The multifaceted resources and microevolution of the successful human and animal pathogen methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is one of themost important bacterial pathogens based on its incidence and the severity of itsassociated infections. In addition, severe MRSA infections can occur in hospitalisedpatients or healthy individuals from the community. Studies have shown theinfiltration of MRSA isolates of community origin into hospitals and variants ofhospital-associated MRSA have caused infections in the community. These rapidepidemiological changes represent a challenge for the molecular characterisation ofsuch bacteria as a hospital or community-acquired pathogen. To efficiently controlthe spread of MRSA, it is important to promptly detect the mecAgene, which is the determinant of methicillin resistance, using a polymerase chainreaction-based test or other rapidly and accurate methods that detect themecA product penicillin-binding protein (PBP)2a or PBP2’. Therecent emergence of MRSA isolates that harbour a mecA allotype,i.e., the mecC gene, infecting animals and humans has raised anadditional and significant issue regarding MRSA laboratory detection. Antimicrobialdrugs for MRSA therapy are becoming depleted and vancomycin is still the main choicein many cases. In this review, we present an overview of MRSA infections in communityand healthcare settings with focus on recent changes in the global epidemiology, withspecial reference to the MRSA picture in Brazil.