New spa types, resistance to sanitisers and presence of efflux pump genes in Staphylococcus aureus from milk

Abstract The genetic diversity by spa typing, the susceptibility to the sanitisers benzalkonium chloride (BC) and chlorhexidine (CHL) and the presence of efflux pump genes to resistance to sanitisers in 31 Staphylococcus aureus isolated from milk, were investigated. The spa type t127 was the most prevalent, which has a close genetic relationship with human isolates, and two new spa types (t18898 and t18899) were found in five isolates. Most of the evaluated isolates showed resistance to BC (90.3%), and all of them were resistant to CHL. The efflux pump genes mepA, norA and norB were more prevalent, detected in 77.4%, 80.6% and 100% of the isolates, respectively. Resistance to BC and CHL, and the presence of efflux pumps were observed in S. aureus isolates from milk, which are results reported for the first time in Brazil, emphasising the need for further studies in this field.