Pneumonia caused by oxacillin-resistant Staphylococcus aureus treated with glycopeptides*

Abstract

OBJECTIVE: To determine whether ventilator-associated pneumonia caused by oxacillin-resistant Staphylococcus aureus (VAP-ORSA) treated with glycopeptides is associated with an increased mortality rate. DESIGN: Retrospective matched cohort study. SETTING: Four intensive care units in teaching hospitals. PATIENTS: Seventy-five patients were matched to 75 controls. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: All adult intensive care unit patients with microbiologically documented VAP-ORSA were matched to intubated controls who did not develop VAP-ORSA, based on disease severity (Acute Physiology and Chronic Health Evaluation II score) at admission (+/-3 points), diagnostic category, and length of stay before pneumonia onset. Population characteristics and intensive care unit mortality rates of patients with VAP-ORSA and their controls without pneumonia were compared. Attributable mortality was determined by subtracting the crude mortality rate of controls from the crude mortality rate of VAP-ORSA patients. Thirty-six of the 75 matched VAP-ORSA patients died, representing a crude mortality rate of 48%, whereas 19 of the 75 controls died, a crude mortality rate of 25.3% (p < .01). Excess mortality was estimated to be 22.7% (95% confidence interval, 2.4-42.9%). Median length of intensive care unit stay in the surviving pairs was 33 days (interquartile range, 25-75%: 25-45 days) for VAP-ORSA patients and 21 days (interquartile range, 25-75%: 15-34.75 days) days for controls (p = .054). CONCLUSIONS: Despite appropriate glycopeptide therapy, there is an increased attributable mortality for pneumonia by ORSA, after careful adjustment for disease severity and diagnostic category.