1. Home>
2. Specialties>
3. Infectious Diseases>
4. Summary and Comment

Linezolid for Multidrug-Resistant Enterococci: A Short-Lived Success?

Rapid development of linezolid-resistant enterococci highlights the need for prudent antibiotic use.

The rapid increase of vancomycin resistance over the past decade left many critically ill and immunosuppressed patients without adequate treatment options for bloodstream infections caused by Enterococcus faecium. Following FDA approval of quinupristin/dalfopristin in 1999 and linezolid in 2000, such infections became treatable, and linezolid, especially, was used increasingly. To evaluate trends in linezolid and quinupristin/dalfopristin susceptibility, researchers tested vancomycin-resistant E. faecium bloodstream isolates obtained from January 1996 through January 2002 from patients at a Houston cancer center. Susceptibility testing was done according to National Committee for Clinical Laboratory Standards protocol, and all isolates were further subdivided into clonal strains using pulsed-field gel electrophoresis.

Of the E. faecium clones identified from isolates obtained during the pre-use periods for these drugs, 76 of 76 (100%) were susceptible to linezolid, and 59 of 67 (88%) were susceptible to quinupristin/dalfopristin. After hospital use of these agents for 6 months, susceptibility to linezolid decreased to 83% (2 of 12 clones showed intermediate susceptibility, P<0.02), whereas susceptibility to quinupristin/dalfopristin increased nonsignificantly (to 22 of 23 clones; 96%). Linezolid was used more than twice as often as quinupristin/dalfopristin during this period. Two different resistance mechanisms were seen in the two clones with intermediate linezolid susceptibility.

Comment: Considering that more than 3 decades were required for vancomycin resistance to develop in enterococci, the emergence of decreased linezolid susceptibility within only a few years is extremely disturbing. This development calls for prudent and restrictive use of linezolid and other antibiotics with a special spectrum.

— Thomas Glück, MD

Published in Journal Watch Infectious Diseases October 8, 2004

Citation(s):

Raad II et al. Clinical-use-associated decrease in susceptibility of vancomycin-resistant Enterococcus faecium to linezolid: A comparison with quinupristin-dalfopristin. Antimicrob Agents Chemother 2004 Sep; 48:3583-5.

• Original article (Subscription may be required)
• Medline abstract (Free)