Insight in methicillin-resistant Staphylococcus aureus (MRSA) biofilms: identification of key determinants in biofilm formation of two highly pathogenic and globally successful MRSA clones, USA300 and EMRSA-15.

Since two decades, methicillin-resistant Staphylococcus aureus (MRSA) has become a major cause of medical device-associated and postsurgical wound infections in hospitals and of pneumonia in the community. In these infections, MRSA favors the biofilm phenotype, living in a community encased in an extracellular matrix that affords protection against the host immune system and antibiotics, making these infections recalcitrant to treatment. Our laboratory has shown that two highly pathogenic and globally successful MRSA clones, USA300 and EMRSA-15, are prolific biofilm formers. Interestingly, our transcriptomics data has revealed spectacularly different mechanisms of biofilm formation between these two clones. For instance, in USA300-S391 biofilms, Hfq, a global regulator of small non-coding RNAs which in turn control rapid bacterial virulence gene expression as well as mecR, which regulates the expression of ß-lactam resistance conferring mecA gene, were both found to be highly upexpressed. EMRSA-15 biofilms, however, were not found to be MecR- or Hfq-dependent, but instead showed upexpression of multiple prophages. This fundamental project aims to dissect the role of mecR, Hfq, and prophages in mediating biofilm formation in USA300 and EMRSA-15. Identifying genes regulated by these key determinants could be better alternatives for biofilm disruption or additive therapies to antibiotics that are currently ineffective against MRSA.

Keywords:MICROBIOLOGY

Disciplines:Microbiology, Systems biology, Laboratory medicine

Project type:Collaboration project