New Class of Antibiotics Fights Resistant Bugs

A multi-center study has demonstrated that linezolid, (Zyvox), the first of a new class of antibiotics, is as effective as oxacillin-dicloxacillin in curing skin and soft tissue infections caused by Gram-positive bacteria and holds promise for fighting infections caused by resistant Gram-positive bacteria. The study, conducted by researchers at the U.S. Department of Veterans Affairs (Los Angeles, CA, USA) and colleagues, was reported in the December issue of Antimicrobial Agents and Chemotherapy.

In test tube tests, linezolid proved very active against methicillin-resistant Staphylococcus, penicillin-resistant Streptococcus pneumoniae, and staphylococci and enterococci resistant to vancomycin. The new class of antibiotics is called oxazolidinones, which attack bacteria at a different point than any previously developed antibiotics. Linezolid works by interfering with protein production at an early stage. Moreover, laboratory tests have shown that the antibiotic stalls toxin production in toxin-producing Gram positive bacteria, even at linezolid levels well below those needed to actually kill the microbes.

"We haven't had any totally new antibiotics in a long time,” said Dennis L. Stevens, M.D., one of the study's authors and chief of infectious diseases at the Boise Veterans Affairs Medical Center. "Linezolid has an entirely different mechanism of action and looks like it can get some of the resistant bugs. It's a new cannon in our arsenal.” Stevens emphasized the need for more research and pointed out that linezolid cannot kill nonGram-positive bacteria.



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