Global distribution and diversity of ovine-associated Staphylococcus aureus

Edward M Smith,Polly F Needs,Grace Manley,Laura E Green

doi:10.1016/j.meegid.2013.09.008

Abstract

Staphylococcus aureus is an important pathogen of many species, including sheep, and impacts on both human and animal health, animal welfare, and farm productivity. Here we present the widest global diversity study of ovine-associated S. aureus to date. We analysed 97 S. aureus isolates from sheep and sheep products from the UK, Turkey, France, Norway, Australia, Canada and the USA using multilocus sequence typing (MLST) and spa typing. These were compared with 196 sheep isolates from Europe (n=153), Africa (n=28), South America (n=14) and Australia (n=1); 172 bovine, 68 caprine and 433 human S. aureus profiles. Overall there were 59 STs and 87 spa types in the 293 ovine isolates; in the 97 new ovine isolates there were 22 STs and 37 spa types, including three novel MLST alleles, four novel STs and eight novel spa types. Three main CCs (CC133, CC522 and CC700) were detected in sheep and these contained 61% of all isolates. Four spa types (t002, t1534, t2678 and t3576) contained 31% of all isolates and were associated with CC5, CC522, CC133 and CC522 respectively. spa types were consistent with MLST CCs, only one spa type (t1403) was present in multiple CCs. The three main ovine CCs have different but overlapping patterns of geographical dissemination that appear to match the location and timing of sheep domestication and selection for meat and wool production. CC133, CC522 and CC700 remained ovine-associated following the inclusion of additional host species. Ovine isolates clustered separately from human and bovine isolates and those from sheep cheeses, but closely with caprine isolates. As with cattle isolates, patterns of clonal diversification of sheep isolates differ from humans, indicative of their relatively recent host-jump.

Highlights

Staphylococcus aureus is widely recognised as a bacterial species that can colonise and infect a variety of hosts including humans, farmed and companion animals and exotic species (Cookson et al, 2007; Espinosa-Gongora et al, 2012; Porrero et al, 2012; Sasaki et al, 2012; Smith et al, 2005a)
Spa types associate with Multilocus sequence typing (MLST) clonal complexes (CCs) (Strommenger et al, 2006), spa typing is often used as an initial screen of study isolates (Eriksson et al, 2013; Porrero et al, 2012)
A total of 97 S. aureus isolates from sheep/ovine cheese were analysed in this study, this included 24 isolates from clinical mastitis, subclinical intra-mammary infections (IMI) and intra-mammary abscesses of sheep in England, from cases of clinical mastitis in Australia, one from a severe case of clinical mastitis in Canada, from cases of clinical mastitis, subclinical IMI, gangrenous mastitis, intra-mammary abscesses and carriage in France, from cases of clinical mastitis, subclinical IMI and carriage in Norway (Mørk et al, 2012; 2007), three from subclinical IMI in the USA (Spanu et al, 2011) and 33 isolates from sheep milk cheeses in Turkey (Ertas et al, 2010), The strains used are described in Supplementary dataset 1

Summary

Introduction

Staphylococcus aureus is widely recognised as a bacterial species that can colonise and infect a variety of hosts including humans, farmed and companion animals and exotic species (Cookson et al, 2007; Espinosa-Gongora et al, 2012; Porrero et al, 2012; Sasaki et al, 2012; Smith et al, 2005a). Multilocus sequence typing (MLST) has become the classical technique for analysis of bacterial population structure, and has been used extensively in the analysis of S. aureus populations from a variety of human and animal sources (Enright et al, 2000; Espinosa-Gongora et al, 2012; Sasaki et al, 2012; Smith et al, 2005b; Smyth et al, 2009). Spa types associate with MLST CCs (Strommenger et al, 2006), spa typing is often used as an initial screen of study isolates (Eriksson et al, 2013; Porrero et al, 2012)

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Conclusion