A 4(1)/(2)-month-old, 26-week premature infant with multiple complications of prematurity required a central venous catheter for venous access and antibiotic treatment of bacterial nosocomial infections. He developed tricuspid valve endocarditis with vegetation caused by Enterococcus faecium resistant to ampicillin, vancomycin and quinupristin-dalfopristin but susceptible to linezolid. He was successfully treated with linezolid intravenously (7 weeks) and then orally (2 weeks).