Complete Nucleotide Sequence and Comparative Analysis of pPR9, a 41.7-Kilobase Conjugative Staphylococcal Multiresistance Plasmid Conferring High-Level Mupirocin Resistance

We have sequenced the conjugative plasmid pPR9, which carries the ileS2 gene, which had contributed to the dissemination of high-level mupirocin resistance at our institution. The plasmid backbone shows extensive genetic conservation with plasmids belonging to the pSK41/pGO1 family, but comparative analyses have revealed key differences that provide important insights into the evolution of these medically important plasmids and high-level mupirocin resistance in staphylococci and highlight the role of insertion sequence IS257 in these processes.