1. Department of Anesthesiology and Critical Care Medicine, George Washington University School of Medicine and Health Sciences, Washington, D.C
2. the Department of Anesthesiology, Program in Trauma, University of Maryland School of Medicine, Baltimore, Maryland
3. the Department of Medicine, Division of Infectious Diseases, Department of Hospital Epidemiology and Infection Control, Armstrong Institute for Patient Safety and Quality, Johns Hopkins University School of Medicine, Baltimore, Maryland