Study Suggests Some Patients Treated With Zyvox for MRSA Infections May Leave the Hospital Sooner Than Those Taking Vancomycin

PEAPACK, N.J. -- The novel antibiotic Zyvox (linezolid injection, tablets and for oral suspension) may shorten hospital length of stay in patients with complicated skin and soft tissue infections caused by known or suspected methicillin-resistant Staphylococcus aureus (MRSA), according to research published this week in the scientific journal Surgical Infections. An analysis of a subset of 230 patients from a Phase III clinical trial suggests that treatment with Zyvox may decrease patients' stay in the hospital by as many as 8 days, compared to the standard treatment, intravenous vancomycin. Earlier data published from this study have shown that Zyvox use also significantly reduced the number of days that patients received IV therapy. [1]

Zyvox comes from the first new class of antibiotics -- the oxazolidinones -- to be introduced in 35 years. It can be used interchangeably between its IV and oral formulations, providing dosing convenience for physicians and patients. Zyvox is the only oral antibiotic approved by the Food and Drug Administration (FDA) for hard-to-treat resistant infections like MRSA.

"Surgical patients are at an increased risk for skin and soft tissue infections that are increasingly being caused by resistant bacteria such as MRSA," said John Weigelt, MD, DVM, professor and vice chairman, department of surgery, chief, division of trauma & critical care, Medical College of Wisconsin. "The availability of an oral agent, such as Zyvox, with efficacy against MRSA infections is a significant advance in the treatment of these patients. The oral form provides physicians with the option to get some patients home from the hospital sooner and also may decrease reliance on IV therapy, which can eliminate the risk of subsequent infections from catheterization."

The length of stay analysis consisted of 230 intent-to-treat patients with complicated skin and soft tissue infections as the primary site of their infections. A clinically evaluable sample of 144 patients and a surgical site infection subsample of 114 patients also were evaluated. Median length of stay for the intent-to-treat patients was 9 days for patients treated with Zyvox vs. 14 days for the vancomycin group (p=0.052), and 8 days vs. 16 days in the clinically evaluable subgroup (p=0.0025). Patients treated with Zyvox in the surgical site infection subgroup also tended to have a decreased length of hospital stay of 10 days vs. 14 days (p=0.29), although these results were not statistically significant.

Data for this analysis were collected as part of a Phase III, randomized registration trial assessing the safety and efficacy of Zyvox compared to vancomycin. Patients with pneumonia, complicated skin and soft tissue infections, urinary tract infections or bacteremia caused by known or suspected methicillin-resistant staphylococci were included in the initial study. Participants were treated with Zyvox (600 mg IV twice daily with an option to switch to 600 mg oral Zyvox twice daily) or vancomycin (1g IV twice daily). The Zyvox group could switch to the oral formulation when they showed clinical improvement. Patients received up to four weeks of treatment followed by up to four weeks of observation. There were no overall differences in the total number of days patients received treatment between the Zyvox and vancomycin groups (13 days vs. 11 days, respectively). Comparable efficacy and safety were observed in the two treatment arms.

Zyvox is indicated for the treatment of infections caused by susceptible strains of designated organisms in adults and children, including patients with complicated skin and skin structure infections caused by Staphylococcus aureus (both methicillin-resistant and -susceptible strains), Streptococcus pyogenes and Streptococcus agalactiae. It has not been studied in the treatment of diabetic foot and decubitis ulcers.

Patients receiving Zyvox should have complete blood counts monitored weekly, since myelosuppression has been reported. This applies particularly to those who are given Zyvox for longer than two weeks, have pre-existing myelosuppression, are receiving concomitant drugs that produce bone marrow suppression, or have a chronic infection and have received previous or concomitant antibiotic therapy. The most commonly reported adverse events in clinical trials were diarrhea, nausea and headache.

The treatment of resistant infections, such as MRSA, contributes to significant human and financial costs. Patients who acquire an infection caused by these resistant bacteria tend to have extended hospital stays and often have a poor prognosis. According to the CDC, the financial burden of treating hospital-acquired infections caused by common forms of resistant bacteria, like MRSA, is estimated to be more than $1 billion annually. [2] Each year nearly 2 million patients in the United States acquire infections in hospitals. [3] In addition, surgical site skin infections are reportedly the third most common type of hospital-acquired infections, accounting for as much as 14-25 percent of the total. [4]

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[1] Li, Z., Wilke RJ, Pinto LA, et al. Comparison of length of hospital stay for patients with known or suspected methicillin-resistant Staphylococcus species infections treated with linezolid or vancomycin; a randomized, multicenter trial. Pharmacotherapy 2001; 21:263-274.

[2] Centers for Disease Control and Prevention. A Public Health Action Plan to Combat Antimicrobial Resistance -- Part 1: Domestic Issues. Atlanta, GA, January 2001.

[3] Centers for Disease Control and Prevention: Hospital infections cost U.S. billions of dollars annually. Atlanta, GA, March 6, 2000.

[4] Li, Jim Zhiming, Wilke, Richard J, Rittenhouse, Brian E and Rybak, Michael J. Effect of Linezolid versus Vancomycin on Length of Hospital Stay in Patients with Complicated Skin and Soft Tissue Infections Caused by Known or Suspected Methicillin-Resistant Staphylococci: Results from a Randomized Clinical Trial. Surgical Infections 2003; 2:45-56.