Case studies in current drug development: 'glycylcyclines'.

Glycylcyclines represent a new class of tetracycline antibiotics with potent antibacterial activities against resistant pathogens. One of the glycylcyclines, Tygacil, was selected for further development and has been approved by the FDA. It has an expanded broad-spectrum of antibacterial activity both in vitro and in vivo. It is active against a wide range of clinically relevant pathogens including Gram-positive, Gram-negative, atypical, and anaerobic bacteria and bacterial strains carrying either or both of the two major forms of tetracycline resistance (efflux and ribosomal protection). Most importantly, it is active against the multiply antibiotic resistant Gram-positive pathogenic bacteria, including methicillin-resistant Staphylococcus aureus (MRSA).