First report of a linezolid-resistant vancomycin-resistant Enterococcus faecium strain in Greece

Sir, The emergence of vancomycin-resistant enterococci (VRE) has raised major concerns because of the limited therapeutic options for treating infections resulting from these organisms. In the USA, the National Nosocomial Surveillance System has described a 20-fold rise in VRE recovered from bloodstream infections during the past 10 years. The limitation in therapeutic options has resulted in the development of new drugs such as quinupristin/dalfopristin and line-zolid. Although linezolid has been used in clinical practice for a relatively short period of time, there are already several reports of linezolid-resistant enterococci. 1–3 In Greece, this antibiotic is only used for the treatment of infections caused by vancomycin-resistant enterococci and teicoplanin-resistant Staphylococcus epidermidis strains, which are circulating in several Greek hospitals (data not shown). To our knowledge, this is the first report of a linezolid-resistant Entero-coccus faecium strain isolated in a tertiary care Greek hospital. The isolate was recovered from a blood culture of a 20-year-old male patient, who was admitted to the University Hospital of Larissa after a car accident. He was operated on immediately for a fractured femur. During corrective surgery, a fatty embolism occurred and he was immediately transferred to the intensive care unit (ICU) where he was treated for about a month. The patient was empirically treated with aminoglycosides, teicoplanin and piperacillin plus tazobactam. However, the isolation from blood culture on the 14th day of an oxacillin-resistant S. epidermidis strain, resistant to teicoplanin and other antimicrobial agents, was the main cause for the replacement of teicoplanin by linezolid. Four days later, an E. faecium isolate, resistant to glycopeptides and linezolid (MIC 16 mg/L) was recovered from blood culture. The microorganism was identified to the species level by the auto-(high-level), streptomycin (high-level), tetracycline, nitrofurantoin and vancomycin was performed using the Vitek System, and susceptibility to erythromycin, rifampicin, linezolid and quinupristin/ dalfopristin was tested by Etest strips (AB Biodisk, Solna, Sweden). MICs of vancomycin, teicoplanin and linezolid were determined by the agar dilution method (NCCLS guidelines). 4 To examine the stability of linezolid resistance, the isolate was subcultured on drug-free agar once weekly for 2 months and then re-tested to determine the final linezolid MIC. Enterococcus faecalis ATCC 29212 was used as a control for the estimation of MICs. PCRs for erm(B), vanA/B and esp genes were carried out as described previously. 5 To elucidate the mechanism of linezolid resistance, the gene encoding domain V of the 23S rRNA was amplified. …