" has been applied to cattle that shed concentrations of E. coli O157:H7 ≥ 10⁴ colony-forming units/g feces. Super-shedders have been reported to have a substantial impact on the prevalence and transmission of E. coli O157:H7 in the environment. The specific factors responsible for super-shedding are unknown, but are presumably mediated by characteristics of the bacterium, animal host, and environment. Super-shedding is sporadic and inconsistent, suggesting that biofilms of E. coli O157:H7 colonizing the intestinal epithelium in cattle are intermittently released into feces. Phenotypic and genotypic differences have been noted in E. coli O157:H7 recovered from super-shedders as compared to low-shedding cattle, including differences in phage type (PT21/28), carbon utilization, degree of clonal relatedness, tir polymorphisms, and differences in the presence of stx2a and stx2c, as well as antiterminator Q gene alleles. There is also some evidence to support that the native fecal microbiome is distinct between super-shedders and low-shedders and that low-shedders have higher levels of lytic phage within feces. Consequently, conditions within the host may determine whether E. coli O157:H7 can proliferate sufficiently for the host to obtain super-shedding status. Targeting super-shedders for mitigation of E. coli O157:H7 has been proposed as a means of reducing the incidence and spread of this pathogen to the environment. If super-shedders could be easily identified, strategies such as bacteriophage therapy, probiotics, vaccination, or dietary inclusion of plant secondary compounds could be specifically targeted at this subpopulation. Evidence that super-shedder isolates share a commonality with isolates linked to human illness makes it imperative that the etiology of this phenomenon be characterized.

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“…Of those studies performed on pasture, most have relied on sampling intervals of 51 week [24,25]. A recent study by Williams et al [7] assessed the presence and concentration of E. coli O157 in dairy heifers on pasture over a period of 5 months using weekly sampling intervals. A similar study, performed in beef cattle but using 3-to 7-day intervals identified a distinct pattern associated with E. coli O157 shedding [26].…”

Section: Introductionmentioning

confidence: 99%

Daily shedding dynamics ofE. coliO157 in an Australian grass-fed beef herd

et al. 2016

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This study aimed to describe the diurnal shedding dynamics of Escherichia coli O157 in cattle managed on pasture. The purpose was to identify the value of a single measurement for predicting the shedding status on subsequent days. Over a 14-day period, 24 beef cows with known E. coli O157 shedding status were sampled twice daily or daily (21 sampling points) and E. coli O157 was enumerated from faeces. No association between shedding status of individual animals within a 7-h period was identified (odds ratio 1·5, P = 0·08). Short-interval sampling demonstrated substantial diurnal volatility in shedding of E. coli O157 that is not evident in studies based on long-interval (>7 days) sampling. The findings contribute to and support previous findings on the question why it has been difficult to achieve progress in understanding the epidemiology of E. coli O157 infection in cattle.

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A longitudinal study of the prevalence and super-shedding of Escherichia coli O157 in dairy heifers

Cited by 19 publications

References 43 publications

Population and evolutionary dynamics of Shiga‐toxin producing Escherichia coli O157 in a beef herd: A longitudinal study

Population and evolutionary dynamics of Shiga‐toxin producing Escherichia coli O157 in a beef herd: A longitudinal study

Perspectives on Super-Shedding ofEscherichia coliO157:H7 by Cattle

Daily shedding dynamics ofE. coliO157 in an Australian grass-fed beef herd

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