An extremely rare genetic element has been linked to an epidemic wave of methicillin-resistant Staphylococcus aureus (MRSA) infection in China, according to a report published online this week in Nature Medicine. This element may be a promising therapeutic target in treatment.
The molecular processes that underlie epidemic waves of MRSA are poorly understood. Michael Otto and his colleagues found that a genetic element, sasX, that can move around in a genome, has a key role in MRSA colonization and pathogenesis in the body. The presence of sasX substantially enhanced nasal colonization, lung disease and abscess formation, and helped the pathogen evade the immune system. The researchers also observed the recent spread of sasX from one strain to invasive clones from other strain types, suggesting that sasX is a quickly spreading determinant of MRSA pathogenicity.