Oxazolidinediones represent a class of antibacterials including linezolid and tedizolid. These agents are primarily active against aerobic gram-positive pathogens, including penicillin-resistant pneumococci, methicillin-resistant staphylococci and enterococci (both E faecalis and vancomycin-sensitive and vancomycin-resistant E faecium), and mycobacteria. Linezolid is bacteriostatic against all of these pathogens. Linezolid-resistant enterococci and VRE and linezolid-resistant S aureus and S epidermidis have been isolated. The oral bioavailability of these medications is complete, with serum levels approaching those observed with intravenous administration. The medications are eliminated primarily by nonrenal mechanisms. An advantage of tedizolid is that it can be administered once daily, whereas linezolid requires twice-daily dosing.
The primary toxicity is bone marrow suppression with long-term therapy, particularly the platelet and WBC lines. Other adverse effects include neuropathy and mitochondrial toxicity with long-term use. While tedizolid appears to differ from linezolid with respect to the incidence of bone marrow toxicity, trials with long-term therapy are lacking. Linezolid is a mild monoamine oxidase inhibitor, and while concomitant use of selective serotonin reuptake inhibitors may result in a serotonin syndrome, most patients can safely receive both agents together. Tedizolid does not interact with serotonergic agents. While linezolid is modestly superior to vancomycin in confirmed methicillin-resistant S aureus pneumonia, it offers little to no advantage in the empiric treatment of hospital-acquired or ventilator-associated pneumonia. In contrast, linezolid has been found to be significantly inferior to daptomycin in the treatment of VRE bloodstream infection. Of particular concern are the increasing reports of linezolid-resistant Enterococcus and staphylococci, which reinforce that this agent should be used judiciously.