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Local and transboundary transmission of methicillin-resistant Staphylococcus aureus sequence type 398 through pig trading

Pirolo, M; Sieber, R N; Moodley, A; Visaggio, D; Artuso, I; Gioffrè, A; Casalinuovo, F; Spatari, G; Guardabassi, L; Stegger, M; Visca, P


M Pirolo

R N Sieber

A Moodley

D Visaggio

I Artuso

A Gioffrè

F Casalinuovo

G Spatari

L Guardabassi

M Stegger

P Visca


Livestock-associated methicillin-resistant Staphylococcus aureus sequence type (ST) 398 (LA-MRSA ST398) is a genetic lineage for which pigs are regarded as the main reservoir. An increasing prevalence of LA-MRSA ST398 has been reported in areas with high livestock density throughout Europe. In this study, we have investigated the drivers contributing to the introduction and spread of LA-MRSA ST398 along the pig farming system in Southern Italy. Whole-genome sequencing (WGS) of LA-MRSA ST398 isolates collected in 2018 from pigs (n=53) and employees (n=14) from 10 farms in the Calabria region were comparatively analysed with previously published WGS data from Italian ST398 isolates (n=45), an international ST398 reference collection (n=89) and isolates from Danish pigs farms (n=283), which are the main suppliers of pigs imported to Italy. Single-nucleotide polymorphisms (SNP) were used to infer isolates relatedness and, together with data from animal trading, factors contributing to LA-MRSA ST398 dissemination were identified. The analyses support the existence of two concurrent pathways for the spread of LA-MRSA ST398 in Southern Italy: i) multiple introductions of LA-MRSA ST398 through the import of colonized pigs from other European countries including Denmark and France and; ii) the spread of distinct clones dependent on local trading of pigs between farms. Phylogenetically related Italian and Danish LA-MRSA ST398 isolates shared extensive similarities including carriage of antimicrobial resistance genes. Our findings highlight the potential risk of transboundary transmission of antimicrobial-resistant bacterial clones with a high zoonotic potential when importing pigs from countries with high LA-MRSA prevalence.


Pirolo, M., Sieber, R. N., Moodley, A., Visaggio, D., Artuso, I., Gioffrè, A., …Visca, P. (2020). Local and transboundary transmission of methicillin-resistant Staphylococcus aureus sequence type 398 through pig trading. Applied and Environmental Microbiology,

Journal Article Type Article
Acceptance Date Apr 1, 2020
Publication Date May 1, 2020
Deposit Date May 22, 2020
Publicly Available Date Aug 18, 2020
Journal Applied and Environmental Microbiology
Print ISSN 0099-2240
Publisher American Society for Microbiology
Peer Reviewed Peer Reviewed
Public URL


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