Key genetic elements and regulation systems in methicillin-resistant Staphylococcus aureus

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA), popularly known as a type of superbug, has been a serious challenge for animal and human health. S. aureus has developed methicillin resistance mainly by expression of β-lactamase and PBP2a, which is regulated by the blaZ–blaI–blaR1 and mecA–mecI–mecRI systems. Other genetic elements, including murE and femA, also participate in expression of methicillin resistance, but the mechanism remains unclear. The evolution of the staphylococcal cassette chromosome mec determines the epidemiological risk of MRSA. The plasmid-located gene cfr might contribute to multiresistance and transmission of MRSA. Some virulence factors, including Panton–Valentine leukocidin, phenol-soluble modulin, arginine catabolic mobile element and other toxin elements enhance the pathogenesis and fitness of MRSA. Two-component regulation systems (agr, saeRS and vraRS) are closely associated with pathogenesis and drug resistance of MRSA. The systematic exploration of key genetic elements and regulation systems involved in multidrug resistance/pathogenesis/transmission of MRSA is conclusively integrated into this review, providing fundamental information for the development of new antimicrobial agents and the establishment of reasonable antibiotic stewardship to reduce the risk of this superbug.