Tigecycline: first of a new class of antimicrobial agents

Tigecycline is the first commercially available member of the glycylcyclines, a new class of antimicrobial agents. The glycylcyclines are derivatives of the tetracycline antibiotics, with structural modifications that allow for potent gram-positive, gram-negative, and anaerobic activity, including certain multidrug-resistant strains. The enhanced activity can be attributed to stronger binding affinity and enhanced protection against several mechanisms of resistance that affect other antibiotic classes such as tetracyclines. Tigecycline exhibits generally bacteriostatic action by reversibly binding to the 30S ribosomal subunit and inhibiting protein translation. In vitro activity has been demonstrated against multidrug-resistant gram-positive pathogens including methicillin-resistant and glycopeptide-intermediate and -resistant Staphylococcus aureus, as well as vancomycin-resistant enterococci. Multidrug-resistant gram-negative pathogens, such as Acinetobacter baumannii and extended-spectrum beta-lactamase-producing Klebsiella pneumoniae and Escherichia coli, are typically highly susceptible to tigecycline. The drug also has displayed significant activity against many clinically important anaerobic organisms. This agent demonstrates a predictable pharmacokinetic profile and minimal drug interactions, and is generally well tolerated, with nausea being the most common adverse event. It was approved in June 2005 for the treatment of complicated skin and skin structure infections (SSSIs) and complicated intraabdominal infections. Currently, a limited number of broad-spectrum antimicrobials are available to combat multidrug-resistant organisms. The addition of new agents is essential to limiting the spread of these pathogens and improving outcomes in patients with these types of infections. Tigecycline has demonstrated promising results in initial in vitro and clinical studies for SSSIs and complicated intraabdominal infections; however, further clinical experience will clarify its role as a broad-spectrum agent.