SAN FRANCISCO, CA—Patients with ventilator-associated pneumonia (VAP) due to methicillin-resistant Staphylococcus aureus (MRSA) achieved an earlier time to clinical stability when treated with linezolid vs. vancomycin, results of the IMPACT-HAP study reported at IDWeek 2013.

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“These data suggest the number of days for patients to reach clinical stability can be used as an early clinical outcome in patients with ventilator-associated pneumonia,” noted Paula Peyrani, MD, of the Division of Infectious Diseases at the University of Louisville, Louisville, KY, and colleagues on behalf of the IMPACT-HAP Study Group.

Time to clinical stability is a well-defined early clinical outcome in hospitalized patients with community-acquired pneumonia, Dr. Peyrani noted, but it has not been evaluated in patients with ventilator-associated pneumonia. In this multicenter, retrospective, observational study, the investigators compared time to clinical stability in patients with MRSA ventilator-associated pneumonia treated with linezolid vs. vancomycin.

A total of 100 nonconsecutive patients requiring intensive care were enrolled from five US academic institutions; 50 were treated with linezolid and 50 with vancomycin. Data was collected from November 2008 to October 2012. Ventilator-associated pneumonia was defined according to the Centers for Disease Control and Prevention criteria, and MRSA ventilator-associated pneumonia was defined as that isolated from a tracheal aspirate or bronchoalveolar lavage.

“A patient was considered to reach clinical stability the day the four criteria were met,” Dr. Peyrani noted; these were afebrile for 24 hours, decrease in WBC >10%, improved PaO2/FiO2 ratio of >20%, and systolic blood pressure >90mmHg.

Among patients treated with linezolid, 64% reached clinical stability compared with 70% of the vancomycin-treated patients (P=0.671). Mean number of days to reach clinical stability was 5.8 days (SD 3.0) for patients treated with linezolid vs. 7.2 days (SD 3.7) for patients treated with vancomycin (P=0.040).

Study investigators were able to conclude that earlier time to clinical stability was achieved for patients with ventilator-associated pneumonia due to methicillin-resistant Staphylococcus aureus when treated with linezolid compared to vancomycin.