Genomic Rearrangement of the mec Regulator Region Mediated by Insertion of IS431 in Methicillin-Resistant Staphylococci

Genomic diversification of the mec regulator region mediated by IS431 was investigated for clinical isolates of methicillin-resistant staphylococci. A single rearranged form of the mecR1 gene due to IS431 insertion was detected in the three staphylococcal species, while another type of mecR1 truncation with IS431 and an IS431 located downstream of mecI were found only in Staphylococcus haemolyticus. Genetic differentiation of IS431 and staphylococcal isolates suggested transmission of mecDNA with IS431-mediated rearrangement among different staphylococcal species.