The arginine catabolic mobile element (ACME) is a mobile genetic element of Staphylococcus bacterial species. This genetic element provides for several immune modulating functions, including resistance to polyamines which serve as a non-specific immune response both on intact skin and following the inflammatory response in wound healing. [1] [2] Diverse ACME are present in several species of Staphylococcus, including Staphylococcus epidermidis . [3] [4]
ACME are not common among antibiotic sensitive S. aureus (MSSA). [5] The elements for the most prominent MRSA ACME appear to have assembled recently in S. epidermidis into the speG-positive ACME which was transferred to virulent S. aureus during the evolution of the epidemic USA300 MRSA strain. [6] [7] This broadened the ability of S. aureus to colonize sites beyond the nose. [8] This strain is able to persist on intact skin and is spread rapidly person-to-person. As a result, the speG-positive ACME is a particularly important element of MRSA pathogenesis.