Transferable genes putatively conferring elevated minimum inhibitory concentrations of narasin in Enterococcus faecium from Swedish broilers

•An ABC-type transporter was found in sequenced isolates with increased narasin MIC.•The transporter was not found in sequenced isolates without increased narasin MIC.•A similar transporter confers resistance to tetronasin, another polyether ionophore.•Presence of the ABC-type transporter was correlated to narasin MIC ≥2mg/L.•This is the first report of transferrable genes giving increased narasin MIC.