New Antibiotic Effective in Treating Gram-Positive Bacteremia

Results from the compassionate use program for linezolid (Zyvox), an investigational new antibiotic still under development, show that the drug is effective in the treatment of patients with bacteremia associated with significant gram-positive infections, including those resistant to current therapies. These data were discussed at a poster session at the 37th annual meeting of the Infectious Diseases Society of America in Philadelphia.

Data were presented on 254 patients with bacteremia from 165 investigational sites. Of the total bacteremic population enrolled in the compassionate use program, 120 were clinically evaluable at short-term follow-up. Of this group, 82.5% were considered to be cured. A total of 64 patients were considered to be microbiologically evaluable at short-term follow-up, and linezolid demonstrated an 85.9% microbiologic cure rate in these individuals.

A third group of 50 patients was studied to assess how rapidly linezolid eradicated the bacteria from patients’ bloodstream. Linezolid eradicated organisms from the bloodstream by day 2 of treatment in approximately 50% of these patients and by day 5 in 75%.

 “Our data from the Zyvox compassionate use program suggest that Zyvox is well tolerated and successful in treating patients with bacteremia,” said study coordinator Mary Birmingham PharmD, program director, The Clinical Pharmacokinetics Laboratory, Millard Fillmore Hospital, and State University of New York, Buffalo. “Zyvox is an excellent treatment option for these seriously ill patients with gram-positive bacteremia.”

Range of Infections Treated

The infections in the patients studied included documented intravenous or catheter-line infections, gastrointestinal infections, skin and soft-tissue infections, urinary tract infections, infected thrombi, and infected devices. The primary causative organism isolated from from the group was vancomycin-resistant Enterococcus faecium (81.4%). Other organisms isolated included methicillin-resistant Staphylococcus aureus (6.2%), methicillin-resistant S epidermidis (2.7%), other strains of vanco-mycin-resistant entercocci (2.7%), vancomycin-susceptible enterococci (2.7%), vancomycin-resistant E faecalis (2.3%), and methicillin-susceptible S aureus (1.2%).

Nonevaluability in a large number of patients was due to repeat baseline blood cultures being negative prior to the initiation of treatment with linezolid or to patients dying from their underlying illnesses. The overall adverse event rate was 25.2%, with 5.5% of these events considered to be serious and 9.0% requiring discontinuation of treatment.