Microevolution of antimicrobial resistance and biofilm formation of Salmonella Typhimurium during persistence on pig farms

Tassinari, Eleonora and Duffy, Geraldine and Bawn, Matt and Burgess, Catherine M. and McCabe, Evonne M. and Lawlor, Peadar G. and Gardiner, Gillian and Kingsley, Robert A. (2019) Microevolution of antimicrobial resistance and biofilm formation of Salmonella Typhimurium during persistence on pig farms. Scientific Reports, 9 (1). ISSN 2045-2322

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Salmonella Typhimurium and its monophasic variant S. 4,[5],12:i:- are the dominant serotypes associated with pigs in many countries. We investigated their population structure on nine farms using whole genome sequencing, and their genotypic and phenotypic variation. The population structure revealed the presence of phylogenetically distinct clades consisting of closely related clones of S. Typhimurium or S. 4,[5],12:i:- on each pig farm, that persisted between production cycles. All the S. 4,[5],12:i:- strains carried the Salmonella genomic island-4 (SGI-4), which confers resistance to heavy metals, and half of the strains contained the mTmV prophage, harbouring the sopE virulence gene. Most clonal groups were highly drug resistant due to the presence of multiple antimicrobial resistance (AMR) genes, and two clades exhibited evidence of recent on-farm plasmid-mediated acquisition of additional AMR genes, including an IncHI2 plasmid. Biofilm formation was highly variable but had a strong phylogenetic signature. Strains capable of forming biofilm with the greatest biomass were from the S. 4,[5],12:i:- and S. Typhimurium DT104 clades, the two dominant pandemic clones found over the last 25 years. On-farm microevolution resulted in enhanced biofilm formation in subsequent production cycle.

Item Type: Article
Additional Information: Funding Information: R.K. was supported by research grants BB/N007964/1 and BB/M025489/1, and by the BBSRC Institute Strategic Programme Microbes in the Food Chain BB/R012504/1 and its constituent projects BBS/E/F/000PR10348 and BBS/E/F/000PR10349. E.T. postgraduate studies were funded by Teagasc Walsh Fellowship 2015028. Publisher Copyright: © 2019, The Author(s).
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/1000
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Depositing User: Admin SSL
Date Deposited: 19 Oct 2022 23:07
Last Modified: 10 Aug 2023 16:05
URI: http://repository-testing.wit.ie/id/eprint/4155

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