From theory to practice: resistance in Staphylococcus aureus and new treatments

ABSTRACTNumerous surveillance studies confirm that methicillin resistance is common among isolates of Staphylococcus aureus, with resistance rates as high as 50%. Long associated with nosocomial infections, methicillin-resistant S. aureus (MRSA) is now emerging as a community-based pathogen. Studies indicate that infections with MRSA are associated with greater morbidity and mortality than similar infections with methicillin-sensitive strains. The spread of MRSA has contributed to an increasing reliance on vancomycin to treat infections caused by this pathogen. However, with isolates of S. aureus becoming increasingly resistant to multiple antibiotic agents, new antimicrobial therapies are urgently required. Daptomycin, the first in a novel class of antibiotics called the cyclic lipopeptides, was approved in the USA in 2003 for the treatment of complicated skin and soft tissue infections (cSSTIs) caused by Gram-positive bacteria. Post-marketing experience in the USA has confirmed the clinical efficacy of daptomycin for the treatment of cSSTIs observed in clinical trials. Studies have also shown daptomycin to be as effective as current standard therapy for the treatment of S. aureus bacteraemia, including those with known or suspected infective endocarditis. A supplemental new drug application for daptomycin for treatment of S. aureus bacteraemia and right-sided infective endocarditis was approved in May 2006 by the US FDA. The availability of daptomycin has improved treatment options for infections caused by Gram-positive pathogens.