SAN FRANCISCO—Independent clinical risk factors for vancomycin failure in patients with methicillin-resistant Staphylococcus aureus infection were infection of the lung or pleura and, to a lesser extent, infection of the bone, results from a small case-control study showed.
“Vancomycin doesn't penetrate the pleura and the lungs as well as newer generations of drugs for MRSA,” Dr. Roger Mar-Tang said in an interview during a poster session at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy. “A consideration may be to use a different agent if you suspect MRSA infection in the lung or pleura.”
He and his associates at the University of California, Davis Medical Center in Sacramento studied 55 cases of MRSA infection that were not successfully treated with vancomycin between July 1, 2003, and June 30, 2005; 75 MRSA patients treated successfully in that period served as controls.
Vancomycin failure was defined as patients who received at least 5 days of therapy and met one of three criteria: They had repeat positive MRSA cultures, showed continued or worsening signs or symptoms of infection, or died after 5 days of therapy for the MRSA infection.
Univariate analysis showed that the clinical risk factors for vancomycin failure were renal insufficiency or failure (affecting 44% of cases vs. 27% of controls), history of myocardial infarction (24% vs. 11% among controls), MRSA infection of the lung or pleura (53% vs. 19% among controls), and MRSA infection of the bone (9% vs. 1% among controls). Multivariate analysis showed that the only independent clinical risk factors for vancomycin failure were MRSA infection of the lung or pleura (odds ratio of 19.5) and MRSA infection of the bone (odds ratio of 8.22).
Dr. Mar-Tang conducted the study during his internal medicine residency at the University of California, Davis Medical Center. The conference was sponsored by the American Society for Microbiology.