Intravenous linezolid administered orally: a novel desensitization strategy

A 41-year-old woman with a history of myasthenia gravis was admitted to a local hospital because of severe muscle weakness, ptosis, shortness of breath, nausea and vomiting, and fever. Blood cultures revealed Enterococcus faecium resistant to several antimicrobial agents. The organism had minimum inhibitory concentrations above 16 microg/ml for vancomycin and above 2 microg/ml for quinupristin-dalfopristin. In the absence of therapeutic alternatives, treatment with linezolid was required (minimum inhibitory concentration 1.5 microg/ml). The first dose of linezolid resulted in a hypersensitivity reaction consistent with an immunoglobulin E-mediated response requiring medical intervention. Because of a lack of intravenous access and because of limited availability of the oral suspension from the manufacturer, a desensitization protocol was implemented in which the intravenous formulation of linezolid was given orally. The patient was successfully desensitized by using an escalating, 14-dose procedure. We believe this is the first case in the English language literature to describe successful desensitization with the oral administration of intravenous linezolid in a patient with E. faecium bacteremia who was allergic to oxazolidinone.