Transferable multidrug resistance plasmid carrying cfr associated with tet(L), ant(4')-Ia, and dfrK genes from a clinical methicillin-resistant Staphylococcus aureus ST125 strain.

A multidrug resistance (MDR) conjugative plasmid of ca. 50 kb (designated pERGB) was detected in a linezolid and methicillin-resistant Staphylococcus aureus strain with sequence type 125 (ST125-MRSA-IVc). This strain was detected in two patients with chronic obstructive pulmonary disease, previously treated with multiple antimicrobials, including linezolid. pERGB was transferable by conjugation and carried the resistance genes cfr (oxazolidinones, phenicols, lincosamides, pleuromutilins, and streptogramin A), ant(4')-Ia (tobramycin), tet(L) (tetracycline), and dfrK (trimethoprim). A novel genetic structure, linking all of these resistance genes for the first time, was elucidated through sequencing of a 15,259-bp fragment from pERGB. Active surveillance to prevent the dissemination of such highly concerning MDR transferable elements is needed.