New drug as effective in MRSA study
In encouraging findings in the ongoing battle to stem antibiotic resistance, linezolid proved to be an effective alternative for vancomycin for certain types of methicillin-resistant Staphylococcus aureus (MRSA) infections, researchers report.
"It’s certainly an alternative for treating MRSA infections," explains lead researcher Dennis L. Stevens, PhD, MD, professor at the University of Washington School of Medicine in Seattle. However, certain severe infections, including endocarditis and decubitus ulcers associated with diabetes, were excluded from the comparative study.
"I would say that in two situations, there would be a question, and that would be endocarditis and osteomyelitis," he says. "We need to do the clinical trials. I would be hesitant to treat MRSA endocarditis [with linezolid] at this point in time. There is the old saw’ that you need bactericidal antibiotics to treat endocarditis. Linezolid is probably somewhere between static and cidal in terms of Staph aureus."
The randomized, open-label trial evaluated patients with presumed MRSA infections at 104 sites in North America, Europe, Latin America, and Asia from July 1998 to July 1999.1 Hospitalized patients were randomized to receive either linezolid (600 mg IV twice daily) or vancomycin (1 g IV twice daily) for at least seven days. When they had shown clinical improvement, linezolid-treated patients could have their treatment changed to oral linezolid (600 mg twice daily) at the discretion of the investigator. Skin and soft-tissue infection was the most common diagnosis, followed by pneumonia and urinary tract infection.
At the test-of-cure visit (15-21 days after the end of therapy) among evaluable patients with MRSA, there was no statistical difference between the two treatment groups with respect to clinical cure rates (73.2% of patients in the linezolid group and 73.1% in the vancomycin group). Both regimens were well-tolerated, with similar rates of adverse events.
MRSA threat growing
A common cause of nosocomial pneumonia and bloodstream infections, MRSA has increased from 2% in 1974 to as high as 64% in surveys of the MRSA proportion of nosocomial staph infections.2-4 Until recently, there were few therapeutic options for the treatment of MRSA infections. Intravenous vancomycin remains the standard therapy, but linezolid and quinupristin-dalfopristin have been developed in recent years. An advantage of linezolid is that the patient can be switched to oral medication, Stevens says.
"You can put them on an oral pill and send them home," he says. "Whereas, with vancomycin what we have had to do in the past is either keep the patient in the hospital longer or send them home with home IV care. That is more costly. The oral option gives you another avenue to maybe not have to use intravenous device in the first place, not have to use home IV, and not have to use intravenous preparations. If you don’t have an IV catheter, that is reducing some [infection] risk."
References
1. Stevens DL, Herr D, Lampiris H, et al. Linezolid versus vancomycin for the treatment of Methicillin-resistant Staphylo-coccus aureus infections. Clinical Infect Dis 2002; 34:1,481-1,490.
2. Maranan MC, Moreira B, Boyle-Vavra S, et al. Anti-microbial resistance in staphylococci: Epidemiology, molecular mechanisms, and clinical relevance. Infect Dis Clin North Am 1997; 11:813-849.
3. Panlilio AL, Culver DH, Gaynes RP, et al. Methicillin-resistant Staphylococcus aureus in U.S. hospitals, 1975-1991. Infect Control Hosp Epidemiol 1992; 13:582-586.
4. Voss A, Milatovic D, Wallrauch-Schwarz C, et al. Methicillin-resistant Staphylococcus aureus in Europe. Eur J Clin Microbiol Infect Dis 1994; 13:50-55.
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