Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Oct;12(10):2352-2362.
doi: 10.1038/s41396-018-0200-3. Epub 2018 Jun 13.

Dissemination and Persistence of Extended-Spectrum Cephalosporin-Resistance Encoding IncI1-bla CTXM-1 Plasmid Among Escherichia Coli in Pigs

Affiliations
Free PMC article

Dissemination and Persistence of Extended-Spectrum Cephalosporin-Resistance Encoding IncI1-bla CTXM-1 Plasmid Among Escherichia Coli in Pigs

Sam Abraham et al. ISME J. .
Free PMC article

Abstract

This study investigated the ecology, epidemiology and plasmid characteristics of extended-spectrum cephalosporin (ESC)-resistant E. coli in healthy pigs over a period of 4 years (2013-2016) following the withdrawal of ESCs. High carriage rates of ESC-resistant E. coli were demonstrated in 2013 (86.6%) and 2014 (83.3%), compared to 2015 (22%) and 2016 (8.5%). ESC resistance identified among E. coli isolates was attributed to the carriage of an IncI1 ST-3 plasmid (pCTXM1-MU2) encoding blaCTXM-1. Genomic characterisation of selected E. coli isolates (n = 61) identified plasmid movement into multiple commensal E. coli (n = 22 STs). Major STs included ST10, ST5440, ST453, ST2514 and ST23. A subset of the isolates belong to the atypical enteropathogenic E. coli (aEPEC) pathotype that harboured multiple LEE pathogenic islands. pCTXM1-MU2 was similar (99% nt identity) to IncI1-ST3 plasmids reported from Europe, encoded resistance to aminoglycosides, sulphonamides and trimethoprim, and carried colicin Ib. pCTXM1-MU2 appears to be highly stable and readily transferable. This study demonstrates that ESC resistance may persist for a protracted period following removal of direct selection pressure, resulting in the emergence of ESC-resistance in both commensal E. coli and aEPEC isolates of potential significance to human and animal health.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
Dynamics and phylogenetic relationships of extended-spectrum cephalosporin resistant E. coli isolated from pigs over a period of four years from an Australian pig farm following the voluntary removal of ceftiofur. Transmission of IncI1-blaCTXM-1 plasmid (pCTXM1-MU2) in the pig farm among multiple E. coli lineages isolated from pigs of different age groups was demonstrated and a maximum parsimony tree using single nucleotide polymorphisms (SNPs) of extended-spectrum cephalosporin-resistant E. coli was generated. Year of isolation is marked with the colours green (2013), blue (2014), pink (2015) and brown (2016). MLST groupings for each cluster are also included. Isolates carrying the eae, ehx and paa gene are marked with an asterisk and written gene name
Fig. 2
Fig. 2
Genomic map of the plasmid pCTXM1-MU2 carried by extended-spectrum cephalosporin-resistant E. coli isolates belonging to multiple E. coli lineages in an Australian pig farm following the voluntary removal of ceftiofur. Positions of gene classes are indicated by colour. a Expanded view of the putative genomic island consisting of aadA5 and dfrA17 on a Tn3 transposase. b Expanded view of the ISEcp1-CTX-M-1 region
Fig. 3
Fig. 3
Genomic map of the plasmid pIncF-MU4 obtained from isolate SA152. Positions of gene classes are indicated by colour. a Expanded view of the aerobactin locus. b Expanded view of the tetracycline resistance cassette associated with an IS2 transposase. c Expanded view of macrolide resistance genes associated with an IS3 transposase

Similar articles

See all similar articles

Cited by 6 articles

See all "Cited by" articles

References

    1. WHO. Critically important antimicrobials for human medicine. 5th revision. Geneva: World Health Organization; 2017.
    1. Marshall BM, Levy SB. Food animals and antimicrobials: impacts on human health. Clin Microbiol Rev. 2011;24:718–33. doi: 10.1128/CMR.00002-11. - DOI - PMC - PubMed
    1. Mukerji S, O’Dea M, Barton M, Kirkwood R, Lee T, Abraham S. Development and transmission of antimicrobial resistance among Gram-negative bacteria in animals and their public health impact. Essays Biochem. 2017;61:23–25. doi: 10.1042/EBC20160055. - DOI - PubMed
    1. Collignon P, Aarestrup FM. Extended-spectrum β-lactamases, food, and cephalosporin use in food animals. Clin Infect Dis. 2007;44:1391–2. doi: 10.1086/516612. - DOI - PubMed
    1. Cavaco LM, Abatih E, Aarestrup FM, Guardabassi L. Selection and persistence of CTX-M-producing Escherichia coli in the intestinal flora of pigs treated with amoxicillin, ceftiofur or cefquinome. Antimicrob Agents Chemother. 2008;52:3612–6. doi: 10.1128/AAC.00354-08. - DOI - PMC - PubMed

Publication types

Feedback