Molecular Risk Assessment and Epidemiological Typing of Shiga Toxin-Producing
            <i>Escherichia coli</i>
            by Using a Novel PCR Binary Typing System

Brandt, Stephanie M.; King, Nicola J.; Cornelius, Angela J.; Premaratne, Aruni; Besser, Thomas E.; On, Stephen L. W.

doi:10.1128/aem.02322-10

Cited by 20 publications

(15 citation statements)

References 67 publications

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“…Although these swine STEC strains were recovered from samples of 95 healthy finishing pigs from three cohorts within 18 months in the same geographic area, they were composed of three major pathotypes with 16 different combinations of virulence gene profiles and serotypes. The panel of virulence genes in this study included 69 targets, and our results were in agreement with those of another study suggesting that increasing the number of virulence genes in the panel would increase the resolution of the virulence gene profiling (57). Various virulence gene profiles in swine STEC strains have also been reported elsewhere (38)(39)(40)(41)(42)(58)(59)(60).…”

Section: Discussionsupporting

confidence: 80%

Diverse Virulence Gene Content of Shiga Toxin-Producing Escherichia coli from Finishing Swine

Tseng

Fratamico

Bagi

et al. 2014

Appl Environ Microbiol

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dShiga toxin-producing Escherichia coli (STEC) infections are a critical public health concern because they can cause severe clinical outcomes, such as hemolytic uremic syndrome, in humans. Determining the presence or absence of virulence genes is essential in assessing the potential pathogenicity of STEC strains. Currently, there is limited information about the virulence genes carried by swine STEC strains; therefore, this study was conducted to examine the presence and absence of 69 virulence genes in STEC strains recovered previously from finishing swine in a longitudinal study. A subset of STEC strains was analyzed by pulsed-field gel electrophoresis (PFGE) to examine their genetic relatedness. Swine STEC strains (n ‫؍‬ 150) were analyzed by the use of a high-throughput real-time PCR array system, which included 69 virulence gene targets. Three major pathotypes consisted of 16 different combinations of virulence gene profiles, and serotypes were determined in the swine STEC strains. The majority of the swine STEC strains (n ‫؍‬ 120) belonged to serotype O59:H21 and carried the same virulence gene profile, which consisted of 9 virulence genes: stx 2e , iha, ecs1763, lpfA O113 , estIa (STa), ehaA, paa, terE, and ureD. The eae, nleF, and nleH1-2 genes were detected in one swine STEC strain (O49:H21). Other genes encoding adhesins, including iha, were identified (n ‫؍‬ 149). The PFGE results demonstrated that swine STEC strains from pigs raised in the same finishing barn were closely related. Our results revealed diverse virulence gene contents among the members of the swine STEC population and enhance understanding of the dynamics of transmission of STEC strains among pigs housed in the same barn.

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Section: Discussionsupporting

confidence: 80%

Diverse Virulence Gene Content of Shiga Toxin-Producing Escherichia coli from Finishing Swine

Tseng

Fratamico

Bagi

et al. 2014

Appl Environ Microbiol

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“…Furthermore, VF that play an important role in toxin production and attachment to host cells were highly associated with PT groups I ϩ II or PT group I alone, while other VF were associated with PT group III. Previous studies also reported that the number of VF present in STEC isolates increases the pathogenic potential of STEC and the strong association of certain accessory VF with severe illness and outbreaks (12,17,22,27,33,34,36,44). Interestingly, the accessory virulence gene content of the stx 2f -positive STEC isolates that clustered in a distinct branch with two stx-negative EPEC isolates was lower than the other STEC isolates categorized in PT group II.…”

Section: Discussionmentioning

confidence: 85%

“…Although the disease severity and incidence of STEC are not based solely on the pathogenic potential of the organism but also on host-associated and environmental factors, enough information has accumulated that the presence of virulence factors (VF) carried in addition to the stx genes varies considerably between STEC strains and, therefore, could be used to categorize the potential risk of STEC (5,17,(33)(34)(35)(36). The detection frequency of the stx genes observed in this study (1.8%) was comparable with previous studies performed in The Netherlands (30,37).…”

Section: Discussionmentioning

confidence: 99%

Assessing the Public Health Risk of Shiga Toxin-Producing Escherichia coli by Use of a Rapid Diagnostic Screening Algorithm

et al. 2015

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dShiga toxin-producing Escherichia coli (STEC) is an enteropathogen of public health concern because of its ability to cause serious illness and outbreaks. In this prospective study, a diagnostic screening algorithm to categorize STEC infections into risk groups was evaluated. The algorithm consists of prescreening stool specimens with real-time PCR (qPCR) for the presence of stx genes. The qPCR-positive stool samples were cultured in enrichment broth and again screened for stx genes and additional virulence factors (escV, aggR, aat, bfpA) and O serogroups (O26, O103, O104, O111, O121, O145, O157). Also, PCR-guided culture was performed with sorbitol MacConkey agar (SMAC) and CHROMagar STEC medium. The presence of virulence factors and O serogroups was used for presumptive pathotype (PT) categorization in four PT groups. The potential risk for severe disease was categorized from high risk for PT group I to low risk for PT group III, whereas PT group IV consists of unconfirmed stx qPCRpositive samples. In total, 5,022 stool samples of patients with gastrointestinal symptoms were included. The qPCR detected stx genes in 1.8% of samples. Extensive screening for virulence factors and O serogroups was performed on 73 samples. After enrichment, the presence of stx genes was confirmed in 65 samples (89%). By culture on selective media, STEC was isolated in 36% (26/73 samples). Threshold cycle (C T ) values for stx genes were significantly lower after enrichment compared to direct qPCR (P < 0.001). In total, 11 (15%), 19 (26%), 35 (48%), and 8 (11%) samples were categorized into PT groups I, II, III, and IV, respectively. Several virulence factors (stx 2 , stx 2a , stx 2f , toxB, eae, efa1, cif, espA, tccP, espP, nleA and/or nleB, tir cluster) were associated with PT groups I and II, while others (stx 1 , eaaA, mch cluster, ireA) were associated with PT group III. Furthermore, the number of virulence factors differed between PT groups (analysis of variance, P < 0.0001). In conclusion, a diagnostic algorithm enables fast discrimination of STEC infections associated with a high to moderate risk for severe disease (PT groups I and II) from less-virulent STEC (PT group III). Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen frequently identified as causative agent of acute diarrheal disease in humans. The outcomes of STEC infections may range from asymptomatic carriage and mild diarrhea to severe disease, such as hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) (1-3).Based on pathogenic properties, a subgroup of STEC is also designated enterohemorrhagic E. coli (EHEC); this subgroup of stx-positive strains also contains the locus of enterocyte effacement (LEE) pathogenicity island (4). EHEC belongs to certain serotypes that are frequently associated with outbreaks and lifethreatening illnesses (5). Worldwide, the most common EHEC serotype both in outbreaks and in sporadic cases of severe disease is E. coli O157:H7 (4, 6, 7). Consequently, public health and regulatory responses have been focuse...

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“…In this study, EHEC (encoding LEE genes, vt , hlyA ) of serotypes O157:H7, O26:H11, O111:H8, O182:H25, and O84:H2 were identified. Serotypes O157:H7, O26:H11, and O111:H8 are part of the “top 7” priority serotypes most frequently implicated in severe illness ( Karmali et al, 2003 ), while O182:H25 and O84:H2 are emerging EHEC that have been previously isolated from humans ( Friedrich et al, 2002 ; Cookson et al, 2006 ; Brandt et al, 2011 ; Delannoy et al, 2013 ). Interestingly, all serotypes excluding O2:H6, O137:H41, O132:H18, and O157:H7 carried the cfaB gene, which codes for part of the colonization factor CFA/I; colonization factors are important virulence determinants which mediate ETEC adherence.…”

Section: Discussionmentioning

confidence: 99%

Multi-Year Persistence of Verotoxigenic Escherichia coli (VTEC) in a Closed Canadian Beef Herd: A Cohort Study

Wang

Jokinen²,

Laing

et al. 2018

Front. Microbiol.

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In this study, fecal samples were collected from a closed beef herd in Alberta, Canada from 2012 to 2015. To limit serotype bias, which was observed in enrichment broth cultures, Verotoxigenic Escherichia coli (VTEC) were isolated directly from samples using a hydrophobic grid-membrane filter verotoxin immunoblot assay. Overall VTEC isolation rates were similar for three different cohorts of yearling heifers on both an annual (68.5 to 71.8%) and seasonal basis (67.3 to 76.0%). Across all three cohorts, O139:H19 (37.1% of VTEC-positive samples), O22:H8 (15.8%) and O?(O108):H8 (15.4%) were among the most prevalent serotypes. However, isolation rates for serotypes O139:H19, O130:H38, O6:H34, O91:H21, and O113:H21 differed significantly between cohort-years, as did isolation rates for some serotypes within a single heifer cohort. There was a high level of VTEC serotype diversity with an average of 4.3 serotypes isolated per heifer and 65.8% of the heifers classified as “persistent shedders” of VTEC based on the criteria of >50% of samples positive and ≥4 consecutive samples positive. Only 26.8% (90/336) of the VTEC isolates from yearling heifers belonged to the human disease-associated seropathotypes A (O157:H7), B (O26:H11, O111:NM), and C (O22:H8, O91:H21, O113:H21, O137:H41, O2:H6). Conversely, seropathotypes B (O26:NM, O111:NM) and C (O91:H21, O2:H29) strains were dominant (76.0%, 19/25) among VTEC isolates from month-old calves from this herd. Among VTEC from heifers, carriage rates of vt1, vt2, vt1+vt2, eae, and hlyA were 10.7, 20.8, 68.5, 3.9, and 88.7%, respectively. The adhesin gene saa was present in 82.7% of heifer strains but absent from all of 13 eae+ve strains (from serotypes/intimin types O157:H7/γ1, O26:H11/β1, O111:NM/θ, O84:H2/ζ, and O182:H25/ζ). Phylogenetic relationships inferred from wgMLST and pan genome-derived core SNP analysis showed that strains clustered by phylotype and serotype. Further, VTEC strains of the same serotype usually shared the same suite of antibiotic resistance and virulence genes, suggesting the circulation of dominant clones within this distinct herd. This study provides insight into the diverse and dynamic nature of VTEC populations within groups of cattle and points to a broad spectrum of human health risks associated with these E. coli strains.

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Molecular Risk Assessment and Epidemiological Typing of Shiga Toxin-Producing Escherichia coli by Using a Novel PCR Binary Typing System

Cited by 20 publications

References 67 publications

Diverse Virulence Gene Content of Shiga Toxin-Producing Escherichia coli from Finishing Swine

Diverse Virulence Gene Content of Shiga Toxin-Producing Escherichia coli from Finishing Swine

Assessing the Public Health Risk of Shiga Toxin-Producing Escherichia coli by Use of a Rapid Diagnostic Screening Algorithm

Multi-Year Persistence of Verotoxigenic Escherichia coli (VTEC) in a Closed Canadian Beef Herd: A Cohort Study

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