Novel structures and temporal changes of arginine catabolic mobile elements in methicillin-resistant Staphylococcus aureus genotypes ST5-MRSA-II and ST764-MRSA-II in Japan

Abstract

Twenty-two of 1,103 methicillin-resistant Staphylococcus aureus (MRSA) isolates containing the type II staphylococcal cassette chromosome mec element (SCCmec) (collected in Hokkaido, Japan, from 2008 to 2011) harbored the arginine catabolic mobile element (ACME). Five genetic variations were identified in the ACME-staphylococcal cassette chromosome mec composite islands, 66 to 79 kb in size. The percentage of ACME carriage temporally increased from 0.85% to 4.5% in parallel with the emergence of shorter variants (66 to 72 kb). Shorter variants may have a selective advantage and accelerate the dissemination of ACME in Japanese MRSA.