Improving Transformation of Staphylococcus aureus Belonging to the CC1, CC5 and CC8 Clonal Complexes

Methicillin resistant Staphylococcus aureus (MRSA) is an opportunistic pathogen found in hospital and community environments that can cause serious infections. A major barrier to genetic manipulations of clinical isolates has been the considerable difficulty in transforming these strains with foreign plasmids, such as those from E. coli, in part due to the type I and IV Restriction Modification (R-M) barriers. Here we combine a Plasmid Artificial Modification (PAM) system with DC10B E. coli cells (dcm mutants) to bypass the barriers of both type I and IV R-M of S. aureus, thus allowing E. coli plasmid DNA to be transformed directly into clinical MRSA strains MW2, N315 and LAC, representing three of the most common clonal complexes. Successful transformation of clinical S. aureus isolates with E. coli-derived plasmids should greatly increase the ability to genetically modify relevant S. aureus strains and advance our understanding of S. aureus pathogenesis.