Current and emerging serious Gram-positive infections.

Serious infections caused by Gram-positive pathogens are increasingly difficult to treat because of pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and penicillin-resistant Streptococcus pneumoniae. The more recent emergence of vancomycin-intermediate and -resistant MRSA (VISA and VRSA) has further compromised treatment options. Reports of resistance to, and clinical failures with newer antimicrobial agents such as linezolid and quinupristin/dalfopristin are also emerging. Consequently, there is a clinical need for new antimicrobial agents that have suitable pharmacokinetic properties and safety profiles, with activity against these Gram-positive pathogens.