Summer and Winter Prevalence of Shiga Toxin–Producing <i>Escherichia coli</i> (STEC) O26, O45, O103, O111, O121, O145, and O157 in Feces of Feedlot Cattle

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen that can cause hemorrhagic colitis and hemolytic-uremic syndrome. Cattle are the primary reservoir for STEC, and food or water contaminated with cattle feces is the most common source of infections in humans. Consequently, we conducted a cross-sectional study of 1,096 cattle in six dairy herds (n ‫؍‬ 718 animals) and five beef herds (n ‫؍‬ 378 animals) in the summers of 2011 and 2012 to identify epidemiological factors associated with shedding. Fecal samples were obtained from each animal and cultured for STEC. Multivariate analyses were performed to identify risk factors associated with STEC positivity. The prevalence of STEC was higher in beef cattle (21%) than dairy cattle (13%) (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.25, 2.47), with considerable variation occurring across herds (range, 6% to 54%). Dairy cattle were significantly more likely to shed STEC when the average temperature was >28.9°C 1 to 5 days prior to sampling (OR, 2.5; 95% CI, 1.25, 4.91), during their first lactation (OR, 1.8; 95% CI, 1.1, 2.8), and when they were <30 days in milk (OR, 3.9; 95% CI, 2.1, 7.2). These data suggest that the stress or the negative energy balance associated with lactation may result in increased STEC shedding frequencies in Michigan during the warm summer months. Future prevention strategies aimed at reducing stress during lactation or isolating high-risk animals could be implemented to reduce herdlevel shedding levels and avoid transmission of STEC to susceptible animals and people. IMPORTANCE STEC shedding frequencies vary considerably across cattle herds in Michigan, and the shedding frequency of strains belonging to non-O157 serotypes far exceeds the shedding frequency of O157 strains, which is congruent with human infections in the state. Dairy cattle sampled at higher temperatures, in their first lactation, and early in the milk production stage were significantly more likely to shed STEC, which could be due to stress or a negative energy balance. Future studies should focus on the isolation of high-risk animals to decrease herd shedding levels and the potential for contamination of the food supply. Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen in both developed and developing countries. STEC can cause hemorrhagic colitis and hemolytic-uremic syndrome (HUS), which can lead to kidney failure and death, particularly in young children (1). STEC strains belonging to serotype O157:H7 have been reported to cause human infections at the highest frequency, although there has been a steady increase in the detection of cases caused by STEC serotypes other than O157 (non-O157 STEC) (2-4). This increase is due in part to changes in laboratory diagnostic practices targeting non-O157 STEC (5). The incidence of non-O157 STEC infections in the United States increased from 0.12 per 100,000 population in 2000 to 0.95 per 100,000 in 2010, while the incidence of STEC O157 infections decreased...

Section: Discussionsupporting

confidence: 92%

Factors Associated with Shiga Toxin-Producing Escherichia coli Shedding by Dairy and Beef Cattle

Venegas-Vargas

Henderson

Khare

et al. 2016

“…For each additional day needed to complete 75% of all calvings on a ranch, the odds of an individual animal testing positive decreased by approximately 4% (e Ϫ0.037 ϫ 1 ϭ 0.96). In contrast to numerous studies on cattle in dairy and feedlot production systems that found higher odds of cattle testing positive during summer than during winter, the odds of testing positive for fecal E. coli O157:H7 were 2 to 3 times lower for cattle from these cow-calf operations tested during spring (March to May) or summer (June to August) than for cattle tested during the winter months (December to February) (25,28). The odds of testing positive for fecal E. coli O157:H7 were 4.2 times higher for beef cattle on ranches that used surface water sources for drinking than for cattle on ranches without surface water access (odds ratio [OR], 4.2).…”

Section: Resultscontrasting

confidence: 68%

Prevalence and Genomic Characterization of Escherichia coli O157:H7 in Cow-Calf Herds throughout California

Worley

Flores

Yang

et al. 2017

Escherichia coli serotype O157:H7 is a zoonotic food-and waterborne bacterial pathogen that causes a high hospitalization rate and can cause lifethreatening complications. Increasingly, E. coli O157:H7 infections appear to originate from fresh produce. Ruminants, such as cattle, are a prominent reservoir of E. coli O157:H7 in the United States. California is one of the most agriculturally productive regions in the world for fresh produce, beef, and milk. The close proximity of fresh produce and cattle presents food safety challenges on a uniquely large scale. We performed a survey of E. coli O157:H7 on 20 farms in California to observe the regional diversity and prevalence of E. coli O157:H7. Isolates were obtained from enrichment cultures of cow feces. Some farms were sampled on two dates. Genomes from isolates were sequenced to determine their relatedness and pathogenic potential. E. coli O157:H7 was isolated from approximately half of the farms. The point prevalence of E. coli O157:H7 on farms was highly variable, ranging from zero to nearly 90%. Within farms, generally one or a few lineages were found, even when the rate of isolation was high. On farms with high isolation rates, a single clonal lineage accounted for most of the isolates. Farms that were visited months after the first visit might have had the same lineages of E. coli O157:H7. Strains of E. coli O157:H7 may be persistent for months on farms.IMPORTANCE This survey of 20 cow-calf operations from different regions of California provides an in depth look at resident Escherichia coli O157:H7 populations at the molecular level. E. coli O157:H7 is found to have a highly variable prevalence, and with whole-genome sequencing, high prevalences in herds were found to be due to a single lineage shed from multiple cows. Few repeat lineages were found between farms in this area; therefore, we predict that E. coli O157:H7 has significant diversity in this area beyond what is detected in this survey. All isolates from this study were found to have pathogenic potential based on the presence of key virulence gene sequences. This represents a novel insight into pathogen diversity within a single subtype and will inform future attempts to survey regional pathogen populations.

“…We further show that transmissibility for serogroup alone for non-O157 was substantially different than transmissibility of EHEC group. While the O157 serogroup has both Shiga toxin and intimin virulence genes, most non-O157 serogroups modeled here were not associated with virulence genes (9). Thus, the O-group and EHEC data sets were very similar for O157 but different for non-O157 serogroups, where prevalence of EHEC was much lower than for the O-group data, especially for O26, O45, and O103.…”

Section: Discussionmentioning

confidence: 71%

“…The methods included enrichment, serogroup-specific immunomagnetic separation, and plating on selective media, followed by a multiplex PCR for serogroup confirmation and virulence gene detection (9). Thus, two types of prevalence data, based on the detection method, were generated: prevalence data based on serogroup identification (the O gene) (called the O-group data here) and data based on serogroup identification plus the presence of at least one Shiga toxin-encoding gene (stx 1 or stx 2 ) and the attaching and effacing intimin-coding (eae) gene (called the EHEC data here).…”

Section: Methodsmentioning

confidence: 99%

“…Healthy cattle, their feces, and their environment are considered the primary reservoirs for STEC (6). STEC strains are ubiquitous on cattle farms, particularly during the summer (7)(8)(9). While the ecology and epidemiology of O157:H7 in cattle populations have been studied extensively, considerably fewer studies on the distribution and determinants of non-O157 serogroups in cattle have been conducted.…”

mentioning

confidence: 99%

See 1 more Smart Citation

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

Chen

Sanderson

Lee

et al. 2016

Self Cite

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.