Seropathotypes, Phylogroups, Stx Subtypes, and Intimin Types of Wildlife-Carried, Shiga Toxin-Producing Escherichia coli Strains with the Same Characteristics as Human-Pathogenic Isolates

Mora, Azucena; López, Cecilia; Dhabi, Ghizlane; López-Beceiro, Ana María; Fidalgo, Luis Eusebio; Díaz, Edgar Patricio Correa; Martínez‐Carrasco, Carlos; Mamani, Rosalía; Herrera, Alexandra; Blanco, Jesús E.; Blanco, Miguel; Blanco, Jorge

doi:10.1128/aem.07520-11

Cited by 105 publications

(89 citation statements)

References 40 publications

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“…STEC can be found in various environmental and food sources (3,(14)(15)(16), and produce is no exception, as many STEC strains have been isolated from produce, especially from spinach, lettuce, and cilantro. To estimate the prevalence rates of STEC in these products, we took the number of STEC strains isolated annually by the MDP in relation to the ϳ2,200 samples of each commodity tested yearly and determined that STEC was present in 0.5 to 0.6% of the spinach, 0.3 to 0.5% of the cilantro, and 0.04 to 0.18% of the lettuce samples.…”

Section: Discussionmentioning

confidence: 99%

Prevalences of Shiga Toxin Subtypes and Selected Other Virulence Factors among Shiga-Toxigenic Escherichia coli Strains Isolated from Fresh Produce

Feng

Reddy²

2013

Appl Environ Microbiol

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b Shiga-toxigenic Escherichia coli (STEC) strains were isolated from a variety of fresh produce, but mostly from spinach, with an estimated prevalence rate of 0.5%. A panel of 132 produce STEC strains were characterized for the presence of virulence and putative virulence factor genes and for Shiga toxin subtypes. About 9% of the isolates were found to have the eae gene, which encodes the intimin binding protein, and most of these belonged to known pathogenic STEC serotypes, such as O157:H7 and O26: H11, or to serotypes that reportedly have caused human illness. Among the eae-negative strains, there were three O113:H21 strains and one O91:H21 strain, which historically have been implicated in illness and therefore may be of concern as well. The ehxA gene, which encodes enterohemolysin, was found in ϳ60% of the isolates, and the saa and subAB genes, which encode STEC agglutinating adhesin and subtilase cytotoxin, respectively, were found in ϳ30% of the isolates. However, the precise roles of these three putative virulence factors in STEC pathogenesis have not yet been fully established. The stx 1a and stx 2a subtypes were present in 22% and 56%, respectively, of the strains overall and were the most common subtypes among produce STEC strains. The stx 2d subtype was the second most common subtype (28% overall), followed by stx 2c (7.5%), and only 2 to 3% of the produce STEC strains had the stx 2e and stx 2g subtypes. Almost half of the produce STEC strains had only partial serotypes or were untyped, and most of those that were identified belonged to unremarkable serotypes. Considering the uncertainties of some of these Stx subtypes and putative virulence factors in causing human illness, it is difficult to determine the health risk of many of these produce STEC strains. Increases in the consumption of fresh produce have resulted in increases in food-borne outbreaks and illness associated with these products, prompting federal agencies to monitor the microbial quality of fresh produce. The FDA has implemented import and domestic compliance programs to check produce samples for the presence of pathogens. Also, the USDA Agricultural Marketing Service initiated the Microbiological Data Program (MDP) in 2001 to conduct microbial surveys of fresh produce samples collected from wholesale distribution centers across the country. On average, 10,000 to 15,000 samples were tested by MDP yearly for the presence of Salmonella, enterotoxigenic Escherichia coli (ETEC), E. coli serotype O157:H7, and other Shiga-toxigenic E. coli (STEC) types. The annual MDP reports (http://www.ams .usda.gov/AMSv1.0/mdp) showed that many of these bacteria can be found in various types of fresh produce. STEC strains are characterized by the production of Shiga toxins (Stx), of which there are two main types, designated Stx1 and Stx2. Within each toxin are many subtypes; currently, there are three known Stx1 (Stx1a, Stx1c, and Stx1d) and seven known Stx2 (Stx2a, Stx2b, Stx2c, Stx2d, Stx2e, Stx2f, and Stx2g) subtypes (1). Some of these subtypes have ...

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Section: Discussionmentioning

confidence: 99%

Prevalences of Shiga Toxin Subtypes and Selected Other Virulence Factors among Shiga-Toxigenic Escherichia coli Strains Isolated from Fresh Produce

Feng

Reddy²

2013

Appl Environ Microbiol

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“…Human infections due to canine exposure were also reported; one outbreak in Sweden resulted in 50 cases in humans after they attended a dog show (168). STEC has also been recovered from the feces of wild canids (169).…”

Section: Petsmentioning

confidence: 99%

Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

2014

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Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.

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“…However, other animals, such as sheep, goats, swine, birds, wild animals, and humans, can also harbor STEC strains in their digestive tracts (35)(36)(37). For typical EPEC, the only reservoir is humans, whereas for atypical EPEC, both humans and other animals can be reservoirs (37).…”

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confidence: 99%

Molecular Profiling of Shiga Toxin-Producing Escherichia coli and Enteropathogenic E. coli Strains Isolated from French Coastal Environments

Balière

Rincé

Delannoy

et al. 2016

Appl Environ Microbiol

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Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) strains may be responsible for food-borne infections in humans. Twenty-eight STEC and 75 EPEC strains previously isolated from French shellfish-harvesting areas and their watersheds and belonging to 68 distinguishable serotypes were characterized in this study. High-throughput real-time PCR was used to search for the presence of 75 E. coli virulence-associated gene targets, and genes encoding Shiga toxin (stx) and intimin (eae) were subtyped using PCR tests and DNA sequencing, respectively. The results showed a high level of diversity between strains, with 17 unique virulence gene profiles for STEC and 56 for EPEC. Seven STEC and 15 EPEC strains were found to display a large number or a particular combination of genetic markers of virulence and the presence of stx and/or eae variants, suggesting their potential pathogenicity for humans. Among these, an O26:H11 stx 1a eae-␤1 strain was associated with a large number of virulence-associated genes (n ‫؍‬ 47), including genes carried on the locus of enterocyte effacement (LEE) or other pathogenicity islands, such as OI-122, OI-71, OI-43/48, OI-50, OI-57, and the high-pathogenicity island (HPI). One O91:H21 STEC strain containing 4 stx variants (stx 1a , stx 2a , stx 2c , and stx 2d ) was found to possess genes associated with pathogenicity islands OI-122, OI-43/48, and OI-15. Among EPEC strains harboring a large number of virulence genes (n, 34 to 50), eight belonged to serotype O26:H11, O103:H2, O103:H25, O145:H28, O157:H7, or O153:H2. IMPORTANCEThe species E. coli includes a wide variety of strains, some of which may be responsible for severe infections. This study, a molecular risk assessment study of E. coli strains isolated from the coastal environment, was conducted to evaluate the potential risk for shellfish consumers. This report describes the characterization of virulence gene profiles and stx/eae polymorphisms of E. coli isolates and clearly highlights the finding that the majority of strains isolated from coastal environment are potentially weakly pathogenic, while some are likely to be more pathogenic. E scherichia coli is a commensal aerobic bacterium of the warmblooded animal intestinal microbiota and is used as a fecal indicator in the environment to classify shellfish-harvesting and bathing areas (1). However, E. coli can become pathogenic through the acquisition of mobile genetic elements such as bacteriophages, pathogenicity islands, and plasmids. Among pathogenic E. coli strains are the Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) strains.STEC can cause infections ranging from uncomplicated diarrheas to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Several STEC serotypes have been involved in numerous food-borne outbreaks worldwide (2, 3), and these strains have been identified as enterohemorrhagic E. coli (EHEC). Although E. coli O157:H7 has been the main serotype implicated in HC and HUS since the early ...

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Seropathotypes, Phylogroups, Stx Subtypes, and Intimin Types of Wildlife-Carried, Shiga Toxin-Producing Escherichia coli Strains with the Same Characteristics as Human-Pathogenic Isolates

Cited by 105 publications

References 40 publications

Prevalences of Shiga Toxin Subtypes and Selected Other Virulence Factors among Shiga-Toxigenic Escherichia coli Strains Isolated from Fresh Produce

Prevalences of Shiga Toxin Subtypes and Selected Other Virulence Factors among Shiga-Toxigenic Escherichia coli Strains Isolated from Fresh Produce

Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

Molecular Profiling of Shiga Toxin-Producing Escherichia coli and Enteropathogenic E. coli Strains Isolated from French Coastal Environments

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