Prevalence of genotypic antimicrobial resistance in clinical Shiga toxin-producing Escherichia coli in Norway, 2018 to 2020

Introduction. Shiga toxin-producing Escherichia coli (STEC) can cause severe to fatal disease in humans. Antimicrobial treatment is sometimes necessary, but contraindicated due to undesirable clinical outcome. However, recent studies have shown promising outcomes following antimicrobial treatment. Before the establishment of a possible antimicrobial treatment strategy for STEC infections, the prevalence of antimicrobial resistance in STEC needs to be determined. Gap Statement. The resistance status of Norwegian clinical STEC is not known and should be assessed. Aim. We aim to characterize genotypic antimicrobial resistance determinants in clinical STEC in Norway, and determine the prevalence of genotypic resistance in order to inform possible antimicrobial treatment options for STEC infections. Methodology. We included all clinical STEC submitted to the Norwegian Reference Laboratory from March 2018 to April 2020. All samples were whole-genome sequenced and screened for genotypic antimicrobial resistance,virulence determinants and plasmid incompatibility groups. We performed phylogenetic clustering of STEC by core-genome multi-locus sequence typing, and statistical association analyses between isolate characteristics and genotypic resistance. Results. A total of 459 STEC were analysed. For 385 (83.9 %) STEC we did not identify any antimicrobial resistance determinants. Seventy-four STEC (16.1 %) harboured antimicrobial resistance determinants against one or more antimicrobial classes. The most frequent genotypic resistance was identified against aminoglycosides (10.5 %). Thirty-nine STEC (8.5 %) had a multi-drug resistance (MDR) genotype. Genotypic resistance was more prevalent in non-O157 than O157 STEC (P=0.02). A positive association was seen between genotypic resistance and the low-virulent STEC O117:H7 phylogenetic cluster (no. 14) (P<0.001). Genotypic resistance was not significantly associated to high-virulent STEC. STEC O146:H28 and isolates harbouring the plasmid replicon type IncQ1 were positively associated with MDR. Conclusion. The overall prevalence of genotypic resistance in clinical STEC in Norway is low (16.1 %). Genotypic resistance is more prevalent in non-O157 strains compared to O157 strains, and not significantly associated to high-virulent STEC. Resistance to antimicrobials suggested for treatment, especially azithromycin is low and may present an empiric treatment alternative for severe STEC infections.

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Distribution and Relationships of Antimicrobial Resistance Determinants among Extended-Spectrum-Cephalosporin-Resistant or Carbapenem-Resistant Escherichia coli Isolates from Rivers and Sewage Treatment Plants in India

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01950-15 ◽

2016 ◽

Vol 60 (5) ◽

pp. 2972-2980 ◽

Cited By ~ 43

Author(s):

Masato Akiba ◽

Tsuyoshi Sekizuka ◽

Akifumi Yamashita ◽

Makoto Kuroda ◽

Yuki Fujii ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Sewage Treatment ◽

Indian States ◽

Content Type ◽

Sewage Treatment Plants ◽

E Coli ◽

Resistance Determinants ◽

Carbapenem Resistant ◽

Extended Spectrum

ABSTRACTTo determine the distribution and relationship of antimicrobial resistance determinants among extended-spectrum-cephalosporin (ESC)-resistant or carbapenem-resistantEscherichia coliisolates from the aquatic environment in India, water samples were collected from rivers or sewage treatment plants in five Indian states. A total of 446E. coliisolates were randomly obtained. Resistance to ESC and/or carbapenem was observed in 169 (37.9%)E. coliisolates, which were further analyzed. These isolates showed resistance to numerous antimicrobials; more than half of the isolates exhibited resistance to eight or more antimicrobials. TheblaNDMgene was detected in 14/21 carbapenem-resistantE. coliisolates:blaNDM-1in 2 isolates,blaNDM-5in 7 isolates, andblaNDM-7in 5 isolates. TheblaCTX-Mgene was detected in 112 isolates (66.3%):blaCTX-M-15in 108 isolates andblaCTX-M-55in 4 isolates. We extracted 49 plasmids from selected isolates, and their whole-genome sequences were determined. Fifty resistance genes were detected, and 11 different combinations of replicon types were observed among the 49 plasmids. The network analysis results suggested that the plasmids sharing replicon types tended to form a community, which is based on the predicted gene similarity among the plasmids. Four communities each containing from 4 to 17 plasmids were observed. Three of the four communities contained plasmids detected in different Indian states, suggesting that the interstate dissemination of ancestor plasmids has already occurred. Comparison of the DNA sequences of theblaNDM-positive plasmids detected in this study with known sequences of related plasmids suggested that various mutation events facilitated the evolution of the plasmids and that plasmids with similar genetic backgrounds have widely disseminated in India.

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An Environmental Shiga Toxin-Producing Escherichia coli O145 Clonal Population Exhibits High-Level Phenotypic Variation That Includes Virulence Traits

Applied and Environmental Microbiology ◽

10.1128/aem.03172-15 ◽

2015 ◽

Vol 82 (4) ◽

pp. 1090-1101 ◽

Cited By ~ 17

Author(s):

Michelle Qiu Carter ◽

Beatriz Quinones ◽

Xiaohua He ◽

Wayne Zhong ◽

Jacqueline W. Louie ◽

...

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Virulence Determinants ◽

Content Type ◽

Clinical Strains ◽

Production Region ◽

E Coli ◽

Virulence Traits ◽

Virulence Potential ◽

High Level

ABSTRACTShiga toxin-producingEscherichia coli(STEC) serotype O145 is one of the major non-O157 serotypes associated with severe human disease. Here we examined the genetic diversity, population structure, virulence potential, and antimicrobial resistance profiles of environmental O145 strains recovered from a major produce production region in California. Multilocus sequence typing analyses revealed that sequence type 78 (ST-78), a common ST in clinical strains, was the predominant genotype among the environmental strains. Similarly, all California environmental strains belonged to H28, a common H serotype in clinical strains. Although most environmental strains carried an intactfliCgene, only one strain retained swimming motility. Diversestxsubtypes were identified, includingstx1a,stx2a,stx2c, andstx2e. Although no correlation was detected between thestxgenotype and Stx1 production, high Stx2 production was detected mainly in strains carryingstx2aonly and was correlated positively with the cytotoxicity of Shiga toxin. All environmental strains were capable of producing enterohemolysin, whereas only 10 strains were positive for anaerobic hemolytic activity. Multidrug resistance appeared to be common, as nearly half of the tested O145 strains displayed resistance to at least two different classes of antibiotics. The core virulence determinants of enterohemorrhagicE. coliwere conserved in the environmental STEC O145 strains; however, there was large variation in the expression of virulence traits among the strains that were highly related genotypically, implying a trend of clonal divergence. Several cattle isolates exhibited key virulence traits comparable to those of the STEC O145 outbreak strains, emphasizing the emergence of hypervirulent strains in agricultural environments.

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Virulence Genes in Expanded-Spectrum-Cephalosporin-Resistant and -Susceptible Escherichia coli Isolates from Treated and Untreated Chickens

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01996-15 ◽

2015 ◽

Vol 60 (3) ◽

pp. 1874-1877 ◽

Cited By ~ 1

Author(s):

S. Baron ◽

S. Delannoy ◽

S. Bougeard ◽

E. Larvor ◽

E. Jouy ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Virulence Factors ◽

Shiga Toxin ◽

Virulence Genes ◽

Phylogenetic Groups ◽

Content Type ◽

E Coli ◽

Heat Stable ◽

Intestinal Infections

This study investigated antimicrobial resistance, screened for the presence of virulence genes involved in intestinal infections, and determined phylogenetic groups ofEscherichia coliisolates from untreated poultry and poultry treated with ceftiofur, an expanded-spectrum cephalosporin. Results show that none of the 76 isolates appeared to be Shiga toxin-producingE. colior enteropathogenicE. coli. All isolates were negative for the major virulence factors/toxins tested (ehxA,cdt, heat-stable enterotoxin [ST], and heat-labile enterotoxin [LT]). The few virulence genes harbored in isolates generally did not correlate with isolate antimicrobial resistance or treatment status. However, some of the virulence genes were significantly associated with certain phylogenetic groups.

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Phylogenetically Related Argentinean and Australian Escherichia coli O157 Isolates Are Distinguished by Virulence Clades and Alternative Shiga Toxin 1 and 2 Prophages

Applied and Environmental Microbiology ◽

10.1128/aem.00365-12 ◽

2012 ◽

Vol 78 (13) ◽

pp. 4724-4731 ◽

Cited By ~ 44

Author(s):

Glen E. Mellor ◽

Eby M. Sim ◽

Robert S. Barlow ◽

Beatriz A. D'Astek ◽

Lucia Galli ◽

...

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Polymorphism Analysis ◽

Escherichia Coli O157 ◽

The Novel ◽

Virulence Determinants ◽

Content Type ◽

E Coli ◽

Uremic Syndrome ◽

Insight Into

ABSTRACTShiga toxigenicEscherichia coliO157 is the leading cause of hemolytic uremic syndrome (HUS) worldwide. The frequencies ofstxgenotypes and the incidences of O157-related illness and HUS vary significantly between Argentina and Australia. Locus-specific polymorphism analysis revealed that lineage I/II (LI/II)E. coliO157 isolates were most prevalent in Argentina (90%) and Australia (88%). Argentinean LI/II isolates were shown to belong to clades 4 (28%) and 8 (72%), while Australian LI/II isolates were identified as clades 6 (15%), 7 (83%), and 8 (2%). Clade 8 was significantly associated with Shiga toxin bacteriophage insertion (SBI) typestx2(locus of insertion,argW) in Argentinean isolates (P< 0.0001). In Argentinean LI/II strains,stx2is carried by a prophage inserted atargW, whereas in Australian LI/II strains theargWlocus is occupied by the novelstx1prophage. In both Argentinean and Australian LI/II strains,stx2cis almost exclusively carried by a prophage inserted atsbcB. However, alternativeq933- orq21-related alleles were identified in the Australianstx2cprophage. Argentinean LI/II isolates were also distinguished from Australian isolates by the presence of the putative virulence determinant ECSP_3286 and the predominance of motile O157:H7 strains. Characteristics common to both Argentinean and Australian LI/II O157 strains included the presence of putative virulence determinants (ECSP_3620, ECSP_0242, ECSP_2687, ECSP_2870, and ECSP_2872) and the predominance of thetir255T allele. These data support further understanding of O157 phylogeny and may foster greater insight into the differential virulence of O157 lineages.

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Antimicrobial resistance in Shiga toxin-producing Escherichia coli other than serotype O157 : H7 in England, 2014–2016

Journal of Medical Microbiology ◽

10.1099/jmm.0.001146 ◽

2020 ◽

Vol 69 (3) ◽

pp. 379-386 ◽

Cited By ~ 2

Author(s):

Amy Gentle ◽

Martin R. Day ◽

Katie L. Hopkins ◽

Gauri Godbole ◽

Claire Jenkins

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Resistance Genes ◽

Shiga Toxin ◽

Type Species ◽

Gastrointestinal Disease ◽

Foodborne Pathogen ◽

Content Type ◽

E Coli ◽

Link Type

Introduction. Despite many ongoing surveillance projects and the recent focus on the veterinary and clinical ‘One Health’ aspects of antimicrobial resistance (AMR), evidence of the extent of any public health risk posed by animal reservoirs with respect to the transmission of resistant strains of Escherichia coli to humans remains varied and contentious. In the UK, the main zoonotic reservoir for the foodborne pathogen Shiga toxin-producing E. coli (STEC) is cattle and sheep. In this study, we adopt an alternative approach to the risk assessment of transmission of AMR E. coli from animals to humans, involving monitoring AMR in isolates of STEC, an established zoonotic, foodborne pathogen, from human cases of gastrointestinal disease. Aim. The aim of this study was to determine the genome-derived AMR profiles for STEC from human cases to assess the risk of transmission of multidrug-resistant STEC from ruminants to humans. Methodology. STEC belonging to 10 different clonal complexes (CCs) (n=457) isolated from human faecal specimens were sequenced and genome-derived AMR profiles were determined. Phenotypic susceptibility testing was undertaken on all isolates (n=100) predicted to be resistant to at least one class of antimicrobial. Results. Of the 457 isolates, 332 (72.7 %) lacked identifiable resistance genes and were predicted to be fully susceptible to 11 classes of antimicrobials; 125/332 (27.3 %) carried 1 or more resistance genes, of which 83/125 (66.4 %) were resistant to 3 or more classes of antibiotic. The percentage of isolates harbouring AMR determinants varied between CCs, from 4% in CC25 to 100% in CC504. Forty-six different AMR genes were detected, which conferred resistance to eight different antibiotic classes. Resistance to ampicillin, streptomycin, tetracyclines and sulphonamides was most commonly detected. Four isolates were identified as extended-spectrum β-lactamase producers. An overall concordance of 97.7 % (n=1075/1100) was demonstrated between the phenotypic and genotypic methods. Conclusion. This analysis provided an indirect assessment of the risk of transmission of AMR gastrointestinal pathogens from animals to humans, and revealed a subset of human isolates of the zoonotic pathogen STEC were resistant to the antimicrobials used in animal husbandry. However, this proportion has not increased over the last three decades, and thismay provide evidence that guidancepromoting responsible practice has been effective.

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Occurrence of Shiga Toxin-Producing Escherichia coli Carrying Antimicrobial Resistance Genes in Sheep on Smallholdings in Bangladesh

10.20944/preprints202107.0405.v1 ◽

2021 ◽

Author(s):

Mukta Das Gupta ◽

Arup Sen ◽

Mishuk Shaha ◽

Avijit Dutta ◽

Ashutosh Das

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Resistance Genes ◽

Shiga Toxin ◽

Significant Proportion ◽

Antimicrobial Treatment ◽

Sheep Population ◽

E Coli ◽

Human Contact ◽

Antimicrobial Resistance Genes

Inappropriate antimicrobial treatment can pose a risk for developing resistance against antimi-crobial drugs in bacteria. Close human contact might have a higher chance of being transmitted to humans from sheep if the sheep population is a potential reservoir of zoonotic pathogens such as shiga toxin-producing Escherichia coli (E. coli) (STEC). Therefore, this study aimed to exam-ine the sheep population in rural Bangladesh for antimicrobial resistant STEC. We screened 200 faecal samples collected from sheep in three Upazila from the Chattogram district. Phenotypical-ly positive E. coli isolates were examined for two shiga toxin-producing genes – stx1 and stx2. PCR positive STEC isolates were investigated for the presence of antimicrobial resistance genes- blaTEM, sul1 and sul2. In total, 123 of the 200 tested samples were confirmed positive E. coli by cul-tured based methods. PCR results show 17(13.8%) E. coli isolates harboured ≥ one virulent gene (stx1 or/and stx2) of STEC. Six of the tested STEC isolates exhibited blaTEM gene; eight STEC isolates had sul1 gene, and sul2 gene was detected in ten STEC isolates. To our knowledge, this study is the first to reveal a significant proportion of STEC isolated from sheep in rural Bangla-desh harbouring antimicrobial resistance genes.

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Application of Metagenomic Sequencing to Food Safety: Detection of Shiga Toxin-Producing Escherichia coli on Fresh Bagged Spinach

Applied and Environmental Microbiology ◽

10.1128/aem.02601-15 ◽

2015 ◽

Vol 81 (23) ◽

pp. 8183-8191 ◽

Cited By ~ 52

Author(s):

Susan R. Leonard ◽

Mark K. Mammel ◽

David W. Lacher ◽

Christopher A. Elkins

Keyword(s):

Escherichia Coli ◽

Food Safety ◽

Shiga Toxin ◽

Rational Design ◽

Pathogen Detection ◽

Antimicrobial Agents ◽

Detection Sensitivity ◽

Metagenomic Sequencing ◽

Virulence Determinants ◽

Content Type

ABSTRACTCulture-independent diagnostics reduce the reliance on traditional (and slower) culture-based methodologies. Here we capitalize on advances in next-generation sequencing (NGS) to apply this approach to food pathogen detection utilizing NGS as an analytical tool. In this study, spiking spinach with Shiga toxin-producingEscherichia coli(STEC) following an established FDA culture-based protocol was used in conjunction with shotgun metagenomic sequencing to determine the limits of detection, sensitivity, and specificity levels and to obtain information on the microbiology of the protocol. We show that an expected level of contamination (∼10 CFU/100 g) could be adequately detected (including key virulence determinants and strain-level specificity) within 8 h of enrichment at a sequencing depth of 10,000,000 reads. We also rationalize the relative benefit of static versus shaking culture conditions and the addition of selected antimicrobial agents, thereby validating the long-standing culture-based parameters behind such protocols. Moreover, the shotgun metagenomic approach was informative regarding the dynamics of microbial communities during the enrichment process, including initial surveys of the microbial loads associated with bagged spinach; the microbes found included key genera such asPseudomonas,Pantoea, andExiguobacterium. Collectively, our metagenomic study highlights and considers various parameters required for transitioning to such sequencing-based diagnostics for food safety and the potential to develop better enrichment processes in a high-throughput manner not previously possible. Future studies will investigate new species-specific DNA signature target regimens, rational design of medium components in concert with judicious use of additives, such as antibiotics, and alterations in the sample processing protocol to enhance detection.

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Evaluation of chromogenic selective agar (CHROMagar STEC) for the direct detection of Shiga toxin-producing Escherichia coli from faecal specimens

Journal of Medical Microbiology ◽

10.1099/jmm.0.001136 ◽

2020 ◽

Vol 69 (3) ◽

pp. 487-491 ◽

Cited By ~ 3

Author(s):

Claire Jenkins ◽

Neil T. Perry ◽

Gauri Godbole ◽

Saheer Gharbia

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Direct Detection ◽

Gastrointestinal Disease ◽

Laboratory Method ◽

Toxin Gene ◽

Reference Laboratory ◽

Macconkey Agar ◽

Content Type ◽

Pcr Targeting

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens that cause symptoms of severe gastrointestinal disease, including haemolytic uraemic syndrome (HUS), in humans. Currently in England, STEC serotypes other than O157:H7 are not cultured at the local hospital laboratories. The aim of this study was to evaluate the utility of CHROMagar STEC for the direct detection of STEC from faecal specimens in a diagnostic setting, compared to the current reference laboratory method using PCR targeting the Shiga-toxin gene (stx) to test multiple colonies cultured on MacConkey agar. Of the 292 consecutive faecal specimens submitted to the Gastrointestinal Bacterial Reference Unit that tested positive for stx by PCR, STEC could not be cultured on MacConkey agar or CHROMagar STEC from 87/292 (29.8 %). Of the 205 that were cultured, 106 (51.7 %) were detected on both MacConkey agar and CHROMagar STEC and 99 (48.3 %) were detected on MacConkey agar only. All 106 (100 %) isolates that grew on CHROMagar STEC had the ter gene cassette, known to be associated with resistance to tellurite, compared to 13/99 (13.1 %) that were not detected on CHROMagar STEC. CHROMagar STEC supported the growth of 36/40 (90 %) isolates harbouring stx2a or stx2d, the subtypes most frequently associated with progression to HUS. Of the 92 isolates harbouring eae, an important STEC virulence marker, 77 (83.7 %) grew on CHROMagar STEC. CHROMagar STEC is a useful selective media for the rapid, near-patient detection of STEC that have the potential to cause HUS.

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Genomic diversity of Escherichia coli isolates from non-human primates in the Gambia

Microbial Genomics ◽

10.1099/mgen.0.000428 ◽

2020 ◽

Vol 6 (9) ◽

Cited By ~ 2

Author(s):

Ebenezer Foster-Nyarko ◽

Nabil-Fareed Alikhan ◽

Anuradha Ravi ◽

Gaëtan Thilliez ◽

Nicholas M. Thomson ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Host Species ◽

Type Species ◽

The Gambia ◽

Genomic Diversity ◽

Multi Drug Resistance ◽

Erythrocebus Patas ◽

Content Type ◽

Link Type

Increasing contact between humans and non-human primates provides an opportunity for the transfer of potential pathogens or antimicrobial resistance between host species. We have investigated genomic diversity and antimicrobial resistance in Escherichia coli isolates from four species of non-human primates in the Gambia: Papio papio (n=22), Chlorocebus sabaeus (n=14), Piliocolobus badius (n=6) and Erythrocebus patas (n=1). We performed Illumina whole-genome sequencing on 101 isolates from 43 stools, followed by nanopore long-read sequencing on 11 isolates. We identified 43 sequence types (STs) by the Achtman scheme (ten of which are novel), spanning five of the eight known phylogroups of E. coli . The majority of simian isolates belong to phylogroup B2 – characterized by strains that cause human extraintestinal infections – and encode factors associated with extraintestinal disease. A subset of the B2 strains (ST73, ST681 and ST127) carry the pks genomic island, which encodes colibactin, a genotoxin associated with colorectal cancer. We found little antimicrobial resistance and only one example of multi-drug resistance among the simian isolates. Hierarchical clustering showed that simian isolates from ST442 and ST349 are closely related to isolates recovered from human clinical cases (differences in 50 and 7 alleles, respectively), suggesting recent exchange between the two host species. Conversely, simian isolates from ST73, ST681 and ST127 were distinct from human isolates, while five simian isolates belong to unique core-genome ST complexes – indicating novel diversity specific to the primate niche. Our results are of planetary health importance, considering the increasing contact between humans and wild non-human primates.

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Plasmids from Shiga Toxin-Producing Escherichia coli Strains with Rare Enterohemolysin Gene (ehxA) Subtypes Reveal Pathogenicity Potential and Display a Novel Evolutionary Path

Applied and Environmental Microbiology ◽

10.1128/aem.01839-16 ◽

2016 ◽

Vol 82 (21) ◽

pp. 6367-6377 ◽

Cited By ~ 9

Author(s):

Sandra C. Lorenz ◽

Steven R. Monday ◽

Maria Hoffmann ◽

Markus Fischer ◽

Julie A. Kase

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Sequence Data ◽

Clinical Manifestations ◽

Virulence Plasmid ◽

Virulence Determinants ◽

Content Type ◽

E Coli ◽

Subtype B ◽

Evolutionary Relatedness

ABSTRACTMost Shiga toxin-producingEscherichia coli(STEC) strains associated with severe disease, such as hemolytic-uremic syndrome (HUS), carry large enterohemolysin-encoding (ehxA) plasmids, e.g., pO157 and pO103, that contribute to STEC clinical manifestations. SixehxAsubtypes (A through F) exist that phylogenetically cluster intoeae-positive (B, C, F), a mix ofeae-positive (E) andeae-negative (A), and a third, more distantly related, cluster ofeae-negative (D) STEC strains. While subtype B, C, and F plasmids share a number of virulence traits that are distinct from those of subtype A, sequence data have not been available for subtype D and E plasmids. Here, we determined and compared the genetic composition of four subtype D and two subtype E plasmids to establish their evolutionary relatedness amongehxAsubtypes and define their potential role in pathogenicity. We found that subtype D strains carry one exceptionally large plasmid (>200 kbp) that carries a variety of virulence genes that are associated with enterotoxigenic and enterohemorrhagicE. coli, which, quite possibly, enables these strains to cause disease despite being food isolates. Our data offer further support for the hypothesis that this subtype D plasmid represents a novel virulence plasmid, sharing very few genetic features with other plasmids; we conclude that these plasmids have evolved from a different evolutionary lineage than the plasmids carrying the otherehxAsubtypes. In contrast, the 50-kbp plasmids of subtype E (pO145), although isolated from HUS outbreak strains, carried only few virulence-associated determinants, suggesting that the clinical presentation of subtype E strains is largely a result of chromosomally encoded virulence factors.IMPORTANCEBacterial plasmids are known to be key agents of change in microbial populations, promoting the dissemination of various traits, such as drug resistance and virulence. This study determined the genetic makeup of virulence plasmids from rare enterohemolysin subtype D and E Shiga toxin-producingE. colistrains. We demonstrated thatehxAsubtype D plasmids represent a novelE. colivirulence plasmid, and although subtype D plasmids were derived from nonclinical isolates, they encoded a variety of virulence determinants that are associated with pathogenicE. coli. In contrast, subtype E plasmids, isolated from strains recovered from severely ill patients, carry only a few virulence determinants. The results of this study reemphasize the plasticity and vast diversity amongE. coliplasmids. This work demonstrates that, althoughE. colistrains of certain serogroups may not be frequently associated with disease, they should not be underestimated in protecting human health and food safety.

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