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- Söderlund, Robert, et al.
(författare)
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Genomic comparison of Escherichia coli serotype O103:H2 isolates with and without verotoxin genes: implications for risk assessment of strains commonly found in ruminant reservoirs
- 2016
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Ingår i: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Escherichia coli O103:H2 occurs as verotoxigenic E. coli (VTEC) carrying only vtx1 or vtx2 or both variants, but also as vtx-negative atypical enteropathogenic E. coli (aEPEC). The majority of E. coli O103:H2 identified from cases of human disease are caused by the VTEC form. If aEPEC strains frequently acquire verotoxin genes and become VTEC, they must be considered a significant public health concern. In this study, we have characterized and compared aEPEC and VTEC isolates of E. coli O103:H2 from Swedish cattle. Methods: Fourteen isolates of E. coli O103:H2 with and without verotoxin genes were collected from samples of cattle feces taken during a nationwide cattle prevalence study 2011-2012. Isolates were sequenced with a 2 x 100 bp setup on a HiSeq2500 instrument producing >100 x coverage per isolate. Single-nucleotide polymorphism (SNP) typing was performed using the genome analysis tool kit (GATK). Virulence genes and other regions of interest were detected. Susceptibility to transduction by two verotoxin-encoding phages was investigated for one representative aEPEC O103:H2 isolate. Results and Discussion: This study shows that aEPEC O103:H2 is more commonly found (64%) than VTEC O103:H2 (36%) in the Swedish cattle reservoir. The only verotoxin gene variant identified was vtx1a. Phylogenetic comparison by SNP analysis indicates that while certain subgroups of aEPEC and VTEC are closely related and have otherwise near identical virulence gene repertoires, they belong to separate lineages. This indicates that the uptake or loss of verotoxin genes is a rare event in the natural cattle environment of these bacteria. However, a representative of a VTEC-like aEPEC O103:H2 subgroup could be stably lysogenized by a vtx-encoding phage in vitro.
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| 2. |
- Söderlund, Robert, et al.
(författare)
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Prevalence and genomic characteristics of zoonotic gastro-intestinal pathogens and ESBL/pAmpC producing Enterobacteriaceae among Swedish corvid birds
- 2019
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Ingår i: Infection Ecology & Epidemiology. - : Taylor & Francis. - 2000-8686. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Wild birds pose a potential threat to animal and human health by spreading infectious diseases. In the present study, we studied the occurrence of bacterial zoonotic pathogens as well as enterobacteria with transferrable antimicrobial resistance genes among Swedish corvids.Materials and methods: Intestines from 66 jackdaws, crows, rooks and magpies from the vicinity of livestock farms at 14 locations in 7 counties were analysed by direct culture or PCR screening followed by culture. Isolates were investigated by whole-genome sequencing.Results and discussion: Campylobacter jejuni were detected in 82% and Yersinia in 3% of the birds. ESBL-producing E. coli were found in one sample (2%) and carried bla CTX-M-55. No Enterobacteriaceae with transferable carbapenem resistance were identified. No Salmonella or E. coli O157:H7 were found, but PCR analysis for enterohaemorrhagic E. coli virulence genes revealed 35% positive samples for intimin, 9% for verotoxin 1 and 17% for verotoxin 2. C. jejuni isolates from corvids were compared to previously published isolates from Swedish sources by multi-locus sequence typing based on genome sequences. All corvid C. jejuni isolates formed a cluster, intermingled with human and chicken isolates. Our results indicate that C. jejuni is ubiquitous among Swedish corvid birds, with sporadic transmission to poultry and humans.
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