Source: Genetics  |  Posted 8 years ago

A case report describing linezolid failure in a dialysis patient with enterococcal endocarditis may be the first reported clinical failure of linezolid in a patient with a drug-susceptible []Enterococcus faecalis[] infection.

Linezolid is the first oxalidinone antibiotic approved for clinical use. It is approved for treatment of pneumonia and skin and soft-tissue infections and has activity against []Staphylococcus aureus[], []E. faecalis[], []Enterococcus faecium[], and []Streptococcus pneumoniae[], note Shanta M. Zimmer, MD, with Emory University, Atlanta, Georgia, United States, and colleagues.

Although linezolid has shown promise against drug-resistant enterococcal species and vancomycin-resistant []E. faecium[] endocarditis, its effectiveness in patients infected with these organisms has not been well studied.

The report describes a 40-year-old man with end-stage renal disease who was admitted to the hospital because of fevers and chills occurring during haemodialysis.

Eight weeks previously, the patient had been treated for group B streptococcal endocarditis of the aortic valve. Treatment with ampicillin was changed to levofloxacin because of allergic response, and the patient completed a total of 6 weeks of therapy. Follow-up blood cultures were negative.

Upon readmission to the hospital, blood samples were positive for []E. faecalis[] susceptible to vancomycin, ampicillin, streptomycin, and linezolid but resistant to levofloxacin and gentamicin.

The patient received 600 mg of intravenous linezolid every 12 hours but developed worsening congestive heart failure in the third week of his hospitalisation. Cultures of blood remained positive for []E. faecalis[]. However, after more than 2 weeks of linezolid therapy, testing revealed continued sensitivity with a minimum inhibitory concentration of 2 mcg/mL.

The patient was treated with 2 grams of ampicillin every 12 hours and 1 gram of streptomycin after each session of haemodialysis, and bacteraemia cleared within 24 hours of ampicillin therapy. He also underwent replacement of the mitral and aortic valves, which were necrotic without discreet vegetations, as well as repair of the tricuspid valve leaflet, from which a vegetation was excised.

After 6 weeks of intravenous therapy with ampicillin and streptomycin following surgery, the patient was healthy 6 months later.

"Linezolid therapy failed in our patient's case, not because of resistance, but presumably because of a combination of host factors and antibiotic failure related to the organisms sequestered within his valvular vegetation," they conclude.