“Preharvest” Food Safety for
            <i>Escherichia coli</i>
            O157 and Other Pathogenic Shiga Toxin-Producing Strains

Besser, Thomas E.; Schmidt, Carrie E.; Shah, Devendra H.; Shringi, Smriti

doi:10.1128/microbiolspec.ehec-0021-2013

Cited by 13 publications

(17 citation statements)

References 108 publications

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“…Similarly, our strict controls on pen and water trough hygiene and our use of the same feed sources and harvest years for both the August and February challenge studies are not representative of routine industry practices but were necessary to minimize the exposure of the study cattle to these (extrinsic to cattle) factors. Therefore, feed and water hygiene and environmental sanitation along with the noncattle reservoir of STEC O157 affecting the fecal-oral transmission remain plausible mechanisms for the seasonal variation observed on farms (46). Finally, the challenge doses of STEC O157 we used may be larger than those that result in natural infection of cattle (47).…”

Section: Discussionmentioning

confidence: 99%

Standardized Escherichia coli O157:H7 Exposure Studies in Cattle Provide Evidence that Bovine Factors Do Not Drive Increased Summertime Colonization

Sheng

Shringi

Baker

et al. 2016

Appl Environ Microbiol

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The increased summertime prevalence of cattle carriage of enterohemorrhagic Shiga toxin-producing Escherichia coli O157:H7 (STEC O157) is associated with the increased summertime incidence of human infection. The mechanism driving the seasonality of STEC O157 carriage among cattle is unknown. We conducted experimental challenge trials to distinguish whether factors extrinsic or intrinsic to cattle underlie the seasonality of STEC O157 colonization. Holstein steers (n ‫؍‬ 20) exposed to ambient environmental conditions were challenged with a standardized pool of STEC O157 strains four times at 6-month intervals. The densities and durations of rectoanal junction mucosa (RAJ) colonization with STEC O157 were compared by season (winter versus summer), dose (10 9 CFU versus 10 7 CFU), and route of challenge (oral versus rectal). Following summer challenges, the RAJ STEC O157 colonization density was significantly lower (P ‫؍‬ 0.016) and the duration was shorter (P ‫؍‬ 0.052) than for winter challenges, a seasonal pattern opposite to that observed naturally. Colonization was unaffected by the challenge route, indicating that passage through the gastrointestinal microbiome did not significantly affect the infectious dose to the RAJ. A 2-log reduction of the challenge doses in the second-year trials was accompanied by similarly reduced RAJ colonization in both seasons (P < 0.001). These results refute the hypothesis that cattle are predisposed to STEC O157 colonization during the summer months, either due to intrinsic factors or indirectly due to gastrointestinal tract microbiome effects. Instead, the data support the hypothesis that the increased summertime STEC O157 colonization results from increased seasonal oral exposure to this pathogen. Shiga toxin-producing Escherichia coli serotype O157:H7 (STEC O157) is an important zoonotic pathogen estimated to cause Ͼ70,000 cases of human infection annually in the United States (1, 2). Human disease is characterized by mild to severe, frequently hemorrhagic diarrhea, and the development of a severe sequela, the hemolytic-uremic syndrome, in approximately 5 to 10% of patients (3). Cattle are an important asymptomatic reservoir host of STEC O157, which may be transmitted to humans by ingestion of contaminated meat, produce, or water or by direct contact with cattle carrying the pathogen (4-6). The seasonal variation in STEC O157 fecal shedding by cattle, specifically the higher summertime prevalence, occurs in diverse regions, including Canada, England, Italy, South Korea, the Netherlands, Turkey, and the United States (7-20). Similar summertime peak shedding is also reported in sheep (11,15,21). Contrary patterns have been occasionally reported, including a higher wintertime prevalence (22, 23) or no seasonal variation (24-26); however, these are unusual and sometimes are confounded by other factors such as a change to indoor housing (22).The seasonal summertime shedding of STEC O157 in cattle parallels both seasonal increases in carcass contamination at abattoirs and the in...

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Section: Discussionmentioning

confidence: 99%

Standardized Escherichia coli O157:H7 Exposure Studies in Cattle Provide Evidence that Bovine Factors Do Not Drive Increased Summertime Colonization

Sheng

Shringi

Baker

et al. 2016

Appl Environ Microbiol

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“…O157 has been shown to survive in several environments, including water and soil. Carriage of O157 has also been described in a variety of organisms, including protozoa, invertebrates, birds, and mammals (38). The R 0 values for non-O157 groups were overall lower than that for O157, which suggests that abiotic and biotic reservoirs other than cattle may even play a greater role in non-O157 ecology.…”

Section: Discussionmentioning

confidence: 87%

Basic Reproduction Number and Transmission Dynamics of Common Serogroups of Enterohemorrhagic Escherichia coli

Chen

Sanderson

Lee

et al. 2016

Appl Environ Microbiol

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Understanding the transmission dynamics of pathogens is essential to determine the epidemiology, ecology, and ways of controlling enterohemorrhagic Escherichia coli (EHEC) in animals and their environments. Our objective was to estimate the epidemiological fitness of common EHEC strains in cattle populations. For that purpose, we developed a Markov chain model to characterize the dynamics of 7 serogroups of enterohemorrhagic Escherichia coli (O26, O45, O103, O111, O121, O145, and O157) in cattle production environments based on a set of cross-sectional data on infection prevalence in 2 years in two U.S. states. The basic reproduction number (R 0 ) was estimated using a Bayesian framework for each serogroup based on two criteria (using serogroup alone [the O-group data] and using O serogroup, Shiga toxin gene[s], and intimin [eae] gene together [the EHEC data]). In addition, correlations between external covariates (e.g., location, ambient temperature, dietary, and probiotic usage) and prevalence/R 0 were quantified. R 0 estimates varied substantially among different EHEC serogroups, with EHEC O157 having an R 0 of >1 (ϳ1.5) and all six other EHEC serogroups having an R 0 of less than 1. Using the O-group data substantially increased R 0 estimates for the O26, O45, and O103 serogroups (R 0 > 1) but not for the others. Different covariates had distinct influences on different serogroups: the coefficients for each covariate were different among serogroups. Our modeling and analysis of this system can be readily expanded to other pathogen systems in order to estimate the pathogen and external factors that influence spread of infectious agents. IMPORTANCEIn this paper we describe a Bayesian modeling framework to estimate basic reproduction numbers of multiple serotypes of Shiga toxin-producing Escherichia coli according to a cross-sectional study. We then coupled a compartmental model to reconstruct the infection dynamics of these serotypes and quantify their risk in the population. We incorporated different sensitivity levels of detecting different serotypes and evaluated their potential influence on the estimation of basic reproduction numbers.

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“…Management practices and cattle type may play a role in the prevalence of STEC in animals and their production environments (6,15,17,31,61,62,68). In one study, a lower prevalence of STEC was detected in feedlot cattle than in dairy and range cattle (17).…”

Section: Discussionmentioning

confidence: 99%

“…Significant association between the detection of an EHEC in fecal samples and detection of the same EHEC on hide samples was determined for EHEC O26, O111, O121, and EHEC-6 and supports the hypothesis that feces are a major source of hide contamination. Effective preharvest interventions that reduce carriage of EHEC in the intestines, e.g., vaccines (6,61,62), may reduce EHEC prevalence on hides.…”

Section: Discussionmentioning

confidence: 99%

Prevalence and Level of Enterohemorrhagic Escherichia coli in Culled Dairy Cows at Harvest

Stromberg

Lewis

Aly

et al. 2016

Journal of Food Protection

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The primary objective of this study was to determine the prevalence and level of enterohemorrhagic Escherichia coli (EHEC) O26, O45, O103, O111, O121, and O145 (collectively EHEC-6) plus EHEC O157 in fecal, hide, and preintervention carcass surface samples from culled dairy cows. Matched samples (n =300) were collected from 100 cows at harvest and tested by a culture-based method and two molecular methods: NeoSEEK STEC (NS) and Atlas STEC EG2 Combo. Both the culture and NS methods can be used to discriminate among the seven EHEC types (EHEC-7), from which the cumulative prevalence was inferred, whereas the Atlas method can discriminate only between EHEC O157 and non-O157 EHEC, without discrimination of the serogroup. The EHEC-7 prevalence in feces, hides, and carcass surfaces was 6.5, 15.6, and 1.0%, respectively, with the culture method and 25.9, 64.9, and 7.0%, respectively, with the NS method. With the Atlas method, the prevalence of non-O157 EHEC was 29.1, 38.3, and 28.0% and that of EHEC O157 was 29.1, 57.0, and 3.0% for feces, hides, and carcasses, respectively. Only two samples (a hide sample and a fecal sample) originating from different cows contained quantifiable EHEC. In both samples, the isolates were identified as EHEC O157, with 4.7 CFU/1,000 cm2 in the hide sample and 3.9 log CFU/g in the fecal sample. Moderate agreement was found between culture and NS results for detection of EHEC O26 (κ =0.58, P < 0.001), EHEC O121 (κ = 0.50, P < 0.001), and EHEC O157 (κ = 0.40, P < 0.001). No significant agreement was observed between NS and Atlas results or between culture and Atlas results. Detection of an EHEC serogroup in fecal samples was significantly associated with detection of the same EHEC serogroup in hide samples for EHEC O26 (P =0.001), EHEC O111 (P =0.002), EHEC O121 (P < 0.001), and EHEC-6 (P = 0.029) based on NS detection and for EHEC O121 (P < 0.001) based on detection by culture. This study provides evidence that non-O157 EHEC are ubiquitous on hides of culled dairy cattle and that feces are an important source of non-O157 EHEC hide contamination.

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“Preharvest” Food Safety for Escherichia coli O157 and Other Pathogenic Shiga Toxin-Producing Strains

Cited by 13 publications

References 108 publications

Standardized Escherichia coli O157:H7 Exposure Studies in Cattle Provide Evidence that Bovine Factors Do Not Drive Increased Summertime Colonization

Standardized Escherichia coli O157:H7 Exposure Studies in Cattle Provide Evidence that Bovine Factors Do Not Drive Increased Summertime Colonization

Basic Reproduction Number and Transmission Dynamics of Common Serogroups of Enterohemorrhagic Escherichia coli

Prevalence and Level of Enterohemorrhagic Escherichia coli in Culled Dairy Cows at Harvest

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