[Linezolid: antibacterial activity, clinical efficacy and resistance]

Linezolid is a synthetic antibiotic, the first available agent in a new class of antibiotic called the oxazolidinones, whose particular mechanism of action consists in inhibiting the initiation of protein synthesis. Its spectrum of in vitro and in vivo activity includes staphylococci, streptococci, enterococci, corynebacteria and some anaerobic bacteria (Peptostreptococcus, Clostridium, and Fusobacterium). The first therapeutic results were very encouraging, leading to the marketing of the product in France in 2002. Linezolid is indicated in the treatment of pneumonia and the complicated infections of the skin. Pharmacocinetics studies have shown that linezolid has an excellent bioavailability allowing a fast relay per os. However, failures of treatment under linezolid were reported and resistant strains of staphylococci and enterococci were obtained in vitro and in vivo after therapeutic use of this antibiotic. Changes in the domain V of 23S rRNA were found in the site of fixation, the most frequent was (G out of U) in position 2576 (numbering E. coli). In a context where resistance to traditional treatments in enterococci, pneumococci and S. aureus do not cease to increase, linezolid can be regarded as a therapeutic alternative to treat the infections with Gram-positive cocci.