Cluster of linezolid resistant Enterococcus faecium ST 117 in Norwegian

22 A linezolid resistant, vancomycin susceptible E. faecium strain was isolated from three 23 patients who had not received linezolid. The first patient was hospitalised in the same 24 hospitals and wards as the two following patients. The E. faecium isolates were resistant to 25 linezolid (MIC 8-32 mg/L), ampicillin and high levels of gentamicin. Resistance to linezolid 26 was associated with a G2576T mutation in 23S rDNA. The cfr linezolid resistance gene was 27 not detected. The three isolates showed identical DNA fingerprints by PFGE, belonged to 28 ST117 and harboured virulence genes esp, hyl, acm, efaAfm, srgA, ecbA, scm, pilA, pilB and 29 pstD typically associated with high-risk E. faecium genotypes. The linezolid resistant E. 30 faecium high-risk clone caused bacteraemia in the first two cancer patients and survived in the 31 hospital environment for more than a year before appearing in the urethral catheter of the third 32